Analysis of direct expansion heat recovery ventilation devices by orthogonal optimization method.

Abstract

Heat recovery ventilation devices include rectangular plate cross-flow, hexagonal plate combined counter and cross-flow, rotary wheel sensible, sorption rotor hybrid sensible and latent heat exchanger. Currently, existing studies have produced no clear findings on which climatic conditions latent heat recovery would be optimal, and therefore sought to determine in which climatic conditions it would be suitable to use devices that perform latent heat recovery. This study analysed the performance of different heat recovery devices in different climatic conditions in a ventilation project of a sample hotel building. In the case study, while there is a useful heat recovery between 44.01 and 58.68kW at low outdoor temperatures in devices with only sensible heat transfer, this value increases up to 158.42kW, as the outdoor temperature rises. In the heat recovery device providing latent heat transfer, the amount of useful heat recovery varies between 51.34 and 352.16kW at low outdoor temperatures, depending on the outdoor relative humidity, while this amount increases to 411.26 from 773.25kW at high outdoor temperatures. Outdoor temperature and humidity levels required for latent heat recovery was also determined by orthogonal optimization method. By using the orthogonal optimization, the study found that under conditions of high temperature that exceeds 35°C in outdoor ambient temperature, and high humidity that exceeds 60% relative humidity, usage of latent heat recovery devices caused significant differences in total heat recovery ratio. Analysis also concludes that these devices can be used under these conditions.