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Air conditioning and refrigeration Question 2 A provision store comprising of 2 refrigerated chambers is to be planned for a large restaurant in Accra. The facility will be constructed from 100 mm thick prefabricated panels having a thermal conductivity of 0.02 W/m K. It will have overall external dimensions of 4 m x 6 m x 3 m and be partitioned into two identical chambers along the 6 m length. One chamber will serve as a frozen store for keeping pre-frozen goods at -18Â°C, while the other will be used for keeping non-frozen goods at +5Â°C. The twin facility is operated by a single refrigeration plant operating with refrigerant R134a. Given the ambient shade temperature of 30Â°C, carry out the following: 1. Given that both chambers operate at an evaporation temperature of -20Â°C, suction superheat of 10Â°C, condensing pressure corresponding to +40Â°C saturation temperature, and saturated condition at condenser exit, determine the required compressor displacement in mÂ³/hr and isotropic efficiency if the discharge gas temperature is +70Â°C. 2. Assuming each store is fitted with an independent refrigeration plant both operating at unchanged evaporating and condensing temperature, what will be the Carnot efficiency of each plant? 3. Recommend improvement(s) to improve the energy efficiency of the facility under these conditions.

          Air conditioning and refrigeration

Question 2

A provision store comprising of 2 refrigerated chambers is to be planned for a large restaurant in Accra. The facility will be constructed from 100 mm thick prefabricated panels having a thermal conductivity of 0.02 W/m K. It will have overall external dimensions of 4 m x 6 m x 3 m and be partitioned into two identical chambers along the 6 m length. One chamber will serve as a frozen store for keeping pre-frozen goods at -18Â°C, while the other will be used for keeping non-frozen goods at +5Â°C. The twin facility is operated by a single refrigeration plant operating with refrigerant R134a. Given the ambient shade temperature of 30Â°C, carry out the following:

1. Given that both chambers operate at an evaporation temperature of -20Â°C, suction superheat of 10Â°C, condensing pressure corresponding to +40Â°C saturation temperature, and saturated condition at condenser exit, determine the required compressor displacement in mÂ³/hr and isotropic efficiency if the discharge gas temperature is +70Â°C.

2. Assuming each store is fitted with an independent refrigeration plant both operating at unchanged evaporating and condensing temperature, what will be the Carnot efficiency of each plant?

3. Recommend improvement(s) to improve the energy efficiency of the facility under these conditions.

air conditioning and refrigeration question2 a provision store comprising of 2 refrigerated chambers is to be planned for a large restaurant in accra the facility will be constructed from 10 60795

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