Experimental Study on the All-fresh-air Handling Unit with Exhaust Air Energy Recovery

Abstract

This paperconductsa performance test for theall-fresh-airhandling unit withexhaustair energy recovery which is under the situation of changing the environment condition and changing the matching ratio between the outdoor fresh air and indoor exhaust air. It researches the unit performance under different working condition and different matching ratio between the outdoor fresh air and indoor exhaust air, in order to select the optimal economic mixing ratio between the outdoor fresh air and indoor exhaust air which adapts the different working condition. This test is tested under 30 kinds of working conditions when the dry bulb temperature of exhaust air is 27℃, the wet bulb temperature is 19.5℃, indoor exhaust air rate is 3000 m3/h, the outdoor environmental temperature is 29℃/21.2℃、32℃/23.6℃、35℃/28℃、38℃/28.6℃、41℃/31.2℃ respectively and the outdoor fresh air flow rate is 0 m3/h、400 m3/h、700 m3/h、1000 m3/h、1300 m3/h、1600 m3/h. It researches the changing rules of the important macroscopic parameters such as unit cooling capacity, input power, energy efficiency ratio etc., and the micro-parameter such as evaporation temperature, evaporator superheat, condensing temperature, and super cooling degree, etc., when the unit working under the different working conditions of fixed new air exhaust ratio and non-fixed ratio. The test results show that when the ratio of fixed indoor exhaust air to outdoor fresh air is 3000:1000, the unit cooling capacity and energy efficiency ratio increases but then decrease along with the increase of outdoor temperature, and the degree of superheat and degree of sub-cooling increase either. Non-fixed outdoor fresh air and indoor exhaust ratio compared with the former fixed situation, the unit energy efficiency ratio can be optimized to 0.16W/W. The variation range of the degree of superheat and sub-cooling decrease along with the outdoor temperature increasing, and the unit operation is more stable and safe. The research results can provide the decision reference for the design of indoor exhaust energy recovery type fresh air unit.