Applied Thermal Engineering 231 (2023) 120941

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Applied Thermal Engineering

journal homepage: www.elsevier.com/locate/apthermeng

Research Paper

Design of a space cooling plant from residual energy of ORC-GSHP assisted

geothermal power plant at Dholera, Gujarat, India
Vaishnavi Pandey, Anirbid Sircar *, Namrata Bist, Kriti Yadav, Dharmesh Morabiya
Pandit Deendayal Energy University, Gandhinagar 382007, Gujarat, India

A R T I C L E I N F O A B S T R A C T

Keywords: More than 45% of the nations around the world use geothermal energy for a wide range of direct and indirect
Space cooling applications pertaining to its stable nature. This paper explores the use of geothermal energy for the direct
Geothermal energy application of space cooling in residential and commercial applications. It introduces a low enthalpy geothermal
Ground source heat pump
energy utilizing space cooling system, a complimentary system to the Organic Rankine Cycle (ORC)-Ground
Low enthalpy geothermal energy
Source Heat Pump (GSHP) assisted geothermal power plant. The configuration of the whole system, including the
Heat exchanger
cooling, heating, and common circuits, is discussed. The main components of the space cooling system consist of
Plate Type Heat Exchanger (PHE), GSHP, Air Handling Unit (AHU), and ORC. This study also built a mathe­
matical model based on heat transfer for heat exchangers, Coefficient of Performance (COP) of heat pump, and
cooling load of the AHU. For system observation and analysis, the experimental data collected over the course of
90 days (March to May) has been used. The results show that geothermal systems can be an effective and efficient
way to cool spaces. A room temperature of 18 ℃ is achieved for an outside ambient temperature range from 19 to
46℃ in summer conditions. The system output placed GSHP’s COP from 1.6 to 4 and the AHU’s average cooling
load is 58.29 kWh with a heat exchange effectiveness rate of 0.46. The system with a few modifications can also
be utilized for space heating during winter and other direct applications during summer.

Geothermal energy is a clean source of power production. It produces

1. Introduction a very small amount of air pollutants compared to conventional fuels
[4]. But beyond energy production, geothermal energy has numerous
The World Geothermal Conference, 2020 reports that 88 nations are applications [5]. One of the most traditional methods of using
currently directly utilising geothermal energy. Today, direct geothermal geothermal energy is direct use. Stories from a Heated Earth - Our
use is present in 30 more countries than it was twenty years ago. Ac­ Geothermal Heritage which details the history of geothermal use for
cording to the geothermal energy 2020 worldwide review [1], approx­ more than 2,000 years, provides thorough documentation of the early
imately 58.8% of geothermal energy is used for geothermal (ground- history of geothermal direct use for more than 25 countries [6]. The
source) heat pumps, 18.0% is used for bathing and balneology, 16.0% is direct usage of geothermal energy can be through food drying [7], milk
used for space heating, 3.5% is used to heat greenhouses, 1.6% is used pasteurization [8], salt production [9], space heating and cooling [10],
for industrial applications, 1.3% is used to heat aquaculture ponds, 0.4% fish farming [11], greenhouse [12], snow melting [13] etc. Geothermal
is used for agricultural drying, 0.2% is used for snow melting, and 0.2% energy can be a long term alternative for both heating and cooling
is used for other applications. The amount of energy saved annually purposes as with judicial use, it can become a long term resource [14].
equates to 81.0 million tonnes of oil equivalent, preventing the emission These direct applications can have much potential in locations where
of 252.6 million tonnes of CO2 and 78.1 million tonnes of carbon into the geothermal power plants exist. Geothermal power plant locations allow
atmosphere [1]. Utilising geothermal energy might reduce CO2 emis­ for clean and sustainable direct uses of geothermal energy in addition to
sions from coal and oil, which together emit a huge 1.08 tonnes of CO2, power generation.
to roughly 0.05 tonnes, or 21 times less than fossil fuels [2]. Renewable At the moment, the amount of energy used for heating and cooling
heat-driven poly-generation systems (including geothermal energy) buildings accounts for almost 45% of all energy used worldwide [15].
have the potential to offer sustainable solutions for the supply of power, Most of the time, the need for cooling and heating, is met with renew­
air conditioning, and many other direct applications [3]. able energy [16]. Geothermal resource is amongst the most efficient and

* Corresponding author.
E-mail address: anirbid.sircar@spt.pdpu.ac.in (A. Sircar).

https://doi.org/10.1016/j.applthermaleng.2023.120941
Received 27 February 2023; Received in revised form 12 May 2023; Accepted 8 June 2023
Available online 13 June 2023
1359-4311/© 2023 Elsevier Ltd. All rights reserved.
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

geothermal power plant in Dholera, Gujarat, India. The Dholera

Nomenclature geothermal power plant was the first of its kind to be established in
Gujarat, India. Gujarat is a low enthalpy geothermal zone of India.
ORC Organic Rankine Cycle Dholera geothermal power plant was established to demonstrate the
GSHP Ground Source Heat Pump utility of low enthalpy geothermal resource in electricity production. For
AHU Air Handling Unit the same, a setup was established in Dholera. An ORC setup for elec­
PHE Plate type Heat Exchanger tricity production from geothermal resource was concluded to be the
COP Coefficient of Performance best possible way. The whole setup comprised of heat exchangers, GSHP
RCOP Relative Coefficient of Performance and ORC. The thermal output directly from the borewell was around
SONATA Son- Narmada-Tapti 42 ◦ C. So, a GSHP was introduced in the power generation loop to in­
MNRE Ministry of New and Renewable Energy crease the temperature from 42 to 70 ◦ C to cater to the ORC of design
consideration of 70 ◦ C.). GSHP was introduced as they are able to lessen
the environmental effect of space cooling and uses they use earth as heat
source [23]. The cooling needs of high-geothermal environments such as
effective sustainable energy sources in the world and is the most Dholera are satisfied by low ground temperature geothermal energy that
promising new energy solutions for space cooling [17]. The direct use is usually present in shallowly buried sections and can be extracted by
industry is dominated by the use of geothermal resources for space GSHP [24].
heating and cooling, accounting for around 37% of total direct use Dholera is a very hot place. During summer conditions, the ambient
development. Although resources can be used at temperatures as low as temperature reaches up to 47 ◦ C. So, a space cooling system was pro­
40 ◦ C in some situations, temperatures above 50 ◦ C are often needed. If posed alongside the geothermal power plant. The space cooling system
geothermal heat pumps are employed, however, space heating can be a utilizes the rejected cooled water from the GSHP to cool the Sabha­
viable alternative to traditional forms of heating at temperatures mandap (meeting hall) of the Dholera Swaminarayan Temple.
considerably below 10 ◦ C. Multiple users can receive space heating and/ The demonstrated space cooling system is established for the first
or cooling from a single well, or from a number of wells or fields, using time in Gujarat, India. It is a sustainable and pollution free system. The
district cooling networks. Over 75% of all space heating and/or cooling cooling doesn’t use any harmful refrigerant that may lead to air pollu­
generated from geothermal resources globally is now delivered via tion. The space cooling system demonstrates a way to utilize cooled
geothermal district heating, which was pioneered by Icelanders and has water that might have gone to waste in any other case. All geothermal
been one of the fastest expanding parts of the geothermal space heating resources in Gujarat, India are present in extremely hot places. Thus, for
business. However, Iceland has been a pioneer in the development of hot places like Gujarat in India alongside energy generation from
geothermal district heating systems, and as of today, more than 97% of geothermal energy, if space cooling systems as demonstrated are
residents of the capital city of Reykjavik and more than 90% of the entire established, they will act as a natural cooling solution.
Icelandic population can rely on geothermal district heating to meet A detailed description of the space cooling system comprising heat
their space heating and domestic hot water heating requirements [18]. exchangers, GSHP, AHU are described in this study. The cooling side of
With a total installed thermal capacity of 54.64 MWt, Algeria is the top the GSHP is utilized to provide low temperature air to the designated
user of geothermal energy in Africa and among first five countries to cooling space of Sabhamandap (Meeting Hall) of Swaminarayan temple
have an air conditioning utilization [19]. Several other nations, like located in Dholera. The system is observed over a period of 90 days of
Hungary, Romania, France, Poland, China, even Sweden and Denmark, summer in India (March to May) and the observations of the heat pump
to name a few, have either created or are creating geothermal district outlet on heating and cooling side, AHU temperature of Sabhamandap
heating systems. Geothermal energy will likely be used for space cooling and Suction and discharge temperature of Sabhamandap are assessed
more frequently as a result of rising demand, recent technology ad­ with respect to efficiency. The system output shows the COP of GSHP
vancements, expanding research into low temperature absorption ranged between 1.6 and 4 depending on the temperature input and
cooling, and other factors. output. The cooling COP ranges from The average cooling load of AHU is
India, may not have been blessed with extreme abundance of calculated to be 58.29 kWh and has provided cooling for a 450 sq. ft.
geothermal energy, but is present densely in four zones namely Hima­ area and a temperature of 18 ◦ C is achieved with 13.30% uncertainty.
layan region, Godwana grabens, SONATA lineament and west coast of
India. Extensive exploration of decades puts India under low to medium 2. Study area: geothermal prospect at dholera
to low enthalpy zone for geothermal energy. Yet, the use of geothermal
energy in India still has been very limited, and even very less is known Based on the geological features of India and heat flows/geothermal
about low enthalpy utilization of geothermal energy in India [20]. gradients predicted from the thermal springs in various provinces, seven
Countries worldwide like Iceland, Turkey, France have decades of geothermal provinces have been discovered. These include the Hima­
experimental data and setup to optimize and improve the applications of layan Geothermal Province, the Sohana Geothermal Province, the West
geothermal energy. India lacks behind here. Even though India has Coast Geothermal Province, the Gujarat-Rajasthan Geothermal Prov­
ample exploration data, exploitation of geothermal resource is still in the ince, the Godavari Geothermal Province, the Mahanadi Geothermal
beginning stage. Geothermal field research and exploration in India first Province, and the SONATA Geothermal Province. One of the substantial
began in 1970. There are 350 or more geothermal energy locations in graben on the Indian Peninsula is the western geothermal province. The
India, according to the Geological Survey of India [20]. The majority of world’s most active volcanic eruptions are linked to anomalous conti­
India’s geothermal resources may be seen on the surface as geysers and nental boundaries. This region, known as the thermal anomaly of the
hot springs that range in temperature from 32 to 97 ◦ C [21]. The study west coast, has a significant heat flux [25]. One of the primary oil and
area of the paper, Gujarat, India, has several low-temperature gas producing zones in India is the Cambay region, which has Tertiary
geothermal resources, and the potential for direct-use applications is sediment layers above straightforward lava flows. By drilling numerous
enormous. An extensive geophysical survey has identified over 17 deep wells, the basin is intensively investigated. In the northern section
potentially exploitable hotspots in Gujarat, with temperatures ranging of the graben, where temperature gradients in certain zones exceed
from 40 to 75 ◦ C [22]. 70 ◦ C/km, there is a high level of heat distribution [26]. At a depth of 3
This paper presents a space cooling system, a complementary system km, the steam discharge rate was roughly 125 m3/hr, and in situ tem­
to the ORC-GSHP assisted geothermal power plant for utilization of low peratures have been recorded as high as 175 ± 25 ◦ C [17].
enthalpy geothermal energy. The space cooling system runs alongside a An old port city in Gujarat called Dholera is 60 km away from the

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V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

main city of Bhavnagar. The coastal town of Dholera is located in an important role in power production, the higher flow rate of the wells
Gujarat’s Ahmedabad district as shown in Fig. 1. One of the historic port is beneficial. The tubular and hole diameter of drilled wells are 0.2032 m
cities on the Gulf of Khambhat is the Dholera Geothermal Field [28]. It is and 0.4572 m respectively.
bordered by water on three sides: the Gulf of Khambhat to the east,
Sonaria Creek to the south, and Bavaliari Creek to the north [29]. On the 3. System description of geothermal space cooling system
western edge of the Saurashtra Peninsula, close to the Western Marginal
fault of the Cambay Basin, are the Dholera thermal springs [30]. Dholera 3.1. Working principle
thermal springs are located along the edge of the Saurashtra Peninsula in
the area of the West shoreline, including west of the West Marginal fault Systems that harness geothermal energy are known as geothermal
in the Cambay Basin. Dholera’s sediment cover is roughly 500–600 m. systems. Geothermal heating and cooling systems offer heating, cooling,
The geothermal hot springs of Dholera date back more than a century. and humidity regulation for specified enclosed spaces. Geothermal
Dholera soil base is in the order Aluvium, Mixture of Clay, sand and Silt based heating and cooling systems use heat energy from the ground,
and mixture of coal, sand and silt. rather than conventional power i.e. burning coal to generate heat, and
Dholera is a relatively warm place. During summers the temperature thus are eco-friendly. There are three main components in every
can go as high as 47 ◦ C. he temperature range at Dholera, Gujarat India geothermal space conditioning system:
can go from as low as 10 ◦ C and as high as 47 ◦ C. The temperature ranges 1. A technology that enables the extraction of heat from the
for Dholera for each month of 2021 are shown in Fig. 2 [31]. During subsurface.
winters, December, January, and February the temperature ranges from 2. A geothermal heat pump to transfer heat from the subsurface to
a minimum of 9 ◦ C to a maximum of 39 ◦ C. During summers, April, May, the structure.
and June, the maximum temperature rises up to 47 ◦ C. 3. A distribution system that supplies the structure with required
As geothermal energy is already being used in Dholera to run the orc space conditioning.
assisted geothermal power plant, more direct uses can be placed for At Dholera, the GSHP provides the basis for the geothermal energy
better utilization of the geothermal energy. Due to the low enthalpy based space cooling system. GSHP is an instrument, which can be used to
resource present at Dholera, a GSHP is used to increase the temperature extract energy from even a low enthalpy reservoir, like the one present
of geothermal water to make it in accordance with the design constraints at Dholera. The GSHP is a device that can provide both heating and
of the ORC. The GSHP has two sides, cooling and heating. The cooling cooling simultaneously while using geothermal energy as a source. The
side of the GSHP has a temperature of up to 18 ◦ C and is utilized to cool GSHP consists mainly of 4 components that are, Condenser, Evaporator,
the Sabhamandap during summers. Expansion Valve, and Compressor.
Shallow wells have been drilled at Dholera and other nearby villages The Space Cooling System utilizes the cooling side of the heat pump,
for domestic usage and irrigation [32]. The geothermal water at Dholera and the output from the evaporator to provide space cooling at Dholera
has a temperature range of 42–47 ◦ C. Three production wells in Dholera Swaminarayan Temple’s Sabha Mandap (Assembly Hall). The higher
have been drilled in order to exploit the geothermal resource present temperature output water from the GSHP’s heating system is used as an
there. The temperature of the wells ranges from 42 to 47 ◦ C. The char­ input source for the ORC, for power generation. The geothermal power
acteristics of the wells are shown in Table 1. Three wells have been plant set up to generate electricity is providing an additional benefit of
drilled up to a depth of 320 m. The surface water temperature range at space cooling.
Dholera is between 42 and 47 ◦ C and the gradient of the subsurface A basic GSHP works on two different sides, a cooling side, and a
temperature increases 3.5 ◦ C for every 100 m. The flow rate of the wells heating side. The cooling side of the GSHP is based on the Evaporator
at the surface is found to be between 18 to 43 m3/hr. As flow rate plays and the heating side is based on a condenser.

Fig. 1. Study area of Dholera, Gujarat, India (Source: Google Maps) [27].

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V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 2. Ambient temperature of Dholera over the year of 2021acquired by Accuweather webiste [31].

In the cooling side, the evaporator, which is the major component of

Table 1
the heat pump’s cold side, cools water by expanding the refrigerant
Description of three production wells used for the space cooling system located
(R134a). AHU loop and geothermal loop are the two operational loops
at Dholera, Gujarat, India.
for cold. In the geothermal loop, on one side of the PHE, high temper­
Parameters Well 1 Well 2 Well 3
ature geothermal water (45 ◦ C) is passed. Low temperature water from
Depth (m) 320 m 320 m 320 m the heat pump passes through the plates for heat exchange. The cooling
Water Up to 47 ◦ C Up to 47 ◦ C Up to 47 ◦ C side of the heat exchanger will absorb the heat energy of the geothermal
temperature
(◦ C)
water. Geothermal water’s temperature will decrease as a result of heat
Water flow 18 m3/hr 14.4 m3/hr 43.2 m3/hr transfer, and it will be used for a variety of purposes. The second loop is
rate the AHU loop. In the AHU loop, fresh water at 30 ◦ C enters the evapo­
Tubular 0.2032 m 0.2032 m 0.2032 m rator and is cooled down to almost 18 ◦ C. This low temperature water is
diameter
passed on to the coils of the AHU. Air from the Sabhamandap is passed
Hole diameter 0.4572 m 0.4572 m 0.4572 m
Casing Sealing Cement Sealing Cement Sealing Cement Sealing through the coils, where heat is exchanged. The normal temperature air
Casing Type 8 Inch (0.2032 m) 8 Inch (0.2032 m) 8 Inch (0.2032 m) from the Sabhamandap gets chilled, as the heat is absorbed by the low
Standard ISI MS Standard ISI MS Standard ISI MS temperature water. The elevated temperature water is again transferred
Casing and Casing and Casing and back to the heat pump. The AHU loop is a closed loop.
strainer strainer strainer
On the heating side, continuous circulation of fresh water takes
Strainer MS Strainer with 2 MS Strainer with 2 MS Strainer with 2
in. (0.0508 m) in. (0.0508 m) in. (0.0508 m) place. As the water moves through the heat pump’s condenser, its
grinder cuts grinder cuts grinder cuts temperature rises. Water temperature increases as a result of R134a
Casing Joints Welding Joint with Welding Joint with Welding Joint with (refrigerant) in the condenser absorbing heat energy. Higher tempera­
3.5 mm (0.0035 3.5 mm (0.0035 3.5 mm (0.0035
ture water can be used for electricity generation by ORC. PHE uses water
m) welding rod m) welding rod m) welding rod
circulation to regulate the hot side’s temperature (70 ◦ C). Water from a
storage tank (5000 L) is passed through PHE-2 on one side, where it

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V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

absorbed heat energy from water that was hot on the other side of the
device. This procedure aids in regulating the heat pump’s hot side’s
temperature.

3.2. Components

3.2.1. Plate type heat exchanger (PHE)

A heat exchanger is a tool that enables the transfer of heat between
two fluids that are at various temperatures [33]. Fig. 3 shows a Sche­
matic diagram of a Heat Exchanger. Heat exchangers primarily can be
divided into two categories on the basis of the medium of heat exchange.
Direct heat exchange, takes place when the two mediums come into
direct touch, and indirect heat transfer occurs through a partitioned
medium. A PHE transfers heat between two fluids using metal plates.
The PHE uses two separate fluids with two different temperatures; one
passes through the inner plates while the other through the outer plates
[34]. One fluid is heated by the other. In comparison to a conventional Fig. 4. Pinch Point analysis for PHE 1.
heat exchanger, PHE has a considerable advantage since the fluids are
exposed to a much wider surface area because they are distributed energy required, which is important for the energy transition [38].
uniformly over the plates. PHE has a specialised design of brazen plates GSHP has four major parts. Compressor, Expansion valve, Condenser,
that works well for transferring heat between fluids with medium and and Evaporator [39]. Fig. 6 and Fig. 7 show the working cycle of a heat
low pressures. pump and GSHP installed at the Dholera Geothermal Power Plant
Two plate types of heat exchangers are used in the Dholera space respectively.
cooling system as shown in Fig. 5. First PHE uses two fluids, higher
temperature water coming from the geothermal well and lower tem­ 3.2.2.1. The evaporator. An evaporator is a heat exchanger where the
perature water coming from the evaporator of the heat pump. The refrigerant enters as a liquid and exits as a low-temperature vapour after
design temperature of the PHE is 60 ◦ C and the pressure is 10 bar. The absorbing heat from the heat source through evaporation. Alfa Laval
heat transfer area between the plates is 2.52 m2. The pinch point is Heat exchangers is used in the GSHP. The expansion valve and com­
calculated as shown in Table 2 for PHE 1 to get a clear idea about pinch pressor’s suction force convert the refrigerant from a liquid to a gas.
point difference for geothermal well. Fig. 4 shows the pinch point
analysis for PHE 1. 3.2.2.2. The condenser. A high-temperature liquid emerges from the
The second PHE exchanges heat between high temperature water condenser after the refrigerant enters as a high-temperature vapour. The
from the condenser and lower temperature water from the storage tank. condenser fan then blows air over the coils to aid in heat transmission. In
The design temperature of the PHE is 90 ◦ C and the pressure is 10 bar. this instance, pressure is used to drive the refrigerant across the coils.
The heat transfer area of the PHE is 2.5 m2. Kelvion Condensers are used in GSHP. It is often composed of copper
tubing with aluminium fins or all-aluminum tubing to quickly conduct
3.2.2. Ground source heat pump (GSHP) heat.
The use of GSHP for space heating and cooling is widely prevalent.
GSHP focus on the heat that already exists in the subsurface. The GSHP 3.2.2.3. The compressor. The GSHP operates on a single compressor.
uses heat that has been stored in the ground or in groundwater [35]. The The type of the compressor used in the system was Copeland Compressor
temperature at 30 feet beneath the surface is fairly stable throughout the ZR380KCE-TWD-523. The technical specification for the compressor at
year. These stable subsurface temperatures are used by geothermal heat 50–60 Hz is given 380–420 voltage and the overall dimension is 427 ×
pumps to effectively exchange heat, cooling places in the summer and 447 × 724 mm (W × L × H) weighing 177 kg. The power utilized by the
heating them in the winter. The GSHP is a very effective heating and compressor is 30 HP and 81.7 kW. Compressor operated within the
cooling system with an average COP of three to five [36]. GSHPs are a pressure range 200 to 2000 kPa.
promising technology for helping to decarbonize the energy industry
[37]. When used holistically GSHP can significantly lower the amount of

Fig. 3. Schematic diagram of a Heat Exchanger.

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V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 5. The PHE on the left side is the first heat exchanger where heat is exchanged between geothermal water and water from Evaporator. The PHE on the right side
is the second heat exchanger where heat is exchanged between water from the conductor and water from the storage tank.

Table 2
Data for pinch point analysis for PHE 1.
Name of Supply Target Cp (water) ΔH
Stream Temp Temp

Hot 43 ◦ C 32 ◦ C 4.18 kJ/kg. 45.98 kJ/

◦
C kg

Cold 20 ◦ C 25 ◦ C 4.18 kJ/kg. 20.9 kJ/kg

◦
C

Fig. 6. Schematic diagram of Heat pump and its four components: (a) evapo­
rator (b) compressor (c) condenser and (d) expansion valve.
Fig. 7. GSHP installed at the Dholera Geothermal Power Plant.

3.2.2.4. Expansion valve. The expansion valve with inner diameter 4

mm, modifies the pressure and temperature for the heat pump, trans­ the evaporator.
ports the high-pressure coolant fluid from the condenser. Expansion Refrigerant R134a is utilized in the GSHP. The refrigerant R134a was
valves maintain the pressure differential between the condenser and the chosen as it exhibits best performance in GSHP. R134a refrigerant is
evaporator in addition to regulating the amount of refrigerant entering chosen pertaining to its favourable safety factors, including its non-toxic

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V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

and non-flammable characteristics [40].

The PH and TS diagram for the GSHP is calculated as shown in Fig. 8
and Fig. 9. The refrigerant R134a’s pressure range 200 kPa to 200 kPa in
the GSHP. For the same temperature and pressure range, PH and TS
diagrams are created. The points in yellow denote the working pressure
range and the predicted model is showcased in red.
The pinch point is calculated for Evaporator and Condenser as shown
in Fig. 11 and Fig. 12 to get an idea about pinch point difference. Table 3
shows the pinch point calculations for the evaporator and condenser.
Fig. 10 shows the Supply and Target Temperature of Evaporator and
condenser.

3.2.3. Air Handling unit (AHU)

Within the building, the air is circulated with the help of air handling
devices. Fresh outdoor ambient air is taken in, cleaned, and cooled, and
Fig. 9. Pressure vs. Enthalpy diagram for R134a refrigerant in the GSHP cycle.
then is passed through pipework structured to take air to the designated
regions inside the building. A second duct is available to transport used,
unclean air from the rooms to the AHU, where a blower will exhaust it
back into the atmosphere [41]. The AHU manages many additional tasks
besides ventilation like control of air quality, temperature, and relative
humidity.
The AHU used in the system consists of an inlet damper, pre-filter,
bag filter, cooling coil/ heating coil, blower, and outlet damper as
shown in Fig. 13.
At the start, there are inlet dampers. These help in the intake of fresh
air by restricting the amount of air intake. After dampers there are fil­
ters. They filter out the dust particles about to enter the machine. If
filters are not present, the dust can choke the machine parts and also can
be harmful to the occupants present in the room. After filters, there are
heating/ cooling coils. These coils heat or cool the air according to the Fig. 10. Supply and Target Temperature of GSHP Evaporator and condenser.
requirement. These maintain the temperature and make sure the tem­
perature is according to the comfort level of occupants. The heating and
cooling coils are basically heat exchangers. After coils, the next
component is the blower. This will draw air in from the outside, pass it
through coils, filters, and dampers, and then push it out into the duct­
work that is placed wherever it is required around the structure. The
ducting transports the air throughout the building to the designated
places. Fig. 14 shows the AHU installed at Dholera with its components,
Inlet Damper, Filters, Cooling Coils, and Blower.

3.2.4. Organic Rankine cycle (ORC)

A thermodynamic cycle called the Rankine Cycle turns heat into
work. Heat is supplied to a closed loop that typically employs water as its
working fluid receives heat from the source [42]. Around 85% of the
world’s electricity is produced by Rankine Cycle. The ORC doesn’t use
water to make steam; instead, it vaporises an organic fluid with a mo­
lecular mass greater than that of water. The ORC operates on the same
Fig. 11. Pinch Point analysis for GSHP Condenser.

principles as the Rankine cycle: the working fluid is sent to a boiler,

where it gets evaporated, after that it is moved via an expander and then
transferred to a condenser heat exchanger, where it is ultimately
condensed again. Fig. 15 shows the working of a basic ORC.
In the ORC, a high pressure gas enters the turbine, where mechanical
energy is recovered by the high pressure gas regulated expansion and
transferred as electrical energy by way of an electrical generator. As a
result of heat being rejected from the working fluid, a low pressure
vapour leaves the turbine and enters the condenser, where condensation
takes place. The working fluid exits the condenser as a low pressure sub
cooled liquid. The pressure of the liquid is then increased by a pump and
fed to the evaporator. A geothermal heat source is used to extract heat
for preheating the evaporator and superheating the working fluid. After
that, the high pressure liquid is transformed into high pressure vapour
and prepared to reenter the turbine.
Fig. 8. Temperature vs. Entropy diagram for R134a refrigerant in the
Geothermal heat sources mainly have varying temperature. The
GSHP cycle.

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V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

mentioned components as numbered in Fig. 16.

1. Well side
2. Storage Tank (5000 L)
3. PHE-1
4. GSHP
5. PHE-2
6. AHU
7. ORC
8. 5 HP Pump (Cooling Side)
9. 7.5 HP Circulation Pump
10. 5 HP Pump (Heating Side)

and Flow Control Valves ( ) and 3 way valves ( ).

For the working of the system, 2 different types of valves are used as
Fig. 12. Pinch Point analysis for GSHP Evaporator. shown in Fig. 19. These valves monitor the flow of fluid. A three way
valve and Flow control valve. The three way valves are used to control
varying ranges of temperature in the system. Flow control valves are
Table 3
used on both the heating and cooling side of the heating pump to control
Data for pinch point analysis for GSHP evaporator and condenser.
the flow of water to and from heat exchangers. Two 5 HP pumps are
Name of Supply Target Cp (R134a) ΔH placed in the heating and cooling side of the heat pump to supply water
Stream Temp Temp
to the condenser bad evaporator. Both the pumps are connected with a 3
Condenser way valve to manage the flow. A 7.5 HP circulation pump is placed
Hot 67.5 ◦ C 56.5 ◦ C 1.4452 kJ/kg. 15.8972 kJ/
between the storage tank and the heat exchanger to circulate the water
◦
C kg
from the source to the system. The pumps installed at the site are shown
Cold 25 ◦ C 30 ◦ C 4.18 kJ/(kg) 20.9 kJ/kg in Fig. 18. In the ORC system, a 7.5 HP pump is placed before the cooling
(◦ C) tower for supply from the cooling tower to the condenser. There are
various locations throughout the system where temperature and pres­
Evaporator sure gauges are placed to continuously monitor the parameters of the
Hot 25 ◦ C 18 ◦ C 4.18 kJ/kg. ◦ C 29.26 kJ/kg system. Temperature gauges of temperature range, 0–100 ◦ C is used in
the system and pressure gauges with a pressure range of 0–20 bar as
Cold − 8.85 C ◦
− 5 C
◦
0.8527 kJ/(kg) 3.28 kJ/kg
(◦ C)
shown Fig. 17.
The parameter of the instruments are provided in Table 4.
The space cooling system is installed in the Sabhamandap of Dholera
Temperature range of geothermal water at Dholera is between 45 and Swaminarayan temple. The space cooling system run as a supplementary
50 ◦ C. ORC is adapted for low temperature potential resources for power system to Dholera Geothermal 20 MW power plant. The power plant
generation. Water enters the hot loop in the Dholera ORC power pro­ runs on a supply from three wells. From the three wells, an average of
duction process at 70 ◦ C, where it exchanges heat, and departs at 69.5 ◦ C 43 ◦ C temperature is supplied to the system. The system uses an ORC of
and 3.38 Bar of pressure. The turbine is powered by the heat source’s 70 ◦ C design condition. For reaching the said design condition, the
output, which exits at 60.99 ◦ C and 1.9 bar of low pressure. This low geothermal water is transferred through a heat pump. The heat pump on
pressure water is directed to the cooling loop of the system, in which it the heating side rises the temperature to 70 ◦ C and on the cooling side,
cools to a value of 19.18 ◦ C, maintaining the energy balance between reaches a temperature of 18 to 20 ◦ C. The cooling side of the heat pump
mass and heat transfer. In order to exchange heat, the feed pump is utilized as an inlet for space cooling unit. An AHU is placed in the
transports the cold loop’s output to the hot loop. Sabhamandap to control the air quality and temperature. The placement
of vents are shown in Fig. 20.
3.3. System layout The setup of the space cooling system in the Sabhamandap is shown
as below. The Sabhamandap dimensions are 30x15x10 m3. There are six
The detailed system layout for providing cooling in the Sabha­ suction vents through which air inside the Sabhamandap is sent to AHU.
mandap is shown in Fig. 16. When the fluid is active in the heating There are several discharge vents through which the cooled air circu­
mode, the red line symbolises it, and when the fluid is active in the lates in the Sabhamandap.
cooling mode, the blue line does. At all times, the Sabhamandap can
receive cooling from the system. The system contains the following

Fig. 13. Schematic diagram of AHU.

8
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 14. AHU with its components (a) Inlet Damper (b) Filters (c) Cooling Coils and (d) Blower.

Fig. 15. Schematic Diagram of Organic Rankine Cycle with its components (a) Evaporator (b) Condenser (c) Pump (d) Turbine (e) Generator(f) Cooling Tower.

9
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 16. Schematic diagram of space cooling plant in Dholera, Gujarat showing Heat Exchanger units, GSHP, and ORC.

Fig. 17. (a) Pressure Gauge (b) Temperature Gauge installed before and after GSHP for continuous pressure and temperature detection.

4. Mathematical modelling ( )
T1g − T2f − (T2g − T1f )
ΔTm = (2)
The mathematical model of the space cooling system’s components (T1g − T2f )
ln (T2g − T1f )
has been developed.
Where:[44].
4.1. Heat exchanger T1g = Inlet fluid 1 (geothermal water) temperature.
T2g = Outlet fluid 1(geothermal water) temperature.
In a plate heat exchanger, the total rate of heat transfer between the T1f = Inlet fluid 2 (fresh water) temperature.
hot and cold fluids can be expressed by the main basic heat exchanger T2f = Outlet fluid 2 (fresh water) temperature.
equation as shown in Equation (1), Measured data on fluid flow rates and temperatures, one can deter­
mine the heat transfer rate, Q. Based on the fluids used, the log mean
Q = U × A × ΔTm (1) temperature differential, ΔTm, and the overall heat transfer coefficient,
Where, [43]. U, are determined.
Q = Heat transfer rate (W). In this study,
A = Heat transfer area (m2). For Heat Exchanger 1 (HE1), the overall heat transfer rate can be
U = Overall heat transfer coefficient (W/(m2 ◦ C)). calculated using Equation (3),
ΔTm = Logarithmic mean temperature difference (◦ C). QHE1 = UHE1 × AHE1 × ΔTm(HE1) (3)
The log mean temperature difference can be calculated as shown in
Equation (2), Where,
UHE1 = Overall heat transfer coefficient for heat exchanger 1(kJ/h.

10
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 18. (a) A 7.5 HP circulation pump placed between storage tank and the heat exchanger (b) Two 5 HP pumps placed on the heating and cooling side of the heat
pump (c) A 7.5 HP pump placed between cooling tower and condenser (d) Pumps installed at the well side.

Fig. 19. (a) 3 way valve to control varying temperature(b) Flow control valve on the cooling side of heat pump (c) Flow control valve on the heating side of
heat pump.

11
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Table 4 ΔTm (HE1) = 14.798 ◦ C, AHE1 = 2.52 m2.

Instruments table. So, Overall Heat Transfer Coefficient (UHE1) calculated with Equa­
Instruments Parameters tion (5) is.
UHE1 = 201.159 kJ/h.m2. ◦ C.
Temperature Gauge Accuracy: CL 1.0 (Class 1)
Sensing element: Coiled bimetal strip Using equation (3),
Stem material: 316 Stainless steel Where,
Ranges: 0 to 100 ◦ C UHE2 = 201.159 kJ/h.m2. ◦ C.
Weather protection: IP65 AHE2 = 2.52 m2.
Stem length: 25 to 1500 mm
Pressure Gauge Accuracy: 1,6% – EN837-1
Thus, the value of QHE1 = 7501.412 kJ/ h.
Process connection material: 316L Stainless QHE1 = 2.083 kW.
steel Thus, the overall heat transfer for Heat Exchanger 1(HE1) is 2.083
Element material: 316L Stainless steel kW.
Pressure ranges: 0–300 psi
The effectiveness of heat exchanger can be defined as shown in
Weather protection:IP54 / IP65
Circulation Pump Motor Phase: Three Phase Equation (6), [46]
Power Source: Electric ( )( )]
Motor Horsepower: 7.5 HP 1 − exp[ − KUA 1 + KKmax
min

(6)
min
Current: 8.3 amps ∈=
(1 + KKmax
min
)
Speed: 2820 rpm
Heating Side/Cooling Side Motor Phase: Three Phase
Where K = m × Cp,
Pump Power Source: Electric
Motor Horsepower: 5 HP The values of the parameters are, m = 360 kg/hr and Cp = 4.18. As,
Current: 6.7 amps both fluids for heat exchange are same, Kmin = Kmax. So, K = 1504.8 kJ/
Speed: 2855 rpm h. ◦ C.
The equation can be rewritten for heat exchanger 1 as Equation (7),
m2. ◦ C).
( )
1 − exp[ − UHE1 K×AHE1 (2)]
AHE1 = Area of heat exchanger 1 (m2). ∈= (7)
(2)
Logarithmic Mean Temperature Difference can be calculated as
shown in Equation (4), ∈= 0.245
( ) ( )
T1g(HE1) − T2f (HE1) − T2g(HE1) − T1f (HE1) Similarly for Heat Exchanger 2 (HE2), the overall heat transfer rate
ΔTm(HE1) = (4)
(T − T ) can be calculated using Equation (8),
ln T1g(HE1) − T2f (HE1)
( 2g(HE1) 1f (HE1) )
QHE2 = UHE2 × AHE2 × ΔTm(HE2) (8)
ΔTm(HE1) = 14.798℃.
Where, T1g (HE1) = 43 ◦ C, T2g (HE1) = 32 ◦ C, T1f (HE1) = 20 ◦ C and T2f Where,
UHE2 = Overall heat transfer coefficient for heat exchanger 2(kJ/h.
(HE1) = 25 C.
◦

Overall heat transfer coefficient can be calculated as show in equa­ m2. ◦ C).
tion (5), AHE2 = Area of heat exchanger 1 (m2).
And Logarithmic Mean Temperature Difference can be calculated as
UHE1 =
V × ρ × Cp × ΔTHE1
(5) shown in Equation (9),
ΔTm(HE1) × AHE1 ( ) ( )
T1g(HE2) − T2f (HE2) − T2g(HE2) − T1f (HE2)
Where, [45]. ΔTm(HE2) = (9)
(T − T )
UHE1 = Overall heat transfer coefficient (kJ/h.m2. ◦ C), V = Flow rate ln T1g(HE2) − T2f (HE2)
( 2g(HE2) 1f (HE2) )
(m3/h), ρ = Density (kg/m3), Cp = Specific Heat (kJ/kg. ◦ C), ΔTHE1 =
ΔTm(HE2) = 7.21℃.
Temperature change (◦ C), ΔTm (HE1) = Logarithmic mean temperature
difference (◦ C), AHE1 = Heat transfer area (m2). Where, T1g (HE2) = 50 ◦ C, T2g (HE2) = 35 ◦ C, T1f (HE2) = 30 ◦ C and T2f
(HE2) = 40 C.
◦
The values of above mentioned parameter are,
V = 0.36 m3/h, ρ = 997 kg/m3, Cp = 4.18 kJ/kg. ◦ C, ΔTHE1 = 5 ◦ C, The overall coefficient of heat transfer can be determined as shown

Fig. 20. The setup of the Space Cooling System at the Sabhamandap (Meeting Hall) in Dholera, Gujarat, India.

12
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

in Equation (10), • QC greater than 0 is the heat added to the system after being taken
from the cold reservoir;
V × ρ × Cp × ΔTHE2
UHE2 = (10) • QH < 0 is the heat transferred into the heated reservoir; as a result,
ΔTm(HE2) × AHE2
the system loses it and the result is negative.
Where,
UHE2 = Overall heat transfer coefficient (kJ/h.m2. ◦ C), V = Flow rate The COP of a heat pump is influenced by its direction. More heat is
(m3/h), ρ = Density (kg/m3), Cp = Specific Heat (kJ/kg. ◦ C), ΔTHE2 = lost to the hot sink than is taken in from the cold source. Thus, as
Temperature change (◦ C), ΔTm (HE2) = Logarithmic mean temperature Equation (18) demonstrates, the heating COP is one greater than the
difference (◦ C), AHE2 = Heat transfer area (m2). cooling COP,
The values of above mentioned parameter are,
COPheating = COPcooling + 1 (18)
V = 0.36 m3/h, ρ = 997 kg/m3, Cp = 4.18 kJ/kg. ◦ C, ΔTHE1 = 10 ◦ C,
ΔTm (HE1) = 7.21 ◦ C, AHE1 = 2.5 m2. The COP can also be stated in terms of temperatures for heat pumps.
So, The overall Heat Transfer Coefficient (UHE2) calculated with The COP cooling can be calculated as shown in Equation (19), [48]
Equation (10) is,
TLT
UHE2 = 832.33 kJ/h.m2. ◦ C. COPcooling = (19)
THT − TLT
Using equation (8),
Where, Where,
UHE2 = 832.33 kJ/h.m2. ◦ C. THT is the higher available temperature,
AHE2 = 2.5 m2. TLT is the lower desired temperature,
Thus, the value of QHE2 = 15002.74 kJ/ h. And COP heating can be calculated as shown in Equation (20), [48]
QHE2 = 4.167 kW. THT
Thus, the overall heat transfer for Heat Exchanger 2(HE2) is 4.167 COPheating = (20)
THT − TLT
kW.
The effectiveness of heat exchanger 2 can be defined as Equation Where,
(11), THT is the higher required temperature,
( ) TLT is the lower input temperature,
1 − exp[ − UHE2 K×AHE2 (2)] COP of the heat pump can be calculated as COP heating, where THT,
∈= (11)
(2) the higher required temperature is Heat Pump Outlet (Heating Side) and
TLT, the lower input temperature is Heat Pump Inlet (Cooling Side). The
∈= 0.4685 higher temperature, ranges from 38 ◦ C to 70 ◦ C and the lower temper­
ature ranges from 24 ◦ C to 30 ◦ C. Thus, COP of the Heat Pump varies
from 1.65 to 4 depending upon varying temperature input and output.
4.2. Ground source heat pump (GSHP)
Similarly, COP cooling is calculated to determine the performance of
cooing. Where, THT, the higher available temperature is Heat pump inlet
The vapour - compression cycle is used by GSHP. The COP which
(cooling side) and TLT, the lower desired temperature is Heat Pump
refers to the ratio of heat produced to work given at the compressor side,
Outlet (cooling side). The higher temperature, ranges from 24 ◦ C to
is used to assess a heat pump’s efficiency.
30 ◦ C and the lower temperature ranges from 17 to 20.2 ◦ C. Thus, COP of
The COP can be calculated by Equation (12), [47]
the Heat Pump varies from 1.42 to 4.55 depending upon varying tem­
Q perature input and output.
COP = (12)
Wnet The actual COP cooling is calculated on the basis of the electrical
consumption of the pump.
Where,
The actual COP can be calculated as,
Q is the useful heat.
Wnet is the net work done on the considered system. Q
ActualCOP =
The first law of thermodynamics is used to determine the COP of the ElectricalPowerconsumption
heat pump as shown in Equations (13), 14 and 15.
Where Q is the heat extracted from evaporator. The measured value
Wnet + Qc + QH = Δcycle U = 0 (13) of it is give in Appendix Part E. On the basis of Electrical power con­
sumption of the pump of 40Kw, the actual COP varies from 0.47 to 1.25.
And,
The %RCOP is varies from 10.32 % to 88.52% depending upon the
|QH | = − QH (14) temperature input and output.

So,
4.3. Air handling unit
DesiredOutput HeatingEffect |QH |
COP = = = (15)
RequiredInput WorkInput Wnet The cooling load for cooling the specified area through the AHU can
be calculated through the total transmission load. Equation (16) can be
For cooling, the COP is the ratio of the heat taken up from the cold
used to calculate the heat load. [49]
reservoir to input work as shown in Equation (16). However, the COP for
heating is the ratio of the amount of heat emitted into the hot reservoir Q = U × A × (Tout − Tin ) × n (21)
to the input work (which is the sum of the heat absorbed from the cold
reservoir and the input work) as shown in Equation (17). Where,
Q = Total cooling Load in kWh
|Qc | U = the overall heat transfer coefficient in W/m2. ◦ C
COPcooling = (16)
W A = Surface Area in m2
Tout = The ambient external air temperature (◦ C)
|QH | Tin = The air temperature inside the room (◦ C)
COPheating = (17)
W n = No. of hours in a day system in working
Where, The overall heat transfer coefficient vary with different surfaces.

13
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

So, for walls it can be calculated as per Equation (22), [49] Sabhamandap. The average cooling load calculation for 24 h has turned
out to be 58.296 kWh.
Qwall = Uwall × Awall × (Tout − Tin ) × n (22)
Where, 4.4. Organic Rankine cycle
Uwall = the heat transfer coefficient of wall (W/m2.K).
Awall = surface area of walls (m2). The efficiency of Organic Rankine Cycle is calculated. [50]
For roof it can be calculated as per Equation (23), [49]
Wout − Win
Efficiency = (26)
Qroof = Uroof × Aroof × (Tout − Tin ) × n (23) Qin

Uroof = the heat transfer coefficient of roof (W/m2.K). Wout = Work done by turbine = 20 kW.
Aroof = surface area of roof (m2). Win = Power consumed by Pump = 3.7285 + 5.59275 = 9.32125 kW
For floor it can be calculated as per Equation (24), [49] [50]

Qfloor = Ufloor × Afloor × (Tout − Tin ) × n (24) Qin = m × Cp × ΔT (27)

Ufloor = the heat transfer coefficient of floor (W/m2.K). Where,

Afloor = surface area of floor (m2). m = mass flow rate = 0.8 to 1.5 kg/s,
The total cooling load can be calculated as shown in Equation (25), Cp = Specific heat of R245fa (Refrigerant) = 1.3732,
[49] Tin = Evaporator Temperature Inlet = 30–70 ◦ C.
Tout = Evaporator Temperature Outlet = 20–60 ◦ C.
Q = Qwall + Qroof + Qfloor (25) as measured, the ΔT remains constant, so lowermost temperature
In this study, condition is taken,
The AHU is cooling the Sabhamandap (meeting hall) of the Dholera From Eq. (27), the efficiency is calculated to be,
Swaminarayan Temple. The dimensions of the Sabhamandap are Tin Tout m Cp (kJ/ Qin Wout Win Efficiency
30x15x10 m3 as mentioned in section 3. The cooling load of the AHU to (◦ C) (◦ C) (kg/ kg. ◦ C) (kW) (kW) (kW)
s)
cool the entire Sabhamandap can be calculated by Equation (21). The
heat transfer coefficient varies for various surfaces. To calculate the 30 20 0.8 1.3732 10.9856 20 9.32125 97.21
30 20 0.9 1.3732 12.3588 20 9.32125 86.41
heating load for the Sabhamandap three different surfaces namely floor,
30 20 1 1.3732 13.732 20 9.32125 77.77
roof and walls are taken into consideration. The area of all surfaces are 30 20 1.1 1.3732 15.1052 20 9.32125 70.70
calculated below, 30 20 1.2 1.3732 16.4784 20 9.32125 64.80
A wall 1 = 30 m × 10 m = 300 m2. 30 20 1.3 1.3732 17.8516 20 9.32125 59.82
A wall 2 = 15 mx 10 m = 150 m2. 30 20 1.4 1.3732 19.2248 20 9.32125 55.55
30 20 1.5 1.3732 20.598 20 9.32125 51.84
A wall 3 = 30 m × 10 m = 300 m2.
A wall 4 = 15 m × 10 m = 150 m2.
A walls = A wall 1 + A wall 2 + A wall 3 + A wall 4 = 300 m2 + 150 m2 +
300 m2 + 150 m2 = 900 m2. 4.5. Uncertainty calculation
A roof = 30 m × 15 m = 450 m2.
A floor = 30 m × 15 m = 450 m2. The standard deviation approach was used to calculate the uncer­
The total cooling load can be calculated for walls, roof and floor can tainty. The standard deviation of the values, which is a gauge of how
be calculated by Equation (22), Equation (23), Equation (24) and dispersed the measurements are, provides the uncertainty of several
Equation (25). Table 5 shows the total cooling load calculation for the measurements.

Table 5
Cooling Load for the AHU.
S. No. Time t in t out u wall A wall q wall u floor a floor q floor u roof a roof q roof q total (Wh) q total (kWh)
(℃) (℃)

1 12 18 29 2.13 900 21,087 2.676 450 13246.2 2.78 450 13,761 48094.2 48.09
2 1 18 29 2.13 900 21,087 2.676 450 13246.2 2.78 450 13,761 48094.2 48.09
3 2 18 28 2.13 900 19,170 2.676 450 12,042 2.78 450 12,510 43,722 43.72
4 3 18 28 2.13 900 19,170 2.676 450 12,042 2.78 450 12,510 43,722 43.72
5 4 18 27 2.13 900 17,253 2.676 450 10837.8 2.78 450 11,259 39349.8 39.35
6 5 18 27 2.13 900 17,253 2.676 450 10837.8 2.78 450 11,259 39349.8 39.35
7 6 18 26 2.13 900 15,336 2.676 450 9633.6 2.78 450 10,008 34977.6 34.98
8 7 18 26 2.13 900 15,336 2.676 450 9633.6 2.78 450 10,008 34977.6 34.98
9 8 18 27 2.13 900 17,253 2.676 450 10837.8 2.78 450 11,259 39349.8 39.35
10 9 18 29 2.13 900 21,087 2.676 450 13246.2 2.78 450 13,761 48094.2 48.09
11 10 18 31 2.13 900 24,921 2.676 450 15654.6 2.78 450 16,263 56838.6 56.84
12 11 18 32 2.13 900 26,838 2.676 450 16858.8 2.78 450 17,514 61210.8 61.21
13 1 18 34 2.13 900 30,672 2.676 450 19267.2 2.78 450 20,016 69955.2 69.96
14 2 18 35 2.13 900 32,589 2.676 450 20471.4 2.78 450 21,267 74327.4 74.33
15 3 18 36 2.13 900 32,589 2.676 450 20471.4 2.78 450 21,267 74327.4 74.33
16 4 18 37 2.13 900 34,506 2.676 450 21675.6 2.78 450 22,518 78699.6 78.70
17 5 18 36 2.13 900 36,423 2.676 450 22879.8 2.78 450 23,769 83071.8 83.07
18 6 18 36 2.13 900 34,506 2.676 450 21675.6 2.78 450 22,518 78699.6 78.70
19 7 18 34 2.13 900 34,506 2.676 450 21675.6 2.78 450 22,518 78699.6 78.70
20 8 18 34 2.13 900 30,672 2.676 450 19267.2 2.78 450 20,016 69955.2 69.96
21 9 18 33 2.13 900 30,672 2.676 450 19267.2 2.78 450 20,016 69955.2 69.96
22 10 18 32 2.13 900 28,755 2.676 450 18,063 2.78 450 18,765 65,583 65.58
23 11 18 31 2.13 900 26,838 2.676 450 16858.8 2.78 450 17,514 61210.8 61.21
24 12 18 31 2.13 900 24,921 2.676 450 15654.6 2.78 450 16,263 56838.6 56.84

14
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

The basic equation of measurement uncertainty is expressed in Eq. and calculated parameters are provided for the following mentioned
(28) state points of the Space cooling system as mentioned in Table 6. A
√̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅ detailed dataset in given in appendix.
∑
(xi − μ)2 The efficiency of the ORC varies in the system accordance to the flow
σ= (28)
N rate. The work done by the turbine of the ORC is measured to be 20 kW
and the power consumed is measured to be 9.32125 kW. The flow rate
Where σ represents Standard Deviation, N represents no. of mea­
varies from 0.8 to 1.5 kg/s, and varying efficiency according to the same
surements, xi represents the measurements and the µ represents mean of
is demonstrated in Fig. 24.
measurements.
In Fig. 25, the heat pump suction and discharge pressure over 30
The relative uncertainty can be found as,
cycles are discussed. The maximum discharge pressure goes up to
AbsoluteUncertainity 2012.9 kPa and the minimum goes to 2068.43 kPa. Similarly, for the
RelativeUncertainity = × 100 (29)
Measurement suction pressure, the maximum range goes up to as high as 268.89 kPa
and the minimum remains at 213.73 kPa. Hourly data for 24 h is
5. Results and discussion collected and same is displayed in Fig. 26.
In Fig. 27 the COP of the heat pump over a period of 90 days from
The space cooling system is observed for a period of 90 days. The March to May are discussed. The COP of the heat pump varies on the
experimental data was recorded for 90 days and is reported in Appendix temperature input of the geothermal water. It ranges from 1.65 to 4. The
Part A where many parameters including COP of heat pump, heat pump COP heating increases when the temperature difference between the
outlet on heating and cooling side, suction and discharge temperature of inlet and outlet is smaller than when it is larger. The COP of the heat
Sabhamandap and AHU temperature are listed. In Appendix Part B, the pump for 90 days is calculated in Appendix Part A. COP cooling is
data over 30 cycles of the heat pump is listed. It lists the suction and calculated to determine the amount of Cooling as shown in Fig. 28. It
discharge pressure over the cycles. The measurement of uncertainties of ranges from 1.42 to 4.55. The COP cooling is calculated for 90 days as
ambient temperature and cooling load was obtained as shown in Fig. 21. mentioned in Appendix Part G. Similarly Hourly calculations of COP are
The uncertainty is calculated for hourly ambient temperature for 24 h. depicted in Fig. 29.
The maximum uncertainty of the ambient temperature and cooling load The outlet for GSHP can be seen in Fig. 30. The heat pump has two
is 13.30% and 4.45%. The uncertainty data calculation is given in the sides, the heating side and the cooling side. The temperature output for
appendix Part C. the heating side outlet ranges from 39 ◦ C to 70 ◦ C. The maximum
The mathematical model has been validated by comparing the Car­ temperature output for the cooling side outlet is 24 ◦ C while the lowest
not COP and the Actual COP of the cooling with measured data from the goes to 18 ◦ C. Hourly data is collected for the GSHP and is displayed in
Ground Source heat pump system installed. The experimental data Fig. 31. The heat pump cooling outlet is connected to the AHU.
recorded every hour for the entire cooling period of one day are reported The observations are of interconnected mechanism of GSHP and
in the Appendix where temperature inlet, outlet of GSHP, suction and AHU for space cooling of Sabhamandap. The rejected cooled water from
discharge temperature of Sabhamandap and AHU temperature are lis­ the GSHP goes into the AHU for temperature maintenance. The AHU is
ted. During the data collections period of March to May, the working connected to the suction and discharge ducts of the Sabhamandap. The
temperature range of the ambient temperature varied from 19 to 46 ◦ C air is sucked in from the Sabhamandap and in the AHU, the air and
as can be noted from Fig. 2. rejected cooled water exchange heat and the air is cooled. The discharge
The Carnot and actual COP of the Heat pump is displayed in the ducts bring back the cooled air in the Sabhamandap. The Figs. 30, 32, 34
Fig. 22. discuss the temperatures of the AHU rejected water and Sabhamandap
The Sabhamandap (Meeting Hall) is ultimately cooled from the space Suction and Discharge temperature. Temperature for a similar time
cooling system. The expected temperature for Sabhamandap is set to be period is collected for the AHU as shown in Fig. 32. Till the temperature
18 ◦ C. The uncertainty in the temperature is shown in the Fig. The reaches the AHU, it experiences loss and the temperature increases from
temperature ranges from 17 to 20.5 ◦ C. The datasheet is given in Ap­ 0.5 to 1.5 ◦ C. Hourly and Daily data is collected for AHU and is depicted
pendix Part D. The uncertainty in the temperature is shown in the in Fig. 33 and Fig. 32 respectively. The temperature range of AHU ranges
Fig. 23. from 18.5 ◦ C to 24.5 ◦ C.
The space cooling system is divided into many state points. Measured The Sabhamandap has suction and discharge ducts for intake of room

Fig. 21. Cooling Load Uncertainty over a period of 24 h.

15
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 22. Actual vs Carnot COP of Heat Pump.

Fig. 23. Expected temperature vs Actual temperature of Sabhamandap (Meeting Hall) after cooling.

Table 6
State point for the space cooling system.
Well side Heat Heat pump AHU
(State exchanger 1 inlet Intake
point 1) (State point 2) (State (State
point 3) point 4)

Measured
Temperature 43 43 25 18.5
Pressure 1 atm 1 atm 31 psi 1 atm

Calculated
Overall Heat – 2.083 kW – –
Transfer
Cooling Load – – – 30.6054
kWh
COP 2.57
– –
Fig. 24. Varying Efficiency of ORC with increasing Flow Rate.

temperature air and outlet of cooled air. The suction and discharge at the Sabhamandap (meeting hall). The outside ambient temperature
temperature of the Sabhamandap is recorded over a period of 90 days as 26 to 37 ◦ C and the average cooling load calculated came out to be
shown in Fig. 34 and hourly data is shown in Fig. 35. The lowest room 58.296 kWh. The highest cooling load calculated is 83.07 kWh and the
temperature achieved through space cooling in the aforementioned least cooling load required is 34.97 kWh. Fig. 36 and Fig. 37 display the
period is 18 ◦ C for the ambient room temperature varying from 20 to varying cooling load with respect to outside ambient temperature.
26 ◦ C.
The cooling load is calculated for the Sabhamandap (meeting hall). 6. Future applications
The outside ambient temperature varies from 19 ◦ C to 46 ◦ C. The cooling
load increase with increase in temperature difference as inside expected The currently designed system only fulfills the cooling needs of the
temperature is kept fixed at 18 ◦ C. The hourly data for a day is collected Sabhamandap (Meeting Hall). Dholera is a relatively warm place and

16
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 25. Heat pump suction and discharge pressure over 30 cycles.

Fig. 26. Heat pump suction and discharge pressure over 24 h.

Fig. 27. COP of GSHP over a period of 90 days.

almost no heating is required even in the time of winter, as can be seen after AHU, the outlet temperature to the designated space will range
from the ambient temperature range of Dholera from Fig. 2. But, for between 30 and 35 ◦ C which will be sufficient for achieving a
places where heating is necessary, this system can be modified to run as comfortable atmosphere during winters.
both a heating and cooling plant in winters and summers respectively. A Thus this high temperature water can be utilized during winter for
heating cycle can be run along with a cooling cycle during the months of space heating but will go unutilized if not used for some other purposes
December, January, and February. For running the heating cycle, the during summer. During summers this high temperature water outlet can
heat pump outlet from the heating side can be consumed as can be seen be used for several direct applications such as food drying, milk
in Fig. 16. During winters the inlet to the AHU can be directed towards pasteurization, greenhouse, and balneology. A food dryer requires a
this heating side outlet, to receive higher temperature water. The temperature ranging from 40 to 60 ◦ C for the process of drying. With
heating coil of the AHU mentioned in Fig. 13 will be utilized in this. The minimal additional external heat input, this outcome can be sustainably
heating side outlet temperature ranges between 40 and 50 ◦ C depending achieved by utilizing high temperature water from the heating side
upon the ambient temperature. With incorporating temperature losses outlet. Similarly for milk pasteurization, with minimal external input, a

17
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 28. COP cooling over a period of 90 days.

Fig. 29. COP of GSHP and COP cooling over a period of 24 h.

Fig. 30. GSHP outlet on heating and cooling side over a period of 90 days.

milk temperature of 75 ◦ C can be achieved by heat exchange between cooling of necessary space. Milk Pasteurization, Food Drying, and
high temperature and milk. A greenhouse system, balneology for health Greenhouse will utilize rejected heat after power production for their
benefits along with a desalination system can lead towards efficient use heat requirements. For ensuring proper health benefits, a desalination
of heat energy available. An energy park can be established as shown in and purification unit can be established before Balneology. In this way,
Fig. 38. The park will be established around power producing unit, water directly from the well can be utilized for societal benefits
comprising many units running solely on geothermal power. Space (Balneology) and drinking and other domestic uses.
cooling will utilize low temperature water after power production for

18
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 31. GSHP outlet on heating and cooling side over a period of 24 h.

Fig. 32. AHU temperature of Sabhamandap over a period of 90 days.

Fig. 33. AHU temperature of Sabhamandap over a period of 24 h.

7. Conclusion • A 30 HP and 81.7 kW hermetic Copeland scroll compressor

ZR380KCE-TWD-523 is used in the GSHP. The discharge and suction
This paper proposed a space cooling system, a complementary sys­ pressure over 30 cycles are in the 200–2000 kPa range.
tem to the ORC- GSHP assisted geothermal power plant utilizing low • Mathematical modelling for the calculation of COP of GSHP, Heat
enthalpy geothermal energy. This paper’s major goal was to evaluate the transfer of PHE and cooling load of AHU for Sabhamandap sized
performance of the GSHP unit, PHE’s, and AHU unit. Daily and hourly 30x15x10 m3. The effectiveness for the rate of heat exchange rate is
simulations were run pertinent parameter changes were investigated. found to be at 0.46.
The key revelations and recommendations can be summed up as follows. • The average cooling load for the room is calculated to be 58.296 kWh
with an uncertainty factor of 4.45%. The experimental data gathered

19
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 34. Suction and discharge temperature of Sabhamandap over a period of 90 days.

Fig. 35. Suction and discharge temperature of Sabhamandap over a period of 24 h.

Fig. 36. Varying Cooling load with respect to Outside Ambient Temperature over a range of temperatures of summers (19 to 46 ◦ C).

throughout the course of 90 days was analysed and the output systems, is fairly steady at about 2.66 when observed on a daily basis.
temperature for the heating side outlet is found to be between 39 and The overall system average COP was found to be 0.96.
70 ◦ C. The cooling side outlet’s highest temperature output was • The AHU faces a temperature loss of 0.5 to 1.5 ◦ C between the heat
24 ◦ C, while its lowest temperature output is 18 ◦ C with an uncer­ pump outlet and the AHU inlet. The Sabhamandap is cooled from the
tainty of 13.30%. average ambient temperature of 26 ◦ C to a cooled temperature of
• Based on heating, cooling, and COPs, the average COP is around 18 ◦ C.
2.21, while the COPs range from 1.60 to 4. The average COP cooling
is 2.48. When the temperature differential between the intake and This study takes a step indicating that direct application of
output is lower, the COP heating rises. The system’s COP, which may geothermal energy that can be sustained alongside power generation
be used to illustrate the benefits of simultaneous heating and cooling and could be a sustainable solution. India still is in the nascent stage of

20
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Fig. 37. Varying Cooling load with respect to Outside Ambient Temperature over a range of Temperatures of one day (24 h) (29 to 31 ◦ C).

conditions. Experimental and demonstrative setups showcasing utiliza­

tion of geothermal energy should be promoted. According to the Min­
istry of New and Renewable Energy (MNRE), geothermal resources have
been detected in India, and a general estimation suggests that there may
be a 10 GW geothermal power potential. MNRE should govern policies
outlining a bright future of geothermal energy in India. Future works
indicate more direct applications alongside space cooling such as winter
heating, food drying and milk pasteurization. Future studies aim to work
towards the efficient utilization of geothermal resources.

Declaration of Competing Interest

The authors declare that they have no known competing financial

Fig. 38. A conceptual Energy Park running on direct and indirect applications interests or personal relationships that could have appeared to influence
of geothermal energy. the work reported in this paper.

efficient utilization of geothermal energy. Years of data collection Data availability

analysis and interpretation will be required for India to modulate
geothermal energy systems as per Indian temperature and enthalpy Authors have added data in the Manuscript.

Appendix A

Part a

No. of Inlet temperature Outlet Heat Pump Heat Pump COP Sabhamandap Sabhamandap AHU
Days (Heat Pump) temperature Outlet (Heating Outlet (Cooling Heat Suction Discharge Temperature
(℃) (Heat Pump) Side) Side) Pump Temperature Temperature (℃)
(℃) (℃) (℃) (℃) (℃)

1 25 40 40 18 2.67 24 22.5 18.5

2 25 62 62 19 1.68 23 21.5 19.5
3 26 58 58 18.5 1.81 22.5 20 19
4 25 39 39 20 2.79 22 20 20.5
5 26 42 42 24 2.63 25 23 24.5
6 28 45 45 18 2.65 26 23.5 18.5
7 29 48 48 17 2.53 23 21 17.5
8 30 60 60 19 2.00 25 23 19.5
9 30 70 70 19 1.75 26 24.5 19.5
10 28 65 65 20 1.76 24 21.5 20.5
11 27 66 66 19.5 1.69 24.5 22 20
12 26 42 42 20 2.63 23 21.5 20.5
13 25 45 45 19.5 2.25 25 23.5 20
14 25 56 56 21 1.81 21 18 21.5
15 26 52 52 20 2.00 22 20 20.5
16 25 46 46 20.5 2.19 25 23.5 21
17 26 66 66 18 1.65 26 24.5 18.5
18 28 63 63 20.5 1.80 21 19 21
19 29 48 48 21 2.53 23 21.5 21.5
(continued on next page)

21
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

(continued )
No. of Inlet temperature Outlet Heat Pump Heat Pump COP Sabhamandap Sabhamandap AHU
Days (Heat Pump) temperature Outlet (Heating Outlet (Cooling Heat Suction Discharge Temperature
(℃) (Heat Pump) Side) Side) Pump Temperature Temperature (℃)
(℃) (℃) (℃) (℃) (℃)

20 30 47 47 19 2.76 24 22.8 19.5

21 30 43 43 20.5 3.31 22 20.5 21
22 26 60 60 22 1.76 21 18.5 22.5
23 25 61 61 18 1.69 22 20.5 18.5
24 24 63 63 18.5 1.62 21.5 19 19
25 28 65 65 19.5 1.76 23 21.5 20
26 29 43 43 20 3.07 24 22.5 20.5
27 30 61 61 18 1.97 21.5 18.5 18.5
28 25 52 52 20.5 1.93 22 20.5 21
29 24 59 59 21 1.69 23.5 21 21.5
30 27 53 53 20.5 2.04 21 19 21
31 29 69 69 18 1.73 23 21 18.5
32 30 56 56 19 2.15 25 22.5 19.5
33 29 45 45 19.6 2.81 25 23.5 20.1
34 26 55 55 20 1.90 26 23.5 20.5
35 25 65 65 20 1.63 23 21.5 20.5
36 28 70 70 21 1.67 25 23.5 21.5
37 29 68 68 18 1.74 21 19.5 18.5
38 27 58 58 19 1.87 24 22.5 19.5
39 28 53 53 20 2.12 22 20.5 20.5
40 26 48 48 21 2.18 21 18 21.5
41 25 49 49 18 2.04 26 23.5 18.5
42 27 47 47 20.2 2.35 25 23.5 20.7
43 29 46 46 21 2.71 21 19 21.5
44 30 42 42 18 3.50 23 21 18.5
45 28 39 39 18 3.55 22 20.1 18.5
46 29 56 56 20 2.07 21 19 20.5
47 30 53 53 23 2.30 24 22 23.5
48 28 54 54 18 2.08 25 23.5 18.5
49 29 58 58 17 2.00 21 18.5 17.5
50 26 69 69 18.5 1.60 22 20 19
51 27 62 62 20 1.77 20 18.5 20.5
52 28 63 63 18 1.80 21 18.5 18.5
53 29 64 64 19 1.83 25 22.5 19.5
54 30 48 48 18 2.67 21 18.5 18.5
55 29 45 45 19 2.80 24 22.5 19.5
56 28 59 59 18 1.90 23 21.5 18.5
57 27 36 36 20 4.00 21.5 18.5 20.5
58 26 54 54 21 1.93 21.5 20 21.5
59 25 56 56 20.2 1.81 23.5 21 20.7
60 30 57 57 19.6 2.11 26.5 24 20.1
61 29 63 63 18 1.85 23 21 18.5
62 28 69 69 18.5 1.68 24.5 22 19
63 27 52 52 19 2.08 23 21 19.5
64 25 51 51 18.5 1.96 21 18 19
65 26 46 46 23 2.30 20 18 23.5
66 30 42 42 21 3.50 25 23.6 21.5
67 28 38 38 20 3.80 21 19 20.5
68 29 63 63 18 1.85 25 23 18.5
69 26 62 62 21 1.72 21 19.5 21.5
70 27 54 54 24 2.00 24 22 24.5
71 25 52 52 21 1.93 20 18.5 21.5
72 30 63 63 20 1.91 26 23.5 20.5
73 27 61 61 18 1.79 23 21.5 18.5
74 29 42 42 18.5 3.23 21 18.5 19
75 28 43 43 20 2.87 21 19.5 20.5
76 25 48 48 18.5 2.09 25 23 19
77 26 54 54 19 1.93 21 18.5 19.5
78 30 41 41 18 3.90 20 18 18.5
79 27 45 45 18.5 2.50 26 24 19
80 29 56 56 19 2.07 23 21 19.5
81 25 43 43 19.5 2.39 24 22 20
82 25 49 49 20.3 2.04 21 18 20.8
83 26 48 48 19.4 2.18 20 18 19.9
84 25 56 56 18 1.81 21.5 18 18.5
85 30 56 56 18.5 2.15 24.5 22.5 19
86 30 59 59 19 2.03 26.5 24 19.5
87 30 58 58 21 2.07 21 18 21.5
88 26 46 46 20 2.30 21.5 19.5 20.5
89 29 52 52 20.2 2.26 20.5 18 20.7
90 30 62 62 18 1.94 23.5 21 18.5

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V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

Part B
No. of Cycles Heat Pump Suction Pressure (kPa) Heat Pump Discharge Pressure (kPa)

1 213.74 2068.43
2 220.63 2075.32
3 234.42 2068.43
4 213.74 2082.22
5 241.32 2089.11
6 248.21 2075.32
7 255.11 2068.43
8 220.63 2082.22
9 241.32 2096.01
10 248.21 2075.32
11 262.00 2102.90
12 213.74 2082.22
13 268.90 2068.43
14 220.63 2075.32
15 241.32 2082.22
16 213.74 2102.90
17 234.42 2068.43
18 241.32 2075.32
19 262.00 2089.11
20 268.90 2082.22
21 255.11 2102.90
22 241.32 2075.32
23 213.74 2096.01
24 220.63 2082.22
25 248.21 2075.32
26 234.42 2068.43
27 241.32 2102.90
28 213.74 2089.11
29 220.63 2082.22
30 227.53 2102.90

Part C
Ambient Temperature (◦ C) Ambient Temperature (%) Cooling Load (kW) Uncertainty for Cooling Load (%)

29 11.93 48.09 3.24

29 11.93 48.09 3.24
28 12.36 43.72 3.56
28 12.36 43.72 3.56
27 12.82 39.35 3.96
27 12.82 39.35 3.96
26 13.31 34.98 4.46
26 13.31 34.98 4.46
27 12.82 39.35 3.96
29 11.93 48.09 3.24
31 11.16 56.84 2.74
32 10.81 61.21 2.55
34 10.18 69.96 2.23
35 9.89 74.33 2.10
36 9.61 74.33 2.10
37 9.35 78.70 1.98
36 9.61 83.07 1.88
36 9.61 78.70 1.98
34 10.18 78.70 1.98
34 10.18 69.96 2.23
33 10.49 69.96 2.23
32 10.81 65.58 2.38
31 11.16 61.21 2.55
31 11.16 56.84 2.74

Part d
No. of Days Expected Temperature (◦ C) Actual Temperature (◦ C)

1 18 18
2 18 19
3 18 18.5
4 18 20
5 18 20.4
6 18 18
7 18 17
8 18 19
9 18 19
(continued on next page)

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V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

(continued )
No. of Days Expected Temperature (◦ C) Actual Temperature (◦ C)

10 18 20
11 18 19.5
12 18 20
13 18 19.5
14 18 20.1
15 18 20
16 18 20.5
17 18 18
18 18 20.5
19 18 20.1
20 18 19
21 18 20.5
22 18 20.2
23 18 18
24 18 18.5
25 18 19.5
26 18 20
27 18 18
28 18 20.5
29 18 18
30 18 20.5
31 18 18
32 18 19
33 18 19.6
34 18 20
35 18 20
36 18 19.6
37 18 18
38 18 19
39 18 20
40 18 18.5
41 18 18
42 18 20.2
43 18 19.5
44 18 18
45 18 18
46 18 20
47 18 20.2
48 18 18
49 18 17
50 18 18.5
51 18 20
52 18 18
53 18 19
54 18 18
55 18 19
56 18 18
57 18 20
58 18 20
59 18 20.2
60 18 19.6
61 18 18
62 18 18.5
63 18 19
64 18 18.5
65 18 18.3
66 18 19.1
67 18 20
68 18 18
69 18 20.1
70 18 20.4
71 18 19.3
72 18 20
73 18 18
74 18 18.5
75 18 20
76 18 18.5
77 18 19
78 18 18
79 18 18.5
80 18 19
81 18 19.5
82 18 20.3
83 18 19.4
84 18 18
85 18 18.5
(continued on next page)

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V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

(continued )
No. of Days Expected Temperature (◦ C) Actual Temperature (◦ C)

86 18 19.3
87 18 20
88 18 18
89 18 19
90 18 20.4

Part E
Higher Temperature Lower Temperature Q Actual COP Carnot COP % RCOP
(℃) (℃) (kW)

25 18 29.26 0.73 2.57 28.45

25 19 25.08 0.63 3.17 19.80
26 18.5 31.35 0.78 2.47 31.77
25 20 20.9 0.52 4.00 13.06
26 20.4 23.408 0.59 3.64 16.06
28 18 41.8 1.05 1.80 58.06
29 17 50.16 1.25 1.42 88.52
30 19 45.98 1.15 1.73 66.55
30 19 45.98 1.15 1.73 66.55
28 20 33.44 0.84 2.50 33.44
27 19.5 31.35 0.78 2.60 30.14
26 20 25.08 0.63 3.33 18.81
25 19.5 22.99 0.57 3.55 16.21
25 20.1 20.482 0.51 4.10 12.48
26 20 25.08 0.63 3.33 18.81
25 20.5 18.81 0.47 4.56 10.32
26 18 33.44 0.84 2.25 37.16
28 20.5 31.35 0.78 2.73 28.67
29 20.1 37.202 0.93 2.26 41.18
30 19 45.98 1.15 1.73 66.55
30 20.5 39.71 0.99 2.16 46.01
26 20.2 24.244 0.61 3.48 17.40
25 18 29.26 0.73 2.57 28.45
24 18.5 22.99 0.57 3.36 17.09
28 19.5 35.53 0.89 2.29 38.72
29 20 37.62 0.94 2.22 42.32
30 18 50.16 1.25 1.50 83.60
25 20.5 18.81 0.47 4.56 10.32
24 18 25.08 0.63 3.00 20.90
27 20.5 27.17 0.68 3.15 21.54
29 18 45.98 1.15 1.64 70.25
30 19 45.98 1.15 1.73 66.55
29 19.6 39.292 0.98 2.09 47.11
26 20 25.08 0.63 3.33 18.81
25 20 20.9 0.52 4.00 13.06
28 19.6 35.112 0.88 2.33 37.62
29 18 45.98 1.15 1.64 70.25
27 19 33.44 0.84 2.38 35.20
28 20 33.44 0.84 2.50 33.44
26 18.5 31.35 0.78 2.47 31.77
25 18 29.26 0.73 2.57 28.45
27 20.2 28.424 0.71 2.97 23.92
29 19.5 39.71 0.99 2.05 48.36
30 18 50.16 1.25 1.50 83.60
28 18 41.8 1.05 1.80 58.06
29 20 37.62 0.94 2.22 42.32
30 20.2 40.964 1.02 2.06 49.68
28 18 41.8 1.05 1.80 58.06
29 17 50.16 1.25 1.42 88.52
26 18.5 31.35 0.78 2.47 31.77
27 20 29.26 0.73 2.86 25.60
28 18 41.8 1.05 1.80 58.06
29 19 41.8 1.05 1.90 55.00
30 18 50.16 1.25 1.50 83.60
29 19 41.8 1.05 1.90 55.00
28 18 41.8 1.05 1.80 58.06
27 20 29.26 0.73 2.86 25.60
26 20 25.08 0.63 3.33 18.81
25 20.2 20.064 0.50 4.21 11.92
30 19.6 43.472 1.09 1.88 57.67
29 18 45.98 1.15 1.64 70.25
28 18.5 39.71 0.99 1.95 50.98
27 19 33.44 0.84 2.38 35.20
25 18.5 27.17 0.68 2.85 23.87
(continued on next page)

25
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

(continued )
Higher Temperature Lower Temperature Q Actual COP Carnot COP % RCOP
(℃) (℃) (kW)

26 18.3 32.186 0.80 2.38 33.86

30 19.1 45.562 1.14 1.75 65.00
28 20 33.44 0.84 2.50 33.44
29 18 45.98 1.15 1.64 70.25
26 20.1 24.662 0.62 3.41 18.10
27 20.4 27.588 0.69 3.09 22.31
25 19.3 23.826 0.60 3.39 17.59
30 20 41.8 1.05 2.00 52.25
27 18 37.62 0.94 2.00 47.03
29 18.5 43.89 1.10 1.76 62.28
28 20 33.44 0.84 2.50 33.44
25 18.5 27.17 0.68 2.85 23.87
26 19 29.26 0.73 2.71 26.95
30 18 50.16 1.25 1.50 83.60
27 18.5 35.53 0.89 2.18 40.81
29 19 41.8 1.05 1.90 55.00
25 19.5 22.99 0.57 3.55 16.21
25 20.3 19.646 0.49 4.32 11.37
26 19.4 27.588 0.69 2.94 23.46
25 18 29.26 0.73 2.57 28.45
30 18.5 48.07 1.20 1.61 74.70
30 19 45.98 1.15 1.73 66.55
30 20 41.8 1.05 2.00 52.25
26 20 25.08 0.63 3.33 18.81
29 20.2 36.784 0.92 2.30 40.06
30 18 50.16 1.25 1.50 83.60

Part F
S. No. t in t out u wall A wall q wall u floor a floor q floor u roof a roof q roof q total (Wh) q total (kWh)
(℃) (℃)

1 18 19 2.13 900 1917 2.676 450 1204.2 2.78 450 1251 4372.2 4.37
2 18 20 2.13 900 3834 2.676 450 2408.4 2.78 450 2502 8744.4 8.74
3 18 21 2.13 900 5751 2.676 450 3612.6 2.78 450 3753 13116.6 13.12
4 18 22 2.13 900 7668 2.676 450 4816.8 2.78 450 5004 17488.8 17.49
5 18 23 2.13 900 9585 2.676 450 6021 2.78 450 6255 21,861 21.86
6 18 24 2.13 900 11,502 2.676 450 7225.2 2.78 450 7506 26233.2 26.23
7 18 25 2.13 900 13,419 2.676 450 8429.4 2.78 450 8757 30605.4 30.61
8 18 26 2.13 900 15,336 2.676 450 9633.6 2.78 450 10,008 34977.6 34.98
9 18 27 2.13 900 17,253 2.676 450 10837.8 2.78 450 11,259 39349.8 39.35
10 18 28 2.13 900 19,170 2.676 450 12,042 2.78 450 12,510 43,722 43.72
11 18 29 2.13 900 21,087 2.676 450 13246.2 2.78 450 13,761 48094.2 48.09
12 18 30 2.13 900 23,004 2.676 450 14450.4 2.78 450 15,012 52466.4 52.47
13 18 31 2.13 900 24,921 2.676 450 15654.6 2.78 450 16,263 56838.6 56.84
14 18 32 2.13 900 26,838 2.676 450 16858.8 2.78 450 17,514 61210.8 61.21
15 18 33 2.13 900 28,755 2.676 450 18,063 2.78 450 18,765 65,583 65.58
16 18 34 2.13 900 30,672 2.676 450 19267.2 2.78 450 20,016 69955.2 69.96
17 18 35 2.13 900 32,589 2.676 450 20471.4 2.78 450 21,267 74327.4 74.33
18 18 36 2.13 900 34,506 2.676 450 21675.6 2.78 450 22,518 78699.6 78.70
19 18 37 2.13 900 36,423 2.676 450 22879.8 2.78 450 23,769 83071.8 83.07
20 18 38 2.13 900 38,340 2.676 450 24,084 2.78 450 25,020 87,444 87.44
21 18 39 2.13 900 40,257 2.676 450 25288.2 2.78 450 26,271 91816.2 91.82
22 18 40 2.13 900 42,174 2.676 450 26492.4 2.78 450 27,522 96188.4 96.19
23 18 41 2.13 900 44,091 2.676 450 27696.6 2.78 450 28,773 100560.6 100.56
24 18 42 2.13 900 46,008 2.676 450 28900.8 2.78 450 30,024 104932.8 104.93
25 18 43 2.13 900 47,925 2.676 450 30,105 2.78 450 31,275 109,305 109.31
26 18 44 2.13 900 49,842 2.676 450 31309.2 2.78 450 32,526 113677.2 113.68
27 18 45 2.13 900 51,759 2.676 450 32513.4 2.78 450 33,777 118049.4 118.05
28 18 46 2.13 900 53,676 2.676 450 33717.6 2.78 450 35,028 122421.6 122.42

Part G
S. No. Heat Pump Outlet (Cooling Side) TLT Heat pump inlet (Cooling Side) THT COP cooling
(℃) (℃)

1 18 25 2.57
2 19 25 3.17
3 18.5 26 2.47
4 20 25 4.00
5 20.2 26 3.48
6 18 28 1.80
(continued on next page)

26
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

(continued )
S. No. Heat Pump Outlet (Cooling Side) TLT Heat pump inlet (Cooling Side) THT COP cooling
(℃) (℃)

7 17 29 1.42
8 19 30 1.73
9 19 30 1.73
10 20 28 2.50
11 19.5 27 2.60
12 20 26 3.33
13 19.5 25 3.55
14 20.1 25 4.10
15 20 26 3.33
16 20.5 25 4.56
17 18 26 2.25
18 20.5 28 2.73
19 19 29 1.90
20 19 30 1.73
21 20.2 30 2.06
22 19 26 2.71
23 18 25 2.57
24 18.5 24 3.36
25 19.5 28 2.29
26 20 29 2.22
27 18 30 1.50
28 20.5 25 4.56
29 18 24 3.00
30 20.2 27 2.97
31 18 29 1.64
32 19 30 1.73
33 19.6 29 2.09
34 20 26 3.33
35 20 25 4.00
36 20.2 28 2.59
37 18 29 1.64
38 19 27 2.38
39 20 28 2.50
40 20.2 26 3.48
41 18 25 2.57
42 20.2 27 2.97
43 19 29 1.90
44 18 30 1.50
45 18 28 1.80
46 20 29 2.22
47 19 30 1.73
48 18 28 1.80
49 17 29 1.42
50 18.5 26 2.47
51 20 27 2.86
52 18 28 1.80
53 19 29 1.90
54 18 30 1.50
55 19 29 1.90
56 18 28 1.80
57 20 27 2.86
58 18.5 26 2.47
59 20.2 25 4.21
60 19.6 30 1.88
61 18 29 1.64
62 18.5 28 1.95
63 19 27 2.38
64 18.5 25 2.85
65 20.1 26 3.41
66 19.8 30 1.94
67 20 28 2.50
68 18 29 1.64
69 20.2 26 3.48
70 20 27 2.86
71 18 25 2.57
72 20 30 2.00
73 18 27 2.00
74 18.5 29 1.76
75 20 28 2.50
76 18.5 25 2.85
77 19 26 2.71
78 18 30 1.50
79 18.5 27 2.18
80 19 29 1.90
81 19.5 25 3.55
(continued on next page)

27
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

(continued )
S. No. Heat Pump Outlet (Cooling Side) TLT Heat pump inlet (Cooling Side) THT COP cooling
(℃) (℃)

82 20.2 25 4.21
83 19.4 26 2.94
84 18 25 2.57
85 18.5 30 1.61
86 19 30 1.73
87 20 30 2.00
88 20 26 3.33
89 20.2 29 2.30
90 18 30 1.50

Sabhamandap Temperature Well Temperature Overall COP

(℃) (℃) (℃)

22.5 43 1.10
21.5 43 1.00
20 43 0.87
20 43 0.87
23 43 1.15
23.5 43 1.21
21 43 0.95
23 43 1.15
24.5 43 1.32
21.5 43 1.00
22 43 1.05
21.5 43 1.00
23.5 43 1.21
18 43 0.72
20 43 0.87
23.5 43 1.21
24.5 43 1.32
19 43 0.79
21.5 43 1.00
22.8 43 1.13
20.5 43 0.91
18.5 43 0.76
20.5 43 0.91
19 43 0.79
21.5 43 1.00
22.5 43 1.10
18.5 43 0.76
20.5 43 0.91
21 43 0.95
19 43 0.79
21 43 0.95
22.5 43 1.10
23.5 43 1.21
23.5 43 1.21
21.5 43 1.00
23.5 43 1.21
19.5 43 0.83
22.5 43 1.10
20.5 43 0.91
18 43 0.72
23.5 43 1.21
23.5 43 1.21
19 43 0.79
21 43 0.95
20.1 43 0.88
19 43 0.79
22 43 1.05
23.5 43 1.21
18.5 43 0.76
20 43 0.87
18.5 43 0.76
18.5 43 0.76
22.5 43 1.10
18.5 43 0.76
22.5 43 1.10
21.5 43 1.00
18.5 43 0.76
20 43 0.87
21 43 0.95
24 43 1.26
21 43 0.95
(continued on next page)

28
V. Pandey et al. Applied Thermal Engineering 231 (2023) 120941

(continued )
Sabhamandap Temperature Well Temperature Overall COP
(℃) (℃) (℃)

22 43 1.05
21 43 0.95
18 43 0.72
18 43 0.72
23.6 43 1.22
19 43 0.79
23 43 1.15
19.5 43 0.83
22 43 1.05
18.5 43 0.76
23.5 43 1.21
21.5 43 1.00
18.5 43 0.76
19.5 43 0.83
23 43 1.15
18.5 43 0.76
18 43 0.72
24 43 1.26
21 43 0.95
22 43 1.05
18 43 0.72
18 43 0.72
18 43 0.72
22.5 43 1.10
24 43 1.26
18 43 0.72
19.5 43 0.83
18 43 0.72
21 43 0.95

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