Entropy generation and exergy destruction analyses for vapour compression refrigeration system with various refrigerants

Abstract

In this experimental work, entropy generation minimization and exergy destruction minimization concepts have been applied on vapour compression refrigeration system. For that, entropy generations and exergy destructions have been found for each component of vapour compression refrigeration system; compressor, condenser, expansion device and evaporator, and also for whole system at different time intervals with various refrigerants. Refrigerants R134a, R600a, 95%R134a + 5%R290, 90%R134a + 10%R290, 85%R134a + 15%R290 and 85%R134a + 15%R152a blend refrigerants have been chosen for this experimental research work. Percentages increments/decrements for the entropy generations and exergy destructions have also been calculated to find best conditions and refrigerant, with developed computer software which eliminate hectic calculations and human mistakes. Minimum entropy generation (i.e. 533.64 J/kgK) and exergy destruction (i.e. 160090.8 J/kg) for the system have been found for R134a, and componentwise least entropy generations and exergy destructions have also been obtained with R134a but it affects environment. After this experimental work, 85%R134a + 15%R290 blend or R600a refrigerants have been recommended for refrigeration systems because of least percentage increments for entropy generation and exergy destruction. R134a as refrigerant is generally used in the refrigerating systems but it has high global warming potential (1430 GWP), so it should be replaced by alternative ecofriendly refrigerant and R600a is favourable which has zero ozone depletion potential and least global worming potential.

Energy and exergy analyses of fabricated solar drying system with smooth and rough surfaces at different conditions: A case study

“…Gouy‐Stodola has introduced an expression for exergy destruction, which is T a S gen 58 . It means exergy destruction depends on ambient temperature and the rate of entropy generation of the system 30,33 . Rates of exergy at inlet and outlet, rates of exergy destruction, and exergy efficiencies have been found for the fabricated solar dryer system at different conditions and at different times/days 54,59,60 .…”

“…Youcef‐Ali et al 27 determined the average coefficient of internal moisture transfer for the drying of potato slices. Exergy analyses have been done on different solar systems: parabolic solar collector, compound parabolic solar collector, evacuated tube, single‐ and double‐solar still by researchers 28–34 . Mugi and Chandramohan 35 calculated the rates of inlet/outlet exergy, exergy losses, and exergy efficiencies of indirect solar dryer systems at free and forced convection techniques with 3.69 and 5.1 sustainability indexes, respectively.…”