Design and analysis of a gas heating/cooling sorption refrigeration system with multi-salt solid sorbent of CaCl2 and MnCl2

Multi-salt sorbents were reported with better performance than single salt sorbents because they could reduce the sorption hysteresis phenomena, but such type of sorbents have not been utilized in the refrigeration systems. In this paper, a gas heating/cooling sorption refrigeration system with multi-salt sorbent of CaCl2/MnCl2 is designed and analyzed, and the results show the maximum SCP gets to about 330 W kg−1. The system is proposed for refrigerated truck transport and it makes the structure much simpler than the previous two-stage refrigeration system because only one sorption bed is required. The critical conditions, such as low heat transfer coefficient of exhaust gas and cooling air as well as high cooling temperature in hot summer, are considered. The sorption bed with a tri-pass structure for exhaust gas is compared with the tetra-pass design, and it shows better performance for that the pressure drop of the modularized sorption bed is only about 380 Pa when the air flow rate is 600 m3 h−1, and the engine performance won't be affect if such a bed is installed at the outlet of exhaust pipe of the truck. The heat transfer performance of the bed with tri-pass for exhaust gas is analyzed by the experimental system set up in the lab, and it has a heat transfer rate of about 60 kW/m3 sorption bed during the desorption process, which is about 2.3 times that of the conventional liquid heating/cooling system. The preliminary test results show that the volumetric refrigeration capacity gets to about 19 kW m−3, increasing by almost 30% when compared with the liquid heating/cooling system.