Question

The transfer of heat across a gap (an interface between mould and casting) is given by_____

(a) q = h+∆T

(b) q = h/∆T

(c) q = h*∆T

(d) q = h-∆T

I have been asked this question in exam.

I need to ask this question from Rate of Solidification topic in portion Cooling and Solidification of Casting-Forming-Welding I

Answer 1

Correct answer is (c) q = h*∆T

Explanation: The transfer of heat across a gap (an interface between mould and casting) is given by q = h*∆T, where q is the heat flux, h is the heat transfer coefficient of the interface and ∆T is the temperature difference between the source and the sink. Values of the heat transfer coefficient may vary from 10 to 102 for large air gap; 103 to 104 for normal castings.