Q.32. The average heat transfer co-efficient on a thin hot vertical plate suspended in still air can be determined from observations of the change in plate temperature with time as it cools. Assume the plate temperature to be uniform at any instant of time and radiation heat exchange with the surroundings negligible. The ambient temperature is 25,c° the plate has a total surface area of 0.1 2m and a mass of 4 kg. The specific heat of the plate material is 2.5 KJ/kgK. The convective heat transfer co-efficient in W/m2 K, at the instant when the plate temperature is 225c° and the change in plate temperature with time dT/dt = 0.02 K/s, is
(A) 200
(B) 20
(C) 15
(D) 10
Answer: (D)
Explanation:
