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1. Hardish TrivediStudent @department of mechanical engineering 2.Prof H A PATELMECHANICAL ENGINEERING
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ContentsIntroductionSolar cooling path and local conditionsPerformances
RefrigerantsHeat-driven systemsElectricity-driven systemsComparisonsReview from the ISES congress
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S o l a r T
C o l l e c- F l a t P l a- E v a c u a
Photovoltaics 7 0 C
F l
a t P l a t
1 0 0 C
1 5 0 C
E T
CC o n c e n
3 0 0 C
h e
a telectricity
D e
E jV
A
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)( W Q
QCOP
in
e
+
=
W
QCOP eelec =
COP of the refrigeration sub-system Thermal-driven system
Electricity-driven system
Performance
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System Performance STR (System Thermal Ratio)?
SEE (System electrical efficiency)?
System efficiency??
)( W QQ
s
e system
+=
s
e
STR =
W Q
SEE e=
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Working fluids
Solar collector sub-cycle
Refrigeration sub-cycle
G e n e r a t o r
E v a p o r a t o r
C o n d e n s e r E j e c t o r
P u m p
T h r o t t l e
v a l v e
S o l a r C o l l e c t o r
W
Q s
Q e
Q c
5
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Refrigerants
1. Physical and thermodynamics characteristics2. Environmental impact
3. Safety4. Economic and availability
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Basic Refrigeration Cycle
Condenser
Evaporator
Compressor
Exp.
device PV
electricity
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Heat-driven systemsAbsorption
Exp valve
Condenser
Regulatingvalve Pump
Heatexchanger
S o l a r c o l l e c t o r
Absorber
Generator
Evaporator
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Heat-driven systemsAdsorption
Sorber
Condenser
Evaporator Q cs
Sorber
Condenser
Evaporator
Desorbedvapour
Refrigeration Regeneration
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Heat-driven systemsChemical reaction
Captor-adsorber generator
Condenser
Evaporator
Reservoir
gas
liquid
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Heat-driven systemsDesiccant system
Desiccant Wheel Heat Exchanger Wheel
Humidifier
Humidifier
Heater
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Heat-driven systems Rankine
Electricityproduction
Exp.device
Alternator Compressor
Pump
Condenser
Boiler
Turbine
Evaporator
Condenser
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Heat-driven systemsEjector
Generator
Evaporator
Condenser Ejector
Pump
Exp.device
Solar Collector
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PV-driven systems Thermo-electric (Peltier)
P N PP N N
Heat absorbing surface
Heat rejecting surface
Q 1
Q2
t1
t2
PV
Hot side
Cold side
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PV-driven systemsStirlingHeat
exchanger HeatExchanger
C o m p r e s s i o n
p i s t o n E x p a n s
i o n
p i s t o n
Expansionspace
Compressionspace
Heatsource
Coldside
Hotside R
e g e n e r a
t o r
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Photovoltaic driven systems
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Systems
Power for 1 W of
refrigeration
effect
(W)
COP WorkingFluids Applications Advantages Disadvantages
Vapor-compression
12-50 3-5 R134a,R290,or etc.
Refrigeration
- High COP- Long term experience
and widely commercialavailable
- Adjustable from asmall to a large system
- Installation cost is highand it requires batteryfor energy backup.
Thermo-electric (Peltier)
A few W 0.5 - Refrigeration
- No working fluid andno moving parts
- Quiet
- Small size and lightweight
- Low COP- Difficult to achieve a low
refrigerationtemperature
- Low reliability especiallywhen the power supplyis cut.
Stirling
3-17 3He,H 2 ,Air
Refrigeration
- High COP for hightemperature difference
- Can be used for cryogenic applicationsand it is mechanicallymore simple than other application for lowtemperature operation.
- Environmental friendlyworking fluid
- Mobility and lightweight
- High production cost- Complexity in design
P N PP N N
Heat absorbing surface
Heat rejecting surface
Q 1
Q 2
t1
t 2
PV
Hot side
Cold side
Condenser
Evaporator
Compressor
Exp.device PV
electricity
Heatexchanger HeatExchanger
C o m p r e s s i o n p i s t o n E x
p a n s i o
n
p i s t o n
Expansionspace
Compressionspace
Heatsource
Coldside
Hotside R
e g e n e r a t o r
Remark: COP is a coefficient of performance of the refrigeration sub-system. It shows how much heat can be removed from a cold region for each unit of energy used.
Photovoltaic-driven systems
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Systems
Gen. /Regen.Temp.
(C)
COP WorkingFluids Applications Advantages Disadvantages
Absorption
80-190
0.6-0.8(single stage)
1.3(2 stages)
NH 3 /H 2 O,H 2 O/LiCl,H 2 O/LiBr
Refrigerationand
Air-condition
- Only one moving part(pump) with possibly nomoving part for a small
system- Low-temperature heat
supply is possible.
- Low COP- It cannot achieve a very low
evaporating temperature.- The system is quite
complicated.
Adsorption
80-300 0.3-0.8
H 2 O/Zeolite,Methanol/Activated
carbonRefrigeration
- No moving part (exceptvalve)
- Low operatingtemperature can beachieved.
- Thermal COP is quitehigh compared to other heat operating system.
- High weight and poor thermalconductivity of the adsorbent.For high capacity system, itcan cause long-termproblems.
- Low operating pressure
requirement makes it difficultto achieve air-tightness.
- Very sensitive to lowtemperature especially thedecreasing temperatureduring nighttime.
- It is an intermittent system.
Desiccant
40-100 0.5-1.5 water Air-condition
- Environmentallyfriendly, water is usedas the working fluid.
- Can be integrated witha ventilation andheating system.
- It cannot function properlyin a humid area.
- It is not appropriate for an
area where water isscarcity.- Requires maintenance due
to moving part in a rotor wheel.
Ejector
80-150 0.3-0.8
Water,butane,R141b,R245fa,or etc.
Air-condition
- Low temperature heatsource can be used.
- Low operating andinstallation cost.
- Low COP
Sorber
Condenser
Evaporator Q cs
Sorber
Condenser
Evaporator
Desorbedvapour
Refrigeration Regeneration
Desiccant Wheel Heat Exchanger Wheel
Humidifier
Humidifier
Heater
Generator
Evaporator
Condenser
Ejector Pump
Exp.device
Solar Collector
Solar thermal-driven systems
Exp valve
Condenser
Regulatingvalve Pump
Heatexchanger
S o l a r c o l l e c t o r
Absorber
Generator
Evaporator
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