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The energy source is 100 kg/s combustion products at 125 kPa, 1200 K. Make sure the air temperature is higher than the water temperature throughout the boiler.
The effect of evaporator temperature on the COP of a heat pump. Plot a curve for the COP versus the evaporator temperature for temperatures from +15 to -25oC.
The condenser pressure is 2.225 lbf/ in.2. Calculate the thermal efficiency of the cycle and the network per pound-mass of steam.
Determine the change in exergy of the water flow and that of the air flow. Use these values to determine the second-law efficiency of the boiler heat exchanger.
A Rankine steam power plant should operate with a high pressure of 3 MPa. Find the maximum water mass flow rate possible and the air exit temperature.
Find the destruction of exergy in four places: inside the heat pump, in the high-T heat exchanger and in the low-T heat exchanger.
Assume both stages have an isentropic efficiency of 85%. Find the second-law efficiencies for both stages of the turbine.
If the steam is throttled down to 2 MPa before entering the turbine, find the actual turbine specific work.
A Rankine cycle with R-410a has the boiler at 600 psia superheating to 340 F. Compute all four energy transfers and the cycle efficiency.
Determine the steam flow rate to the high pressure turbine and the power required to drive each of the pumps.
A smaller power plant produces 50 lbm/s steam at 400 psia, 1100 F in the boiler. Find the net power output and the required mass flow rate of the ocean water.
The source for the boiler is at constant 350 F. Compute the extraction flow rate and state 4 into the boiler.
A closed FWH in a regenerative steam power cycle heats 40 lbm/s of water from 200 F, 2000 lbf/ in2. What is the required mass flow rate of the extraction steam?
Calculate the thermal efficiency of the cycle and the network per pound-mass of steam.
If the steam is throttled down to 300 lbf/ in.2 before entering the turbine, find the actual turbine specific work.
What is the minimum high P and the maximum low P it can use? Determine the COP of this refrigerator for the working fluids R-134a and R-410a.
If 3000 Btu of heat is required in the generator (solar collector) per pound-mass of ammonia vapor generated, determine the overall performance of this system.
The molten salt has 5 kg/s flow with Cp = 1.5 kJ/kg K. What is the possible water flow rate, the rate of energy transfer, and the rate of entropy generation?
Steam enters the turbine of a power plant at 5 MPa, 400oC. Find the thermal efficiency of the power plant and how it compares with that of a Carnot cycle.
The turbine efficiency is 85%, and other cycle components are ideal. If the boiler superheats to 800oC, find the cycle thermal efficiency.
A new air conditioner using R-410a is used in heat pump mode. Find the COP, the heating rate, and the rate of entropy generation for the heat pump.
Find the high temperature, the condensing temperature and the COP if it is used in a standard cycle with high and low pressures of 6 MPa and 3 MPa respectively.
After the compressor, the temperature is measured to be 60oC. Find the actual compressor work and the actual cycle COP.
Determine the amount of energy saved by using the heat pump instead of directly heating the water from 15oC to 60oC.
Determine the entropy generation in the compression process, the refrigeration capacity, and the COP for this cycle.