Optimization analysis of a hybrid fresh air handling system based on evaporative cooling and condensation dehumidification

Abstract

This paper studies a fresh air handling system, which is composed of a mechanical compression refrigeration system and an evaporative cooling system. In an effort to improve the basic systems, a single-stage total heat recovery module consisting of a cooler and a spray packing is incorporated into the system (process I). The results show that when keeping the total heat and mass transfer capability constant, the coefficient of performance (COP) of process I first increases and then decreases with increasing heat and mass transfer capability of the total heat recovery module. Under typical summer conditions, the optimum COP of process I is 8.5% higher than that of the conventional system. To reduce the exergy destruction in the total heat recovery module and increase the supply air temperature, a single-stage sensible heat recovery module is also incorporated (process II), leading to a further increase in the optimum COP of 3.3% and suitable supply air temperature. A test device based on process II was constructed to experimentally validate the simulation results. The experimental results demonstrate that the system performance is better for high temperature and humidity fresh air conditions owing to the higher proportion of total heat recovery.