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Estimating Electric Motor Heat Production

Estimating Electric Motor Heat Production

Estimating Electric Motor Heat Production

(OP)
Does anyone have a quick calculation method for estimating the heat generated by an electric motor?  I'm curious if I can provide sufficient heating from a pump motor to keep a pump house above freezing while the pump is running.

RE: Estimating Electric Motor Heat Production

Wattsloss=I2R

RE: Estimating Electric Motor Heat Production

(OP)
That's concise, but is there an easy way to estimate the resistance for a pump motor?

RE: Estimating Electric Motor Heat Production

Bekirk,

If you have the motor efficiency, it is pretty safe to assume that the rest of the input power is lost to either friction or I^2R losses.  Either one comes out in the form of heat.

Say you have a 10 hp motor with a full-load efficiency of 90%, and operating at full load.  The heat generated would therefore be the remaining 10%.  Converted to heat, that would be 2544 BTU/hr (1.0 Hp).

Regards,

speco

RE: Estimating Electric Motor Heat Production

(OP)
Speco,

Thanks for explaining.  That's pretty simple.  The complicated question then becomes how much heat is transferred to the water being pumped vs. the air around the pump.  

Thanks!

Bekirk

RE: Estimating Electric Motor Heat Production

That depends on who built the coolant system.  If the manufacturer did, and it requires water cooling, we use a 90/10 rule, i.e., 90% of the heat goes to the water.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: Estimating Electric Motor Heat Production

(OP)
IRstuff,

As far as I know, the centrifugal pump used in this case was designed to be air-cooled, and that heat transfer to the product being pumped (i.e. water) was intended to be minimized.  So I was guessing that in this case heat transfer to water was much less than 90%, but to be honest, I really don't know.

RE: Estimating Electric Motor Heat Production

Sorry, I read your description as if there was a separate water cooling system.  

In your case, the heat rejection into the air should be at least 90% of the motor heat load.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: Estimating Electric Motor Heat Production

(OP)
Great!  I think in total that pretty much answers my original question enough for what I need it for.

Thanks,

Barton

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