Heat Transfer

Thermal conductivity of a material may be defined as the

by
quantity of heat flowing in one second through a slab of the material of area 1 cm2 and thickness 1 cm when its faces differ in temperature by 1° C
quantity of heat flowing in one second through one cm of material when opposite faces are maintained at a temperature difference of 1° C
heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces
all of the above
✅ The correct answer is option D.

The operating temperature of a cold storage is – 2° C. The heat leakage from the surrounding is 30 kW for the ambient temperature of 40° C. The actual C.O.P. of refrigeration plant used is one fourth that of ideal plant working between the same temperatures. The power required to drive the plant is

by
1.86 kW
3.72 kW
7.44 kW
18.6 kW
✅ The correct answer is option D.