Micro CoGen.

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

Below is a link to a video showing a 48Vdc battery charging generator I have been tinkering with for a while. I used a 8 HP Honda engine and a 24 Pole PMG. I electronically control the engine speed to regulate the output of the PMG according to the load. For this setup I programmed the charging voltage to 56Vdc and the charging current is limited to 75Amps so peak power is 4200 Watts. Attached to the generator is a load bank and 48Vdc 200 A/hr battery string. At the beginning of the video I apply 60 Amps of load to the battery to start discharging it. I then start the engine. It has electric start and auto choke. The engine idles for a short period and then begins to increase the engine speed to raise the output voltage of the PMG. It does this slowly to walk into the charging load. The control system monitors the output current via a shunt. It will limit the charging current to 75 Amps so to not overload the engine. I then begin to turn off some load and the engine speed increases to raise the voltage but yet maintain only a 75 Amp charge. Once the voltage reaches 56Vdc the controller maintains 56Vdc regulation and the charging current begins to taper off. As I drop more load you can hear the engine speed slow to keep regulation.

http://www.youtube.com/watch?v=1CvYcCUZqOI

Hello, I have 2 enclosed diesel generators I'm wanting to part with. They have a Yanmar L70 engine, 24 Pole PMG and inverter. As configured they output 3.0KW 120Vac/60Hz. Engine runs at a set 3600 RPM. These are old military prototype units. They have very low hours but were built in mid-90s. I started them for the first time in a couple of years the other day and both started on the first pull. They do have electric start but is set up for 24Vdc.

I do have access to some low voltage PMG alternators I could swap on the units to allow for battery charging possibly through a solar charge controller to regulate the output. If you have some interest in something like this let me know and lets see what we can put together. I hate to see some nice generators sitting on the shelf doing nothing.