Cooling System for Fluid Power Applications

[13392017]

Hello Guys,
I am beginner in designing fluid power applicaton. I need your expertise advice for the problem we have now.
We are designing some electrohydraulic system for spooling cable. The system will equiped with 2 discbrakes for controlling the cable tension, Hydraulic accumulator, one hydraulic motor, one hydraulic pump & 11 kW electric motor as power source.
The system almost finish unless the heat exchangers for cooling system.
I have no idea to size the cooling system.
We planned to make some air cooled HE, with fan installed on shaft of Elect. Motor & Hyd. Pump. And Circular tubing with fin at the outer side of fan. The size of tubing is about 1/2 " ID.
I need some formula to size the diameter of circular tubing and how much circle i should build.
(The power loss which is converted to heat, estimated will be about 25 % of Power Supply (2.75 kW))

 

[saxon]

133, Try an air/oil cooler. Thermodynamics tells us that any energy put into a system that is not converted to work will be converted to heat. So where is the energy coming from? The motor. Assume that all energy from the motor is being converted to heat (worse case scenario). In order to get the heat flow that needs to be rejected, convert the hp/hr to btu's, multiply by 2545. This is the amount of heat the cooler must reject. Size the cooler on this number. It's slightly overkill, but you'll never have an over heating problem.

Try the following site for coolers:

http://www.boschrexroth.com

Hope this helps.
saxon

 

[rmw]

Since it is such an unknown issue, I agree with Saxon regarding sizing to the worst case scenario.

Have you considered eddy current retarders with torque control (set up like a dynomometer) for the tensioning hold back instead of disc brakes?

I have seen it done, and the flywheels of the eddy current retarders dissapate the heat of the braking.

rmw

 

[MikeHalloran]

133, if the homemade heat exchanger you seem to be proposing doesn't work well enough, or fails in some unforeseen way, "Who you gonna call?".

BUY a heat exchanger, large enough to dissipate all the heat that the motor could possibly add.

You'll have trouble enough, getting the _system_ to work right, without also developing a component.



Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[unclesyd]

Adding to rmw’s post here is website for the tensioning device.

http://www.magnetictech.com/index.htm

 

[rmw]

Unclesyd,

That is a great site, but I notice that their maximum capability was only 140 in-lb., and suspect that 133... is looking for more capacity than that.

I was thinking more along the lines of equipment line the links below, all of which is commonly used in automotive dynamometers at torques and speeds that 133... will never get to.

I once did a project like this, and this for highline tensioning for a company out in Utah, I think it was, and it worked well.

Some links are:

http://www.zelusl.com/

http://www.tmm.es/webtmmi/default.htm

click on products, click on retarders.

http://www.dynocomp.com/tuner.php

This ought to give a direction to start out on if 133... is interested in this approach.

rmw

 

[unclesyd]

rmw,

Appreciate bringing me up to speed. I just remember them being used and didn’t stop to look at the physicals.

Take a look at the picture on the lower right side. This is a an Aluminum Beam filled with synthetic yard and in our case weighs in at 2200 lbs when full. You have gotten me thinking was this tensioning device coupled through a gear box.

http://www.magnetictech.com/applications.htm

 

[13392017]

Thank you guys for your valuable comment,
I forget to told you about time usage of equipment above, which is about 2 - 3 hours a time. rest of it, will use just about 5 % of pump power, and supplied by Accumulator.
At the first 2 -3 hours, the system filled the accumulator.

About retarders, at the first stage of designing this system, we already decided that the system will use all hydraulic power instead of electric for braking system.

Thank you
RK a.k.a 13392017