A commercial refrigerator using R-134a as the refrigerant is used to keep the refrigerated environment at -35 ° C. The refrigerator releases the waste heat to the cooling water entering the condenser at 18 ° C with a flow of 0.25 kg / s and leaving the condenser at 26 ° C. The refrigerant enters the condenser at a pressure of 1.2 MPa and a temperature of 50 ° C, and leaves the condenser at the same pressure and supercooled at a temperature of 5 ° C. Since the compressor consumes 3.3 kW of power, Calculate a) Mass flow rate of the refrigerant, b) Cooling load and COP value c) The least power consumed by the compressor for the same cooling load

A commercial refrigerator using R-134a as the refrigerant is used to keep the refrigerated environment at -35 ° C. The refrigerator releases the waste heat to the cooling water entering the condenser at 18 ° C with a flow of 0.25 kg / s and leaving the condenser at 26 ° C. The refrigerant enters the condenser at a pressure of 1.2 MPa and a temperature of 50 ° C, and leaves the condenser at the same pressure and supercooled at a temperature of 5 ° C. Since the compressor consumes 3.3 kW of power, Calculate a) Mass flow rate of the refrigerant, b) Cooling load and COP value c) The least power consumed by the compressor for the same cooling load

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter44: Geothermal Heat Pumps

Section: Chapter Questions

Problem 1RQ: Geothermal heat pumps, or water-source heat pumps, are classified as either _____loop or _____loop...

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Condensers in these refrigerators are all_______cooled.
Geothermal heat pumps, or water-source heat pumps, are classified as either _____loop or _____loop systems.
A refrigerator using fluid-134a as a work fluid is used to keep the cooling medium at -25 oC. The refrigerator releases the waste heat, which enters the condenser at 18 oC with a flow of 0.30 kg / s and from the condenser at 26 oC to the cooling water. The refrigerant enters the condensate at a pressure of 1.2 MPa and 50 oC, and leaves the condenser at 40 oC at the same pressure. Find a) the mass flow rate of the refrigerant, b) the power consumed by the compressor, c) the COP value, and d) the minimum power that the compressor will consume for the same cooling load.They watch the specific heat of water as ?? = 4.22 ?? / ???.
A vapor-compression refrigeration system circulates refrigerant 134a at a rate of 0.15 kg/s. The refrigerant enters the compressor at -10 degrees Celcius and 100 kPa, and exits the compressor at 800 kPa. The isentropic efficiency of the compressor is 76%. Pressure drop through the condenser and evaporator are negligible. The refrigerant exits the condenser at 30 degrees Celcius and 800 kPa. Ignoring the heat transfer between the compressor and its surroundings, determine: The rate at which heat energy is removed from the refrigerated space in kW. The coefficient of perfromance.
Refrigerant -134a enters the compressor of a refrigerator as superheated vapour at 0.10 MPa and -10 oC with a mass flow rate of 0.21 kg/s, and it leaves at a pressure of 1 MPa. The refrigerant enters the condenser at 1 MPa and leaves as a saturated liquid, and then throttled back to 0.10 MPa. The isentropic efficiency of the compressor is 88 percent. Disregard any heat transfer and pressure drops in the connecting lines between the components. 2.1 Show the cycle on the T-s diagram with respect to saturation lines. Determine: 2.2 the refrigeration capacity, 2.3 the power input to the compressor, 2.4 the refrigerant temperature at the compressor exit, and 2.5 the coefficient of performance.
Saturated vapor Freon 12 refrigerant at 219.12 kPa leaves the evaporator and enters the compressor at -5 °C. The refrigerant leaves the condenser as saturated liquid at 25°C and enters the ex pansion valve at 22°C. Heat rejected from the condenser amount to 75 kW. The work to the compressor is 55.5 kJ/kg, while the heat lost from the compressor is 4.2 kJ/kg. If 1.15 kJ/kg of heat are lost in the piping between the compressor and condenser, cal culate the refrigeration capacity in tons.
A commercial refrigerator using R-134a as a refrigerant is used to keep the cooled environment at -35'C. The refrigerator releases the waste heat to the cooling water that enters the condenser at 18'C with a flow of 0.25 kg / s and leaves the condenser at 26'C. The refrigerant enters the condenser at a pressure of 1.2 MPa and a temperature of 50'C, and leaves the condenser at the same pressure and supercooled at 5 ₒC. Since the compressor consumes 3.3 kW of power, a) Mass flow rate of the refrigerant, b) Cooling load and COP value c) Calculate the minimum power consumed by the compressor for the same cooling load.
The two-stage compression refrigeration system shown below is used to remove heat from refrigerated space using R-410a as the coolant. The R-410a leaves the evaporator at state 1 and is first compressed in a low-pressure compressor (W, Pc=-250 kW) to an intermediate pressure of 933.9 kPa before it is mixed with saturated vapor and then further compressed in a high-pressure compressor to 3000 kPa. Heat is then removed from the R-410a as it passes through the heat exchanger and exchanges heat with cooling water. The R-410a is then expanded in the throttling valve to the intermediate pressure and passed through a type of mixing chamber called a flash chamber where it is separated into a saturated vapor leaving at state 7 and a saturated liquid leaving at state 8. Finally, the liquid is expanded before entering the evaporator at state 9. Note that the mass flow rate of R-410a leaving the mixing chamber is mypC = 10 kg/s. Neglect changes in kinetic and potential energy across all devices…
Refrigerant-134a enters the compressor of a cooling system as superheated vapor at 0.18 MPa and 0°C with a flow rate of 0.15 kg/s. It exits the compressor at 0.8 MPa and 60°C. Post compression, the refrigerant is cooled in the condenser to 28°C and 1.4 MPa. Subsequently, it's throttled to 0.16 MPa. Neglecting any heat transfer and pressure drops in the pipelines between the components, represent the cycle on a T-s diagram concerning saturation lines. Calculate: (a) The rate of heat extraction from the cooling area and the energy input to the compressor. (b) The isentropic efficiency of the compressor. (c) The Coefficient of Performance (COP) of the cooling system.
A refrigeration system using R-12 is to have a refrigerating capacity of 70 kW. The evaporating temperature is -10°C and the condensing temperature is 42°C, determine the volume flow rate in L/s of the refrigerant at the inlet of the compressor. (Use h₂ = 440 kJ/kg)
A commercial refrigerator using R-134a as a refrigerant is used to keep the cooled environment at -35 C. The refrigerator releases the waste heat to the cooling water that enters the condenser at 18 C at 0.25 kg / s and leaves the condenser at 26 C. The refrigerant enters the condenser at a pressure of 1.2 MPa and a temperature of 50 ° C, and leaves the condenser at the same pressure, supercooled at 5 ° C. Since the compressor consumes 3.3 kW of power, a) Mass flow rate of the refrigerant, b) Cooling load and COP value c) Calculate the minimum power consumed by the compressor for the same cooling load.
Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 MPa and – 10°C at a rate of 0.12 kg/s, and it leaves at 0.7 MPa and 50°C. The refrigerant is cooled in the condenser to 24°C and 0.65 MPa, and it is throttled to 0.15 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, show the cycle on a T-s diagram with respect to saturation lines, and determine (a) the rate of heat removal from the refrigerated space and the power input to the compressor, (b) the isentropic efficiency of the compressor, and (c) the COP of the refrigerator. T 0.70MPA 2s 50°C 0.65MPA 24°C Win 0.15 MPa 0.14MPA -10°C