MODES OF HEAT TRNSFER

Modes of heat transfer

Heat transfer may be defined as the transmission of the energy from one region to another region as a result of the temperature gradient.

Heat transfer takes place in three modes.

1. Conduction

Conduction is the transfer of heat from one part of substance to another part of same substance or from one substance to another which is in physical contact with it.

While transferring heat there is no appreciable displacement of molecules forming that substance is occur.

In solid, the flow of heat is result of vibrational energy.

In liquid, the flow of heat is result of kinetic energy.

2. Convection

Convection is the transfer of heat within a fluid which is arises due to mixing of one portion of the fluid with another.

In a fluid, the flow of heat results in the microscopic motion of a fluid.

There are two types of Convection.

Natural Convection:- Heat transfer is caused by differences in density arising from a temperature gradient

Forced Convection:- Heat transfer is caused by use of external means of agency

3. Radiation

Radiation is the transfer of heat through space or matter by means other than conduction or convection.

Transfer of heat is occurred without any material medium or through a perfect vacuum.

Transfer of heat is in the form of electromagnetic waves.

When this wave falls on another body, a part of the energy is reflected, transmitted through the body and remaining absorbed by the body.

Figure of Conduction Convection and Radiation

Comments

Dracie Bradley said…

Hey, thanks for sharing such an informative blog. I was searching for heat transfers fast turnaround and found your blog. Keep it up.

29 June 2022 at 23:07

Science and technology said…

I read this blog and found this as worth reading. I also share my knowledge on my blog. Visit and read it.

24 September 2022 at 09:51

S Smith said…

This comment has been removed by the author.

5 October 2023 at 22:50

COMPARISION OF SINGLE AND MULTIPLE EFFECT EVAPORATOR

Comparison of single and multiple effect evaporator Single-effect evaporators Single-effect evaporators are used when the throughput is low, when a cheap supply of steam is available, when expensive materials of construction must be used as is the case with corrosive feedstocks when the vapour is so contaminated so that it cannot be reused. The feed and saturated steam with temperature at T F and T S respectively enter the heat- exchange section Condensed steam leaves as condensate or drips. The solution in the evaporator is assumed to be completely mixed. Hence, the concentrated product and the solution in the evaporator have the same composition. Temperature T 1 is the boiling point of the solution. The temperature of the vapor is also T 1 , since it is in equilibrium with the boiling solution. The pressure is P 1 , which is the vapor pressure of the solution at T 1 If the solution to be evaporated is assumed to be dilute and like wat

EXAMPLES OF MASS TRANSFER

Example of mass transfer Mass transfer operations The operation carried out for separating the component of the mixture, involving the transfer of (mass) material from one homogeneous phase to another, due to the difference in vapor pressure, solubility or diffusivity and in which driving force for transfer is a concentration the difference is called mass transfer operations Example:- Distillation, Gas absorption, Liquid Extraction, Drying Example of mass transfer operations Depending upon phase contact between Gas, liquid and solid phase following are the classification of the mass transfer operations Gas-gas phase contact The fragrance of incense sticks after lightning diffuse from one room to another room. Gas-liquid contact A cup of water left in a room eventually evaporate as a result water molecules diffusing into the air. This is liquid to gas diffusion. Gas absorption:- If a mixture of ammonia and air is contacted with liquid water, a large portion of

DIFFERENCE BETWEEN UNIT OPERATION AND UNIT PROCESS

Difference between Unit operation and Unit process The chemical process is a combination of unit processes and Unit operation. Hence the Difference between Unit operation and Unit process as follows. Unit process The unit process involves a chemical change or sometimes it referred to as chemical changes along with physical change leading to the synthesis of various useful product It also provides basic information regarding the reaction temperature and pressure, the extent of chemical conversions and yield of product of the reaction, nature of reaction whether endothermic or exothermic, type of catalyst used. Example: hydrogenation, oxidation, nitration, etc Unit operations The operations carried out in the chemical process industry involving physical changes in the materials handled or in the system under consideration are called Unit operations Hence unit operations involve the physical separation of the products obtained during various unit processes. I

CHEMICAL ADDA

Search This Blog