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Specialty Chemistry Forums => Chemical Engineering Forum => Topic started by: ian123 on July 04, 2015, 11:23:19 AM

Title: Help me. {Work}
Post by: ian123 on July 04, 2015, 11:23:19 AM

A geothermal plant pumps water at 15 degrees celsius into the ground. The water travels through the pipes underground before returning to the surface at a temperature of 90 degrees celsius. If the efficiency of the plant is 10%, how much water must be pumped into the ground every second for the plant to generate 1MW of power?

I used Q=cm(deltaT)
and
n=W/(Q1)
 
Q1=energy input
W=work done of the engine
n=efficiency
c=energy gained per second
delta T= temperature difference
m=mass flow rate

(Q1)=1MW/0.1=10MW
m=(deltaQ)/(c*(deltaT))=10^4kW/((4.2kJ/kg*K)*(75K))=31.75kg/s
I want to know if I what I've done is right or wrong?

Title: Re: Help me.
Post by: Borek on July 04, 2015, 11:46:54 AM

You are on the right track, but lousy with math (which makes your answer wrong).

Title: Re: Help me.
Post by: ian123 on July 04, 2015, 11:48:37 AM

What have done wrong and what can I do to make it right?

Title: Re: Help me.
Post by: ian123 on July 04, 2015, 11:57:46 AM

I think I have done it. Have I done it?

Title: Re: Help me.
Post by: ian123 on July 04, 2015, 11:58:12 AM

Yes or no?

Title: Re: Help me.
Post by: Borek on July 04, 2015, 05:50:25 PM

Be patient, I don't spend my whole life on the forum.

Yes, it looks reasonably correct now.

Title: Re: Help me.
Post by: ian123 on July 04, 2015, 07:28:40 PM

Thanks ;D