OPTIMAL ALLOCATION OF A HEAT-EXCHANGER INVENTORY IN HEAT DRIVEN REFRIGERATORS

This paper reports the thermodynamic optimization (or entropy generati on minimization) of a heat-driven refrigeration plant, that is, a refr igerator without work input, which is driven by a heat source. The tre atment accounts for the heat transfer irreversibilities of the three h eat exchangers, and for the finiteness of the total heat-exchanger inv entory. The operating conditions for maximum refrigeration rate are de termined. It is shown that the heat-exchanger inventory must be divide d optimally between the three heat exchangers. For example, half of th e inventory must be placed in the hear exchanger used to reject heat t o the ambient. The maximum refrigeration rate per unit of total heat e xchanger inventory is reported. These thermodynamic optimization princ iples are then applied to a refrigerator driven by heat transfer from a solar collector.