Frost Thickness Variation on a Circular Tube Under Heat Pump Condition

The present study measured frost pattern on a circular tube to propose empirical correlation equations for the local and average frost thickness, frost density and frost mass. The key parameters were diameter of the circular tube (7mm, 20mm), cooling surface temperature of the circular tube, absolute humidity of air, air temperature, and air velocity. A 50% ethylene glycol aqueous solution was applied as a coolant. The effect of the air temperature was smaller parameters for the frost formation than the other parameters. The frost thicknesses at both front and rear of the tube were larger than those at the other parts, while they became higher with increasing the diameter of the circular tube. The local frost thicknesses at high air velocity were more uniform than those at low air velocity. The values predicted by the correlation under the freezer condition showed larger by the maximum of 30∼50% than the measured data under heat pump condition. The empirical correlations for the local and average frost thickness and frost mass were proposed. The empirical correlations for the local and average frost thickness, frost density and frost mass were proposed, and they agreed with the literatures within 10%.