Heat Rejection of Pump

[Funkytown]

Hello! I have a 2000 horsepower reciprocating pump, and I'm trying to determine how much horsepower is being dumped into the lube oil. I know the volume of the tank, the flow rate, the oil properties, and the beginning and ending temperatures over a 30 minute period of time. Where do I go from here???? Thanks for any help.

 

[StoneCold]

Funkytown
If you are looking for the horsepower used then measure the amps that the pump is drawing. Then volts*amps = watts. Convert the watts to horsepower.
If you are looking for how much heat is added to the system then take heat capacity (Btu/lb/°F)* total amount of oil(lbs)*(Final temp - initial temp)/30min That will give you approximately Btu/min. It ignores the metal mass of the system and the current heat loss.
I assume you are looking to add an oil cooler or something?

Hope this helps.

StoneCold

 

[Funkytown]

Thanks, StoneCold. Yes, I'm trying to size a cooler. We advertise a 90% mechanical efficiency on the pump, so I could just say that 10% of the pump's brake hp was going to the oil, but that makes for an enormous cooler.

When you say "*total amount of oil*", do you mean the mass of oil that was circulated over the 30 minutes or the total mass that resides in the lube tank?

 

[StoneCold]

funkytown
What I meant was the total amount of oil in the system.
It does not matter how many times it goes around.

The heat is actually coming from the 90% mechanical efficiency on the pump. Friction of the oil pumping around is where the heat is coming from.

StoneCold

 

[quark]

As the heat input due to inefficiency of the pump system is continuous and more or less constant, I would rather check the temperature difference(inlet and outlet of the pump) of oil at regular intervals. If this is constant, then I would go with the oil flowrate and the temperature difference.

 

[Funkytown]

Thanks for all of your help! I think I have found the answer!