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Class 2 (2nd Engineer) MEKG 📅 Aug 2024

Exam Question

(a) Explain with a sketch the operation of an automatic expansion valve as fitted in the direct expansion refrigeration plants. How is this valve adjusted? (6)

(b) Explain how critical temperature restricts plant operation and how these limitations can be overcome? (5)

(c) Explain how this system maintains the provision rooms at different temperatures. (5)

Exam question diagram

Reference Answer

### (a) Automatic Expansion Valve (AEV) Operation and Adjustment
An Automatic Expansion Valve (AEV), also known as a Constant Pressure Expansion Valve, is a refrigeration control device designed to maintain a constant pressure in the evaporator, regardless of the load. This, in turn, maintains a constant evaporator temperature.
#### Construction
An AEV consists of the following key components:

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