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Heat generated by pump

Heat generated by pump

(OP)
Hi guys,

I am running a heat transfer experiment along with my PhD that involves a closed pipe-in-pipe system. My coolant (jacket) fluid is flowing from a tank by a centrifugal pump through the jacket and it comes back to the tank while my hot fluid goes through a same process.
In my inner pipe, hot fluid is oil and the test takes several hours so the heat can be transferred then I can measure it. Obviously, since I have a closed system, both hot fluid and coolant fluid are going to get cooler and hotter respectively by time. However, the increase in coolant's fluid temperature is partially due to pump. Therefore, I need to know how much heat is generated by pump so I can rule it out from my main heat transfer calculation.
[b]Can anyone help me with a methodology that is able to give the produced heat by pump without knowing its efficiency? please also be aware that, I know the temperature increase versus time for different coolant fluid volumes with no hot fluid inside the inner pipe (which means the temperature increase is only due to pump).
The attached picture is the graph of temperature increase versus time for different coolant fluid volumes.


Thank you so much :)

RE: Heat generated by pump

for a closed loop system, nearly all the energy you put into the pump from the motor (measure volts x amps x 0.9) turns into fluid heat. The efficiency will give you the temperature rise within the pump itself, but the remainder of the energy is then dispersed as friction in the fluid until the fluid is at virtual rest in you tank.

You will have some energy leaving the system due to the pipes and tank getting hotter, but in terms of energy in for this sort of system that's the basic way of thinking about it. In your system the temperature seems to stabilise around the 90F level where heat input from your pump = heat loss to the atmosphere from your pipes and tank.

I suspect for a laboratory sized equipment the pump power / motor power is pretty low?? some numbers would be good to know.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Heat generated by pump

Due to the account of power loss in pumps, the generated heat can rise fluid temperature. You can estimate this temp. rise by using-I.J Karassik eq
ΔT=BP*(1-η)/(Cp*Q*Ρ) [T-oC, BP-kW, η-%eff, Cp-KJ/kgoC, Q-cu.m/hr, P-density kg/cu.m)

RE: Heat generated by pump

Without checking, I would say there is lots of good data on the net related to your question. And, as you are writing a PhD thesis, part of your research would need lengthy discussion on the very question you are posing, otherwise your results would be compromised without this discussion.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Heat generated by pump

(OP)
LittleInch
The picture has some information about the motor. However, I tried to call the manufacturer to get the efficiency and he told me that information is not publicly available!!!
But he said it is roughly 60%. Does this percentile reasonable to you?
By knowing the efficiency as (Vijay. said), I can simply calculate the temperature raise and then the produced heat.

RE: Heat generated by pump

60% for a pump of that size is fairly standard.

Error edit

60% for a motor is low, but I'm used to larger ones and from nameplate data appears correct or even high.

Shaft output 0.375 kw but elec of 1 kw (210v x 5A) indicates even lower. However measure current and volts as power consumed is dependant on flow rate and head.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Heat generated by pump

Li, that was motor eff. not pump, assume a typo?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Heat generated by pump

"I know the temperature increase versus time for different coolant fluid volumes with no hot fluid inside the inner pipe (which means the temperature increase is only due to pump)."

With this information you know the heat input from the pump and need no other pump information.

Ted

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