A refrigeration unit utilises ammonia as the refrigerant. The diagram for the circuit is shown in Figure Q3 below, with the following conditions: point (1) is a saturated liquid at -30 °C, points (3), (4) and (7) is a saturated liquid at 10 °C and point (5) is a saturated vapour at -30 °C. The isentropic efficiency of the compressor and pump is 80% and it is assumed there are negligible heat losses to the surroundings. The liquid ammonia has a specific volume of 0.0015 m³ kg-¹. (a) Discuss which factors must be considered when selecting an appropriate refrigerant? (b) Calculate the coefficient of performance (COP) of the cycle. (c) If the effect of refrigeration is 10 kW, determine the required mass flow rate. 6 Compressor Condenser y 5 7 1 4 3 Spray Flash chamber Pump Figure Q3. Refrigeration circuit diagram. 1 Evaporator 2

A refrigeration unit utilises ammonia as the refrigerant. The diagram for the circuit is shown in Figure Q3 below, with the following conditions: point (1) is a saturated liquid at -30 °C, points (3), (4) and (7) is a saturated liquid at 10 °C and point (5) is a saturated vapour at -30 °C. The isentropic efficiency of the compressor and pump is 80% and it is assumed there are negligible heat losses to the surroundings. The liquid ammonia has a specific volume of 0.0015 m³ kg-¹. (a) Discuss which factors must be considered when selecting an appropriate refrigerant? (b) Calculate the coefficient of performance (COP) of the cycle. (c) If the effect of refrigeration is 10 kW, determine the required mass flow rate. 6 Compressor Condenser y 5 7 1 4 3 Spray Flash chamber Pump Figure Q3. Refrigeration circuit diagram. 1 Evaporator 2

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Reference Book: Introduction to Chemical Engineering Thermodynamics by Smith, Van Ness, etc. 7th or 8th Ed.
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