Heat Transfer

Introduction

Heat and the absence of heat that is cold are phenomena studied in physics. Heat transfer is a process where heat is transferred from one body to the other. In aerospace engineering and elsewhere, heat transfer is a crucial area of study. Heat transfer deals with the concepts of using, generating and exchanging, and converting energy or heat. This is achieved in physical bodies. Heat transfer is also known as heat flow. It measures and studies the flow of heat from one body to the other. The article has focused on heat conduction, radiative heat transfer, and convective heat transfer.

Heat Transfer

Heat and its associated topics are very important in competitive exams. Many kinds of questions come from heat. Heat transfer is a discipline in aerospace engineering. Heat transfer is concerned with thermodynamics and how the energy is transmitted. Heat transfer studies the flow of energy. Heat transfer deals with the concepts of using, generating and exchanging, and converting energy or heat. This is achieved in physical bodies. Several mechanisms are involved with heat transfer which are:

• Radiation
• Convection
• Conduction

Heat Conduction

Heat conduction is a process of heat transfer. Heat conduction is based on the conduction mechanism. Heat conduction also necessitates that there is a temperature difference. This temperature difference is the key to heat transfer. During heat conduction, the kinetic energy that has the most value flows towards the object where the kinetic energy is least. That is why a pan taken from a shelf and put on the stove is hot to touch. The cold surface of the pan is colder than the heat emitted from the stove. So, the heat flows from the stove to the surface of the pan. This causes the surface of the pan to heat up. Heat conduction is represented as:

• Q = [C B (th-tc)] / G

• Q = heat transfer
• C = thermal conductivity of the object
• B = area where heat transfer occurs’
• G = thickness of the object
• th = temperature of hot body
• tc = temperature of cold body

Radiative Heat Transfer

Radiative heat transfer is yet another type of heat transfer. Radiation is a slow process but not as slow as conduction. Radiative heat transfer occurs where kinetic energy in the form of electromagnetic waves is expelled from a body and those waves are then absorbed by another body. The heat waves that are expelled from a hot object are either absorbed or transmitted or get reflected elsewhere. The heating up of the earth is an example of radiative heat transfer. The heat waves transmitted from the sun heat the surface of the earth. While some degree of heat is captured by the atmosphere, a small portion of it is reflected in space. That transmission is in the form of a heatwave. Radiative heat transfer involves the following properties:

• Heat transfer happens at the surface in the form of heatwaves
• Thermal motion occurs at the particle level in the matter
• Subatomic particles like protons as well as electrons are converted into waves of electromagnetic radiation
• Radiative heat transfer can occur in all objects other than object temperature of absolute zero. 

The equation of radiative heat transfer is based on the calculations of Stefan-Boltzmann. 

Convective Heat Transfer

Convection is a type of heat transfer that happens with fluids or gases which when heat transfer is heat quickly. Convective heat transfer is concerned with the flow of heat. It looks at the medium of liquid. Convective heat transfer is based on two other mechanisms. Advection, as well as conduction, are the process involved here. The heating up of milk is an example of convective heat transfer.

Conclusion

The heat transfer happens between objects adjacent to one another. While conduction is slow convection is quick and happens rapidly. Heat transfer involves all the actions and steps mentioned here. These mechanisms are generally based on their phases. So, the transfer of heat involves all of these processes. Heat transfer is a process where heat is transferred from one body to the other. In aerospace engineering and elsewhere, heat transfer is a crucial area of study. Heat transfer deals with the concepts of using, generating and exchanging, and converting energy or heat.