Frost prevention research of the enthalpy wheel in air conditioning systems and industrial heat recovery systems

Abstract

Enthalpy wheels are often used for air dehumidification and waste heat recovery. Application scenarios include air conditioning systems and industrial systems.Frost formation inside the enthalpy wheel is common in cold climates and has serious impacts on operational reliability and heat recovery performance. It is found that frost type, frosting area and frosting limit vary between different scenarios. Experimental and numerical investigations are conducted in the present research. For a certain wheel, inlet parameters of supply air and outlet parameters of exhaust air are the key factors influencing frosting formation. The enthalpy wheel will operate regularly without frost formation if exhaust temperature is higher than the frosting limit. Reducing the enthalpy wheel rotation speed below 6 rpm is an effective method to prevent the enthalpy wheel from frosting, but heat recovery efficiency is correspondingly reduced. Industrial systems are less affected by the cold climate, especially at higher exhaust air temperatures. Even if the climate temperature drops to −30 °C, the heat recovery efficiency can still exceed 85%. The research is anticipated to be useful for the application of enthalpy wheels in cold climates.