Basics
What are modes of heat transfer
conduction, convection, and radiation
Define conduction
If a temperature gradient exists in a continuous substance for which heat transfer occurs without any observable motion of matter.
Define convection
If there is a heat transfer between a solid surface and an adjacent fluid, that heat transfer is associated with the movement of the fluid then it is known as convection heat transfer.
Define radiation
Heat transfer in the form of electromagnetic waves without the presence of any intervening medium is called Radiation.
Heat flux units
W/m2
Fourier's law?
Heat flux ∝ Temperature gradient
Newton’s law of cooling?
Convective flux usually proportional to the difference between the surface temperature and the temperature of the fluid, as stated in Newton’s law of cooling.
Stefan-Boltzmann law?
Total emissive power of a black body is proportional to the fourth power of the absolute temperature
Heat transfer rate units
Watts or J/s
Example for conduction
The process of heating a pan on a stove
Define Forced convection
If there is a heat transfer between surface and flowing fluid, the flow of fluid is caused by external means, such as fan or pump then it is called forced convection.
Example for radiation
The transfer of heat energy from the sun to the earth is an example of radiation
What is the driving force for heat transfer
temperature difference
Thermal conductivity units
W/mK
heat transfer coefficient units
W/m2K
Stefan-Botzmann’s constant units?
W/m2K4