Performance analysis and cycle time optimization of a single evaporator three-bed solid-sorption refrigeration system driven by low-temperature heat source.

This paper discusses performance analysis and cycle time optimization of a three-bed silica-gel/water adsorption chiller. Presented study builds upon the fact that desorption phase requires noticeably less time than adsorption phase, i.e. desorption is 2.2-3.5 times faster than adsorption. The operating cycle was simulated using a numerical model. Lengths of adsorption/desorption phases and the offset time between individual adsorbers were varied for optimal performance. The results show that third bed increased cooling capacity of adsorption chiller. The optimal total cycle time that yields the highest cooling capacity is slightly shorter than in a two-bed setup. The difference is larger if the chiller is driven by lower temperature, 65°C instead of 85°C. The optimal ratio between the time of desorption and the time of adsorption in a three-bed system is f ~ 0.6, while it is f ~ 0.8 in a two-bed system. The optimal offset time is 1/3 of the total cycle time. The cycle time optimization presented in the paper allowed increasing of the cooling capacity by ~6%.