# An Explanation to “The Concept of Heat Transfer”

Category: Syllabus 20 0

### An Explanation to “The Concept of Heat Transfer”

Heat Transfer is one of the most important concepts and subjects in the stream of Mechanical Engineering. I have already written an article on Mechanical Engineering, you could visit our Educational Website www.careersamosa.com or click here http://careersamosa.com/career-mechanical-engineering/ and even here

http://careersamosa.com/mechanical-engineers-actually/

In the above mentioned link I have already explained in great detail about the work profile of Mechanical Engineers, as to what they do? And what is their work comprising of? Therefore keeping in mind their scope of duty , it becomes an absolute necessity to know about important subjects such as the strength of material, thermodynamics and heat transfer.

For the first two topics I have already written exclusive articles, but for the latter, here is an article that would not only introduce you to the concept of “Heat Transfer” but would also explain in a very clear and lucid language, keeping in mind not only those Engineering Geeks and Students but also for those who are not from the stream of Engineering.

But before we could understand the concept of the heat transfer, it might be beneficial to understand the scientific and technical explanation of these two words Heat and Transfer.

Technical Definition of Heat/ What is Heat?: we all know that all substance and matter comprises of atoms and molecules. And these atoms and molecules are always in motion, vibration, translation or even rotation. The intensity of the motion of atoms and molecules generates heat or energy, the greater the intensity, the greater the Heat Generated.

Thus to put it in another words, the more the motion of the atoms and the molecules the more the heat and the intensity would be generated. On perfect e.g. would that be the comparison of normal water and cold water. You can just make out the difference in the reaction of both the liquids.

Technical Definition of Transfer: transfer would simply mean the movement from one place to another. Thus whether it is the goods or commodities or heat, the basic priniciple will always remain the same “movement from one place to another”

Heat Transfer: Thus from the above we could conclude that the transfer of heat from one place to another is called Heat Transfer. According to scientific principle heat always transfers and moves from a hot place to a cold place.

Most of us, “No Scratch that all of us are aware that heat transfers from a hot substance  to a cold substance and Hot Air is always lighter than cold Air, and hot air is always above Cold Air and will always rush towards cold Air.

Even the first law of Thermodynamics, explicitly states that Heat Transfer modifies and changes the Internal Energy of both the systems involved in the process.

Modes of Heat Transfer: usually there are 3 modes by which the heat is transferred and these are Conduction, Convention and Radiation.

Conduction:  Heat Transfer by the Conduction Mode in done by the molecular agitation that take place within any material or substance, without any notion of any material or substance as a whole. One perfect e.g. of heat transfer by conduction is when the one end of the metal rod is heated up at a higher temperature then automatically the heat/energy is transferred towards the other end which is cold.

The above change does take place because of the atoms and the molecules that are heated, start moving at higher speeds and collide with the atoms and molecules at the other end which are not heated at all. So there is a net transfer of the atoms and molecules form the hotter end of the metal to the colder end of the metal.

Convection: Heat Transfer by the Convection Mode takes place by the Mass Motion of Fluid such as water or Air. So when water or air is caused to heat, then it carries heat with it during its movement to colder places.

Convection of Heat over a heated surface takes place because hot air is light and less dense, as compared to cold air, so hot air expands and becomes less dense and arises above cold air. Convection also induces to the circulation of liquid just as the same way as a pot heated with water in it.

Thus heated water becomes less dense and expands and evaporates, while the cold water which is denser takes its place and this is how the circulation of liquids takes place by the convection mode of heat transfer.

Radiation: Heat Transfer by the Radiation mode is very unique and different when compared to the above two modes of heat transfer. Radiation of heat is a mode of heat transfer in which there is no relation or contact between the heat source and the substance that is heated (like the conduction and the convection)

In the Radiation of Heat Transfer mode, the heat can be transferred even by the empty space by the thermal radiation also called infrared radiation. Infrared Radiation is a type of Electromagnetic Radiation in which no mass or substance is exchanged, even no medium is required in the process of Radiation. The best e.g. of radiation is that of the heat or the energy, which is emitted from the sun or any light bulb.

The above article was written on the definition and the concept of the “Heat Transfer” and the “Modes of the Heat Transfer”.  Please visit our website www.careersamosa.com for more information on other such related articles such as Thermodynamics, Strength of materials and the books relative to the subject Etc.