Ambient Temperature vs Coolant Temperature In Diesel Engines

Your coolant coil should be of sufficient size, your fan of sufficient CFM, your coolant fluid, of sufficient quantity, that your coolant temperature should remain in the same temperature range according to specifications.....

The equipment manufacturer may have tested this equipment for use in high ambient temperatures in order to sell and warrant for use the equipment in lower latitudes, and may already have this information. So, how did the phone call with their Technical Helpline go?

Feed it some 45° C air and see what happens.

Or, do as a good engineer would and call the gen set tech line.

No one here has any obligation to help you, but the gen set people do.

Is the coolant temperature before or after the cooling radiator? Is the coolant thermostat fully open or partially open at this coolant temperature? Is the electric fan ON or is the cooling air movement solely regulated by engine RPM? How much power reserve is still left in this generating set? When will you cut me a check for doing your work? What media is the liquid coolant? How many quarts of oil does the engine burn? What is the sulphur content of the diesel fuel? Did the generator manufacturer rate this generator set for continuous duty at 45°C? How much sun loading will the building heat add? Do you understand differential equations? How did the conversation with the generator manufacturer go? How much back pressure will the exhaust generate and will the exhaust heat leave the building?

Will you answer any question at all?

Coolant temp is sampled before radiator. Thermostat is fully open. Radiator fan is engine driven. 20% power reserve is still left in this genset. Coolant media is water mixed with anti corrosive additives. Did u mean cheque?

_{In no particular order nor a fully comprehensive list of considerations .......}

If, as you say the thermostat is fully open (how did you determine that?), then the coolant temperature will rise about the same amount as ambient rise.

80% loading and only 78ºC....I think that there may be more overhead (>20%) than you think.(or the thermostat has been removed or has failed in a fully open condition)

The load is 600kW.....what is your genset's prime kVA rating? What's the PF?

What make and model genset/primemover is this?

At what temperature does the thermostat open? 78°C seems to be fairly low to me personally, I would have expected 10°C more or thereabouts......

If this is a pool, I'll buy the 98dC square.

Maybe, depending on RH, etc.

What kind of loading cycle it is subjected to?. Is it continuous, intermittant, varying, periodical/cyclic,short time etc?.

Loading cycle????????????????????????????????????????????????????????????

You're asking me?????????????????????????????????????????????????????????

7

Try to keep up.

There are a few evaporatively cooled engine radiators, but most are air-cooled; thus RH is likely to play only a minor role.

It's all I could come up with. It's late.

Anyway, who cares????????????????????????????

Many a time I've had to hose a radiator with water to get the temperature down when things are operating outside their normal limits and imminent shutdown is not an option.

A first approximation suggests that, if the thermostat may be discounted (Develop Service says it is already fully open) the temperature differential will remain the same.

A shift of 20° will move the coolant temperature to 98° which is not acceptable for an unpressurised coolant system, because 98° is a bulk mean and necessarily implies local boiling. If a better cooling system cannot be acheived, a severe restriction of load is needed

How could the OP "know" that the thermostat is fully open? Thanks in advance for any answer.

I would have removed it completely and then seen what the effect on temperature was.

If the system was well designed for tropical usage, I would expect to see a far lower temperature only when running at some specific load, showing that the motor was now being "over" cooled....and that the thermostat was therefore probably doing its job.

At the same time, the thermostat could be checked fully in hot water to see at what exact temperature it actually opens for example.....and what temperature is marked on it and is it the right one!!!

The OP will find out soon enough when he gets a 45°C day. (OP, have a hose ready)

Pulling a thermostat out just to see, when there doesn't really seem to be a problem, is in violation of the "If it aint broke don't fix it" rule.

If the OP wants to know more, I see no other way....but my ideas are both simple and will deliver useful valuable information.....he doesn't have to follow them though......

I agree that the OP probably doen't know if the thermostat is fully open. If it is fully open then Geoffrey is correct that this cooling system is inadequate for 45°C ambient air operation. If the more likely scenario of a thermostat is not fully open then we cannot tell anything about the cooling system. For all we know the water flow rate through the radiator could be at only 10% with 25°C cooling air to maximize engine efficiency. We do not know enough here to answer the question.

True.

If a thermostat does not open fully or stuck in the closed position, and a new one is not at hand....just break out the thermostat valve for time being. Do not remove the complete thermostat.

The restriction that the thermostat body gives cause the water pump to build up a little pressure and that raises the boiling point of the water. [Found out coping with overheating in the Kalahari desert in South Africa]

Fit a thermostat as soon as possible.

If the cooling system of an engine was made correctly a 20 degree air temperature rise should make no difference to the engine running temperature.

Yea... you are correct. Thermostat have been removed completely. So, i mentioned that, thermostat is fully open. And, the recorded temperature was at its steady state. Means, no further increase in temperature was recorded at this load condition. So, i wanted to know whether, with this cooling system, is it possible to run the machine at safe operating temperature, if the ambient temp reaches 45 deg.C?

Thanks for all the expert feedbacks....

NOW YOU TELL US ??????? WTF?

Fix it on your own.....there is enough infos here already for anyone with a brain.

Byeeeee

Develop Service did say it had coolant in with the water. So boiling temperature will go up. Boiling temp goes up under pressure too.

Surely it is a pressurised system.....or it typically would be....we don't really know do we?

Stop guessing. Where is the OP?

DS said, "Coolant media is water mixed with anti corrosive additives."

Pay attention!!!!!!!!

Radiator water with anti corrosive additives sounds like coolant to me.

..anti rust and all that.

I put in a carefully reasoned response and it was not allowed. Yet unhelpful guesswork was worried like a dog with a bone. What is up with you guys? Who is moderating?

Thanks for asking woodpower,

I'm fine. The other "you guys" may answer for themselves.

How are things with you?

I have no idea who is moderating.

Why do you ask?

You've been here since 2010. You should know how to operate the system and the quirks of the time-out of the response window.

Quit whining. No one killed your response. You did it yourself, and to yourself.

Which post was that? You have only posted once in this blog as far as I can tell.....

Even if Admin deletes a post, they do not erase it completely without any trace.....

I cannot see another post from you here.......nor is one recorded. It looks like you made a mistake, maybe in a different blog.....

With respect, this isn't the place to discuss what happens to threads,

To return to the subject, coolant will raise the boiling point - say 110°C. A pressure cap would increase it further. However the thermal capacity (ability to move heat) of a coolant mixture may be 10%-20% less than plain water. The surprise is that the thermostat is reported as open at 78°C. One would expect a typical radiator wax thermostat to stay closed until 90 - 100°C.

If all the figures are right, the diesel engine should tolerate about 20°C more but temperatures need watching. A new thermostat might be an idea. The best efficiency is obtained if the coolant is at the intended (design) temperature.

Yes provided Thermostat Bypass (also called sometime Wax Valve) line is fully closed at 25 Deg Ambient.

It should not be as in most cases it starts closing around 78 Deg (that means partially closed) and fully closes above approximately 87 Deg C (varies from engine to engine).

To confirm if the By pass is opened (partially or fully) touch the bypass line (carefully and very lightly) if it is cooler than return line from radiator then by pass is fully closed.

If it is warmer than return from radiator then it is partially opened and hence you can not co relate the values at higher than 25 Deg C.

It isn't clear whether the thermostat in the subject aystem is inline with the radiator (open when cylinder block hot) or a bypass (open to bypass radiator when block cold).

In both cases the coolant goes through the radiator as the system heats up.

Normally it would say that the temperature would stay about the same at 78°C. As you state the temperature was taken at the output from the block. Which temperature is controlled by the thermostat.

With the coolant at 78°C with the ambient air at 25°C. You state the thermostat is fully open. Since the thermostats are design to be fully open at about 10° above their rating. You're passed limit of what heat transfer rate the radiator can handle. Adding 20°C to the ambient air would at least increase the coolant 20°C.