The Study of the Heated Air Flow Patterns From the Condensing Unit Effecting on the Air Conditioning Efficiency and the Drying Application

Abstract

This work was aimed to investigate the effects of the heated air flow patterns from a 24000 Btu/h air-conditioning (A/C) condensing unit on the system efficiency and to study a residential application, a fabric dryer, using this exhausted heat. The experimental setup consisted of an aluminum frame and a plastic cover which could be opened in 4 sides to arrange 5 patterns of air flow in 4 weather conditions; normal and rainy daytime and nighttime. The fabric drying application was also simulated as the barriers surrounding the condenser in its installation environment. Moreover, the effects of the system cleanness and the heat convection enhancement by putting a fan driven by electricity from the solar cell on the setup were observed. In two experiments, the inlet and outlet condenser air velocities, relative humidity and temperatures of air that were inside and outside the application, solar intensity, electrical powers consumed by the AC system and the fabric weights obtained before and after the experiments, were measured and used to calculate Specific Moisture Extraction Rate (SMER) and Energy Efficiency Ratio (EER). In the first experiment, the AC was just cleaned, the results obtained from 5 flow patterns in 4 weather conditions showed that the best EER were from the 2nd (opened left and right sides or tee-way flow), 3rd (opened top and right or left sides or right-up flow) and 4th (opened back and right or left sides or right-direct flow) patterns while the best SMERs were from 2nd, 3rd and 5th (all sides was closed or collected flow) in normal and rainy daytime and nighttime. The 1st (opened back and top sides or free-end flow) pattern provided the least EER almost in all 4 weathers. One year later with the same AC without cleaning, three patterns providing the first-three best SMERs from the first experiment were tested again by coupling the setup with the fan and simulating the heavier rain condition to find the effects of the system cleanness and the heat convection enhancement. The second sets of the results showed that the 5th pattern could provide the best SMERs with the following EER at 0.593 kg/kW-hr (12.414), at 0.247 kg/kW-hr (11.613), at 0.530 kg/kW-hr (11.25) and at 0.17 kg/kW-hr (12.414) with respect to normal and rainy daytime and nighttime weathers. The cleanness was found to affect the AC efficiencies because the EERs were reduced; especially in the nighttime. The air flow patterns and the barriers affected the efficiencies of the cleaned AC more than that of the uncleaned AC. For the heated air utilization in the drying application, the convection was reconfirmed to enhance the SMERs in the drying process and the EERs. © 2014, Begell House Inc. All rights reserved.