A review of recent progress in active frost prevention/control techniques in refrigeration and HVAC systems

Abstract

Frost accretion is a common problem in HVAC and refrigeration systems. Frost accretion strongly impacts the operating efficiency of HVAC equipment and leads to a considerable increase in energy consumption. Therefore, energy-effective frost control techniques can significantly enhance the coefficient of performance of HVAC systems while also enhancing the lifecycle durability of the equipment. More recently, passive and active frost control and defrosting techniques have been proposed to reduce/control frost growth on heat transfer surfaces and ultimately enhance the thermal/hydraulic performance of HVAC systems. This review paper is focused on active prevention and frost removal techniques in HVAC, heat pumps, and refrigeration systems. This work was conducted by categorizing the defrosting methods into frost prevention strategies and frost removal strategies. Frost prevention strategies include treating and conditioning the upcoming inlet airflow and vapor injection techniques. On the other hand, frost removal strategies include reverse cycle defrosting (RDC), oscillation and ultrasonic vibration, hot gas bypass, and the use of applied electric and magnetic fields, among other techniques. Despite extensive theoretical and experimental work on active frost removal and control techniques, no baseline for comparison has been established, making it challenging to compare different techniques. Finally, future prospects and conclusions are discussed in detail, and future research and development directions are proposed.