changes in temperature, changes in phase, reactions änd mixing 1. Steam tables a
ID: 2321709 • Letter: C
Question
changes in temperature, changes in phase, reactions änd mixing 1. Steam tables are frequently used to obtain values of internal energy or enthalpy for solving problems in which there are changes in these properties. Use values from the steam tables E5 and E6 in the Appendix of your textbook for this problem. Assume that internal energy is not dependent on pressure, allowing values from the table at the correct temperature to be used even if the pressure is different. Enthalpy of the liquid, however, does depend on pressure. Make an adjustment for pressure by adding (PV) to the value read from the table. For (PV) calculation you can use the specific volume at the saturated pressure, the pressure difference is the desired pressure minus the saturation pressure. Complete the table below using values from the steam table and adjusting enthalpy values for Complete the table below using values from the steam table and adjusting halpy valus for pressure differences as needed. Values from Table, at saturation adjusted enthalpy Desired Conditions pressure values Temp, Pressure, Psat at Vol, Internal Bar given T m/kgEnergy d(PV) Enthalpy for Enthalpy Phase uid Liquid 0.01 0.00611 0.00611 0.001 Zero Liquid 25 1.01325 Liquid 100 1.01325 Vapor 100 1.01325 Liquid 25 10 Liquid 1799 10 Vapor 179.9 10 Liquid water flowing at 12.0 liters per minute is drawn into a pump from a reservoir at 1.00 atm pressure, 25°C. The pump raises the pressure of the liquid to 10.0 Bar. This pressurize water enters a boiler, coming out as saturated steam at 10.0 Bar. Determine the rate of work needed for the pump and the rate of heat needed for the boiler. You should be able to use values from above. After Boiler Before Pump 25 1.0 Sub-cooled After Pump 25 10.0 Sub-cooled l emperature, C 10.0 Saturated Pressure, Bar condition Mass flow, kg/s Specific volume, m3/kg Internal Energy. kJ/kg Enthalpy, kJ/kg
Explanation / Answer
Using the steam table provided the following values were obtained
Desired Conditions Values from table at sat. pressure Adjusted Enthalpy Values Phase Temp C Pressure Psat Vol m^3/kg Internal Energy kJ/kg Enthalpy kJ/kg d(PV) Adjusted Enthalpy Liquid 0.01 0.00611 0.00611 0.001 Zero 0 0 0 Liquid 25 1.01325 1.01325 0.001 105 105 0.101325 105.101325 Liquid 100 1.01325 1.01325 0.00104 419.00 419.00 0.105378 419.105378 Vapor 100 1.01325 1.01325 1.67 2510.00 2680.00 169.21275 2849.21275 Liquid 25 10 0.0317 0.001 105.00 106.00 0.00317 106.00317 Liquid 179.9 10 10 0.001130 761.00 763.00 1.13 764.13 Vapor 179.9 10 10 0.194 2580.00 2780.00 194 2974Related Questions
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