oil in tank heat load calculation

[abbasi]

Hi


how would u calculate the heat load in a tank which has hydraulic oil and its temperature is to be brought down.

will we use


Q= mCpdT

[chemi-cool]

Hi Ali,
Whats the P stands for?
What doe's the oil do and what is the entering temp and leaving desired temp?

The flow, L/H is important too.

Chemi

[binman54]

Hi


how would u calculate the heat load in a tank which has hydraulic oil and its temperature is to be brought down.

will we use


Q= mCpdT

Use the formula if you are pumping the oil through a heat exchanger. It will allow you to calculate the load on the exchanger.
Where:
m is the mass flow rate through the exchanger in gpm, l/sec, etc.
Cp is the specific heat of the oil. Usually about 40% of water
dT is the temperature difference between the inlet and outlet of the oil through the exchanger.
As long as all the units are compatible you should get good results.
Another formula is Q= UAdT. This is used to calculate the heat transfer through the walls of the tank from the oil into the ambient (or out of the ambient into the oil). It works both ways. The trick here is to determine U.
A is the surface area of the tank that is touching the oil.
dT is the difference in the temperature between the ambient and the oil.
The easiest way to do anything like this is to have the supplier of the exchanger do the calculations for you.

Brian

[PobodysNerfect]

Hi


how would u calculate the heat load in a tank which has hydraulic oil and its temperature is to be brought down.

will we use


Q= mCpdT

So why do you need to cool the oil down, or why is the oil getting to hot? Is it working in some extreme temperature conditions?

Normally in a hydraulic system all the heat is coming from the pump, i.e., the electric motor.

In normal working condition the energy the electric motor delivers will go into some work the hydraulic system performs, and only a small part will go into heating of the oil. However, when the system is idling, i.e., when no work is done, all the energy the motor delivers goes into heating of the oil.

In bigger hydraulic systems, the pump will regulate so higher pressure means lower flow. The pump would also likely have an internal regulation to limit the flow when the pump is idling. So maybe the system is not adjusted correctly.

Lets say the system is working correctly and still the oil is getting to hot. How do you plan to cool down the oil?

Saludos,

Jan

[Peter_1]

On all the hydraulic systems we service - and there are at least 25 units - are mechanical cooling systems mounted.

Mostly on metal working machines like lathes, milling machines...

Also in cars and big farmer machines, you always find oil coolers.
The transfomation from pressure to work is not a 100% conversion. The losses heats up the oil.

[abbasi]

hmmmm

Guys one of our team members here used bare tube Dx coil and temperature was to be lowered from 60 to 45 (F) and it worked. He maintains that Dx coil will do the job and it Did. What i studied was formulae I and then Binman also mentioned but how can this guy calculate w/out mass flow rate is it sheer experience or hit and trial may be both. coz he isnt very well qualified.

Q=UAdt is more suitable but how to calculate U

[Peter_1]

It's like Cheme says: you can't calculate the heat load without a mass flow rate, unless you only need to cool the mass oil in a tank in a certain time and have a start and a stop temperature.
Then you can submerge a DX coil. We serviced some time the German cooling units (DKW) of Trumpf lasercutting machines.
They had a bare dx coil in it surrounded with a plastic pipe. Worked very well.

[chemi-cool]

In plastic moulding injection machines, this is the method for cooling the oil, Not a DX but from a central cold water reservoir.

No problems.

Chemi