2 kW lithium bromide absorption machine with heat recovery and recirculation for novel fluid testing

The objective of this work is to present the design, construction, and testing of a lithium-bromide absorption machine with recirculation and recovery coils in the generator and absorber. A heat transfer analysis was performed to size the heat exchange surfaces in the vacuum side of the system as well as in the cooling water loop. General heat transfer correlations provided information for the generator, evaporator, and condenser, while a more detailed analysis which included calculations for coil wetting factors was performed on the absorber. The machine was constructed of stainless steel shells with coiled copper heat exchangers, and the fluid distribution was handled by capillary action drippers. For ease of operation a refrigerant recovery tank was included along with an ejector operated purge for nonabsorbable gas removal. Running at 61% high concentration provided information on the effects of recovery coils and recirculation; it was found that a baseline COP of 55.8% can be increased by 8% using recovery methods. The results are promising, indicating a reasonable decision for further testing along with machine improvements.