Author Topic: DIY propane-powered motor/generator set.  (Read 11801 times)

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Offline rossw

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DIY propane-powered motor/generator set.
« on: January 19, 2012, 05:04:44 pm »
I've made several references to my "genset", so probably time I documented it.
After several years working in the automotive test equipment repair and calibration field, I ended up with severe intolerance to petroleum products, so a diesel generator was out of the question. Also, diesel particulate fallout onto potentially drinking-water collection surfaces isn't an ideal combination, and we were going to need propane for cooking anyway, so one thing and another, the choice was to go this way.

I chose an old small car engine to be the power source. They're fairly reliable, parts are readily available, they don't have too many rare and exotic parts, so keeping it going shouldn't be too hard. The engine I used is a 4-cylinder, 16-valve, double overhead cam engine from a Ford Laser (actually made by Mazda, I think).

We stripped out all the electronics, the engine computer, the fuel injection etc. Fitted a "conventional" distributor, added a single point gas mixer before the inlet manifold.

The waterpump and as much other unnecessary stuff as possible was removed. We now had a working "starting point".

I wanted the unit to take the smallest amount of physical floor space I could, so I elected to stack the motor and generator.
We built a solid steel frame and had it powder-coated for long, resilient life.

I brought home the engine and generator in the back of the Toyota. They're too heavy to manage single-handed. The generator is a 3-phase, 14KVA, 1500 RPM (50Hz) machine made by sincro.

The alternator is bolted securely in the bottom. Here, the motor is ready to be lifted into place.

Motor in place now, supported by the stock engine mounts to minimise vibration.

The engine speed control is via a dedicated controller made by Woodward in the USA. It counts pulses from the ring gear on the flywheel. 112 pulses per revolution. The sensor is visible here at about the 10-oclock position.

I added an external oil reservoir/cooler. This roughly doubles the oil in the system, and extends service intervals.

Engines are not terribly efficient, and propane is not cheap. I wanted to recover as much energy as possible, so we extract heat not only from the engine block, but from the exhaust. I found a large, industrial tube-in-tube type heat exchanger at the scrap yard. With some modifications, it will do fine.

The old gaskets were shot, years of scale and mineral deposits need cleaned away, and cleaning the tubes. I've ordered some long tube-brushes.

The two end caps had all their webbing milled out to make them act more like plenum caps

Looking a bit better. The grey high-zinc anti-rust paint is a bit rough, but might help protect the steel a bit.

Custom exhaust from the exchanger outlet, through a flexible coupling (not really needed)

Out through a car muffler, and ducted outside. Can hardly hear the exhaust when its running.

Looking down from above, the exhaust goes through a flexible coupling straight into the heat exchanger. Getting the bends, length and angles just right took some mucking about and a length of fencing-wire as a template.

The engine drives the generator via a large stepped-tooth timing belt.

Speed control operates a linear actuator that operates the butterfly where the throttle cable would have attached.

The single-point gas mixer ring is in this rubber hose on the inlet. A stepper-driven valve lets the system continuously monitor the exhaust oxygen level and adjust the air:fuel ratio for optimum under all load conditions.

High pressure propane comes in after being pre-regulated at the tank, down from around 1500 kpa to 150 kpa. A conventional automotive gas converter and regulator is fitted, along with a safety valve and cutoff. If there is no ignition pulse for 2 seconds, it kills the gas.

A decent air filter is a necessity.

The controller maintains speed reasonably well. Here is a picture of RPM change with different load. The dip in the middle of the screen was when an additional 2.4kW load was turned on. The small cyclical variations are the air:fuel control constantly tweeking the mixture.

Offline bvan1941

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Re: DIY propane-powered motor/generator set.
« Reply #1 on: January 20, 2012, 10:29:20 pm »
very nice installation both on this and the "Genset Controller" !
You and Chris Olsen makae some extremely nice equipment !!!

Offline oztules

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Re: DIY propane-powered motor/generator set.
« Reply #2 on: January 21, 2012, 04:20:19 am »
Not much anyone can add really.... except WOW.... nice one.

Flinders Island...... Australia

Offline WooferHound

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Re: DIY propane-powered motor/generator set.
« Reply #3 on: February 03, 2012, 06:35:01 pm »
Do you get much condensation from cooling the exhaust down that much ?
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Offline rossw

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Re: DIY propane-powered motor/generator set.
« Reply #4 on: February 03, 2012, 07:57:47 pm »
Do you get much condensation from cooling the exhaust down that much ?

Quite a lot....

In this photo, you can see a bolt smack in the top of the end cap of the heat exchanger:

There is another one at opposite, at the bottom. I put in a brass fitting, and a length of hose, which drains the condensate straight out and into the waste-water drain a couple of feet away.

It used to drain into a bucket under the exchanger, but I got sick of emptying it all the time!

Offline bj

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Re: DIY propane-powered motor/generator set.
« Reply #5 on: February 04, 2012, 06:21:31 am »
   A very sweet build.  I was wondering about the condensation as well.  Draining it constantly
is probably a good idea, as it's probably a bit acidic, and you would hate to mess up that nice
"Even a blind squirrel will find an acorn once in a while"