Basics Of Heat Transfer

Heat Transfer basically means that the heat is either given out or absorbed in to reach at normally room temperature or specified ambient temperature.It is obtained when two or more bodies from different temperature environment are brought into contact. The hot body will initiate heat transfer and will tend to loose heat while the cold body will tend to gain heat to reach optimum temperature where both bodies acquire same temperature.

If we talk more about basics let us first understand about the phenomena occurring.
The process of letting heat out into the environment is termed as Exothermic reaction.The enthalpy (total energy of a system) gives off a positive sign.A common example may be taken of fire or flame.When we increase our proximity,we feel the heat.
The process of absorbing heat inside from the environment is termed as Endothermic Reaction.The enthalpy gives off a negative sign.A common example may be taken of evaporation of water.Evaporation takes place at every temperature gathering the heat from surroundings and hence water droplets get evaporated.Some examples are also defined in
http://antoine.frostburg.edu/chem/senese/101/thermo/faq/exothermic-endothermic-examples.shtml

Now let us talk a bit more on heat transfer.
There are three modes of heat transfer stated as conduction,convection and radiation.
Conduction maybe defined as heat transfer taking place in solids (and stationery fluids which occurs rarely) due to intermolecular forces which transfers the heat from one molecule to its neighboring molecule and so on.
Convection takes place due to fluid motion.
Radiation takes place when heat is transferred through electromagnetic waves and doesnt require any medium.

Heat transfer is directly related to laws of thermodynamics.
First law of thermodynamics states the phenomena of law of conservation of energy that is energy can neither be created nor be destroyed but can be converted from one form to another.
Second Law of thermodynamics states that heat is always transferred from hot to cold body.

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