Theoretical study of the performances of an absorption refrigerating machine in sub-sahelian climatic conditions

The cooling for air conditioning or foodstuff refrigeration is ensured in most cases with compression refrigeration machines which are high electrical energy consumers. They are responsible of much greenhouse effects, especially when chlorofluorocarbons (CFCs), hydro chlorofluorocarbons (HCFCs), or certain hydro fluorocarbons (HFCs) are involved as refrigerants due to their high global warming capacities. A promising alternative to these systems is the use of absorption type refrigeration machines. Indeed, these equipments provide a very low power consumption and allow the use of refrigerants with quite low global warming potential as water, or ammonia which are natural refrigerants. In tropical countries, solar energy can be associated for heat supply making the technology more competitive and eco-friendly. In this paper a focus was made in the modelling of an absorption machine using the water-lithium bromide (LiBr-H2O) binary mixture withinsouthern Beninese climatic conditions. The effect of the operating temperatures of the main elements of the device on the coefficient of performance (COP) were analysed. The parameters that ensure optimum performance have also been determined. The results showed that the efficiency of the internal heat recovery heat exchanger and the temperatures (at the heater and the evaporator) have a significant impact on the COP. The numerical study also made it possible to determine the temperature ranges for which the absorption machine may provide good performances in tropical environments.