What is the Enthalpy of Water at 45 Degrees and 1.2 Bar Pressure?

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SUMMARY

The enthalpy of water at 45 degrees Celsius and 1.2 bar pressure is 188.51 kJ/kg, as referenced from the NBS/NRC Steam Tables. The discussion highlights the importance of understanding the quality of the water, as the user is dealing with a liquid-vapor mixture below the saturation temperature of 104.81 degrees Celsius at 1.2 bar. To accurately calculate heat transfer from condensing steam, the quality value must be specified. This ensures the correct enthalpy values are used in calculations.

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Students and professionals in thermodynamics, chemical engineering, and mechanical engineering who are involved in heat transfer calculations and the properties of water under varying pressures and temperatures.

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Homework Statement


Finding the enthalpy of water with the following known data:
Water, temperature 45 degrees, pressure 1.2 bar


Homework Equations


Q' = m'(steam) * h(gas) - m'(steam) - h(fluid)


The Attempt at a Solution


I need to find the enthalpy of water under the circumstances above, to calculate a quantity of heat transferred by condensing steam. However I seem to be unable to find the enthalpy of the fluid. All attempts to find the enthalpy, I end up with either tables of saturated water or compressed water at pressures way above 1.2bar. Anybody can help me with the problem?
 
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Just look the values up in the steam tables.

I am assuming that you are using degree C because your pressure is in bars. From my copy of the NBS/NRC Steam Tables I have the following value.

h for compressed water is 188.51 kJ/kg @ 45 C and 1.2 bars.

You haven't specified at quality and you clearly do not have superheated steam because the saturation temperature @ 1.2 bar is 104.81 C and you are well below that temperature. Therefore, you have a liquid-vapor mixture which means that you need a quality value in order to determine the other enthalpy value that you need.

Do you follow?

Thanks
Matt
 

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