Solar-driven hybrid absorption-thermochemical refrigeration systems: performance estimation.

This paper discusses the selection of appropriate ammonia-based working pairs as well as the performance estimation for the hybrid absorption/thermochemical refrigeration cycle that we recently proposed. This system requires a low-grade heat source, especially by solar thermal collector, and combines an absorption continuous cycle with a thermochemical discontinuous cycle, to combine the former’s better performance with the latter’s high energy density of storage with negligible heat losses. In the hybrid system, both subcycles share the same refrigerant fluid (ammonia), condenser and evaporator, but have different sorbent pairs. For selected evaporation temperatures between -10 ºC and 10 ºC and condensation temperatures between 20 ºC and 30 ºC, we carry out a parametric study of the system and identify some suitable working pairs. In addition, we estimate, for demand profiles typical of refrigeration applications, the cycle’s Coefficient Of Performance (COP), and compare these values when different working pairs are used.