Chapter 6, Problem 6.122P

One kg of fluid expands reversibly according to a linear law from 4.2 bar to 1.4 bar. The initial and final volume are 0.004 and 0.02 m² respectively. The fluid then cooled reversibly at constant pressure, and finally compressed reversibly according to a law PV=C back to initial condition of 4.2 bar and 0.004 m². Calculate the work done for each process, the net work done and sketch the cycle on the P-V diagram. (4480, -1120, -1845 &1515 N-m)

A water pump operating at steady state has 76 mm diameter inlet and exit pipes, each at the same elevation. The water can be modeled as incompressible and its temperature remains constant at 20°C. For a power input of 1.5 kW, determine the pressure rise from inlet to exit, in kPa at the volumetric flow rate of A m/s (A=0.015 m/s, 0.017 m/s, 0.02 m/s). Plot the A- the pressure rise from inlet to exit in graph.

One can store energy by compressing air and use it later to power a turbine to create energywhen needed. The air must be heated to make this effective, which can be accomplished by compressing the air under adiabatic conditions. This is called adiabatic compressed air energy storage (CAES). Inside a typical power plant, 5.8×10^6 kg of N2 gas is at 25 °C is compressed from atmospheric to pressure into a volume of 300,000 m3 (they use abandoned salt mines). The process is done reversibly and adiabatically. What is q, n, Vi, Pf, T, U,w, and H and for this process? (Cp,m = 29.12 J/K/mol and Cv,m = 20.80 J/K/mol for N2). Assume perfect gas behavior.