SEMINAR REPORT ON STUDY OF CONDENSER
Department of Chemical Engineering Madhav Institute of Technology & Science Gwalior-474005
Report submitted By
Vipin Mishra CM10031
B.E.3rd year
Introduction:
Condenser is a heat exchanger equipment employed to condense a vapour or a mixture of vapours by removing their latent heat.The latent heat is removed by absorbing it in a cooler liquid, called coolant. Since the temperature of the cooloent is increased in condenser, the unit also act as a heater but functionally it is the condensing action and the name reflects this fact. Heat transfer devices used to liquefy vapours by removing their latent heat are called condenser. There are two types of condensers: 1. Horizontal condenser 2. Vertical condenser Vertical condenser Condenser is a device used to convert phase of matter from vapor phase to liquid phase usually by cooling or by applying pressure. Vertical Condenser is a unit used where film condensation is preferable over drop wise condensation as the name indicates this unit is installed vertical so it requires large head area for cleaning and dismantle purposes. It requires more power for pumping and also requires less floor area for installation so it is preferable to use vertical condenser where less space is available. Condensation inside vertical tubes follows essentially the same mechanism as condensation outside vertical tube. If the inner surface of the shell baffles is neglected the condensate film has an ability to grow continuously in its descent down the inside or outside the tube, it may change from streamline to turbulent flow at some height between the top and the bottom. The local condensing coefficient decreases continuously from the top downward until at some point the film
changes to turbulent flow after the transition to turbulent flow the coefficient increases in accordance with the usual behavior of forced convection.
NUSSELT THEORY FOR CONDENSATION ON SURFACES:
In condensation on a vertical surface a film of condensate is formed as shown in figure and further condensation and heat transfer to the surface occurs by conduction through the film which is assumed to be in laminar flow downward. The thickness of this film greatly influence the rate of condensation, since the heat accompanying the removal of vapours from the vapour phase encounters the condensate film as a resistance which may be quite large. The thickness of the film is a function of the velocity of drainage which varies with the deviation of the surface from a vertical position. For a vertical surface the thickness of the film cumulatively increases from top to bottom. For this reason the condensing coefficient for a vapour condensing on a vertical surface decreasing from top to bottom, and for the attainment of a large condensing coefficient the height of the surface should not be very great. The velocity of the drainage for equal quantities of condensate is also a function of the viscosity of the condensate. For all liquids the viscosity decreases the temperature increases, and the condensing coefficient consequently increases with the condensate temperature. The deviation given in this chapter through equation =0.725 are those of Nusselt.
The following assumptions are involved: 1. The heat delivered by the vapour is latent heat only. 2. The drainage of the condensate film from the surface is by laminar flow only, and the heat is transferred through the film by conduction. 3. The thickness of the film at any point is a function of the mean velocity of flow and of the amount of condensate passing at that point. 4. The velocity of the individual layers of the film is a function of the relation between fractional shearing force and the weight of the film. 5. The quantity of condensate is proportional to the quantity of heat transferred, which is in turn related to the thickness of the film end of the temperature difference between the vapour and the surface. 6. The condensate film is so thin that the temperature gradient through it is linear. 7. The physical properties of the condensate are taken at the mean film temperature. 8. The surface is assumed to be relatively smooth and clean. 9. The temperature of the surface of the solid is content.
Applications
1. In laboratory for practical purpose 2. In chemical industry process 3. Air cooled condensers- air cooled condenser are used due to scarcity of water and to reduce water pollution. Air cooled condensers are used in air conditionals. 4. Water cooled condensers 5. In nuclear industry- nuclear effluents coming out from effluent stream needs condensation to liquefy certain solvents used. 6. Thermal power stations.
