# Assumptions 1 there are no irreversibilities involved

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Unformatted text preview: ake the water in the cylinder as the system (Fig. 7–69). This is a closed system since no mass crosses the system boundary during the process. We note that the pressure and thus the temperature of water in the cylinder remain constant during this process. Also, the entropy of the system decreases the process because of heat loss. Assumptions 1 There are no irreversibilities involved within the system boundaries, and thus the process is internally reversible. 2 The water temperature remains constant at 100°C everywhere, including the boundaries. Analysis (a) Noting that water undergoes an internally reversible isothermal process, its entropy change can be determined from ∆Ssystem Q Tsystem (100 600 kJ 273 K) 1.61 kJ/K T = 100°C 600 kJ H2O Tsurr = 25°C FIGURE 7–69 Schematic for Example 7–21. cen54261_ch07.qxd 11/18/03 9:57 AM Page 330 330 FUNDAMENTALS OF THERMAL-FLUID SCIENCES (b) To determine the total entropy generation during this process, we consider the extended system, which includes the water, the piston-cylinder device, and the region immediately outside the system that experiences a temperature change so that the entire boundary of the e...
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