Thermal Design Studies and Thermodynamic Modeling of a Double- Absorption Open Cycle Hybrid Solar Space-conditioning System

摘要

This paper presents the thermodynamic and thermal design studies of a double-absorption open cycle hybrid solar space-conditioning system comprising of an open cycle vapor-absorption and liquid desiccant cycles. A systematic thermal design procedure using well known empirical correlations for various parameters has been developed and evaluated the sizes of various components viz. open absorber, closed absorber-evaporator assembly, heat exchangers and open solar collector-cum-regenerator for a 1 ton cooling capacity double-absorption hybrid space conditioning system for LiBr-H_2O as a potential working fluid. The system has been designed for fixed outside air conditions (dbt 40°C, RH 40%) as well as desirable room air conditions (dbt 28°C, RH 60%) with a regenerator temperature of 65°C, the evaporator temperature of 12.8°C, recirculating cooling water temperature of 32.2°C and solution flow rate (FR) of 18. It is found that the system design is practical and can be used for the prototype development of the unit. The performance comparison of closed and open cycle hybrid double-absorption solar cooling system was also carried out and it was established that the open cycle hybrid double-absorption solar cooling system is better having an overall coefficient of performance (COP) of 0.27. From the thermodynamic and thermal design studies it is concluded that the open cycle double-absorption hybrid cooling system is technically and economically feasible with solar energy.