Micro CoGen.

It uses a 155K BTU Tube and Shell Heat Exchanger. You can find them on Ebay. The engine coolant does go through a plate exchanger in series with the radiator. Through the plate first. The plan is to install an electric fan that will turn on if the plate isn't capable of removing the engine heat. We thought about a radiator bypass but elected to keep the radiator in the system and use a fan when needed. It was simple that way and eliminated a lot of design work.

Here is a short video showing the unit running.

I will send you a PM

Here are some pictures of the version I have.

This is a 24 pole PMG. It was originally made by Libby Corp. Eagle Picher made a copy of it as well....both are out of business now.

I'd be willing to bet the output of the PM is a high voltage providing a minimum of 200V rectified DC to the inverter. Probably even closer to 300 - 400Vdc. The inverter can then switch the high voltage DC rail through an IGBT H-Bridge to produce the 120Vac / 60 Hz output. The 120Vac sine wave has a peak of 170V so the inverter will likely require a greater than 200Vdc rail to account for voltage loss in the IGBTs and filter.

I have an older version of the Alpha unit. Its PMG had 3 outputs on it each being 3 phase. One set for 48Vnom, one set for 36Vnom and one high voltage for an inverter. It is a 3KW output with a honda 6.5HP engine with a variable speed controller on it. It can regulate at 39 or 52 Vdc. They (Alpha) ran the output of the PMG into a control board that has a bunch of SCRs on it. The SCRs control which set of windings is rectified (36 or 48) and also help to regulate the voltage during load dumps until the engine speed can slow. I would assume the new 36/48Vdc would work about the same way. Only concern I would have is these were meant for maintaining the load on the batteries and not really charging. I don't know if there is any adjustment to increase the battery voltage to an acceptable charging point.

I'm not using the generator if anyone has interest in it. It only has a few hours on it.

Running the engine slower will increase life but will also lower output of electrical & heat output. I wouldn't suspect this to be a 24/7 application. It would be something that would cycle on/off on battery voltage or hot water needs. We started down the path of getting the most out of engine. Designing the automation to be flexible enough to operate under various installation will be the next challenge. Depending on the load, battery A/hr capacity, hot water usage and storage will require the generator to operate differently.

Hello All -

A colleague of mine and I have been working on a Combined Heat and Power unit. As a disclaimer this is a project we are attempting to develop and market. We have some of the major components put together and have run some test data. We have decided to post some information to this forum to see if we can get some feedback on the concept and its performance.

We used a Yanmar 2TNV70 diesel engine and attached a 24 pole PMG generator. An electronic governor was installed on the engine so it can be controlled for variable speed to regulator the output of the PMG. We are able to get 8KW of electrical power out of the system @ 3600 RPM. We configured the unit for 48Vdc but could be configured for 24Vdc as well. During testing the output of the generator was roughly 54Vdc and 150Amps. We installed heat exchangers on the exhaust and engine cooling water.

Without getting too winded in the details here is what we were able to extract in heat and electrical energy running at full electrical output. The below data is based on a 160deg F input water temperature from the water storage tank.

Fuel Input: 0.7 gal/hr (2.7L/hr) = 93,000 BTU/hr
Electrical Output: 7.9KW = 27,000 BTU/hr
Exhaust Heat Captured = 12,000 BTU/hr
Engine Heat Captured = 30,000 BTU/hr
Sum of Electrical Energy and Heat Captured = 69,000 BTU/hr
System Efficiency = 74%

Our next step in the process is to package the systems in an enclosure and work on the automation. Thank you in advance for any feedback. I will post more as we move along and if any questions arise.

Regards, Eric

Did anyone ever get one of these kits installed on the Yanmar? How did it work out? I'm looking to do the same.

Somebody on the forum had a used Kubota Z482 with the marine cooling kit up for sale. Kubota calls out the engine to weigh 117lbs.

http://www.microcogen.info/index.php?topic=2872.0

Put one of the PMGs on it with a variable speed controller and you would have a nice light compact generator. Probably should be able to get 7KW out of it.

bentcrafter - Here is the information you requested. This is a low speed test of 2 different stators I have. I kept the output voltage at 28Vdc and adjusted the speed of the engine according to load. The blue graph is the smallest stator stack/rotor combination I have and the red graph is the largest stator stack/rotor I have. I could mix & match to move those lines some to match your engine HP. I did not max out the red curve. I was only looking for 150 Amps when I did this test last time so I didn't reach the alternators limits. On the blue curve you can see the slope is getting vertical meaning it is at its max.

Hi Bob, I don't have the exact turns count but I think it is closer to 5 turns than 9. I believe it is 24AWG wire. The low voltage generators probably have 15-20 wires in hand and just a few turns. The high voltage gen have just a few wires in hand and many turns per poles. The high voltage versions only came out with about 16ga leads.

Bob you are right on track. Only thing would be that the windings are wound using many parallel small gauge wires in order to get a high density slot fill. They were wound with as much copper as possible for low I²R losses.

Frank S,

I don't think anything was ever published on these PMG ends. They were mainly used on products built by the generators manufacturer and never sold to end users as a piece part. I do have some good knowledge of the generators and have some on hand in various fashions. I'd be willing to share some info about them if you have some particular questions. I wouldn't have the time to develop a full analysis and spec sheet but could answer some general questions.

Henry,

Glad to see it made it and fits properly. Looks great. I don't think you will have any issues with heat transferring to the PM for the muffler.