Performance analysis of a membrane-based energy recovery ventilator: Effects of outdoor air state

A theoretical study has been carried out to investigate the effects of the outdoor air humidity and temperature on the performance of a membrane-based energy recovery ventilator operating in both hot and cold seasons. The results show that the outdoor humidity and temperature affect not only the moisture transfer resistance but also the heat transfer resistance through membrane, resulting in the ventilator performance being a complex function of the outdoor humidity and temperature. In hot weather, the sensible effectiveness changes barely with the outdoor temperature but decreases gently with increasing outdoor humidity. The latent effectiveness decreases slightly with increasing outdoor temperature but increases rapidly with increasing outdoor humidity. As the resultant of sensible and latent effectiveness, the enthalpy effectiveness initially decreases and then increases, with the minimum occurring at a certain outdoor humidity. In cold weather, the sensible effectiveness changes scarcely with the outdoor air temperature and humidity, the latent effectiveness decreases with increasing outdoor temperature but increases with increasing outdoor humidity, with the variation of the enthalpy effectiveness being similar to that of the latent effectiveness.

► Membrane thermal and moisture resistances are both outdoor air state dependent.
► Enthalpy effectiveness first decreases and then increases with increasing outdoor humidity in hot weather.
► Enthalpy effectiveness increases with increasing outdoor humidity in cold weather.
► Enthalpy effectiveness is significantly lower in hot weather than in cold weather.