Boiler efficiency question

[CR1310]

Hi guys i am getting some trouble with a boiler question here. i am looking for guidance.

i am to find the fuel consumed in a boiler.

given:

steam flow rate
superheated temperature
feed water temperature
pressure
boiler efficiency
calorific value of fuel
and the cp of the superheated steam

my question is how to i calculate the enthalpy of the feed water to plug that back into the boiler efficiency equation?

i would normally go into the steam tables but they specified that they should not be used

if anyone could help me it would be much appreciated

 

[DRWeig]

Here's a non-steam water table:

http://www.engineeringtoolbox.com/water-thermal-properties-d_162.html

There are calculators available online too. Google "enthalpy of water."

Good on ya,

Goober Dave

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[CR1310]

thanks dave for the reply but i am to use only the information given to me.

how exactly should i use the cp value in my calculations?

this is the only thing keeping me back rite now. I have a feeling it is used somehow to help calculate the feed water enthalpy

 

[DRWeig]

If you know the enthalpy of the entering water, the enthalpy of the leaving steam, and the mass flow rate, you can compute the amount of total heat added by the boiler, yes?

Good on ya,

Goober Dave

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[CR1310]

I got some help from a university lecturer and he told me the exact same thing. I have solved the problem.

thanks for the help dave. it was much appreciated.