Free convection frost growth in a narrow vertical channel

Processes involving heat transfer from a humid air stream to a cold plate, with simultaneous deposition of frost, are of great importance in a variety of refrigeration equipment. In this work, frost growth on a vertical plate in free convection has been experimentally investigated. The cold plate (0.095m high, 0.282 m wide) was placed in a narrow (2.395m high, 0.01m deep) vertical channel open at the top and bottom in order to permit the natural circulation of ambient air. The cold plate temperature and the air relative humidity were varied in the –40 to –4°C and 31 to 85% range, respectively, with the air temperature held fixed at 27°C (1°C). The main quantities (thickness, temperature and mass of frost, heat flux at the cold plate), measured during the time-evolution of the process, are presented as functions of the input parameters (relative humidity and cold plate temperature); in particular, the role exerted by the plate confinement on the frost growth is discussed. Data are recast in order to identify compact parameters able to correlate with good accuracy frost thickness, mass and density data.