Combined Convection and Radiation
Since these two modes of heat transfer are completely independent, there would be no mutual effect between them. Thus net heat exchange of the surface is the sum of the…
Analogy between Heat Transfer and Electric Circuits
There exists an analogy between the diffusion of heat and electrical charge. Just as an electrical resistance is associated with the conduction of electricity, a thermal resistance may be associated…
Radiation Heat Transfer (Heat transfer by thermal radiation)
All bodies radiate energy in the form of photons moving in a random direction, with random phase and frequency. When radiated photons reach another surface, they may either be absorbed,…
Heat Exchangers
The general function of a heat exchanger is to transfer heat from one fluid to another. The basic component of a heat exchanger can be viewed as a tube with…
Some Considerations in Modeling Complex Physical Processes
In Sections 5 and 6, a number of assumptions were made about the processes that we were attempting to describe. These are all part of the general approach to modeling…
Transient Heat Transfer (Convective Cooling or Heating)
All the heat transfer problems we have examined have been steady state, but there are often circumstances in which the transient response to heat transfer is critical. An example is…
Heat Transfer From a Fin
Fins are used in a large number of applications to increase the heat transfer from surfaces. Typically, the fin material has a high thermal conductivity. The fin is exposed to…
Temperature Distributions in the Presence of Heat Sources
There are a number of situations in which there are sources of heat in the domain of interest. Examples are: 1) Electrical heaters where electrical energy is converted resistively into…
Thermal Conductivity, k
As noted previously, thermal conductivity is a thermodynamic property of a material. From the State Postulate given in thermodynamics, it may be recalled that thermodynamic properties of pure substances are functions of two independent thermodynamic intensive properties, say temperature and pressure. Thermal…
Heat Transfer: Radiation
So we’ve learned that conduction moves heat easiest through solids, and convection moves heat through liquids and gases. So how does the heat from the Sun get to Earth? There…
