[Own Little World]

Dear all,

I am after a bit of advice regarding radiator sizing. My intended power plant is a 9okW Hyundai motor with AC inverter, both are fluid cooled, sharing the same coolant system and pump.

I originally reckoned on being able to significantly reduce the size of the rad due to the increased efficiency of the motor. I was hoping that I could use an oil cooler slung underneath and block up the grill for added aerodynamics.

However, I have heard people advising that due to the lower temperature tolerance of the inverter electronics the radiator size needs to be pretty much unaltered.

That would be a bit of a pain and require a rethink of the layout.

Does anyone have any advice?

Many thanks,

Alec

 

[Duncan]

Run the numbers!

The original engine would have required - at least 100 kw of cooling and the delta T would have been about 70C

Your new layout will need less than 5 kw - but the delta T will go down to about 35C

So you will need about 1/10th of the radiator

In practice that would only be at full power - and only for a few seconds so you will not need as much as that

 

[Own Little World]

Hi again Duncan. Thanks for getting back.

I did run the numbers and that is what got me looking at a few mocal oil coolers until I saw some advice (maybe here but I don't remember now) from someone who had gone through the process themselves.

Generally, I do tend to put a lot of trust into my spreadsheets but I am very aware that I am only really dipping my foot in here, with little practical experience.

I suppose the most important thing is to make sure that the coolant pump is up to snuff. However, as an electrical item that could fail (rather than a mechanical pump that will only stop if the engine does too) I imagine that it would be a good idea to have some passive cooling capacity in reserve.

Or maybe a monitor on the pump status/coolant temp that will cut off the motor power if necessary.

Thanks again for your insights as ever.

Alec

 

[Duncan]

Hi Alec
Just for some real world experience I have a water cooled controller
I'm running 1200 amps and 340volts
I use a small solar hot water pump to circulate the water through my controller and through my Chevy Volt battery

I have no radiators in the circuit - here (Southland NZ) I have zero need for any cooling and I keep thinking about adding heating to get my batteries up to their optimum (for power) temperature

In the hottest days in the summer (while competing) I have seen controller temperatures of 25C - the optimum battery temperature is 30C - but the highest I have seen was 22C

 

[Yabert]

Some real world experience.
1980 Vanagon with Chevy bolt drivetrain. I use a tiny radiator from a POLARIS SPORTSMAN 700.
To add, the radiator is not in the air flow when the car is moving since it is in rear of the van, but in front of the motor.
Despite that, no overheating problem during 30°C summer day.
The worst temperature see was 60°C after an hour of highway and it's why I plan to add a fan in front of the radiator.

 

[Own Little World]

Duncan, Yabert,


Thanks for the insights I did reply yesterday on the train but it seems to have got lost in the ether.


That is good news that you manage to get away with such minimal heatsinking. I am thinking that in the worst case I could cut a small hole in the fibreglass belly pan I have made and mount a small rad edge, flush with the outer surface so it is open to the outside world but not disrupting airflow too much.


Or alternatively trail the ipes around the batteries too keep the chill off in winter.


By the way, in your setups do your motor and inverter share the same coolant system?


Many thanks.


Alec

 

[Yabert]

By the way, in your setups do your motor and inverter share the same coolant system?

Yes. Motor, inverter, charger, DC/DC all same coolant loop.
Battery on another cooling loop.

 

[Duncan]

By the way, in your setups do your motor and inverter share the same coolant system?

Coolant loop is controller and battery

Motor is air cooled