Lister Engines > Lister Based Generators

Cogen would this work?

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Gregmm:
All rightly then, I have been toying with an Idea on the cogen possibilities for a lister 6/1. I was looking at a corn stove that sets outside your home and is automated with an auger system the heats an open system water tank of 180 gallons, to 180 to 200 degrees. Then it is pumped through a heat exchanger that is mounted inside the plenum of your forced air furnace. It works off the thermostat that kicks on the blower as needed. What are the thoughts of doing the same thing with the cooling water from the lister. If it would not retain enough of the heat after the fan has been blowing through the exchanger maybe you could run a modified sealed muffler as a second heat exchanger in the cooling tank to capture more BTUs to keep the temp up. Has anyone done anything like that or any Ideas or comments?

Greg
 

quinnf:
Greg,

Cogen is definitely possible, and George has some info on it in the files on his CD.  However, consider that any small diesel engine isn't burning THAT much fuel to begin with.  For example, a 6/1 burns about a quart an hour when loaded pretty heavily.  The engine's pretty large in size, so it loses a lot of heat by direct radiation.  The cooling water won't hold a whole lot of heat, too.  Most of the heat will be in the exhaust, but the problem you face with trying to capture exhaust heat is that unless the exhaust pipe stays hot, carbon will deposit and slowly begin to choke down the pipe. 

A quick way to calculate is at a fuel burn rate of 1 quart/hour, that's 150,000 btu/hr in a gallon of diesel, so that's 37500 btu/hr in a quart.  Mechanical efficiency might be 30% in this kind of engine, so that leaves 70% or 26250 btu/h left over, mostly as heat.  But the engine's large and has a lot of hot surfaces to radiate and convect heat away, especially with the wind the flywheels whip up blowing the heat around.  So you're left with maybe 20,000 btu/h that you still have to extract from the cooling water and exhaust, should you decide to attempt that. 

By the time you capture the waste heat from cooling water and maybe exhaust, you might do 15,000 btu/h which is about what you'd get from a plug-in electric space heater.  If you live in a cold climate you know that's not much heat.  Don't wish to dissuade you from what might be an interesting project, just be mindful that there isn't very much heat available from such a small engine to capture. 

One thing you could do to save energy.  Pre-heat the domestic cold water line that goes into your domestic hot water heater by passing it through your engine cooling tank.  Code, I believe, would prohibit that, but that is a way to make longer hot showers less expensive.

Quinn

Gregmm:
It could be possible to use a ele hot water heater as the coolant tank and let it cycle on and off maybe using only one elament as needed letting the gen power it. if it did not work out shut the powerto the tank off, no harm no foul. A heating and cooling place in my area have the tanks from time to time with the elaments bad
{ a $20.00 fix} this would be a cheap way to try it .
Greg ???

quinnf:
Greg, yes but you'd still be burning diesel to heat the water, if I read that right.  As a cooling tank, it would have to be stripped of all instulation, so it's really just a big cylindrical radiator.  The minute you turn a switch on to heat an element, then you would want to insulate the tank or you're paying to heat the whole world.  I was thinking more of getting a nice big propane bottle or 55-gal drum, cut the top off it, fill it with coolant, and immerse a coil of 1/2" copper in the tank for the domestic water line.  Inlet at the top, outlet at the bottom .  Outlet then goes to the cold water inlet of your domestic water heater.  So you're pre-heating the domestic water coming into your somestic hot water heater by first passing it through the engine cooling water.  But if you're using electricity to heat water, you're paying way more per btu than you'd pay by using power from electrical utility or if you used propane or natural gas. 

Quinn

hotater:
Great replies!!!

My engine is set up as an 'on demand fresh water' system.  It expels almost exactly 5 gallons per HOUR of 195 degree water.  That's not much heat for home use except hot water.    Quinn got it right about the exhaust heat transfer, too.  By heating something else the exhaust pipe looses heat and that causes particulates to gather and grow.  Check out the propane hot water heater/heat exchanger on George's site.  THAT'S the way to use exhaust heat.

An alternate source of very useful engine heat is one that I found by accident---
  I traded for a 3.5 mini-Peter water pump last spring to use as irrigation and pumping hot spring water for heating.  These NEAT engines are cooled by a tap coming from it's own water pump that's bolted to the side of the engine.  The cylinder water intake is blocked off completely and an intake is located opposite the outlet in the head.   Water still occupies the clyinder and is replenished as needed, but it's actually flowing through the head.
   I put a common faucet on the hot water outlet to slow the water circulating through the head to warm it up some and now it produces about three gallons a minute of water heated 15 degrees above my nominal 110 degree spring water that it's pumping from the spring.  
  HERE'S the neat part!!!!   The engine is now siphoning hot spring water through its self.  It was plus two deg. F this morning and the engine is still a hundred degrees.  I put a plastic tub over it to hold a little heat and keep the snow off.  I'll bet green money that MP engine will start within three tries (always much more stubborn than the Lister) after a night of zero cold!

Heres a home heating idea---  build or buy a concrete tank as big as you can fit in the basement or locate in a central place.  (New septic tanks are cheaper than building one.)    Fill this tank with water then pump that water, with a cheap to run MP (that can still be hooked to an alternator or any other 2 to 3 HP load in addition to teh pump), ....pump the water BACK into the same tank along with the engine cooling water.  By hooking a solar collector system to the tank and using the same water to cool other things, a BUNCH of BTUs can be stored and used in a radiant or convective way.  IT'll take a while to build up heat with nothing but a MP!

Another idea....one that I'll get around to doing one day,  is to install a water inlet in the back of a Listeroid head and block the bottom one just like the MP pump sets.  It's a great way to cool an engine and have a constant source of hot water, too.  
  BUT,  you DO have to worry about pump failure causing overheating.  Since I'm pumping out of a spring that just barely keeps up with what the MP is pumping, I watch water levels very close.  If the spring goes dry the MP pump fails and that's what's keeping it cool.  Just to satisfy my own curiousity, I shut the cooling water off going to the engine and kept track of temperatures in the head and cylinder.... it would have to go dry and run dry for at least twenty minutes to even think about getting TOO hot.  That's comforting.  A good way to extend that time by hours would be run the cooling water up to a large gravity tank before it goes to the engine.  It pumps WAY more than in needs to keep cool, anyway.  Let it store it's own cooling water.

In order to keep the site free of commercials I'll take questions by email or PM as to where I got the MPs and make recommendations out of the public forum.

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