A TEST METHODOLOGY FOR MEASURING GASEOUS CONTAMINANT TRANSFER IN ENERGY WHEELS

Abstract

This thesis meets some of the objectives of ASHRAE Research Project 1780, titled “Test method to evaluate cross-contamination of gaseous contaminants within total energy recovery wheels” and contains a literature review and experimental measurements of contaminant transfer in energy wheels. The literature review showed that there is no established test methodology for measuring the contribution of adsorption/desorption to gaseous contaminant transfer in energy wheels. Furthermore, most of the studies lacked a rigorous uncertainty analysis. Analysis of the data in the literature revealed that the energy wheel design parameters such as face velocity have a more significant effect on the contaminant transfer rate, i.e., Exhaust Air Transfer Ratio (EATR), than operating conditions such as temperature and humidity. Furthermore, the EATR due to adsorption/desorption was higher for acetic acid, phenol, and acetaldehyde than for other contaminants, which may be due to the high water solubility and small molecular size of acetic acid, phenol, and acetaldehyde. The thesis shows that the test facility used to measure gaseous contaminant transfer in energy wheels conserved mass and energy, provided steady state flow parameters and satisfied ASHRAE Standard 84 (2020) requirements. Experimental data showed that EATR consistently decreased with increasing air flow rate and did not change significantly with changes in outdoor air temperature. The EATR values for carbon dioxide and sulfur hexafluoride were nearly equal, indicating that carbon dioxide does not transfer by adsorption/desorption. A proposed test method for determining the contribution of adsorption/desorption in gaseous contaminant transfer in energy wheels was applied for ammonia, methanol, isopropyl alcohol, and carbon dioxide. The EATR values due to adsorption/desorption were highest for ammonia, followed by methanol, isopropyl alcohol, and carbon dioxide. The reason for the high adsorption/desorption of ammonia might be because its physical properties are similar to water.