Help with estimating the outlet temp of a fluid through a process
Help with estimating the outlet temp of a fluid through a process
(OP)
Firstly, I don't know a lot about heat transfer, that's why I'm here. (and no I'm not a student or studying for any exams etc etc. :)
I'm designing a pump system, and the lubrication on the system needs to be cooled using a blast air cooler.
The environment is offshore indoors with temps of -20 degC to +25 degC.
My max oil temp into my process pump is 55 degC and I'm going to be putting approximately 120 kw of energy into the oil as heat (give or take a bit).
The oil is ISO 100, pressure 3-8 bar, flow rate 130 lpm.
What I'm in need of help with, is the calculation on how to estimate the heat of the oil when it returns to the system, (with 120kw of energy in it).
Then I can set my system temp. and hopefully get a reasonable pressure drop across my cooler (which is the main problem).
Any assistance greatly appreciate.
Basic drawing attached for anyone interested.
I'm designing a pump system, and the lubrication on the system needs to be cooled using a blast air cooler.
The environment is offshore indoors with temps of -20 degC to +25 degC.
My max oil temp into my process pump is 55 degC and I'm going to be putting approximately 120 kw of energy into the oil as heat (give or take a bit).
The oil is ISO 100, pressure 3-8 bar, flow rate 130 lpm.
What I'm in need of help with, is the calculation on how to estimate the heat of the oil when it returns to the system, (with 120kw of energy in it).
Then I can set my system temp. and hopefully get a reasonable pressure drop across my cooler (which is the main problem).
Any assistance greatly appreciate.
Basic drawing attached for anyone interested.





RE: Help with estimating the outlet temp of a fluid through a process
deltaT = Q/(M*cp)
Q = 120000 W = 120000 J/s
M = 1.84 kg/s mass flow rate (for ISO 100 @ 55 °C is approx 850 kg/m^3)
cp = 2009 J/ (kg*°C) specific heat of ISO 100 @ 55 °C
deltaT = 32.5 °C
So Tf = Ti + deltaT = 55 + 32.5 = 87.5 °C
RE: Help with estimating the outlet temp of a fluid through a process
Not wanting to get too (out of my depth) deep, did you calculate the M and cp figures or were they taken from a table?
Looking to calculate the same with different inlet temperatures and energy and draw some kind of graph, to show peak temperature scenario.
I've attached the drawing as a .doc now (was a .pdf)
RE: Help with estimating the outlet temp of a fluid through a process
Further to your question:
Mass flow rate has been calculated from your flow input (130 lpm) and the density of ISO 100 (tabulated value).
Specific heat is tabulated too.
You can download a spreadsheet (Lubricant_properties_calculator.XLS) which reports ISO 100 and many other lubricants properties vs temperature.
http://www.xlrotor.com/resources/files.shtml