How to achieve energy efficiency in buildings without compromising indoor air quality: A case study on enthalpy exchangers

As a representative heat recovery device, the fixed-plate enthalpy exchanger possesses the advantages of high recovery effectiveness, low pressure drop, and small space occupied. Still, indoor contaminants may transfer to fresh air through the enthalpy exchanger simultaneously, causing cross-contamination risk. However, the cross-contamination risk of the fixed-plate enthalpy exchanger has been under-researched in previous studies. As a result, this study experimentally investigates the energy performance, formaldehyde and ammonia transfer rates of paper-based and membrane-based enthalpy exchangers. The results illustrate that the enthalpy recovery effectiveness of the plate exchangers ranges from 60%–85%. The formaldehyde transfer rate through the exchangers varies from 5%–23%, and the ammonia transfer rate is 0–15%. The high effectiveness and low contaminant transfer rates are conducive to the promising application of the fixed-plate enthalpy exchangers. In addition, the energy reclaimed increases with the increase of the absolute indoor-outdoor enthalpy difference. The formaldehyde and ammonia transfer rates and cross-contamination risk slightly decrease with increasing temperature but significantly increase with increasing humidity. Moreover, the experimental results demonstrate that the contaminant transfer rates through the membrane-based exchanger are lower than those of the paper-based exchanger. This study provides a reference for the fixed-plate enthalpy exchanger design in practical applications.