An efficient enthalpy exchanger for economical ventilation.

A cross-flow polymer membrane enthalpy exchanger has been designed which provides both heat recovery and moisture dissipation in the ventilation of living spaces. The exchanger is of benefit in providing fresh air during both cooling and heating seasons with minimum loss of energy. A prototype of the enthalpy exchanger has been constructed and tested. The air leakage of the equipment has been found to be negligible; that is, the two air streams are indeed non-mixing. Testing for efficiency of the equipment involved the measurement of dry bulb and wet bulb temperatures in each of the four ports. The measured temperature values were used to calculate the efficiency of the exchanger. The results show a total efficiency of 72%, with 71% sensible heat recovery and 74% latent recovery. These efficiencies were achieved at an air flow rate of 1.7 m³/minute (60 cfm) . The measured moisture transfer rates exceed the predicted moisture transfer rates by factors of two and three.