Abstract:

In contrast to standard vapor compression cooling systems, diffusion absorption refrigeration (DAR) systems are heat-driven and contain no moving parts. Solar diffusion absorption cooling systems can extract heat from a cooling chamber without electricity, enabling food and medicine to be cooled in remote places where there is high solar radiation with unavailable or unreliable electricity. This work aims to model the performance of a solar-driven DAR system with an evacuated tubes collector. The model inputs were the local hourly ambient temperature and solar irradiance for the time of June to August in Ashdod, Israel. Also, collector data, ammonia concentration in the solution, evaporator temperature and the DAR system geometry were considered. The model results showed that as the generator heat input increased rapidly the evaporator cooling capacity was kept almost constant for a given concentration and collector area. This resulted in reduction in the COP values at peak hour. An increase in the collector area had more impact on the heat applied to the generator and not resulted in a significant growth of the cooling capacity, thus, the authors concluded that for optimal COP it is advised to operate the system with lower collector areas.

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