I have a disc with drilled holes with a 0.1 mm tolerance. The plate is 6061 T6 Aluminum and I want to insert a polyethylene tube with water in it that is frozen. Assuming some tubes are in full contact with the Aluminum and some have a 0.1 mm air gap. How much will this affect the defrosting time.
Heat transfer coefficient
- K_aluminum = 170 W/m.K
- K_polyethylene = 0.5 W/m.K
- K_air = 2.5 - 10 W/m.K
I have chosen the low range of the air heat transfer coefficient as the air between the tube and aluminum would be relatively still so I assume convection effect is smaller.
further assumptions are that the Aluminum stays at 35C.
my calculations show negligible effect of <1% but my intuition is that the effect is larger as there is no direct contact and air is known as a good insulator.