Monday, November 12, 2018

Download Lecture Note's On Expansion Devices

An expansion device is another basic component of a refrigeration system. The basic functions of an expansion device used in refrigeration systems are to:
1. Reduce pressure from condenser pressure to evaporator pressure, and
2. Regulate the refrigerant flow from the high-pressure liquid line into the evaporator at a rate equal to the evaporation rate in the evaporator
Under ideal conditions, the mass flow rate of refrigerant in the system should be proportional to the cooling load. Sometimes, the product to be cooled is such that a constant evaporator temperature has to be maintained. In other cases, it is desirable that liquid refrigerant should not enter the compressor. In such a case, the mass flow rate has to be controlled in such a manner that only superheated vapour leaves the evaporator. Again, an ideal refrigeration system should have the facility to control it in such a way that the energy requirement is minimum and the required criterion of temperature and cooling load are satisfied. Some additional controls to control the capacity of compressor and the space temperature may be required in addition, so as to minimize the energy consumption.

Please Download The PDF File To Read About The Lecture On Expansion Devices which are discussed about the Follow Specifications .

The specific objectives of this lecture are to:
1. Discuss the basic functions of expansion devices used in refrigeration systems and their classification.
2. Discuss the operating principle, concept of balance point, the effect of load variation, selection of capillary tubes using analytical and graphical methods and the advantages and disadvantages of capillary tubes.
3. Explain the working principle of an automatic expansion valve, its performance under varying loads and its applications.
4. Present a simple analysis for fluid through orifices.
5. Explain the working principle of a thermostatic expansion valve, its performance under varying loads, variations available such as cross-charging, external equalizer and limit charging, advantages and disadvantages of TEVs.
6. Explain the working principle of low-side and high-side float valves.
7. Explain the working principle of an electronic expansion valve.
8. Discuss briefly some of the practical problems with expansion devices.

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