Q7. A vapour compression refrigeration cycle using Ammonia operates between saturation temperatures of -24ºC and +20ºC. The refrigerant enters the compressor as a dry saturated vapour and during compression the specific entropy increases by 2.95 %. After cooling it enters the expansion valve as a saturated liquid. The compressor has a stroke of 200 mm and a bore of 100 mm, with a volumetric efficiency of 85% at 300 rev/min. The mechanical efficiency of the drive is 90%.
(a) Sketch the cycle on p-h and T-s diagrams.
(b) Calculate EACH of the following:
(i) The mass flow of refrigerant
(ii) The cooling load based on the mass flow obtained Q6 b (i)
(iii) The input power
(iv) The coefficient of performance of the plant, including the mechanical efficiency of the drive.
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