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Air in a piston/cylinder arrangement is at 110 kPa, 25oC. Find the total work (including that of the external device) and the heat transfer from the ambient.
The intercooler in the previous problem uses cold liquid water to cool nitrogen. Find the flow rate of the water and the exergy destruction in this intercooler.
Find the exergy at the initial and final states and the destruction of exergy in the process.
A turbine receives steam at 3000 kPa, 500oC and has two exit flows, one at 1000 kPa 350oC with 20% of the flow. Find the isentropic and second-law efficiencies.
Find the second-law efficiency for the compressed air system in Problem 8.65. Consider the total system from the inlet to the final point of use.
A compressor in a refrigerator receives R-410a at 20 psia, -40 F and it brings it up to 100 psia, using actual specific work. Find the specific reversible work.
Find the heat transfer out of the R-134a, the extra work input to the refrigerator due to this process and total irreversibility including that of refrigerator.
A heat exchanger increases the exergy of 6 lbm/s water by 800 Btu/lbm using 20 lbm/s air. What are the irreversibility and the second law efficiency?
The air inlet to compressor is at 14.7 lbf/in.2, 60 F and compressor isentropic efficiency is 80%. Find total compressor work and change in exergy of the air.
For the air system in the previous problem, find increase in air exergy from inlet to the point of use. How much exergy was lost in flow after compressor exit?
A constant-pressure piston/cylinder has 1 kg of saturated liquid water at 100 kPa. Find the required amount of air and the work out of the heat engine.
A rock bed consists of 6000 kg granite and is at 70oC. If the process is reversible, find the final temperature and the work done in the process.
Find the specific reversible work for a steam turbine with inlet 4 MPa, 500oC and an actual exit state of 100 kPa, x = 1.0 with a 25oC ambient.
An air compressor takes air in at the state of the surroundings, 100 kPa, 300 K. Determine the minimum compressor work input.
Assume it is reversible and find the power output. How much power could be produced if it could reject energy at T0 = 298 K?
Is the exergy equation independent of the energy and entropy equations? Find the change in exergy of the control mass for each of the three cases.
Why are reversible work and availability (exergy) connected? The total exergy is based on the thermodynamic state and the kinetic and potential energies.
Flow of 0.1 kg/s hot water at 70oC is mixed with flow of 0.2 kg/s cold water at 20oC in shower fixture. What is the rate of exergy destruction for this process?
At the start of the process, what is the rate of exergy transfer by (a) electrical input, (b) from the heating element, and (c) into the water at Twater?
Find the rate of both energy and exergy (a) from the hot gases and (b) from the condenser.
A heat engine receives 1 kW heat transfer at 1000 K and gives out 400 Was work, with the rest as heat transfer. What are the fluxes of exergy in and out?
The automatic transmission in a car receives 25 kW of shaft work and gives out 23 kW to the drive shaft. Find all the exergy transfer rates.
It now heats from ambient, 25oC, to 70?C in an adiabatic process as the computer is turned on. Find the amount of irreversibility.
Two flows of air, both at 200 kPa mix in an insulated mixing chamber. Find the irreversibility in the process per kilogram of air flowing out.
A constant flow of steel parts at 2 kg/s at 20oC goes into a furnace. Find the reversible work and the irreversibility in this process.