Impact Of Supply Air Flow Rate On System Performance And Space Comfort Of Residential Air Conditioning Systems
Abstract
The amount of air flow rate supplied to the space by the residential air conditioning system can have significant effect on the whole system performance and on the thermal comfort level. This study investigates the impact of air flow rates when they are higher or lower than the current practices or manufacture's specified values on system performance and on space comfort. In addition, this work examines the performance operation data such as (1) the annual and hourly energy consumption, (2) the system operation hours, (3) the temperature of air supplied to the space, (4) humidity ratio of the space, (5) system efficiency, and (6) the amount of sensible / latent load that can be added / removed from the space. Experiments are conducted on the air conditioning heat pump located at the HVAC laboratory of the Civil, Architectural & Environmental Engineering (CAEE) department in order to identify experimentally the fan performance and define the fan performance curve and efficiency. Simulations are also done to investigate the whole system performance of air conditioning systems and associated thermal comfort with different USA locations based on ASHRAE climate zones. The model is developed by the energy simulation software eQuest, using the characteristics of the tested lab system for a 1600 ft2 typical residential house conditioned by 3-ton residential air conditioning heat pump system. The simulation model is tested on various air flow rates, ranging from 900 cfm to 1400 cfm and considering 1200 cfm as baseline. The results show an increase in the fan energy and total annual energy consumption with the higher airflow rate supplied. A higher temperature of the airflow causes elevated humidity in space that can become an issue in terms of space comfort, especially in humid weather locations.