Transient analysis and performance prediction of a solid absorption solar refrigerator

Abstract

The transient analysis and performance prediction of an intermittent solar powered solid absorption refrigerator is presented. The refrigerator uses CaCl 2 stabilized with 20% CaSO 4 as absorbent and NH 3 as refrigerant. Transient models of heat transfer in the collector plate and heat and mass transfers in the absorbent are developed and linked with heat and mass transfer models of the refrigerant as appropriate for each operating mode. Vapour accumulation in the absorber/generator tubes is neglected. Lumped parameter analysis is utilised for the glazing covers, the collector tubes, the refrigerant and the entrapped air. The moving boundary problem arising from ice formation or melting is solved using the enthalpy method. System pressure prediction models are incorporated in the analysis. The analytical model of the refrigerator is used to build a computer simulation programme, COSSOR, version 4.0, for its performance prediction. Predicted results compared well with experimental data over the major seasons of the year at Nsukka, Nigeria. The model, with its implementation in COSSOR, is therefore a useful tool for the design, performance analysis and optimization studies of the refrigerator, and may find applications in related systems.