A one meter cubed rigid tank contains 100 kg of R-410a at ambienttemperature, 15

Question

A one meter cubed rigid tank contains 100 kg of R-410a at ambienttemperature, 15 degrees C. A valve on top of the tank isopened, and saturated vapor is throttled to ambient pressure, 100kPa an flows to a collector system. During the process, thetemperature in the tank remains at 15 degrees C. The valve isclosed when no more liquid remains inside. Calculate the heattransfer to the tank and the total entropy generation in theprocess.

I realize how to calculate Sgen but i need help startingthe calculation for Q (heat transfer). What equations do weneed? Please help. I rate high. Thank you foryour time and expertise.

Explanation / Answer

Continuity Equation: m2 - m1 = me Energy Equation: m2u2 -m1u1 = Q mehe Entropy Equation: m2s2 -m1s1 = Q/TSUR mese + Sgen v1 = V1/m1 => 1/100 =0.000812 + x1* 0.02918 =>x1 = 0.3149, u1 = 61.88 + 0.3149 × 169.47 = 115.25 kJ/kg s1 = 0.2382 + 0.3149 × 0.668 = 0.44855 he = hg = 255.0 kJ/kg v2 = vg = 0.02999, u2 = ug = 231.35, s2 = 0.9062 kJ/kg K he = 255.0, Pe = 100 kPa Te = -4.7°C, se = 1.0917 m2 = 1/0.02999 = 33.34 kg; me = 100 - 33.34 = 66.66 kg Q = m2u2 - m1u1 +mehe =>Q= 33.34×231.35 - 100×115.25 + 66.66×255 =>Q = 13,186 kJ Scv = m2s2 - m1s1= 33.34(0.9062) - 100(0.44855) = -14.6 SSUR = Q/TSUR +mese = -13186/288.2 + 66.66(1.0917) = 27 Sgen = -14.6 + 27 Sgen = 12.4 kJ/K

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