A standard vapor heat pump cycle using CO2 operates with the following characteristics: Evaporator temperature is 2°C and the compressor (isentropic efficiency 0.85) draws saturated vapor. Condenser pressure is 7 MPa, and throttle inlet temperature is 26°C. The heating rate is 2500 W.

A standard vapor heat pump cycle using CO2 operates with the following characteristics: Evaporator temperature is 2°C and the compressor (isentropic efficiency 0.85) draws saturated vapor. Condenser pressure is 7 MPa, and throttle inlet temperature is 26°C. The heating rate is 2500 W.

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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Why is two-stage compression popular for extra-low-temperature refrigeration systems?
An ideal vapor-compression heat pump cycle with Refrigerant 134a as the working fluid provides 15 kW to maintain a building at 200°C when the outside temperature is 50°C. Saturated vapor at 2.4 bar leaves the evaporator, and saturated liquid at 8 bar leaves the condenser. Calculate (a) The power input to the compressor, in kW (b) The coefficient of performance. (c) The coefficient of performance of a reversible heat pump cycle operating between thermal reservoirs at 20 and 50°C. (h, = 244.09kJ/ke, 5 = 0.9222 kJ/kg -K; h, = 268.97 kJ/ kg; h, = 93.42 kJ/ kg)
Rankine cycle, the pressure and the temperature entering the turbine is 1800 Kpa at 380 Degrees celcius and the pressure leaving the turbine is 20 KPa. The quality of steam entering the condenser is 90%. What is the turbine work in Kj/Kg? A. 833.3 B. 799.9 C. 633.3 D. 423.2
Consider the ideal vapor compression cycle operating between 1.4 bar and 9bar using R-125 as the refrigerant, which removes heat from a cold space at a rate of 100kW. If the evaporator outlet was suddenly superheated by 2℃ above saturation, what will be the resulting effect on the cycle? a.Refrigerant flowrate will decrease, Condenser duty will decrease b.Refrigerant flowrate will increase, Condenser duty will decrease c.Refrigerant flowrate will increase, Condenser duty will increase d.Refrigerant flowrate will decrease, Condenser duty will increase
Water is the working fluid in an ideal Rankine cycle. Steam enters the turbine at 1400 lbf/in2 and 1600°F. The condenser pressure is 2 lbf/in.2 The net power output of the cycle is 350 MW. Cooling water experiences a temperature increase from 60°F to 76°F, with negligible pressure drop, as it passes through the condenser. (a) the mass flow rate of steam, in Ib/h. (b) the rate of heat transfer, in Btu/h, to the working fluid passing through the steam generator. (c) the percent thermal efficiency. (d) the mass flow rate of cooling water, in Ib/h.
Air enters the compressor of an ideal Brayton refrigeration cycle at 100 kPa, 300 K, with a volumetric flow rate of 0.90 m3/s, and is compressed to 430 kPa. The temperature at the turbine inlet is 330 K. Determine: (a) The net power input, in kW (b) The refrigerating capacity, in kW. (c) The coefficient of performance. (d) The coefficient of performance of a reversible refrigeration cycle operating between reservoirs at TC = 300 K and TH = 330 K.
2 Water is the working fluid in an ideal Rankine cycle. Steam enters the turbine at 1400 lbf/in2 and 1200°F. The condenser pressure is 2 lbf/in.2 The net power output of the cycle is 250 MW. Cooling water experiences a temperature increase from 60°F to 76°F, with negligible pressure drop, as it passes through the condenser. a) The mass flow rate of steam, in lb/hb) The rate of heat transfer, in Btu/h, to the working fluid passing through the steam generatorc) The thermal efficiencyd) The mass flow rate of cooling water, in lb/h
Can you also draw the schematic diagram, p-h and t-s diagrams? Air enters the compressor of an ideal Brayton refrigeration cycle at 100 kPa, 300 K, with a volumetric flow rate of 0.90 m3/s, and is compressed to 430 kPa. The temperature at the turbine inlet is 330 K. Determine: (a) The net power input, in kW (b) The refrigerating capacity, in kW. (c) The coefficient of performance. (d) The coefficient of performance of a reversible refrigeration cycle operating between reservoirs at TC = 300 K and TH = 330 K.
A two -stage staged refrigeration cycle works at a lowest pressure of 0.8 bar and a highest of 8 bar. Each stage works as an ideal vapor compression system with R-134a as the working fluid. The release of heat from the lower cycle to the upper cycle takes place in an adiabatic heat exchanger of opposite flow where both flows in at a pressure of 3 bar. If the refrigrant mass flow rate in the upper cycle is 0.075 kg/s, calculate: a). Refrigerant mass flow rate at the bottom cycle b). Heat absorption power of the cooled room, in kW c). Supply power to compressor d). COP refrigerator Note: siklus is cycle and below the environment the purple one is QH,(the image was blur) so i explain on the note,thx
Steam at 4800 lbf/in.2, 1000 deg F enters the first stage of a supercritical reheat cycle including two turbine stages. The steam exiting the first-stage turbine at 600 lbf/in.2 is reheated at constant pressure to 1000 deg F. Each turbine stage and the pump have an isentropic efficiency of 85%. The condenser pressure is 1 lbf/in.2 If the net power output of the cycle is 100 MW, determine (a) the rate of heat transfer to the working fluid passing through the steam generator, in MW. (b) the rate of heat transfer from the working fluid passing through the condenser, in MW. (c) the cycle thermal efficiency.
A standard ammonia vaporcompression cycle developing 20 tons of refrigeration operates with a condensing temperature of 32°C and an evaporating temperature of 14°C. Calculate the (a) refrigerating effect, (b) circulating rate of refrigerant, (c) theoretical power, (d) COP, (e) gallons per minute of cooling water in the condenser, if ∆t is 8°C, (f) quality of the refrigerant entering the evaporator, and (g) temperature of the refrigerant leaving the compressor. (1 gallon contains 8.33 lb. of water) Answers: (a) 1093.7 kJ/kg, (b) 3.86 kg/min., (c) 15.44 kW, (d) 4.56, (e) 40.6 gpmShow your complete solution.
Air enters the compressor of an ideal Brayton refrigeration cycle at 100 kPa, 270 K. The compressor pressure ratio is 3 and the temperature at the turbine inlet is 310 K. Determine:d).the coefficient of performance of a Carnot refrigeration cycle operating between thermal reservoirs at TC 270 K and TH 310 K, respectively. The above Brayton refrigeration cycle is modified by introducing a regenerative heat exchanger. In the modified cycle, the compressed air enters the regenerative heat exchanger at 310 K and is cooled to 280 K before entering the turbine. Determine for the modified cycle:(e).the lowest temperature, in K.f).the net work input per unit mass of air flow, in kJ / kg.