CHEMICAL ENGINEERING….. TOPIC… HEAT TRANSFER ….

Double pipe heat exchanger Content Definition of Heat Transfer Modes of Heat Transfer Double pipe heat exchanger

Heat Transfer Definition it is the transfer of heat from one body to another body due to temperature difference.

Modes of heat transfer it is three types of heat transfer 1 conduction 2 convection 3 radiation

CONDUCTION It is transfer of heat from one body to another body which are in physical contact it is called conduction

Convection it transfer of heat from one point to another point with in fluid by mixing of hot and cold portion of the heat . EXAMPLE HEATING BY ROOM OF STEAM RADIATION

Radiation : It refer to the transfer of heat energy from one body to another body ,not in contact with it by electromagnetic waves through space EXAMLE : THE TRANSER OF HEAT FROM SUN TO EARTH

Types of heat Exchanger Double pipe heat Exchanger SHELL AND TUBE heat exchanger DOBLE PIPE HEAT EXCHANGER; It is simplest type of heat exchanger used in industry. it is used when the heat area required is relatively small. it consist of concentric pipes connecting, tees or return head and return band. the packing gland support the inner pipe with in the outer pipe. A double pipe heat exchanger arranged in the two legs .tees are provide with nozzle or screwed connection .for permitting entry and the exit of the annulus fluid which cross from one leg to another leg . Through the return head .the return bend connect two legs of the inner pipe to each other. this exchanger can be very easily assembled in any pipe fitting shop as it consist of standard parts it provides in expensive heat transfer surface .in this exchanger one of the fluid flow through the pipe and the other fluid flow through the annular space, created between two concentric pipes either in co-current or counter current fashion it is usually employed for decreasing the temp. of hot fluid with the cold fluid .when flow rates are low . These are commonly used in refrigeration service

SHELL AND TUBE HEAT EXCHANGER ; It is used where large heat transfer surface are required shell and tube .heat exchanger are commonly used. These heat exchanger equipment can be fabricated from a wide range of material of construction .

SENSIBLE HEAT : It is heat transfer that must be transfer either the rise or lower of the temp. a substance. It is the heat that absorbed or given out by a substance during a change of temp. which is not temp. without face change

LATENT HEAT: When matter under goes a face change. Enthalpy change associated with a unit amount of matter at a constant temp. and pressure are called latent heat

HEAT TRANSFER COEFFICENT : Heat transfer coefficient is the quantity of heat transfer in a unit area at the temp. diff. At the temp. diff. of 1*c between the surface and surrounding. Is called heat transfer coefficient . IT is denoted by (h) Its unit by watt/m2

FOLING FACTOR :- When the heat transfer equipment is put industries ,after some time ,scale, dirt and other solid deposit on both. Side the pipe wall, providing two more resistance to the heat flow. The edit resistance must be taken into account in the calculation of the overall heat transfer coefficient. The additional resistance is reduce original valve of all heat transfer U and the required amount of heat number longer transfer by the original. Original heat transfer surface hence. Heat transfer equipment are dession by taking into account the deposition dirt and scale by into dosing a resistance is known foiling factor .

BAFFLES: Baffles are commonly employed within the shell of heat exchanger to increase the rate of heat transfer by increasing the velocity and turbulence of the shell side fluid and also as structure supports for the tubes and to act as dampers against vibration . The fluid flow in shell due to baffles flow through the shell the right angel to the axes of tubes. The centre distance between adjacent baffles are called baffles

DROPWISE CONDENSATION :- Drop wise condensation takes place when the surface over. Which condensation take place is non wet-able. In this made, steam condenses. the droplets are formed. When the drop becomes bigger they simply fail under the gravity. In drop wise condensation high heat transfer rates are achieved and hence, many time chemicals are used to ensure that condensation takes place drop wise condensation

Film wise : in film wise condensation the surface over. Which the steam condenses is wet-able and hence, as the steam condenses film condensate. is formed generally film wise condensation result in low heat transfer rate. as the film of condensate impels heat transfer

CONDENSATION:- Condensation is the change of the physical state of matter from gas phase into liquid phase and is the reverse of vaporisation . The word most often refers to the water cycle. it can also be defined as the change in the state of water vapour to liquid water. When in contact with liquid or solid surface or cloud condensation nuclei. With in the atmosphere. When the transition happens from the gaseous. Phase into the solid phase directly change is called deposition.

BOILING:- Boiling is the a the rapid vaporization of a liquid BOILING:- Boiling is the a the rapid vaporization of a liquid. Which occur when a liquid is heated to its boiling point the temp at which the vapors pressure of the liquid is equal to the presser exerted on the liquid by the surrounding atmosphere .the higher presser the higher boiling point . There are two many types of boiling nucleate boiling. Where small bubbles of vapors from at direct point and critical heat flux boiling .

EVAPORATOR Evaporation is a types of vaporisation that occurs on the surface of a liquid as it is change into the gaseous phase 1) the surrounding gas mute not be saturated with the evaporating substance . They transfer energy to each other based on how they collide. 2)when evaporator occurs, the energy removed from the vaporized liquid will reduce the temp.

SUBMITTED BY; RANJEET KUMAR & SUKHDEV SINGH SUBMITTED TO; MR. JITENDER

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