Efficiency of Water Cooled Motors

What type of motor?

A water-cooled motor will be smaller than an air-cooled one for the same power output. Complexity increases with water, as there needs to be heat-exchange equipment elsewhere to accompany it.

Efficiency is another issue altogether. The two are unrelated.

I disagree about your comment about efficiency and temperature of an engine. As the Carnot cycle shows, with a broader temperature difference the gas experiences, more thermal energy can be converted into mechanical energy. Now there are many more thermal concerns in operating an engine (fuel knock, vapour lock, lubricant breakdown, etc.) than just this efficiency aspect but an engine working in its designed operating temperature range will be more efficient than a cold engine.

Now as far as the OP's question about the advantages of water cooling over air cooling. Water can carry considerably more heat than air since water is certainly much heavier than air. Also one can much more easily control the flow of water in a closed system than the flow of air in an open system. So one can engineer (control) the heat exchange that happens in an engine cooled by water (and air through a radiator) much easier than with an engine cooled only by air.

Is heat dissipation is equal to total loss of motor..?

Click Here, and provide an answer, then we can all go forward without thrashing about in the dark.

Do you think we're all mind-readers?

Normally these motors are designed for tube well bores,and diameter of tube well bore is guiding parameter for motor designer, To get the smallest possible diameter of motor with maximum power output is normal objective of every manufacturer in these applications, As making a larger diameter bore is more expensive for tube well owner. so the reduction in diameter means increase in length and that too in square relation, you half the diameter of rotor, and length required will be four times. This increase in the motor length means increase of total coper/aluminium conductor length in both rotor and stator,that leads to more I²R losses. But since motor stay inside of water in normal application and that keeps motor temp rise in control.

Thermal expansion.

Ron

Water cooling increases the "Output Coefficient" which is defined as output of electrical rotating machine per unit volume per revolution. It is also a function of electrical loading (current density in windings) and magnetic loading (magnetic flux density) in various active parts. So by use of water as coolant, higher magnetic and electrical loadings (off course, other parameters like reactance etc. also are affected and are to be considered suitably) can be used. This would mean lower active material weight and therefore lower size of the machine.

As regards its effect on efficiency, it may increase as mechanical losses of the rotating parts (rotor, fan etc.) may get reduced due reduction in size and weight. However, extra power required for circulating water for cooling may or may not off set that gain. Change in efficiency may vary from case to case. As far large size generators (where I have experience), water cooling when used in large size generators, efficiency definitely increases.

A water cooled motor can be designed to run in a very tight temperature range, therefore the clearances can be finer and far more exact.

Air cooled motors run with generally far wider temperature ranges and usually have to be designed with greater tolerances for that and therefore usually they wear out sooner because of the wider clearances, all other things being equal of course.

Its difficult to generalize accurately and cover all bases at the same time......naturally there are air cooled engines that have lasted longer than water cooled ones.......somewhere!

WATER COOLED APERATIUS IS CONGELED AT VECTOR,THERE IS ONE ADVANTAGE IN CONFLUENCE THE APERATIUS IS IN HEAT DIERFCATION BUT NOT RECCOMENED FOR MOTORS WITH HEAT RANGES AT 181 DEGREES OR HIGHER. THANK YOU ED MARTINEZ M.L.D. MOLECULAR LINEAR DYNAMICS.

To my undersatnding OP is talking of this.

I thought we were debating the cooling fundamentals between a Rolls-Royce Merlin engine and a Pratt & Whitney Wasp engine. How in the world did you get the idea that this was about a submersible electric well pump?

If the question is about engines used in vehicles:

If something goes wrong with water cooling systems and the driver does not notice overheating he could scrap the engine.

Air cooled engines are a bit noisier but lighter.

I prefer an air cooled engine to watercooling.........The only one I could find is my 1974 1220 Citroen that I am still driving....no concerns with overheating ever.

jurie

We are in an ELECTRICAL ENGINEERING forum, the OP asked a specific question about MOTORS, yet a leap was made to COMBUSTION ENGINES?.

I don't get it.

Yes, I leaped to a conclusion. Regardless of which section this question is posted in, I find the most common motors that can be either air or water cooled are internal combustion motors. Obviously there are water immersed electric motors but I don't think that many of these require the water to cool them. Well maybe a few ship thrusters will overheat if run too long out of water.

It would be nice if the OP clarified the question.

This always happens when an OP does not specify his question correctly......

I personally have never actually seen a water cooled electric motor.....

If a motor needs water cooling (not just because its placed somewhere, where no air cooling works), it probably is quite inefficient to my uninformed mind.....

Just a though...

Didn't kmow they made water-cooled electric motors outside of submersible pumps.

Many many larger electric motors are water cooled. The reason usually is because the motor is operating in a very high ambient and the efficacy of trying to cool a hot motor with hot air is very poor. So they bring in cooler water to a jacket around the stator (and sometimes bearing housing) so that the heat can be removed to a different area via a heat exchanger.

In general the efficiency of the motor itself is no different. but a water cooled system has the added burden of the energy to move the water through the heat exchanger. At the same time, you eliminate the windage losses in the motor's cooling fan (it no longer has one), but still, I believe the net losses are slightly higher in a water cooled system. but if you need one, you need one; efficiency is not the deciding criteria in my opinion.

if however your query was for the purpose of trying to justify the added cost of a water cooled electric motor by comparing efficiencies, forget it. There is a SIGNIFICANT added capital expense to a water cooled system and that trumps all other issues. You only use water cooling if you absolutely must.

There is also a lot of consideration being given to it for EV motors, maybe because with the nature of the application, the heat exchanger (radiator)and water movement system is already there for other reasons anyway and it would then offer a slight benefit in efficiency to not have air cooling fans on the motors. The same is often true for marine electric motors because the water is just flushed through, no heat exchanger at all.

I agree. I'd add only one thing. For the water cooled motors (and generators) that I'm familiar with, the purposes for water cooling it was to 1) prevent any air contaminants from coming near the windings, 2) hermetically seal the entire motor and pump (i.e. zero fluid leakage), 3) ensure that the windings would always have adequate cooling regardless of ambient temperature conditions.

amith, I replied to your OP (asking for clarification) eleven minutes after you posted it.

Now (over 100 hours later) you have not provided any clarification.

Your introductory statement was "Good day to CR4 friends".

If you wish to retain "CR4 friends", I suggest you explain.

Sorry John DG,

I made you people to wait...

I was talking about Water cooled Torque motors...

& data sheet of TMB0210-050, Which says heat dissipation in water cooled motor is higher than air cooled motor....

If Heat dissipation is Equal to Loss of motor, then efficiency of water cooled motor is low.?

correct...