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Solar refrigeration system with calulations
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SOLAR REFRIGERATION SYSTEM
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BASIC CONCEPT
Utilisation of solar energy for cooling purpose
In this system ,solar energy is coupled with vapour absorption refrigeration system
VAPOUR ABSORPTION REFRIGERATION SYSTEM
The main parts of basic VARS are: Absorber
Pump Generator Condenser Throttling valve Evaporator
VARS PAIRS
Ammonia Water Water LiBr R22 - dimethyl ether tetraethylene glycol
(DMETEG) R21 - DMETEG R22 - dimethyl formamide (DMF) R12 - dimethyl acetamide R22 - dimethyl acetamide R21 - dimethyl ester
LAYOUT
WORKING
• Ammonia vapour produced in the generator at high pressure from strong solution of NH3 by an external heating source.
• The water vapour carried with ammonia is removed in the rectifier and only dehydrated ammonia gets enters into the condenser
• The cooled NH3 solution is passed through throttle valve and the pressure and temperature of refrigerant are reduced below the temperature to be maintain in the evaporator.
The low temperature refrigerant enters the evaporator and absorbs the required heat from evaporator and leaves the evaporator as saturated vapour
Slightly superheated low pressure NH3 vapour is absorbed by weak solution of NH3 which is sprayed in the absorber
Weak NH3 solution(aqua-ammonia) entering the absorber becomes strong solution after absorbing NH3 vapour and then it is pumped to the generator through heat exchanger
The pump increases the pressure of strong solution to generated pressure.
The strong NH3 solution coming from the absorber absorbs heat from high temperature weak NH3 solution in heat exchanger
The solution in the generator becomes weak as NH3 vapour comes out of it
The weak high temperature ammonia solution from the generator is passed to the heat exchanger from throttle valve
The pressure of the liquid is reduced to absorber pressure by the throttle valve
COMBINING VARS WITH SOLAR ENERGY
The main power consumption of VARS is generator.
So,the power is supplied by solar energy
Hence the amount of energy required to run the generator is calculated for the desired conditions.
CALCULATIONS
Calculations are performed for the ammonia water VARS based on
Condenser PressureEvaporator PressureGenerator TemperatureAbsorber Temperature
Calculations related to heat
Calculations related to radiation
MONTHS EQUIVALENT DAYS
JANUARY 17
FEBRUARY 16
MARCH 16
APRIL 15
MAY 15
JUNE 11
JULY 17
AUGUST 16
SEPTEMBER 15
OCTOBER 15
NOVEMBER 14
DECEMBER 10
EQIVALENT DAYS FOR MONTHS
MONTHS AVG. SUNSHINE HOURS
JANUARY 8.6
FEBRUARY 9.5
MARCH 9.8
APRIL 9.2
MAY 8.4
JUNE 6.5
JULY 4.8
AUGUST 5.3
SEPTEMBER 6.2
OCTOBER 6.5
NOVEMBER 6.9
DECEMBER 7.6
AVERAGE SUNSHINE HOURS FOR MONTHS
TIMELINE
REFERENCES
Refrigeration and air conditioning -
C.P.AroraSolar Energy-Principles of Thermal
Collection and Storage - S.P.
Sukhatme www.ashrae.orgwww.wikipedia.org