2300_hw_4_sol

2300_hw_4_sol - data. Assumptions The process is...

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Solutions for 4 4-15 Air in a cylinder is compressed at constant temperature until its pressure rises to a specified value. The boundary work done during this process is to be determined. Assumptions 1 The process is quasi-equilibrium. 2 Air is an ideal gas. Properties The gas constant of air is R = 0.287 kJ/kg.K (Table A-1). Analysis The boundary work is determined from its definition to be kJ 272 - = = = = = kPa 600 kPa 150 ln K) K)(285 kJ/kg kg)(0.287 (2.4 ln ln 2 1 2 1 1 2 1 1 ou , P P mRT P d P W t b V Discussion The negative sign indicates that work is done on the system (work input). 4-23 Several sets of pressure and volume data are taken as a gas expands. The boundary work done during this process is to be determined using the experimental
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Unformatted text preview: data. Assumptions The process is quasi-equilibrium. Analysis Plotting the given data on a P-diagram on a graph paper and evaluating the area under the process curve, the work done is determined to be 0.25 kJ . 3-2C A liquid that is about to vaporize is saturated liquid; otherwise it is compressed liquid. 3-10C At supercritical pressures, there is no distinct phase change process. The liquid uniformly and gradually expands into a vapor. At subcritical pressures, there is always a distinct surface between the phases. 3-14C Yes. Otherwise we can create energy by alternately vaporizing and condensing a substance. P 1 2 T =...
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