solar cooling (06m55)

8/9/2019 Solar Cooling (06m55)

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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

06M55(8TH MECHANICAL)


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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

06M55(8TH M

ECHANICAL)


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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

QQ

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


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


S l th l d i t


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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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06M55(8THMECHANICAL)

solar cooling (06m55)

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