ABSTRACT
The frost growth on a cold horizontal circular cylinder under natural convective has been investigated experimentally. The cylinder is placed in an isolated test room in order to permit the natural circulation of ambient air. The ambient air relative humidity changed in the range 30 to 60 percent for the temperature of 20 to 35°C. The ethylene-glycol/water solution is used as a refrigerant to control and kept the temperature of the test section at a constant value. The cold surface temperature has been varied in the –10 to –4°C range.
The frost thickness is measured with a digital camera. Images of frost deposition on the top and bottom surface of the cylinder are acquired every 15 minutes and frost thickness was determined by image processing technique.
The frost thickness was found to depend mainly on time and on the temperature difference between ambient and the cold surface.
Effects of variations of ambient air temperature and relative humidity and cold surface temperature on the frost growth rate are also investigated.
Three stages of frost formation (column growth, fully developed stage, and melt-back) which are reported by many researchers for other geometries than circular cylinder in forced convection conditions are observed similarly for circular cylinder in natural convection conditions.
