A refrigerator using R-134a is located in a 20°C room. Consider an ideal cycle, but the compressor is neither adiabatic nor reversible. Saturated vapor at -20°C enters the compressor, and the R-134a exits the compressor at 1017 kPa. The mass flowrate of refrigerant around the cycle is 0.2 kg/s and the COP is measured and found to be 2.3. Draw the T-s diagram, indicating the temperature and pressure lines. Determine the temperature at the outlet of the condenser and the power input to the compressor in kW. Determine, the temperature at the exit of the compressor, if the heat that the compressor losses is 11.53 kJ/kg. Note: Perform energy balance. For this part, take 1017 kPa as 1000 kPa.

A refrigerator using R-134a is located in a 20°C room. Consider an ideal cycle, but the compressor is neither adiabatic nor reversible. Saturated vapor at -20°C enters the compressor, and the R-134a exits the compressor at 1017 kPa. The mass flowrate of refrigerant around the cycle is 0.2 kg/s and the COP is measured and found to be 2.3. Draw the T-s diagram, indicating the temperature and pressure lines. Determine the temperature at the outlet of the condenser and the power input to the compressor in kW. Determine, the temperature at the exit of the compressor, if the heat that the compressor losses is 11.53 kJ/kg. Note: Perform energy balance. For this part, take 1017 kPa as 1000 kPa.

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

See similar textbooks

Similar questions

P
A cycle has a compression at a high temperature and expansion at low temperature. Draw a p-v diagram and indicate both work areas, including which is positive work and which is negative. Is this an engine or a refrigerator?
A vapor-compression cycle is used as a refrigerator to extract 8 kW of heat from a cold space at 0°C and rejects heat into a space at 25°C. R-134a enters the compressor at 140 kPa superheated by 4°C above the saturation temperature and leaves at 900 kPa. It exits the condensor as a saturated liquid. Assume that pressure losses are negligible and that the compressor is isentropic. Report your answers to four significant digits using rounding. QUESTION 1 Report the maximum possible COP. QUESTION 3 Report the power required by the compressor. QUESTION 2 Report the mass flow rate in kg/s. QUESTION 4 Report the COP for the cycle.
An engine works with two reservoirs: Ta at 400 degrees Celsius and the other Tb at 200 degrees Celsius. It goes through processes with first adiabatic compression absorbing 150 J then isothermal expansion on Ta then adiabatic expansion then isothermal compression on Tb. Output of the engine operates between the same two reservoirs, with adiabatic expansion, then isothermal expansion at Tbthen adiabatic compression then isothermal compression at Ta. Output of engine runs refrigerator. What is the coefficient of performance of refrigerator and what is the total change in entropy in running the system?
A refrigerated room is kept at −18◦C by a vapor-compression cycle with R-134a as the refrigerant. Heat is rejected to cooling water that enters the condenser at 14◦C at a rate of 0.35 kg/s and leaves at 22◦C. The refrigerant enters the condenser at 1.2MPa and 50◦C and leaves at the same pressure subcooled by 5◦C. If the compressor consumes 5.5 kW of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load and the COP, (c) the second-law efficiency of the refrigerator and the total exergy destruction in the cycle, and (d) the exergy destruction in the condenser. Take specific heat of water to be 4.18 kJ/kg·◦C.
Define the h-s diagram of the actual and isentropic processes of an adiabatic compressor.
A high pressure steam turbine receives steam from a boiler under unknown conditions. The isentropic efficiency of the turbine is 75% and it produces 1MW. The high pressure turbine outlet steam is at 1.4 MPa under saturated conditions. The high pressure turbine exhaust supplies 1000kg/min for use in a process, in addition to an unknown flow of steam that follows the path, being supplied to a low pressure turbine that produces 820kW when it releases steam at 10kPa and has a isentropic efficiency of 60%. The steam that was used for the process (out of the high pressure turbine) after being used, returns to the cycle taken by the pump, which also takes the outlet of the condenser and does so at 10kPa as saturated liquid. Consider the efficiency of the pump equal to 90%. Determine: A) the mass flow through the boiler B) the pressure and temperature at the outlet of the boiler C) the thermal efficiency of the cycle
Consider a reversible Carnot cycle with 1.75 mol of ideal gas with Cv = 3R/2 as the working substance. The initial isothermal expansion occurs at the hot reservoir temperature of Thot = 920. K from an initial volume of 4.00 L (Va) to a volume of 11.50 L (Vb). The system then undergoes an adiabatic expansion until the temperature falls to Tcold = 375 K. The system then undergoes an isothermal compression and subsequent adiabatic compression until the initial state described by Ta = 920. K and Va = 4.00L is reached. a. Calculate Vc and Vd. b. Calculate w for each step in the cycle and the total cycle. c. Calculate the efficiency, ε, and the amount of heat that is extracted from the hot reservoir to do 1.00 kJ of work in the surroundings.