FUND OF THERMODYNAMICS- UND CUSTOM
2nd Edition
ISBN: 9781119694205
Author: Borgnakke
Publisher: WILEY C
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Chapter 5, Problem 5.59P
A heat pump receives energy from a source at 80°C and delivers energy to a boiler that operates at 350kPa. The boiler input is saturated liquid water and the exit is saturated vapor, both at 350kPa. The heat pump is driven by a 2.5−MW motor and has a COP that is 60% that of a Carnot heat pump. What is the maximum mass−flow rate of water the system can deliver?
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A heat pump receives energy from a source at 80∘C and delivers energy to a boiler that operates at 350 kPa. The boiler input is saturated liquid water and the exit is saturated vapor, both at 350 kPa. The heat pump is driven by a 2.5-MW motor and has a COP that is 60% that of a Carnot heat pump.
What is the maximum mass-flow rate of water the system can deliver?
4. A Camot heat pump with refrigerant-134a as the working fluid is used to keep
a room at 78*F by absorbing heat from geothermal liquid water that enters the
evaporator at 60°C at a rate of 3.78 kg/min and leaves (still as a liquid) at 40°c
The refrigerant, meanwhile, enters the evaporator at 12°C with a quality of 25%
and leaves at the same pressure as saturated vapor. If the compressor
consumes 1.8 kW of power, detemine (a) the mass flow rate (in kg/s) of the
refrigerant at the evaporator, (b) the rate of heat (in kW) supplied to maintain
the room temperature, and (c) the COP. Also, what is (d) the ambient
temperature at the outside, in "C, that necessitates the use of the heat pump?
Assume steam properties to compute for the thermodynamic conditions of
geothermal water.
Outside Inside
Expansion Ve
Condenser
Evaporator
Compresser
A heat pump with refrigerant-134a (R-134a) as the working fluid is used to keep a space at 21 °C by absorbing heat from geothermal water that enters the evaporator at Ti,water = 60 °C at a rate of 0.067 kg/s and leaves at To,water = 40 °C. The specific heat of liquid water is 4.18 kJ/(kg∙K). Refrigerant enters the evaporator at TR-134a = 10 °C with a quality of x = 12 % and leaves at the same pressure as saturated R-134a vapor at the same temperature. The compressor consumes 1.4 kW of power.
1)Determine the mass flow rate (in kg/s) of the refrigerant.
2)Determine the rate of heat (in kW) supplied to the space.
2)Determine the COP of the heat pump.
4)Determine the ideal minimum power input (in kW) to the compressor for the same rate of heat supply
Chapter 5 Solutions
FUND OF THERMODYNAMICS- UND CUSTOM
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- A reversible heat pump is working between 9°C and 28°C. The minimum power required per ton on heating effect is W.arrow_forwardA heat pump operates with a Coefficient of Performance equal to 8. What is the COP if this cycle were to operate as a refrigerator?arrow_forward2. The thermal efficiency of a basic steam power plant is 40% with heat rejection of 350 kJ/kg. If the steam turbine inlet is at 5MPa and 400c, find the boiler inlet temperature.arrow_forward
- 2. 11-43 A heat pump with refrigerant-134a as the working fluid is used to keep a space at 25°C by absorbing heat from geothermal water that enters the evaporator at 50°C at a rate of 0.065 kg/s and leaves at 40°C. The refrigerant enters the evaporator at 20°C with a quality of 23 percent and leaves at the inlet pressure as saturated vapor. The refrigerant loses 300 W of heat to the surroundings as it flows through the compressor and the refrigerant leaves the compressor at1.4 MPa at the same entropy as the inlet. Determine (a) the degrees of subcooling of the refrigerant in the condenser, (b) the mass flow rate of the refrigerant, (c) the heating load and the COP of the heat pump, and (d) the theoretical mini- mum power input to the compressor for the same heating load. 1.4 MPa Condenser Win Expansion valve Compressor Evaporator sat. vapor 20°C x= 0.23 Water 50°C 40°Carrow_forwardFrom the given data, if refrigerant circulation rate is 0.025kg/s, find the refrigerant effect of the ideal vapour compression cycle.arrow_forwardThe COP of a Carnot heat pump operating between 6°C and 37°C is.arrow_forward
- Find the refrigeration capacity (in TR ) required to cool 29 m³/min from 29°C to 18°C if air from the outside has 90% RH?arrow_forwardJust to check the answer no need calculationarrow_forwardWith a 1 kW pump, the energy leakage per unit time is 0.6 kW for a 1 ℃ temperature difference between a house to be heated and the outside environment. Coefficient of performance of the heat pump used to keep this house at a constant temperature of 20 ℃; If it is up to the theoretical heat pump performance coefficient; What is the minimum outdoor temperature ℃ for this heat pump to meet its needs and be used?arrow_forward
- A:- A commercial refrigerator with refrigerant-134a as shown in Fig. Q3A as the working fluid is used to keep the refrigerated space at -35 °C by rejecting waste heat to cooling water that enters the condenser at 18 °C at a rate of 0.25 kg/s and leaves at 26 °C. The refrigerante enters the condenser at 1.2 MPa and 50 °C and leaves at the same pressure subcooled by 5 °C. If the compressor consumes 3.3 kW of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load, and (c) the COP. 12 MPa 5°C subcooled Expansion valve Fig. Q3A Condenser Evaporator Qu Water 18% 1.2 MP 56PC Compressorarrow_forwardFind out the COP of a Carnot heat pump operating between 6°C and 37°C.arrow_forwardA Carnot heat pump works between 27° C and 327°C. What will be its COP?arrow_forward
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