An internally reversible refrigerator has a modifiedcoefficient of performance accounting for realistic heattransfer processes of
where
where
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- 2. A power cycle receives energy QH by heat transfer from a hot reservoir at TH = 1200 R and rejects energy QC by heat transfer to a cold reservoir at TC = 400 R. For each of the following cases, determine whether the cycle operates reversibly, operates irreversibly, or is impossible. (a) QH = 900 Btu, Wcycle = 450 Btu (b) QH = 900 Btu, QC = 300 Btu (c) Wcycle = 600 Btu, QC = 400 Btu (d) Eff. = 70%arrow_forwardAn inventor claims to have developed a refrigerator that at steady state requires a net power input of 1.1 horsepower to remove 12,000 Btu/h of energy by heat transfer from the freezer compartment at -30°F and discharge energy by heat transfer to a kitchen at 70°F. Evaluate this claim. This claim is a) impossible b) possiblearrow_forwardAs shown in the figure, an air conditioner operating at steady state maintains a dwelling at 70°F on a day when the outside temperature is 90°F. The rate of heat transfer into the dwelling through the walls and roof is 30,000 Btu/h and the net power input to the air conditioner compressor is 3 hp. Determine a. the coefficient of performance for the air conditioner b. power input required in hp c. coefficient of performance for a reversible air conditioner providing the same cooling effect while operating between the same cold and hot temperatures.arrow_forward
- A reversible cycle receives 40 kJ of heat from one heat source at a temperature of 127 ℃ and 37 kJ from another heat source at 97 ℃. The heat rejected (in kJ) to the heat sink at 47 ℃ is. A. 36 B. 49 C. 64 D. 81arrow_forward1.Refrigerator 1 simulates an ideal refrigerator and therefore operates on a Carnot cycle using R-134a as the refrigerant at a flow rate of 1.4 kg/sec. The condensing and evaporating temperatures are 30 °C and -10 °C, respectively. To assess the performance of Refrigerator 1, you must submit the report. of the project with the following information: a) Enthalpies corresponding to the states indicated in the cycle (1, 2, 3 and 4); b) The cooling rate (Q L ); c) The work supplied to the fluid by the compressor; d) The work generated by the turbine; e) The condenser heat rejection rate (Q H ); f) The coefficient of performance of the cycle. Important detail: For the energy balance, make the following considerations: ✓ Permanent regimen; ✓ Kinetic and potential energy variations are negligible; ✓ Compressor and turbine operate adiabatically; ✓ Evaporation and condensation steps are labor-free.arrow_forwardtrue or false A refrigerator (COP = 2.5) is used to maintain a lab temperature at 18° C for that 80 MJ of heat is absorbed. Then its work input would be 8.889 kJ/s.arrow_forward
- 3. Gaseous nitrogen actuates a Carnot power cycle in which the respective volumes at the four corners of the cycle, starting at the beginning of the isothermal expansion ,are V1 = 10.10, V2 = 14.53, V3 = 226.54 ,and V4 = 157.73L. The cycle receives 21.1 KJ of heat. Determine a) the work and b) the mean effective pressure.arrow_forwardAt steady state, Refrigerant 22 enters (1) the compressor at 40C, 5.5bar and is compressed to 60C, 13.8bar. R-22 exiting (2) the compressor enters a heat exchanger where energy transfer to air as a separate stream occurs and the refrigerant exits (3) as a liquid at 13.5bar, 32C. Air enters (4) the condenser at 27C, 1.0bar with a volumetric flow rate of 21.2m3/min and exits (5) at 43C. Assuming ideal gas behavior for the air and stray heat transfer and kinetic and potential energy effects are negligible, determine the compressor powerarrow_forwardA six 6.7 x 5.7 cm refrigerant 22 compressor operating at 30 rps indicate a refrigerating capacity of 96 kW and a power requirements of 19 kW at an evaporating temp of 50C and a condensing temp of 350 C. Given that, c= 5% v2= 20 L/kg, h2 = 428 kJ/kg, h1 = 407.143 kJ/kg, h3 = 243.114 kJ/kg, v1 = 40.3556 L/kg compute: a.) clearance volumetric eff b.) actual volumetric eff c.) compression effarrow_forward
- An AC with a heat transfer rate of 55000 BTU/HR from air @14.7 psia and 95 degrees F, with rate of 1500 ft3/min. Refrigerant 134a is used and evaporates at a constant pressure of 50 psia from compressed liquid conditions, 30F, to exit temperature of 50 F. For air, Cp=0.24 Btu/lbm-R and Rair=53.3 ft-lbf/lbm-R; Determine the mass-flow-rate of liquid refrigerant required and the exit temperature of the air. Sorry for the missing infoarrow_forwardPROBLEM 2A household refrigerator has a coefficient of performance of 3 and requires a net powerinput of 0.8 kW. Question:(a) Determine the rate of heat transfer removed from the refrigerated space.(b) Determine the rate of heat transfer discharged from the refrigerator to thesurrounding kitchen.(c) Determine the annual cost in $ for supplying power to the refrigerator assuming24/7 operation and a cost of 12 cents per kWh.arrow_forwardWhat is the coefficient of performance of a refrigerator that operates with Carnot efficiency between temperatures -3.00°C and +20.0°C?arrow_forward
- Refrigeration and Air Conditioning Technology (Mi...Mechanical EngineeringISBN:9781305578296Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill JohnsonPublisher:Cengage Learning