Author Topic: Cogen would this work?  (Read 10939 times)

Gregmm

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Cogen would this work?
« on: December 05, 2005, 06:34:20 PM »
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

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Re: Cogen would this work?
« Reply #1 on: December 05, 2005, 07:49:16 PM »
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

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Re: Cogen would this work?
« Reply #2 on: December 05, 2005, 08:11:44 PM »
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

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Re: Cogen would this work?
« Reply #3 on: December 05, 2005, 08:29:01 PM »
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

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Re: Cogen would this work?
« Reply #4 on: December 05, 2005, 08:31:29 PM »
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.
7200 hrs on 6-1/5Kw, FuKing Listeroid,
Currently running PS-Kit 6-1/5Kw...and some MPs and Chanfas and diesel snowplows and trucks and stuff.

Gregmm

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Re: Cogen would this work?
« Reply #5 on: December 05, 2005, 09:08:13 PM »
Well I will be using waste oil to run the Lister so my cost for that is nominal as it is for all intensive purposes free. I am thinking of using the heating element in the ele hot water heater powered by the lister just to keep the heat up to the 180 to 200 degrees so I can blow it in the house with the blower of my furnace by way of the heat exchanger. When it is not cold out I can shut the electric elements in the hot water tank off. And use the tank as cooling only in an open or closed system. I will play around and see what can be done as a test. Thanks for letting me bounce ideas of you all

Greg
 ::)

quinnf

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Re: Cogen would this work?
« Reply #6 on: December 06, 2005, 12:20:26 AM »
Y'know, Jack mentions some neat things about hot wate that remind me of past projectsr. 

Several years ago in a former life I was growing orchids.  Orchids being a mostly tropical plant require tropical night-time temperatures, yet where we were living at the time was in a coastal canyon.  For about 6 months of the year I really had a problem keeping my greenhouse above 50F at night.  So I did some surfing and found some information on solar heating water.  I calculated that a 500 gallon hot tub containing 105F water would contain enough heat to keep my greenhouse at 70F on a 30F night when the water was pumped through plastic tubing beneath the plant benches. 

During the day, solar pool collectors would heat the water to 105F at which time the pump would shut off.  I never got the chance to build the system.  Life got in the way.  If'n I were building anew, I'd figure out a way to store a large quantity, like 1000 gallons, of hot water for heat during the winter, and during the summer, for cooling.  Water chilled by a refrigeration unit is a very efficient way to move heat into or out of a house or building, and it's easy to plumb and set up controls to condition the air in any part of the house.  The same heat pump can be used to heat in the winter.  If you're living off grid, Ii think you have to take advantage of any and all resources available: solar, wind (maybe), and even hydrothermal, if you should be so lucky.  There are a few orchid growers in New Zealand who use hydrothermal heat in their greenhouses.

Quinn

SHIPCHIEF

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Re: Cogen would this work?
« Reply #7 on: December 11, 2005, 06:01:39 AM »
If the heat rejection is the average 1/3 work, 1/3 jacket water, 1/3 exhaust, then you can calculate the recoverable heat as previously discussed........BUT:
Exhaust heat exchangers will condense exhaust carbon and must be cleaned. I experienced this on a diesel ship with an exhaust heat recovery boiler. It would no longer generate enough steam to run the evaporator (to make fresh water at sea) after less than a week. It would eventually cook out the carbon from a dry boiler, but you couldn't put water back in until it was cold again.
My point is this: Your exhaust heat recovery system needs to be straight enough to run a flu brush thru it, and have caps at the ends to run the brush in and let the carbon fall out the bottom.
Ashwamegh 25/2 & ST12
Lister SR2 10Kw 'Long Edurance' genset on a 10 gallon sump/skid,
Onan 6.5NH in an old Jeager Compressor trailer and a few CCK's

quinnf

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Re: Cogen would this work?
« Reply #8 on: December 17, 2005, 04:11:59 PM »
Yeah, that's sort of a problem.  Somebody ought to e-mail Mike Rowe for his TV show, "Dirty Jobs."  Can't imagine anything dirtier than cleaning out a diesel exhaust with a brush!   ;D

quinn

cujet

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Re: Cogen would this work?
« Reply #9 on: December 18, 2005, 02:08:02 AM »
We might be able to design a heat exchanger with the ability to prevent carbon buildup. Because diesel exhaust is not too hot, an anti stick coating similar to the fryin' pan would prob work.

Chris
People who count on their fingers should maintain a discreet silence

SHIPCHIEF

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Re: Cogen would this work?
« Reply #10 on: December 18, 2005, 01:52:43 PM »
If the exhaust heat recovery system used a straight pipe it could be built with a scraper inside. It could be on a rod passing thru a valve stem packing gland, and pushed in and out like cleaning a rifle barrel, then stored in the retracted position and the gland nut re-tightened. The running of the engine would blow the residue out into the neighbor's yard, so do it at night.... ;)
If it was a sheet metal strip with 'S' bend as seen looking down the pipe, rotating it clockwise would scrape the carbon; so rotate and push / pull like using a hone in a cylinder. You wouldn't even have to shut down the engine.
Scott
Ashwamegh 25/2 & ST12
Lister SR2 10Kw 'Long Edurance' genset on a 10 gallon sump/skid,
Onan 6.5NH in an old Jeager Compressor trailer and a few CCK's

Bansonyankee

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Re: Cogen would this work?
« Reply #11 on: January 15, 2006, 02:36:11 AM »
I'm planning on using the Listeroid for cogeneration at my shop.  It may be only ~20,000 BTU/hr, but since it's on all the time, it will contribute a lot to keeping the shop warm.  After all, every BTU that comes from the engine cooling and exhaust is one less that comes from the heating system. 

I bet if you put a Listeroid in your basement (don't laugh just yet...) and a cast-iron radiator in the living room immediately overhead, you would find the house toasty-warm.  After all, your domestic heater may be rated at 100,000 Btu, but it only fires on average 20% of the time or less. 

If your spouse were deaf, it would be a very economical heat source. 

JS

Tom

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Re: Cogen would this work?
« Reply #12 on: January 15, 2006, 04:20:53 AM »
JS, you been talking to my wife, or they all basically the same. My darling wife gets all frosty when the subject of a lister in the basement comes up.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

Stan

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Re: Cogen would this work?
« Reply #13 on: January 15, 2006, 05:03:58 AM »
Tom, with just a little bit of an exhaust leak from a listeroid in the basement and you could wake up dead ???
Stan

SHIPCHIEF

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Re: Cogen would this work?
« Reply #14 on: January 15, 2006, 06:31:19 AM »
If the engine room was far enough from the house to be safe (and quiet, and no thumping vibrations), it would be too far for cogen. Even with good insulation on the pipes, the water would be cold by the time it got into the house!
Ashwamegh 25/2 & ST12
Lister SR2 10Kw 'Long Edurance' genset on a 10 gallon sump/skid,
Onan 6.5NH in an old Jeager Compressor trailer and a few CCK's