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The condenser must reject 25 MW from the water to the air. Find the flow rate of air and the second-law efficiency of the heat exchanger.
Determine the flow of exergy into or out of the reservoirs per kilogram of steam flowing in the cycle. What is the overall cycle second-law efficiency?
A heat source is available at 100oC. Also find the efficiency of the heat engine part and the COP of the refrigeration cycle part.
A Rankine cycle flows 5 kg/s ammonia at 2 MPa, 140oC to the turbine, which has an extraction point. Find the extraction flow rate and state 4 into the boiler.
A power plant with one closed FWH has a condenser temperature of 45oC. Find the fraction of extraction steam flow and the two specific pump work inputs.
Consider an ideal steam regenerative cycle in which steam enters the turbine at 3.0 MPa. Calculate the thermal efficiency of the cycle and the specific network.
If the river water should not be heated more than 5oC, how much water should be pumped from the river to the heat exchanger (condenser)?
An open FWH receives steam at 1 MPa, 200oC from the turbine and 1 MPa, 100oC water. Find the required fraction of the extraction flow in the turbine.
Calculate the cycle thermal efficiency and the moisture content of the steam leaving the low pressure turbine.
Find the reheat temperature so that the turbine output is saturated vapor. For this reheat, find the total turbine power output and the boiler heat transfer.
Consider the supercritical cycle in Problem 9.30. Find the combined specific turbine work and the total specific heat transfer in the boiler.
The power plant in Problem 9.16 has too low a quality. What should the superheat for the reheat be so that the turbine quality stays above 92%?
Consider an ideal Rankine cycle using water with a high-pressure side of the cycle at a supercritical pressure. What is the steam quality at the turbine exit?
Find the temperature out of the boiler/super heater so that the turbine exit temperature is 60oC, and find the overall cycle efficiency.
For a turbine power output of 8 MW, find the work and heat transfer in all components and the cycle efficiency.
A Rankine cycle with R-410a has the boiler at 3 MPa superheating to 180oC, and the condenser operates. Find all four energy transfers and the cycle efficiency.
Find the plant efficiency and the efficiency of a Carnot cycle with the same temperatures.
A heat pump uses carbon dioxide, and it must condense at a minimum of 22oC and receives energy. What restrictions does that place on the operating pressures?
A refrigerator in my 20oC kitchen uses R-134a, and I want to make ice cubes at -5oC. What is the minimum high P and the maximum low P it can use?
What is the difference between an open and a closed FWH? In a cogenerating power plant, what is cogenerated?
Find from the literature the amount of energy that must be stored in a car to start the engine. Discuss the feasibility and cost.
The exit pressure is 10 psia and the actual exit temperature is 1780 R. What is the actual exit velocity and the second-law efficiency?
Use constant heat capacities and find the exit temperature and the second-law efficiency for the heat exchanger, assuming ambient at 68 F.
A heat exchanger increases the exergy of 3 kg/s water by 1650 kJ/kg using 10 kg/s air coming. What are the irreversibility and the second-law efficiency?
A piston/cylinder has forces on the piston, so it maintains constant pressure. Find the work out of the heat engine using the exergy balance equation.