Question 1 A refrigerator has working temperatures in the evaporator and condenser coils of 234 K...
Question 1 A refrigerator has working temperatures in the evaporator and condenser coils of 234 K and 305 K respectively. 1.1 What is the maximum COP possible? (2) 1.2 If the actual refrigerator has a COP of 0.75 calculate the required power input for a refrigerating effect of 5 kW. [10 Marks] (8)
(12 points) A refrigerator using refrigerant-134a as the working fluid operates on the vapor compression cycle. The cycle operates between 200 kPa and 1.2 MPa. The refrigerant flows through the cycle at a rate of 0.019 kg/s. The (actual) refrigerator has a compressor with an isentropic efficiency of 85%. The refrigerant enters the compressor slightly superheated by 56 C hint add this to the saturation temperature). The refrigerant leaves the condenser slightly subcooled by 1.9°C. What is the rate of...
Tt (12 points) A refrigerator using refrigerant-134a as the working fluid operates on the vapor compression cycle. The cycle operates between 200 kPa and 1.2 MPa. The refrigerant flows through the cycle at a rate of 0.015 kg/s. The actual) refrigerator has a compressor with an isentropic efficiency of 82%. The refrigerant enters the compressor slightly superheated by 6.2°C (hint: add this to the saturation temperature). The refrigerant leaves the condenser slightly subcooled by 1.8°C. What is the rate of...
2. MULTIPLE EVAPORATOR/ EXPANSION VALVE A refrigeration installation using Freon 12, comprises one compressor, one condenser and three evaporators of 10 tonnes, 20 tonnes, and 30 tonnes capacities maintained at 10 C, 5 C and -10 C respectively. The system comprises multiple expansion valves and back pressure check valves. The condenser pressure is 9.609 bar (saturation temp. 40 C). The vapours leaving the evaporator are dry saturated. The liquid refrigerant is sub-cooled by 10 C in the condenser sub-cooler. Assume...
QS. An air-conditioner with a power input of 1.5 kW is working as a refrigerator (B-3) or as a heat pump (B' 4). It maintains an office at 20C year round which exchanges 0.5 kW per degree temperature difference with the atmosphere. There is a range of the outside temperatures for which this unit is sufficient a) Write the expressions that define the coefficient of performance (COP) for a refrigerator (B) and a heat pump (B) b) Calculate the maximum...
A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at by The refrigerant enters the condenser at compressor consumes 3.3 kW of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load, (e) the COP, and (d) the g waste heat to cooling water that enters the condenser at 18°C at a rate of 0.25 kg/s and leaves at 26°C. 1.2 MPa and 50°C and leaves at the same...
ler SHVAC SV Ref Cycles lGalgillg Worked Examples Example 3.4 The evaporator and condenser temperatures of a standard vapor compression cycle using R134a as the refrigerant are -5°C and 40°C respectively. The isentropic efficiency of the adiabatic compressor is 75% and the refrigeration capacity is 25 kW. Calculate () the refrigerant flow rate, () the compressor work input, and (ii) the COP Solution The T-s diagram of the vapor compression cycle is shown in Fig. E3.5. For purposes of comparison...
1) A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -30°C by rejecting its waste heat to cooling water that enters the condenser at 16 °C at a rate of 0.25 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 65°C and leaves at 42°C. The inlet state of the compressor is 60 kPa and -34°C and the compressor is estimated to gain a net heat of...
Problem #4 (20 points) A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -30°C by rejecting its waste heat to cooling water that enters the condenser at 18°C at a rate of 0.25 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 65°C and leaves at 42°C. The inlet state of the compressor is 60 kPa and-34°Cand the compressor is estimated to gain a net heat of...
A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at −25°C by rejecting waste heat to cooling water that enters the condenser at 20°C at a rate of 0.25 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 50°C and leaves at the same pressure subcooled by 5°C. If the compressor consumes 3.3 kW of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration...