Problem 4.10 - A Novel Water/Steam Air Conditioner

We wish to do an initial evaluation of an air-conditioner proposed for an extremely warm and humid environment, in which an evaporative (swamp) cooler would be ineffective because of the high humidity. A novel suggestion is to use an extremely low-pressure water/steam vapor-compression air conditioning system, as sketched in the figure below. Notice the de-aerator pump and accumulator, in which the saturated liquid water at station (3) (10 kPa) is pumped to a pressure of 100 kPa at station (4) before entering the throttle.

Carefully draw the complete air conditioning cycle above on the P-h diagram provided, showing clearly all five processes (1) - (2) - (3) - (4) - (5) - (1). Using the conditions shown on the diagram above and values obtained from the steam tables, evaluate the Coefficient of Performance (COPAC) of the air conditioning system. In this case we define the COPAC as the heat transferred to the evaporator divided by the work done on the compressor plus the work done on the de-aerator pump. [COPAC = 5.1]

Justify all values used and derive all equations used starting from the basic steady flow energy equation.


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