Sample interview questions: How do you calculate the rate of heat transfer in a system?
Sample answer:
Calculating the Rate of Heat Transfer
The rate of heat transfer, also known as heat flux or thermal power, is determined by several factors, including the temperature difference between the system and its surroundings, the area of heat transfer, and the thermal conductivity of the material separating the system from the surroundings.
Calculating Heat Transfer Rate by Conduction:
Q = -kA * (dT/dx)
where:
- Q is the heat transfer rate (in watts)
- k is the thermal conductivity of the material (in W/mK)
- A is the area of heat transfer (in m²)
- dT/dx is the temperature gradient (in K/m)
Calculating Heat Transfer Rate by Convection:
Q = hA(T_s - T_∞)
where:
- Q is the heat transfer rate (in watts)
- h is the convective heat transfer coefficient (in W/m²K)
- A is the surface area of heat transfer (in m²)
- T_s is the surface temperature (in K)
- T_∞ is the fluid temperature (in K)