Diesel Engine Driven Generator 2

[EEJaime]

We've got a project where we are specifying a 2 Mw genset with a remote radiator package. The manufacture's rep just told me that as of Jan 1, 06, the Environmental Protection Agency here in California will no longer permit any air to water aftercoolers for the engines. For the project I'm involved in the remote radiator package was the only way we could fit the unit in the existing generator room. If the unit cannot have a remote radiator, I'm going to need more room. The rep also told me there was as yet no data on the new units.

Has anyone out there run across air to air aftercooled engines on Generator sets? The unit is a 2000kw, 480y/277v, 3ph, 4w. unit using a CAT 3516 TA engine that we've spec'd now. Does anyone know of other manufacturer's that use the air to air aftercoolers. And last but not least can one of you engine-eers explain to this electrical type what exactly an aftercooler does? After what?

Any input would be greatly appreciated.

 

[dwedel]

I would get a second opinion on the EPA code for California. I have been trying to listen to the air quality rules and their future applications and I haven’t heard of anything like this. If you find out why this is required please post it here as I would like to know. Or maybe when you find out why it is required the rules or terms will make more sense.

To give my background, we run natural gas compressors for pipelines, and use Waukesha 7044’s which is similar to the Cat 3500 series.

An aftercooler is used in the air intake and cools the air after the turbocharger compresses it. It is virtually the same as an intercooler in an auto application. The turbo both from compression and some from the high exhaust temp heats up the air that is used to burn the fuel in the cylinder. By cooling the air by using engine coolant, the air temperature is reduced and more air can be stuffed into the cylinder, this creates a more efficient engine.

Yes, air to air exchangers are made, but I have not personally seem them in this application.

Good Luck


dwedel
Hotrod Big Engines!
For site policies and guidelines
see faq731-376

 

[MikeHalloran]

A 3516 has two turbochargers, axes athwartships, at the flywheel end of the engine, hot ends facing each other, cold ends outboard. Air exiting each compressor travels forward and inboard through an angled arm-sized pipe, where it enters a ribbed metal housing atop the engine. That's the aftercooler; cooled air exits from the bottom into the intake manifold.

Inside the aftercooler is a long radiator core. In marine applications it's cooled by seawater exiting the seawater pump, usually the coolest water available in quantity. From there, the slightly warmed seawater travels to the main heat exchanger(s), and then back to the sea.

Maybe the Cal EPA is assuming that you'd use a flow of groundwater to cool the aftercooler, and then discard the water after using it just once. It should be possible to
cool the aftercooler by circulating water/glycol through it and a remote radiator.

That would likely be smaller than, and separate from, the remote radiator used to cool the engine coolant. You want the aftercooler's coolant temperature lower than the engine's coolant temperature if at all possible.

Your Friendly Local Caterpillar Dealer should be able to bury you in technical information, including specific detailed data on a bewildering assortment of heat exchangers and radiators.



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

 

[dwedel]

On our land based units we have a main and auxiliary coolant systems. The main is for the engine block jacket water system, and the auxiliary is for the aftercoolers, oil cooler, and compressor cylinders depending on temperature requirements. Both are re-circulating glycol/water mixtures. In my experience the radiator (cooler) for the engine will have both the main and the aux coolers mounted on the same fan housing. For one of our 12 cylinder Waukesha 7044 packages the main coolant system runs with an inlet of 180F and an outlet of 157F and the aux system runs with an inlet of157F and an outlet of 130F.

As you can see EEJamie, there are many options to chose from. Boats are different from compressor packages and both may be different from a genset in California. Good luck searching for your information.


dwedel
Hotrod Big Engines!
For site policies and guidelines
see faq731-376

 

[EEJaime]

Thank you all for your input. Just to let you all know, the reason this change is happening as I've come to find out, is that as of January 1, 2006, the EPA will require that all engines in Generator sets, (I do not know if it applies to compressors, etc..., but it may), diesel engines that is, of from 751 HP to 3500 HP to meet EPA Tier II emissions standards. According to Caterpillar, (and apparently Cummins-Onan as well), these cannot be met with an air-water aftercooler. The reason being that in order to do so the aftercooler will need water in the 90 deg. F range. Apparently in the most efficient air-water units the water is at around the 150 deg. F range. So the manufacturer's are saying that the only way to get to the Tier II levels is with an air-air aftercooler.

I'm just repeating what the manufacturer told me, so don't get too technical on this sparky. We are contacting other manufacturers to try to confirm this.

Again, thank you for all your help.

EEJAIME

 

[dwedel]

To meet the emissions, it would help to lower the air intake temperature; then you could have a lower combustion temp. I would guess that as you are approaching air temperature it makes the air-air more reasonable. Too bad you don't have some 60F seawater on the other side of the hull to use. ;-) But then you wouldn't necessarily worry about the EPA.

I think the difference in EPA requirements comes from the fuel, as you noted. You use diesel, and we use natural gas. (My second guess on this post.)

Thanks for replying with your information.

dwedel
Hotrod Big Engines!
For site policies and guidelines
see faq731-376

 

[MikeHalloran]

We don't have 60F seawater here, either. It usually runs about 90F near the surface. ;-)



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

 

[dwedel]

LOL. You can tell how much I know about the ocean!

dwedel
Hotrod Big Engines!
For site policies and guidelines
see faq731-376