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Friday, July 19, 2013

PowerPoint Presentation On Vapor Absorption Refrigeration System

PPT On Vapor Absorption Refrigeration System

Vapor Absorption Refrigeration System Presentation Transcript: 

Principle of Operation
Working Fluid for Vapor Absorption Refrigeration System (VARS)
Some Experimental Results for Different Fluid
Various Designs of VARS
Cost Analysis

The basic aim of this presentation is to provide basic background and review existing literatures on VARS.
VARS is also belongs to class of vapor cycle is similar to the VCRS.
However, in VCRS mechanical work is required as input so it is called work operated cycle and unlike VCRS the required input in VARS is low grade thermal energy so, called heat operated cycle.
VARS is heat operated system then waste industrial heat or solar thermal energy can be used for it.
It helps to reduce problems related to global environmental, such as green house effect from CO2 emission from the utility plant.

3.Electricity purchased from utility plant for VCRS can be reduced.
Another major difference is VCRS commonly used CFCs as refrigerants or working fluid which is cause of ozone layer depletion that will make VARS more prominent.
VARS use natural refrigerants such as NH3 and H2O.
COP of VARS is much lower than the VCRS.
Although VARS seem to be many advantages , VCRS still dominate all market sectors.
In order to promote the use of absorption system, further development is required to improve performance and reduce cost.

Working fluid in VARS is a binary solution  consisting of refrigerant and absorbent .
Absorbent absorb refrigerant causing  pressure to reduce and rejecting some amount of heat and make a stable solution.
from fig. Refrigeration is obtained by connecting two vessel left vessel containing pure refrigerant while right containing solution of  refrigerant and absorbent.

5.This is basically an intermittent system means  continuous refrigeration effect we can not get.
As the cooling process can not be produced continuously so we need a system which gives continuous refrigeration.



8.Mechanical work is less in VARS compared to VCRS because here pump is used instead of compressor.
However, a large amount of heat is required so the solution pump work is negligible compare to it.
Now COP of VCRS and VARS is given by
            COPVCRA   =

            COPVARS    =        =

Since VARS uses heat energy  its COP is much smaller then VCRS.
Comparing of system is not fully justify by only COP as mechanical energy is more expansive than thermal energy.

9.Sometimes a second law efficiency (i.e. Ratio of actual COP to that of Carnot COP) or exergetic efficiency.
It is seen that exergetic efficiency for VARS system is of the same order as that of a VCRS system.

COPideal VARS   =         =                     =

   Thus COP of ideal VARS increases as:
Evaporator temperature increases
Generator temperature increases
Heat sink (absorber + condenser) temperature decreases.
The COP of actual VARS is much smaller than ideal because of irreversibilities.

10.Working Fluid for Vapor Absorption Refrigeration System (VARS)
Properties of Working Fluid (Refrigerant – Absorbent System):
Low viscosity to minimize pump work.
Low freezing point by which we can maintain the low evaporator temperature.
Thermal stability.
Irreversible chemical reaction of all kinds, such as decomposition, polymerization, corrosion, etc. Are to be avoided.
It must be  completely miscible both in liquid as well as in vapour as well as in    vapour phase.
In addition to above, two main thermodynamic requirements of the mixture are.

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