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Nuts & Volts
31 May 2012, 1532
Hello guys,

So I am trying to size a radiator for liquid cooling a motor and a controller. I haven't taken my Heat Transfer class yet (im studying Mechanical Engineering right now) so I'm not entirely sure how to do the analysis. I have an idea, but don't quite know the process. I am starting to collect relevant numbers for the calculations (specific heats, temperature estimates, flow rates, and heat rejected). But I need some help with this. Can anyone link me to a good book or webpage that I can read through? OR if you want to run through my calculations with me let me know?

My specific heats are 1.005 for air, 2.35 for opticool, and 3.55 for 50/50 glycol water mix. Two different radiators will be used for the motor and controller. I am assuming a peak heat for the motor circuit to be around 15-20kW and my controller to be around 3-5kW. This gives me a small margin because they won't be run at peak at all times and the efficiency will change over time. I was going to assume an air in temp of 30C and something like 90C coolant in and 50C coolant of radiator. I'm not sure what to guess for air temp out of radiator. Flow rate for controller and controller will be ~8L/min to start with.

Do my assumptions seem reasonable? Any suggestions?

I will update this weekend when I do more research
Thanks
Kyle

Allen_okc
01 June 2012, 0530
curious, what kind of water pump will you be using to circulate the anti freeze???

do you need separate radiators for the motor and controller, i would think that one radiator will be sufficient for the both???

and will you need a fan for the air flow???

:cool: please keep us informed when you start building the system...

Richard230
01 June 2012, 0650
You might want to look at the radiator that is installed on the Empulse R to cool its motor and battery systems. That radiator looks pretty big to me, about the size of the radiator on a Suzuki SV650. So my suggestion would be to just buy a used radiator and other cooling system parts from a small Japanese IC motorcycle at a salvage yard. I would think that would have plenty of cooling capacity for your purpose. Using a coolant thermostat would keep things from getting too cool, if that is a concern.

Allen_okc
01 June 2012, 0926
maybe this will help...


http://www.youtube.com/watch?v=Sw6TVymq0hg

Nuts & Volts
01 June 2012, 1232
Allen,

The suggested pump is this one http://koolance.com/pumps/bare-pumps?path=0_122_111&product_id=334.

We have to run two different radiators because we need two different coolant loops. The motor may operate around 80-100 C and generates a lot more heat while the controller should be more at 40-60 C. This means we would most likely be heating the controller and not cooling it. The two parts also specify different coolants for each. I wanted to run one loop, but it was discouraged by one of the controller engineers.

Thanks for the info Richard. I measured the old radiator from my R6 and it is ~10inx12inx1in, but I don't really know how much heat it is outputting to give myself a comparison.

Athlon
01 June 2012, 1505
the right temperature for the coolant is less than 50 , above this temperature you are cooking your electronic , running motor and inverter on same circuit is fine as long you keep the inverter before the motor in the loop , so fresh coolant go from radiator to inverter first , ans after inverter you go to motor.

Circulation pump should be placed between radiator and inverter to stay as coolest as possible ( improving reliability) , also having a little reservoir between radiator and pump help to manage heat pikes.

After the motor coolant should go directly into the radiator to maximize temperature differential between coolant and air to maximize heat transfer.

an aluminium finned reservoir can act also as additional radiator , also copper piping may add some advantage

Allen_okc
04 June 2012, 0810
in my case i like the ideal of a heat pump for the batteries during the winter rides and cooling the controller during the summer...

but i understand now why the two radiators - please when you start building, plenty of photos...

the temperatures during the august months here can reach into the 114 degree F down to -20 degree F during the winter from which i intend to ride during those points of extreme temperatures - my motorcycle will not be stored during the winter months, but on the road running...

so any information pointed out on this thread, very much interests me...

Thank You for bringing this subject up...

Nuts & Volts
04 June 2012, 0859
the right temperature for the coolant is less than 50 , above this temperature you are cooking your electronic , running motor and inverter on same circuit is fine as long you keep the inverter before the motor in the loop , so fresh coolant go from radiator to inverter first , ans after inverter you go to motor.

Circulation pump should be placed between radiator and inverter to stay as coolest as possible ( improving reliability) , also having a little reservoir between radiator and pump help to manage heat pikes.

After the motor coolant should go directly into the radiator to maximize temperature differential between coolant and air to maximize heat transfer.

an aluminium finned reservoir can act also as additional radiator , also copper piping may add some advantage

Thanks! I just saw your post today and will talk to the controller company more about running a single coolant loop with controller first, but I am still hesitant about the ability of the coolant to get down to 40C when its enters the controller. I am going to do some calculations later today to get a baseline calculation.