Experimental investigation on a novel air-cooled single effect LiBr-H2O absorption chiller with adiabatic flash evaporator and adiabatic absorber for residential application

Abstract

Air-cooled single effect LiBr-H2O absorption chiller has shown advantages in residential solar cooling applications. It can be driven by common non-focusing solar collectors, and save water, maintenance expense and space, due to the absence of cooling tower. However, there is no available small capacity commercial air-cooled LiBr-H2O absorption chiller yet, because of the crystallization risk and difficulty of miniaturization. In this work, a novel air-cooled single effect LiBr-H2O absorption chiller with adiabatic flash evaporator and adiabatic absorber was fabricated and tested. The secondary heat exchanging between refrigerant water and chilled water is avoided by introducing the adiabatic flash process, therefore the conventional chilled water circulation pump and the heat transfer pipes in evaporator are removed. In this way, it is capable of improving the COP and cooling capacity with a lower size and cost of material, as well as less electricity consumption. Furthermore, three sets of experiments were conducted with different operating conditions. The evaporation temperature at 8.6 °C can be achieved and it is able to control the indoor air temperature to 26.6 °C with a raised evaporation temperature at 14.5 °C when the ambient temperature is 35 °C. The cooling capacity and COP under low and high ambient temperature are 5.3 kW/0.72 and 4.6 kW/0.65, respectively. When the hot water temperature is raised from 80 °C to 90 °C, the thermal COP is ranged from 0.76 to 0.64. During the 9 h outdoor experiment, the average thermal COP of this prototype is 0.65. In addition, the average cooling capacity is about 5 kW and the average COPele of this prototype reaches 8.3 during the test.