Making my own 20 KW Genset

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A few weeks ago we lost power for 18 hours, but I have a Kubota Tractor and a 20 KW generator, so the kids did not even know the power was out. But as I checked on the tractor now and then, I realized how much heat was being generated...and wasted. I like the PTO generator, but it is too bad to put 18 hours on the tractor just to make a little power. I knew it would be best if my PTO generator had its own engine, and then route the engine coolant to my radiant floor heat.

I really had the major components for this. A few engines to pick from, the pto generator, a fuel oil tank, and a general ability to put this all together.

But I had to make a few choices. I had a White 6 cylinder engine on an engine stand, rebuilt and ready to go, but that was kind of overkill, and so my other choice was a reefer engine. Always wanting to take on a challenge, I decided to get the reefer engine fired up, some because it had been 32 years since it last ran, and because it was less horsepower and would consume less fuel.

My general plan was to stick the engine in my old lambing barn, about 100 feet from the house, mount the pto generator to it, then plumb the coolant lines to a firewood/coal boiler beside it, then run lines to my radiant floor heat.

So I hooked onto the reefer unit and hauled it down to the house, and somehow managed to roll the engine and chiller up a ramp, and into the lambing barn by rolling it on pipes. Then I ripped off the chiller, plumbing, wiring and fuel lines, and was left with a bare engine block. With the help of my wife, I managed to get the coal/firewood boiler beside the engine, then hauled in a 275 gallon oil tank, and got that into position.

 

[rockinmywaypa]

you're well on your way to chp, or combined heat and power. There are websites galore on the topic. If you can pull it together you will have a great little project. try throwing in a wood gas generator and run the motor on that for true emergency power.

 

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To my surprise, I put a lining bar on the engine and got it to roll over pretty easy. I would not call it seized, but just "stuck". It just took a little tug and it was broke free. Just to be sure, I tore down some of the engine, and it looked like it had run yesterday. I also dug out the glass of the broken hour meter so I could read it, and the engine only had 2607 hours on it. Since reefers were designed to run for 35,000 hours, this engine has a whole lot of kick left in it!

Energized that this was a lofty project, I took an old gasoline generator that I also had kicking around, and tore off the starter circuit off that old 3 phase generator, and rewired my reefer engine with the canabalized parts. This was a lesson in frustration because no matter what I did, I could not get the engine to turn over. I even direct hooked the battery to the starter and all I got was a whole lot of nothing.

So then I got serious and undid the starter and tore it down. It looked like Mars...the red planet...everything was rusted! So I spent four hours and broke everything down, cleaned everything up, and got everything unstuck, because everything was stuck. But then...as I was sliding the housing back in, it hung up on the brush and ...snap! That did not make my day!

I had been told this was a Kubota, because that was all that Carrier ever used, but it was hard to tell, even Carrier had no records for a 1979 Carrier Transicold Reefer unit! So when I asked the starter shop to rebuild it, they said it was not a Kubota. We chased some numbers, and finally deduced this was a Perkins 4.108 engine. Since they were made from 1958 to 1992, and there was 1/2 a million made, there is plenty of parts for them. A brand new starter ended up being $139 and has higher torque and thus higher spin-speed!

It also had more power than I thought, at 55 HP, spinning a 20 KW generator will hardly make it get above idle speed!

 

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you're well on your way to chp, or combined heat and power. There are websites galore on the topic. If you can pull it together you will have a great little project. try throwing in a wood gas generator and run the motor on that for true emergency power.

Yeah I call it co-generation.

For me, this will allow my house to be heated by:

Coal
Firewood
Electricity
Diesel
Propane
Wood Pellets (back-up)

Then for electricity:

On-Grid
Off-grid

It will just give me a lot of options: and I like options!

 

[3930dave]

It also had more power than I thought, at 55 HP, spinning a 20 KW generator will hardly make it get above idle speed!

Neat project. Pics please !

Surprisingly high HP #..... yet another example of olde-school overbuilt :thumbsup:

Rgds, D.

 

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Neat project. Pics please !

Surprisingly high HP #..... yet another example of olde-school overbuilt :thumbsup:

Rgds, D.

Here, is a photo of the Reefer Engine as I found it as a barn-find.

I know the history behind it, and know it has been sitting for years and years, but thankfully it is in really good shape.

You can also see from the photo that it was the chiller that was disassembled, which is pretty common with these reefers; the chiller break long before the engines do. That appears to be the case here.

 

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This is the 1942 3 phase/1 phase generator in which I am borrowing parts, in order to get it to work.

 

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This is the 20 KW Pto generator I have to spin behind the Perkins Engine...

 

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And finally, this is the Firewood/Coal boiler that is sitting next to the genset.

The good thing about the way this whole thing will be set up is; if the engine is down, or the firewood/coal boiler is not being used, the propane boiler in my house will come on, and circulate warm water back through the boiler and engine, and keep them always at 100-150 degrees. That will make the engine easy to start anyway. (Naturally, being a reefer engine, it has exceptionally powerful glow plugs).

 

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Just in case anyone is interested in the math on this, it is very easy to convert some known calculations into how this will work.

For instance we know that this is a 55 mechanical Horsepower engine. Since we know that 100 hp equates to 7.5 boiler horsepower, this engine is the equivalent of 4.15 boiler horsepower. Since we know a boiler horsepower is equal to 33,000 btu's...it would be around 139,000 btu's...but that is BEFORE some losses.

We know an engine consists of 75% heat energy, and 25% mechanical energy.

That means the engine has about 104,000 btu's...but about 10% of that energy goes up the exhaust stack, so it is in total about a 94,000 btu heater-equivalent.

But we can also do the math backwards too. If our engine consumes about 1.5 gallons of fuel, at 131,000 btus per gallon, we get about the same amount of btus per hour, based upon throttle position and load!