How to write the fuel and product exergy balances in the cascade heat exchanger in the cascade refrigeration system?
We can probably answer your question, but we need more information. For example, why would the calculations for each component or section of the process for a cascaded refrigeration system be any different than countless other systems? The arrangement of the components is somewhat different, but the same sort of components are used in a variety of systems.
Please refer: The exergy method of thermal plant analysis by T J Kotas
Dear Kenkar,
Refrigeration systems have the priority in design for residential and industrial applications. The couple of major refrigeration systems: vapor-compression refrigeration; ammonia-water absorption refrigeration; gas refrigeration where standard air is the most popular refrigerant; multi-pressure refrigeration including multistage, cascade, and multipurpose refrigeration system; and heat pump systems are quite common. Energy and exergy analysis can be presented for most of the systems. Energy and exergy analysis of gas refrigeration system and cascade refrigeration system where heat exchange is used can be calculated [Refer 1].The heat exchanger that connects the 2 cycles together has an energy balance equation, Refer as follows [1].
The energy balance for the entire refrigeration system can be given as
QL=QL+ Wcomp
[1] Çengel YA, Boles MA.Thermodynamics: A EngineeringApproach. 8th ed. USA: McGraw-HillEducation; 2015. DOI: 10.1109/MILCOM.2005.1605829.
[2]Arora CP. Refrigeration and AirConditioning. 3rd ed. New Delhi: TataMcGraw-Hill Publishing CompanyLimited; 200
Ashish
It appears that stream 13-14 is a hot stream and 2-3 is cold stream. Then the fuel component of exergy will be (Ex13-Ex14) and the product component is (Ex3-Ex2). Similarly, the corresponding exergy balance equation will be:
ExF=ExP+ExD+ExL
Ex13-Ex14=Ex3-Ex2+ExD+ExL(i.e. 0 in this case)
Ex13+Ex2=Ex14+Ex3+ExD
where 'Ex' is exergy flow rate and 'D' and 'L' stands for destruction and loss.
Regards
~JOY~
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