SOLAR REFRIGERATION
REFRIGERATION T
The process of continuously cooling a system by removing the
heat in it is known as refrigeration. It involves boiling and
condensation of a refrigerant to cool a surface or volume.
Refrigeration is used in :
• Food Preservation
• Household refrigerator
• Comfort air conditioning
• Industrial air conditioning
• Laboratory, textile industries
SOLAR REFRIGERATION
The process of cooling a system continuously by electricity provided by the
solar engery is known as solar refrigeration. Solar refrigerator is a device that
runs on the energy from the sun and may include photovoltaic or Solar
thermal energy.
HOW DOES SOLAR REFRIGERATION
WORK?
Solar- powered refrigeration system employs a PV panel, vapor compressor, thermal storage and reservoir and
electronic controls. The process that makes the refrigeration possible is the conversion of sunlight into DC electrical
power, achieved by the PV panel. The DC electrical power drives the compressor to circulate refrigerant through a
vapor compression refrigeration loop that extracts heat from an insulated enclosure. This enclosure includes the
thermal reservoir and a phase change material. This material freezes as heat is extracted from the enclosure. This
process effectively creates an “ice pack,” enabling temperature maintenance inside the enclosure in the absence of
sunlight
Proper sizing of the highly insulated cabinet phase change thermal storage, variable speed compressor and solar PV
panel allow the refrigerator to stay cold all year long. To optimize the conversion of solar power into stored thermal
energy. A compressor control method fully exploits the available energy Other power optimization measures include:
• Smoothing the power voltage vin a capacitor, providing additional current during compressor start-up.
• Monitoring the rate of change of the smoothed power voltage using a controller to determine if the compressor is
operating below or above the available maximum power,enabling adjustment of the compressor speed if necessary.
• Replacing the capillary tube in the refrigerator system with an expansion valve, improving energy efficiency in
These adjustments to the compressor operation contribute to the conversion of the
majority of the available solar power into stored thermal energy. Applications may
include a cold side water loop or incorporation of the evaporator into the thermal
storage.
TYPES OF SOLAR
REFRIGERATION
Photovoltaic operated refrigeration cycle
• Solar mechanical refrigeration
• Absorption refrigeration
PHOTOVOLTAIC OPERATED REFRIGERATION
CYCLE
Photovoltaics (PV) involve the direct conversion of solar radiation to direct current
(de) electricity using semiconducting materials. In concept the operation of a PV
powered solar refrigeration cycle is simple, Solar photovoltaic panels produce de
electrical power that can be used to operate a de motor, which is coupled to the
compressor of a vapor compression refrigeration system. The major considerations
in designing a PV-refrigeration cycle involve appropriately matching the electrical
characteristics of the motor driving the compressor with the available current and
voltage being produced by the PV array. The rate of electrical power capable of
being generated by a PV system is typically provided by manufacturers of PV
modules for standard rating conditions, Le, incident solar radiation of 1,000 W/m
(10800 W/s) and a module temperature of 25’C (77 F).
Considerations regarding system
Must match voltage imposed on PV array to the motor churacteristics and power requirements of
the refrigeration cycle.
For given operating condition (solar radiation and module temperature), single voltage provides
maximum power output.
• Must find compressor motor closely matched to the electric characteristics of the PV module.
SOLAR MECHANICAL REFRIGERATION
Solar mechanical refrigeration uses a conventional vapour compression
system driven by mechanical power that is produced with a solar-driven
heat power cycle. The heat power cycle usually considered for this
application is a Rankine cycle in which a fluid is vaporised at an elevated
pressure by heat exchange with a fluid heated by solar collectors.
A storage tank can be included to provide some high temperature thermal
storage. The vapour flows through a turbine or piston expander to produce
mechanical power, as shown. The fluid exiting the expander is condensed
and pumped back to the boiler pressure where it is again vaporised.
Considerations
• Efficiency optimization based on delivery temperature
• Efficiency of Rankine cycle increases with increased heat exchanger
temperature
• Efficiency of solar collector decreases with increase in temperature
ABSORPTION
REFRIGERATION
Absorption refrigeration is the least intuitive of the solar refrigeration alteratives. The absorption
refrigeration system is considered a “beat driven” system that requires minimal mechanical power
for the compression process. It replaces the energy-intensive compression in a vapor compression
system with a heat activated “thermal compression system. Absorption cooling systems that use
lithium bromide-water absorption refrigerant working fluids cannot be used at temperatures
below 0”C (32”F). The condenser, throttle and evaporator operate in the exactly the same manner
as for the vapor compression system. In place of the compressor, however, the absorption system
uses a series of three heat exchangers (absorber, regenerating intermediate heat exchanger and a
generator) and a small solution pump.
Ammonia vapor exiting the evaporator (State 6) is absorbed in a liquid solution of water-ammonia
in the absorber. The absorption of ammonia vapor into the water ammonia solution is analogous to
a condensation process. The process is exothermic and so cooling water is required to carry away
the heat of absorption. The principle governing this phase of the operation is that a vapar is more
readily absorbed into a liquid solution as the temperature of the liquid solution is reduced.
The ammonia-rich liquid solution leaving the absorber (State 7) is pumped to a higher pressure, passed
through a heat exchanger and delivered to the generator State 1). The power requirement for the pump is
much smaller than that for the compressor since the specific volume of the liquid solution is much smaller
than the specific volume of a refrigerant vapor. The liquid solution is heated, which promotes desorption
of the refrigerant (ammonia) from the solution. Unfortunately, some water also is desorbed with the
Ammonia, and it must be separated from the ammonia using the rectifier.
Without the use of a rectifier, water exits at State 2 with the ammonia and travels
to the evaporator, where it increases the temperature at which refrigeration can
be provided. This solution temperature needed to drive the desorption process
with ammonia-water is in the range between 120°C to 130°C (248-F to 266°F).
Temperatures in this range can be obtained using low cost non-tracking solar
collectors. At these temperatures, evacuated tubular collectors may be more
suitable than flat-plate collectors as their elficiency is less sensitive to operating
temperature.
PROBLEM STATEMENT
Electricity consumption increasing everyday, thereby harming the economic
stability of people.
WHY IS THIS A
PROBLEM?
DATA ANALYSIS
APPLICATIONS
Household and Commercial indoor cooling purpose
Refrigeration in off-grid rural areas for preserving food and vaccine
Use in cold storage system to preserve rotten-prone food Use to make ice
cream and other related products
• Cooling purpose for Transportation vehicle like bus, car etc
IMPORTANCE
There is environmental concern regarding conventional refrigeration technologies including
contribution to ozone layer depletion and global warming. Refrigerators which contain ozone
depleting and global warming substances such as chlorofluorocarbons (CFCs).
Hydrochlorofluorocarbons (HCFCs) in their insulation foam or their refrigerant cycle, are the most
harmful. If a conventional refrigerator is inefficient or used inefficiently, it will also contribute more
to global warming than a highly efficient refrigerator. The use of solar energy to power refrigeration
strives to minimize the negative impacts refrigerators huve on the environment
• All vaccines love to be kept within a limited temperature range throughout transportation and
storage. The provision of refrigeration for this known as the Vaccine Cold Chain is a major logistical
undertaking in areas where electricity supplies are non-existent or erratic. The performance of
refrigerators fuelled by kerosene and bottled gas is often inadequate. Diesel powered systems
frequently suffer fuel supply problems, Solar power is therefore of great importance to health care.
THANK YOU!!!!!
