MAPÚA UNIVERSITY
SCHOOL OF
Table of Contents
Title Page..................................................................................................................................... 1
Objectives .................................................................................................................................... 2
Theories and Principles ............................................................................................................... 2
List of Apparatus (Individual Definitions) .................................................................................. 3
Procedures ................................................................................................................................... 6
Set-up of Apparatus ..................................................................................................................... 8
Final Data Sheet .........................................................................Error! Bookmark not defined.
Sample Calculations .................................................................................................................. 10
Test Data Analysis .................................................................................................................... 13
Industry Applications (Individual) ............................................................................................ 13
Conclusion (Individual)............................................................................................................. 13
Recommendation (Individual)................................................................................................... 14
References ................................................................................................................................. 14
Objectives
1. To be able to acquaint ourselves with the basic components of an air-conditioning
system.
2. To determine the coefficient of performance of the M.E. laboratory air-conditioning unit.
Theories and Principles
Air conditioning is the technique of regulating the condition of air to provide a comfortable
environment for man and for making industrial products. According to the American Society of
Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) it is the process of treating the
air to control its temperature, humidity, cleanliness, and distribution to meet the requirements of a
conditioned space. An air conditioning system must be able to remove heat and moisture from the
conditioned space. The device which serves this purpose is cooling and dehumidifying coils. Most
air conditioning coils consist of tubes with fins attached to the outside of the tubes. Refrigerant
flows inside the tubes while the air flows over the outside of the tubes. Heat transfer between the
coils and the air causes the air temperature to drop. The capacity of an air conditioning unit to
deliver its work efficiently and effectively is determined by its coefficient of performance. It makes
use of a ratio that weighs production to the environment against expenditure to determine the unit's
efficiency. It is crucial to remember that the two things to consider when getting a greater
coefficient of performance are increasing the evaporator operating temperature or decreasing the
condenser operating temperature. When these two elements are combined, increasing the
evaporator operating temperature simply results in a larger system unit coefficient of performance
than lowering the condenser operating temperature. The main components of a refrigeration unit
are the compressor, which serves as the unit's main engine and is responsible for compressing the
working substance, the condenser, which rejects the working substance's heat to the environment,
and the evaporator, which absorbs heat from the space to be conditioned.
According to the diagram below of a simple vapor compression cycle, state 1 contains the
evaporator output and compressor inlet, and the working substance is in a saturated vapor state.
The compressor transforms the condition of the substance into a superheated vapor (point 2), which
is then processed. The working substance is then processed by the condenser from point 2 to point
3, releasing it into a saturated liquid condition. Its next passes through a throttling valve or
expansion valve, which sends it to the evaporator's inlet (point 4). The working substance is then
released as a saturated vapor by the evaporator, which repeats the process.
Figure 1. Basic Vapor Compression Cycle
Equation 1 represents the coefficient of performance, which is made up of the ratio of refrigeration
cooling capacity to compressor effort. The cooling capacity of an evaporator is calculated by
multiplying the mass of the working substance by the enthalpy difference between points 1 and 4
in kilojoules. While the compressor's work is calculated by multiplying the mass of the substance
by the difference in enthalpy between points 1 and 2. It is also measured in kilojoules.
List of Apparatus
1. Thermal System T7082
2. Environmental Application System T7083
3. Hygrometer
4. Stopwatch
Procedures
Condition #1 (Damper Open)
Condition #2 (Condenser Damper Adjusted)
Condition #3 (Evaporator Damper Adjusted)
Set-up of Apparatus
Final Data Sheet
Enthalpy Enthalpy
Gauge Number Pressure Temperature
(Theoretical) (Actual)
(Mpaa) (KJ/kg) (°C) (KJ/kg)
1 0.300 399.00 3.33 401.90
2 1.170 439.40 54 438.60
3 1.170 264.50 32 244.60
4 0.300 264.50 -1.11 244.60
Low Inner Room Temperature: 11.77°C Low Inner Room Temperature: 10.5°C
High Inner Room Temperature: 10.5°C Average Inner Room Temperature: 10.8°C
Classroom Temperature: 22.2°C
Enthalpy Enthalpy
Gauge Number Pressure Temperature
(Theoretical) (Actual)
(Mpaa) KJ/kg (°C) KJ/kg
1 0.300 399.00 3.33 401.90
2 1.240 428.50 57 441.70
3 1.240 267.90 32 244.60
4 0.300 267.90 -1.11 244.60
Average Inner Room Temperature: 11.16°C Classroom Temperature: 22.22°C
Enthalpy Enthalpy
Gauge Number Pressure Temperature
(Theoretical) (Actual)
(Mpaa) KJ/kg (°C) KJ/kg
1 0.300 399.00 3.33 401.90
2 1.200 427.80 60 445.10
3 1.200 265.90 31 243.20
4 0.300 265.90 -1.11 243.20
Average Inner Room Temperature: 10.33°C Classroom Temperature: 22.22°C
Condition COP(max) COP(Theoretical) COP(Actual)
Damper Open 24.91 3.33 4.29
Condenser Damper
25.71 4.44 3.95
Adjusted
Evaporator Damper
23.84 4.62 3.67
Adjusted
Sample Calculations
Condition 2: Condenser Damper Adjusted
Point 1 (entrance of compressor):
𝒉𝟏 = 𝟑𝟗𝟗 𝒌𝑱/𝒌𝒈
𝑇1 = 0.7℃
Point 2 (Condenser):
𝒉𝟐 = 𝟒𝟐𝟖. 𝟓 𝒌𝑱/𝒌𝒈
𝑇2 = 52.6℃
Point 3 (Expansion Valve):
𝒉𝟑 = 𝟐𝟔𝟕. 𝟗 𝒌𝑱/𝒌𝒈
𝑇3 = 47.6℃
Point 4 (Evaporator):
𝒉𝟒 = 𝟐𝟔𝟕. 𝟗 𝒌𝑱/𝒌𝒈
𝑇4 = 0.7℃
Coefficient of Performance (Theoretical):
ℎ1 − ℎ4
𝐶𝑂𝑃𝑡ℎ𝑒𝑜 =
ℎ2 − ℎ1
399 𝑘𝐽/𝑘𝑔 − 267.9 𝑘𝐽/𝑘𝑔
𝐶𝑂𝑃𝑡ℎ𝑒𝑜 =
428.5 𝑘𝐽/𝑘𝑔 − 399 𝑘𝐽/𝑘𝑔
𝐶𝑂𝑃𝑡ℎ𝑒𝑜 = 4.4441
Actual:
𝑆𝑢𝑝𝑒𝑟ℎ𝑒𝑎𝑡𝑖𝑛𝑔 ∆𝑇 = (273 + 3.33) − (273 + 0.7) = 𝟐. 𝟔𝟑𝑲
𝑆𝑢𝑏𝑐𝑜𝑜𝑙𝑖𝑛𝑔 ∆𝑇 = (273 + 47.6) − (273 + 32) = 𝟏𝟓. 𝟔𝑲
𝜂𝑐𝑜𝑚𝑝𝑟𝑒𝑠𝑠𝑜𝑟 = 𝟗𝟐. 𝟖% (𝑏𝑦 𝑡𝑟𝑖𝑎𝑙 𝑎𝑛𝑑 𝑒𝑟𝑟𝑜𝑟)
Point 1 (entrance of compressor):
𝒉𝟏 ′ = 𝟒𝟎𝟏. 𝟒 𝒌𝑱/𝒌𝒈
Point 2 (Condenser):
𝒉𝟐 ′ = 𝟒𝟑𝟑. 𝟔 𝒌𝑱/𝒌𝒈
Point 3 (Expansion Valve):
𝒉𝟑 ′ = 𝟐𝟒𝟒. 𝟔 𝒌𝑱/𝒌𝒈
Point 4 (Evaporator):
𝒉𝟒 ′ = 𝟐𝟒𝟒. 𝟔 𝒌𝑱/𝒌𝒈
Coefficient of Performance (Actual):
ℎ1 ′ − ℎ4 ′
𝐶𝑂𝑃𝐴𝐶𝑇𝑈𝐴𝐿 =
ℎ2 ′ − ℎ1 ′
401.4 𝑘𝐽/𝑘𝑔 − 244.6 𝑘𝐽/𝑘𝑔
𝐶𝑂𝑃𝐴𝐶𝑇𝑈𝐴𝐿 =
433.6 𝑘𝐽/𝑘𝑔 − 401.4 𝑘𝐽/𝑘𝑔
𝐶𝑂𝑃𝐴𝐶𝑇𝑈𝐴𝐿 = 4.8696
Coefficient of Performance (Max):
𝑇𝑙𝑜𝑤
𝐶𝑂𝑃𝑚𝑎𝑥 =
𝑇ℎ𝑖𝑔ℎ − 𝑇𝑙𝑜𝑤
(11.16 + 273)𝐾
𝐶𝑂𝑃𝑚𝑎𝑥 =
(22.2 + 273)𝐾 − (11.16 + 273)𝐾
𝐶𝑂𝑃𝑚𝑎𝑥 = 25.74
Test Data Analysis
The experiment yielded the following data seen in the previous pages of the report in the
final data sheet page. As per the given two tables in the Final Data Sheet, we have here presently
four pressure gauges in the tables present, where in the tables present are the various conditions of
the parameters being tested in the experiment. On all three tables, the first given enthalpies were
theoretic in which they were approximately equal with the given actual enthalpies per pressure
given in the tables. The first condition of the lab experiment yielded a lower room temperature of
11.7 degrees C and 10.5 degrees C with the average room temperature yielding an amount of 10.8
degrees C with a higher inner temperature equal to the low inner temperature at 10.5 degrees C.
On the first condition, the classroom temperature is at 22.2 degrees C.
On the second condition, the enthalpies remained constant with the parameters of the room.
But the average inner temperature of the classroom changed into 11.16 degrees C thus yielding a
22.22 degrees C. On the next condition, the average room temperature changed from 11.16 degrees
C to 10.33 degrees C and still the similar room temperature of 22.22 degrees C.
Next, we present the three conditions and their coefficient of their performance (COP).
When the dampers are open the max COP yielded a rate of 24.91, while both the theoretic and
actual COPs yielded a rate of 3.33 and 4.29 respectively. On the other hand, when the condenser
damper is adjusted, the max COP is at 25.71, with both the theoretic and actual COPs yielding a
rate of 4.44 and 3.95 respectively. Lastly, when the evaporator damper is adjusted, the max COP
is at 23.84, while both the theoretic and actual COPs yielded a rate of 4.62 and 3.67 respectively.
These digits and ratings were justified with the presence of the sample computations right after the
final data sheet of the report.
Industry Applications
Refrigeration Systems
The heat extracted from the cold reservoir (within a refrigerator) divided by the work W
done to remove the heat is the refrigerator's coefficient of performance, or COP (the work done by
the compressor). The work is not output in heat pumps and refrigerators, though. Thermal
efficiency refers to the amount of energy added by work that is transformed to net heat output in
refrigeration or heat pumps. The optimal refrigeration cycle from an economic standpoint is one
that removes the most heat from the inside of the refrigerator (cold reservoir) with the least amount
of mechanical work or electric energy. As a result, the relevant ratio is, and the higher this ratio is,
the better the refrigerator. The coefficient of performance, abbreviated as COP, is the name given
to this ratio. For heat pumps, the coefficient of performance, or COP, is also defined, but we're
interested in the net heat added to the hot reservoir at this time. Because, rather of just converting
work to heat, heat pumps pump additional heat from a heat source to where it is needed, the COP
frequently exceeds one.
In general, COP is strongly influenced by operating circumstances, particularly absolute
and relative temperatures between the heat sink and the system.
Conclusion
The compressor is the first stage in the cycle for an air conditioning system’s major
component; it elevates the working gas's pressure and temperature. As the refrigerant enters the
device, it is compressed, and it escapes at a higher temperature and pressure. With no friction or
heat transmission, the compressor compresses the incoming saturated vapor into a superheated
vapor. The superheated vapor flows through numerous coils in the condenser, extracting heat from
the hot refrigerant vapor before condensing into a saturated liquid. The process continues after
condensation at the expansion valve, where expansion occurs without friction or temperature
transmission. The expansion valve's job is to create a pressure drop once the refrigerant leaves the
condenser. As a result of the pressure drop, the refrigerant will boil, resulting in a mixture. The
refrigerant then passes through the evaporator, where it absorbs heat. The refrigerant enters the
evaporator as a low-temperature, low-pressure liquid, and a fan blows air through the fins,
absorbing heat from the environment and transferring it to the system's refrigerant. M.E. The
theoretical coefficient of performance for a laboratory air conditioning unit was computed using
the pressure values at the gauge numbers and the refrigerant table of values using the pressure
values at the gauge numbers and the refrigerant table of values.
Recommendation
Even though we were able to comprehend the experiment's objectives, the apparatus
material does not emphasize the importance of knowing how to use the equipment that we may
use in the future. Knowing how to use the equipment that we may use in the future will provide a
better experience in learning how to handle the subject of this experiment. Making a taped video
on how to use it and how it works is a great way to enjoy it and learn more about it.
References
Araner. (n.d.). Industrial Application of Refrigeration. ARANER. Retrieved March 30, 2022, from
https://www.araner.com/blog/industrial-refrigeration-applications-district-cooling
Jayamaha, L. (2016). Energy-efficient industrial systems: Evaluation and implementation.
McGraw-Hill Education.
