Performance Analysis on Evaporators in Air Source Heat Pumps: A Comparative Study of Finned-Tube and Microchannel Heat Exchangers with Varying Superheat under Dry Conditions
This study analyzes the thermal performance of evaporators in air source heat pumps, focusing on various operational conditions that affect thermal resistance. The research is conducted on a specialized test rig equipped with a variable adjustable refrigeration circuit within a climate-controlled chamber, allowing for precise simulation of real-world scenarios. This setup enables comprehensive evaluation of heat transfer and frost behavior under controlled conditions, including variations in temperature, humidity, and airflow rates. In the study, two distinct types of heat exchangers are examined: A fin-and-tube heat exchanger and four microchannel heat exchangers. These designs are compared based on their thermal performance, pressure drop characteristics, and susceptibility to frost buildup. By varying the operational parameters, especially the refrigerant heat exchanger outlet superheat, the study aims to understand how this factor influences the rate and pattern of thermal performance and subsequent frost accumulation on the evaporators. The findings of this research offer valuable insights into optimizing the operation of evaporators in air source heat pumps, particularly concerning superheat controlling. Additionally, the benefits and drawbacks of different evaporator types are discussed, and potential optimization pathways for microchannel heat exchangers are outlined to promote their increased implementation in heat pumps.