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1. Heat Transfer by Conduction,Convection,Radiation Name:-Shaikh Juvairiya Zakir Roll No:-91 S.Y.B.Pharmacy

2. Heat Transfer Heat transfer is the process of transfer of heat from higher temperature system to a low temperature system.

3. Conduction Heat can flow only when there is a temperature gradient , i.e. heat flows from a hot surface to a cold surface . The rate of conduction through solids can be studied easily. The basic law of heat transfer by conduction can be written in the form of a rate equation as follows: Rate= driving force resistance Driving force is the temperature drop across solid surfaces, the greater the temperature drop, the greater will be the rate of heat flow.

4. Conduction The flow of heat will also depend on conductivity of material through which it is flowing For example ,conduction of heat is faster through an iron rod than wooden log.

5. Convection Convection is a process in which heat flow is a achieved by actual mixing of warmer portion with cooler portion of the same material . When we boil water we have seen bubbles and currents develop in water. This is example of convection, in which hot water at bottom become lighter and moves upwards, forcing the cold and denser water at the top to come down and thus heated up. Types:- Forced Convection :- Mixing of fluid may be obtained be use of stirrer or pumping of fluid for recirculation. Such process in heat transfer is known as forced convection.

6. Convection Natural Convection :-Mixing of fluid accomplished by current set up when body of fluid is heated . Such process known as Natural Convection. Heat Transfer Coefficient:- Consider a case of heat flowing from hot fluid through a metal wall into a cold fluid.

7. Radiation Radiation is a energy transfer process in which heat is transferred through space by means of electromagnetic waves Thermal radiation: Heat transfer by radiation is known as thermal radiation . Radiation is effective across perfect vacuum and also through layers of air. All solid bodies radiates energy when their temperature are above the absolute zero. The amount and kind of thermal energy radiated increases rapidly with temperature .

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