Enthalpy recovery in HVAC systems by means of membrane vapour exchangers and hygroscopic solution

ABSTRACT The present paper deals with the enthalpy recovery between the renewal air and the exhaust air in HVAC systems, by using a salt solution as the intermediate fluid. The device investigated consists of two air-solution membrane contactors: one acts on the renewal air flow and the other on the exhaust air flow. In summer climatic conditions, the supply air, which is warm and humid, is dehumidified and cooled, while the discharged air, which is cold and dry, can be used to regenerate the solution. The opposite process takes place in winter climatic conditions. The analysis has been carried out by means of a SIMULINK program. The performances, which are expressed in terms of the effectiveness of the device, have been evaluated on varying some significant parameters, such as the air and solution flow rates, the exchange surface of the contactors and the climatic conditions of the outdoor air. Results of simulations show a considerable effectiveness, which can yield significant energy saving in both summer and winter conditions