Fan Heat Gain
Fan Heat Gain
(OP)
Dear Engineers,
I read in a book where FAN HEAT GAIN is given by the formula:
Fan Heat Gain = Nameplate ShaftPower/Overall efficiency of motor+drive+fan.
I believed the heat gain to be a part of energy that is being lost due to inefficiency. In other words, "Power input*(1-overall efficiency)". When this is written in terms of break power "Break Power*{(1-eff)/eff)". But after reading the above formula for heat gain, I am just wondering how come all the power absorbed contribute to heat gain? How come the part of energy that helps air to gain pressure and velocity account for heat gain?
Even I referred ASHRAE Fundamentals 1997, Table 4 on Chapter 28, Pg: 28.10. The values given there are in line with the formula given above. I'm interested to find the heat gain for an AHU motor which falls under the "motor in, drive equipment in" category.
I am struck up here. Kindly do advice or suggest me an article regarding this.
Thanks in advance for the support.
I read in a book where FAN HEAT GAIN is given by the formula:
Fan Heat Gain = Nameplate ShaftPower/Overall efficiency of motor+drive+fan.
I believed the heat gain to be a part of energy that is being lost due to inefficiency. In other words, "Power input*(1-overall efficiency)". When this is written in terms of break power "Break Power*{(1-eff)/eff)". But after reading the above formula for heat gain, I am just wondering how come all the power absorbed contribute to heat gain? How come the part of energy that helps air to gain pressure and velocity account for heat gain?
Even I referred ASHRAE Fundamentals 1997, Table 4 on Chapter 28, Pg: 28.10. The values given there are in line with the formula given above. I'm interested to find the heat gain for an AHU motor which falls under the "motor in, drive equipment in" category.
I am struck up here. Kindly do advice or suggest me an article regarding this.
Thanks in advance for the support.





RE: Fan Heat Gain
RE: Fan Heat Gain
RE: Fan Heat Gain
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Fan Heat Gain
I just need a clarification that how come a 0.75kW 3ph motor will contribute a heat gain of 0.993kW in a motor in, drive in configuration. Please refer ASHRAE 1997 Fundamentals, Chapter 28-Table 4 on Pg:28.10.
I asked this question just to increase my level of understanding. I wish NOT to follow anything only because it is being followed by some.
RE: Fan Heat Gain
This should help
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Fan Heat Gain
I also know there might be some reasons for doing so. I'm trying to figuring it out. Any justifications for the above will be highly appreciated.
RE: Fan Heat Gain
The only way you can get more than shaft power going into the air is if the motor is in the air flow and then you need to add electrical motor efficiency.
Maybe that's what it is trying to calculate?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Fan Heat Gain
RE: Fan Heat Gain
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Fan Heat Gain
RE: Fan Heat Gain
And for fans, yes, the mesured electric power at fan input will ALL be translated to heat.
Ingenieur Minier. QuTbec, Canada.
RE: Fan Heat Gain
RE: Fan Heat Gain
RE: Fan Heat Gain
No. The Energy goes into Potential Energy of Rock. Or Heat.
Explanation :
The energy balance is the same, whatever the counterweigh. Ore is still hoisted to surface. The energy required to do that is not reduced by the counterweigh.
Counterweigh is there to reduce required Power.
Ingenieur Minier. QuTbec, Canada.
RE: Fan Heat Gain
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Fan Heat Gain
How it's being calculated? I didn't. My bad. As I get older (maybe to my detriment) calculations of unnecessary values takes a back seat to things that matter. Like I said, it's honestly 1-3°F repeatedly and routinely. Higher temperature rises might indicate a problem.
RE: Fan Heat Gain
I am still not completely clear on the actual sensible heat gain that is experienced across the fan. It is a conservation of energy problem, but the pressure imparted to the air does not manifest as temperature gain across the fan. So I have found it to be difficult to quantify the actual sensible temperature gain of the air.
RE: Fan Heat Gain
RE: Fan Heat Gain
And I believe this can be a solid reason.