7.18/A typical refrigeration (vapor-compression) cycle uses refrigerant 134a operating between the evaporator at a temperature of -5°C and the condenser at a temperature of 35°C. During your research you found an interesting substance that appears to have better properties than refrigerant 134a. You have measured its vapor pressure and enthalpy of vaporization to be 0.6 bar and 35 kl/mol at T= -5°C, and 4.2 bar and 30 kJ/mol at T = 35°C. For simplicity, consider the gas to behave like an %3D ideal gas. Your best estimate for a constant ideal gas heat capacity is of Cp = 110 J/mol K. The

7.18/A typical refrigeration (vapor-compression) cycle uses refrigerant 134a operating between the evaporator at a temperature of -5°C and the condenser at a temperature of 35°C. During your research you found an interesting substance that appears to have better properties than refrigerant 134a. You have measured its vapor pressure and enthalpy of vaporization to be 0.6 bar and 35 kl/mol at T= -5°C, and 4.2 bar and 30 kJ/mol at T = 35°C. For simplicity, consider the gas to behave like an %3D ideal gas. Your best estimate for a constant ideal gas heat capacity is of Cp = 110 J/mol K. The

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

Chapter28: Special Refrigeration Applications

Section: Chapter Questions

Problem 15RQ: Why is two-stage compression popular for extra-low-temperature refrigeration systems?

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Condensers in these refrigerators are all_______cooled.
A simple vapor - compression cycle develops 13 tons ofrefrigeration. Using ammonia as refrigerant and operating at acondensing temperature of 24 °C and evaporating temperature of-18°C and assuming that the compression are isentropic and thatthe gas leaving the condenser is saturated. Find the followinga). Draw the p-h diagramb.) Refrigerating effect in kJ/kgc.) Circulation flow in kg/mind.) Power requiremente.) Volume flow in cubic meter per minute per tonf.) Coefficient of performanceg.) Power per ton
A four-cylinder, 8 cm x 10 cm, single acting, V-type compressor operates at 600 rpm. Iti s used in a Freon-12 vapor compression system with condenser and evaporatort emperatures of 29OC and -14OC, respectively. If the compression is dry and isentropic,the clearance is 2 percent. (a) Draw the cycle schematic diagram and (b) draw the corresponding p-h diagram and determine (c) the refrigerating capacity in tons, (d) the heat given off in the condenser, and (e) the COP. The gas constant, k for R-12 is 1.126.
An ideal ammonia (R – 717) vapor-compression refrigeration cycle has an evaporator temperature of –20 C and a condenser pressure of 12 bar. Saturated vapor enters the compressor, and saturated liquid exits the condenser. The mass flow rate of the refrigerant is 3 kg/min. Determine the temperature of the superheated ammonia vapor exiting the compressor.
A refrigerator operates on an ideal vapour-compression refrigeration cycle and uses refrigerant R−134?? as the working fluid. The condenser operates at 1.6MPa and the evaporator at −6℃. If an adiabatic, reversible expansion device were available and used to expand the liquid leaving the condenser, how much would the COP improve by using this device instead of the throttle device?
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An ideal vapor-compression refrigeration cycle employs refrigerant 134a as the working fluid and operates at a steady state. At the compressor inlet, saturated vapor enters a -20 degrees celcius, and the saturated liquid leaves the condenser at 42 degrees celcius. The mass flow rate of the refrigerant is 0.5 kg/s. Determine: a) The rate of heat rejection from the condenser in kW b) The compressor power in kW c) The coefficient of performance
Refrigeration Cycle: A refrigerator operates on the ideal vapor-compression refrigeration cycle and use R-134a as the working fluid. The condenser operates 1.4 MPa and the evaporator at 0.140 MPa. (a) Show the cycle on a T-s diagram, indicating the enthalpies at the end of each process, with respect to saturation lines. For a mass flow rate of 0.100 kg/s, determine (b) the net power input to the compressor, in kW, (c) the heat rejection to the environment, in kW, (d) the heat rejection from the cold refrigerated space to the evaporator, in kW, and (e) the coefficient of performance. use the formula in the picture
A refrigerator operating using vapor-compression cycle uses R-134a as a working fluid. The condenser temperature is 65oC and the evaporator temperature is -15oC. The compressor operates at 80% efficiency. a. Determine the coefficient of performance of the refrigeration cycle. b. How much refrigerant is needed to deliver 3 kW of cooling? c. Sketch the vapor compression cycle indicating the states of each stream (in terms of H, P, T, and S) and showing the values of energy input/output in the system d. Suppose that we replace the expansion valve in the vapor- compression cycle with a turbine that operates at 80% efficiency. Determine the coefficient of performance of the refrigeration cycle. Provide the new state properties (i.e. H, P, T and S) for this changes Please use CATT for any values needed
. Refrigerant-134a at a rate of 0.08 kg/s enters the compressor of a refrigerator as superheated vapor at 0.18 MPa and 0 ℃ and leaves at 0.9 MPa and 80 ℃. The refrigerant is cooled in the condenser to 31.3 ℃ and 0.8 MPa and it is throttled to 0.18 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, a) Show the cycle on a T-S diagram b) Determine the rate of heat removal from the refrigerated space and the power input to the compressor c) Determine the adiabatic efficiency of the compressor d) Determine the coefficient of performance of the refrigerator.
Refrigerant-134a at a rate of 0.08 kg/s enters the compressor of a refrigerator as superheated vapor at 0.18 MPa and 0 ℃ and leaves at 0.9 MPa and 80 ℃. The refrigerant is cooled in the condenser to 31.3 ℃ and 0.8 MPa and it is throttled to 0.18 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, a)Show the cycle on a T-S diagram
1. Consider a steam power plant that operates on a simple ideal Rankine cycle and has a net power output of45 MW. Steam enters the turbine at 7 MPa and 500°C and iscooled in the condenser at a pressure of 10 kPa by runningcooling water from a lake through the tubes of the condenserat a rate of 2000 kg/s. Show the cycle on a T-s diagram withrespect to saturation lines, and determine (a) the thermal efficiency of the cycle, (b) the mass flow rate of the steam, and(c) the temperature rise of the cooling water. Answers:(a) 38.9 percent, (b) 36 kg/s, (c) 8.4°C 2. Consider a 210-MW steam power plant that operateson a simple ideal Rankine cycle. Steam enters the turbine at10 MPa and 500°C and is cooled in the condenser at a pressure of 10 kPa. Show the cycle on a T-s diagram with respectto saturation lines, and determine (a) the quality of the steamat the turbine exit, (b) the thermal efficiency of the cycle,and (c) the mass flow rate of the steam. Answers: (a) 0.793,(b) 40.2 percent, (c) 165…