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Q: heat generation fluid friction ( Answered 4 out of 5 stars,   2 Comments )
Question  
Subject: heat generation fluid friction
Category: Science > Physics
Asked by: 3rrotec-ga
List Price: $20.00
Posted: 20 Nov 2002 15:26 PST
Expires: 20 Dec 2002 15:26 PST
Question ID: 111553
Interested in any research on generating steam from water using high
velocities and resonable pressures. Need rpm's, volumes of water,
horsepower input etc. If answers are satisfactory more questions will
follow. A typical example is pumping water thru a centrifugal pump
right back into the suction side. Heat generated will burn up the
seals. Thanks! 3rrotec

Request for Question Clarification by hedgie-ga on 21 Nov 2002 04:33 PST
3rrotec

          Can you elaborate  meaning of 'reasonable pressures'. Other things -
such as temperature - being equal, lower pressure means more evaporation.
By steam we mean vapor, that is H2O in gasesous state, reight?

Clarification of Question by 3rrotec-ga on 24 Nov 2002 04:09 PST
Sorry for delay. Hard drive problems. According to Machinery's
Handbook 1 H.P.=2.64 lbs. H2O evaporated per hour. If desired amount
H2O is 875 gal. per hour: 875 x 8.33 = 7289 lbs. per hour.
7289/2.64=2760 h.p. Does this mean we have to run a 2760 h.p. engine
for one hour to evaporate 875 gallons of H2O assuming 100% efficiency?
If you agree we just need to use electricity or cord wood! If you
disagree please explain. Thanks 3rrotec
Answer  
Subject: Re: heat generation fluid friction
Answered By: hedgie-ga on 30 Nov 2002 03:41 PST
Rated:4 out of 5 stars
 
3rrotc

  Answer to your question is yes, aproximately.

 The numbers I am getting based on two data

1)  Latent heat of evaporation for water = 2.5 kJ per g   (see
https://answers.google.com/answers/main?cmd=threadview&id=114825

2)1 gallon ~ 3.78 l  has mass about 3.78 kg and weight ~ 8.33 lb

 Your requirement   7289 lb per hour is 3307.5 kg/h = .91875 kg/s 
(kg/s =kilogram per second) using conversion 2.

 Using constant 1) that requires  2.29 MW  (mega watts) of power. 

Converting MW to HP ( 1HP=750W) we get 3065 H.P. engine.

 This is reasonably close to your number 2760, considering that
 density of water depends on temperature and we are assuming 100%
 efficiency.

  hedgie
3rrotec-ga rated this answer:4 out of 5 stars
Good answer.

Comments  
Subject: Re: heat generation fluid friction
From: neilzero-ga on 20 Nov 2002 15:52 PST
 
This seems like the reverse of what we do in a steam turbine: Is it
possible to turn a small "off the shelf steam turbine" in the reverse
direction with a motor while spraying (low pressure) cold or warm
water into what is normaly the exhaust end and get hot high presure
steam from what is normally the input end. This should not stress =
damage the turbine. If it works even slightly, a more efficient design
should be possible. I'm just guessing = brainstorming.   Neil
Subject: Re: heat generation fluid friction
From: 3rrotec-ga on 24 Nov 2002 04:23 PST
 
Sorry for delay. Hard drive problems. According to Machinery's
Handbook 1 hp is equal to 2.64 lbs. water evaporated per hour. If
desired quanity of water is 7289 lbs per hour: 7289/2.64=2760 hp per
hour. Does this mean we have to run a 2760 hp engine for one hour to
evaporate 875 gallons of water assuming 100% efficiency? If you agree
we should use cord wood! If you disagree please explain. Thanks!
3rrotec

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