Question

Identify the \(p\text{-}h\) diagram that denotes a vapor compression refrigeration cycle with flash intercooling from the following.
The pressure and specific enthalpy of the working fluid are represented by \(p\) and \(h\) respectively.

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

Count how many states the working fluid passes through and check whether both throttling steps around the flash chamber are drawn.

Answer 1

The Correct Option is D

Step 1: List what a flash intercooling cycle must contain.
A two stage vapor compression cycle with flash intercooling needs two compressors, a condenser, a flash chamber at an intermediate pressure, and two expansion valves. That gives seven distinct states: 1 (evaporator exit), 2 (after the low stage compressor), 3 (saturated vapor leaving the flash chamber), 4 (state after 2 and 3 mix), 5 (after the high stage compressor), 6 (condenser exit, saturated liquid), and 7 (after the first expansion valve, entering the flash chamber).

Step 2: Drop the four state options.
Options A and B each draw only states 1, 2, 3 and 4, a single compression stage with a single throttle valve. That is an ordinary vapor compression cycle, not one with flash intercooling, so both get ruled out no matter how small the drawing difference between them is.

Step 3: Compare the two seven state options.
Both C and D put 6 and 5 on the high pressure line, and 7, 4, 3 on the intermediate pressure line, with 1 and 2 on the low pressure line, so the skeleton is right in both. The liquid leaving the flash chamber still has to throttle a second time, from 7 down to 1, before it reaches the evaporator. Option C does not mark this second expansion as its own process, while option D draws both throttling legs, 6 to 7 and 7 to 1, as separate arrowed steps.

Final Answer:
Only option D shows the full sequence: two compressions, one condensation, flash chamber mixing, and two throttling steps, which is what defines a flash intercooling cycle. \[ \text{Correct option} = D \]