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Combined Heat and Power use, Kohler 10RY62?


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  #1  
Old 01-25-2018, 05:28:57 PM
BergmanJ BergmanJ is offline
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Default Combined Heat and Power use, Kohler 10RY62?

Folks,

I’ve run this past LenK already via PM; and, he had some very good information for me; thanks Len!

He also suggested lastly that I put this out for public comment/further input – so, here goes:

Background: I have a propane-fueled Kohler 10RY62 10 KW backup generator for my totally off-grid homestead; and, I’m looking for additional ideas/information regarding how much heat (BTUH) is specifically “wasted” via each of: 1. The radiator; and, 2. The exhaust.

I’m intending to use this waste heat (as much as I can “collect”) to store in a superinsulated stainless steel 1,000 gallon underground tank to enable its use in heating my hydronically-heated home (already heated with a propane-fired mod-con boiler).

Most of the heat “collection” will come from the generator’s cooling system, as presently factory configured; the rest will come from a tank-and-tube type of stainless pool heat exchanger (rated at 250,000 BTUH liquid-to-liquid) with the “tank” plumbed into the existing engine circulating coolant system, and the remaining exhaust going through the tubes (essentially a “fire-tube-boiler” arrangement). I’m hoping to be able to condense the exhaust in order to capture that phase-change heat, also.

My Kohler spec. sheet (@ full-load / 10 KW, & 122 oF Ambient Air / 30 CFM intake combustion air / 68 CFH of Propane Fuel (X2,570 BTU/Cu Ft=174,760 BTUH) / 800 oF DRY exhaust temperature @ 75 CFM; but, it has factory wet exhaust manifold! – Exhaust OUT of wet manifold measures around 460 oF (at ~ 25% load) shows the following:

1. Generator releases 85 BTU/minute (5,100 BTUH): 5,100 BTUH

2. Generator converts 34,130 BTUH to 10 KW: 34,130 BTUH

3. Engine releases 12,000 BTUH: 12,000 BTUH

4. Wet exhaust transfers 36,600 BTUH to coolant: 36,600 BTUH

5. Radiator at 1.7 H.P. = 4,328 BTU: 4,328 BTUH

6. Radiator heat rejection is unknown – I need this figure calculated.

7. Cooled exhaust is unknown – I need this figure calculated.

Propane Fuel Input Total 174,760 BTUH
Known Losses Total 92,158 BTUH
Unknown - split between Radiator & exhaust Total 82,602 BTUH

Can anyone here help to calculate the Radiator & Exhaust heat split?

p.s., My background was in electrical/electronics engineering – many years ago. So, right now I remember/know just enough about the required calculations to be really “dangerous”: I really need folks who know what they’re doing to chime in!

Regards, JLB
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  #2  
Old 01-25-2018, 06:00:21 PM
Rich Mc Rich Mc is offline
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Default Re: Combined Heat and Power use, Kohler 10RY62?

White papers and other resources at this link may thru inferences give you the information you're looking for.

https://www.tecogen.com/american-dg-energy
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Old 01-25-2018, 07:53:47 PM
Vanman Vanman is offline
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Default Re: Combined Heat and Power use, Kohler 10RY62?

I'm going to do the same type of installation on my bus conversion. In condensing the exhaust gas, make sure to use a heat exchanger that will withstand the acidic condensate, and to include a relief valve so as to mitigate a boiler explosion.
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Old 01-25-2018, 08:59:58 PM
Birken Vogt Birken Vogt is online now
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Default Re: Combined Heat and Power use, Kohler 10RY62?

I know this series of engine/generator very well. I also know the theory of what you are trying to do. I don't know the actual calcuations behind it but I also don't think detailed calculation is necessary.

Quote:
Originally Posted by BergmanJ View Post
5. Radiator at 1.7 H.P. = 4,328 BTU: 4,328 BTUH

6. Radiator heat rejection is unknown – I need this figure calculated.
I don't understand these questions. The only figures it seems to me you need to worry about are engine and wet exhaust manifold heat inputs.

-----

If I was you what I would do is to run the heater hose on the engine into your heat recovery device. Maybe put a 160° thermostat in the heater hose so the engine does not run too cool. And make sure the engine thermostat itself (located in the lower rear of exhaust manifold on this model) is 180° or higher so it does not open unless necessary.

Practicality says do not mess with condensing exhaust because I doubt you would see payback. The heater loop is the low hanging fruit. But I can understand if you would like to make it a challenge/project. I have always wanted to see someone do CHP with a water cooled machine.

If you need more specifics of the engine ask me, I have been through these things a lot.
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Old 01-25-2018, 09:49:52 PM
armandh armandh is offline
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Default Re: Combined Heat and Power use, Kohler 10RY62?

big oops
a Swiss fellow I knew had 1/4 of a unique 4 home system
solar augmented with....diesel fuel
the fuel fed a variable speed diesel engine.....
scavenged engine heat, DC [I think] electric hot water heat,
and it used an engine driven heat pump compressor
to get nearly the last BTU from the bunker.
[before it blew up resulting in lawsuits]
the problem was a control system that allowed run-away with low Freon.
the diesel engine self dissembled and the design firm went out of business.

ware the complexity vs reliability trade-off
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Last edited by armandh; 01-25-2018 at 10:12:12 PM.
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Old 01-25-2018, 10:20:04 PM
Vanman Vanman is offline
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Default Re: Combined Heat and Power use, Kohler 10RY62?

Yes, so, the take away is- don't do away with your governor!
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Old 01-25-2018, 11:27:27 PM
armandh armandh is offline
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Default Re: Combined Heat and Power use, Kohler 10RY62?

and don't set the governor above a max sustainable speed
not a problem with an AC traditional generator.
and that was a unique case
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Old 01-25-2018, 11:42:05 PM
BergmanJ BergmanJ is offline
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Default Re: Combined Heat and Power use, Kohler 10RY62?

Thanks, guys.

I still really just (?) need to know what the "split" calculates out to because I want to know what additional BTU's are going out the exhaust per my original post:

"Propane Fuel Input Total 174,760 BTUH
Known Losses Total 92,158 BTUH
Unknown - split between Radiator & exhaust Total 82,602 BTUH

Can anyone here help to calculate the Radiator & Exhaust heat split?"

Birken: What "questions" don't you understand? I need more specific elaboration from you to help me to try & answer you.

Thanks, JLB
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Old 01-26-2018, 12:43:20 AM
Birken Vogt Birken Vogt is online now
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Default Re: Combined Heat and Power use, Kohler 10RY62?

I don't understand what you mean by:

"5. Radiator at 1.7 H.P. = 4,328 BTU: 4,328 BTUH"

and

"6. Radiator heat rejection is unknown – I need this figure calculated."

the radiator does not make heat, it only dissipates it. Maybe this is radiator fan in #5? The HP seems about right. #6 makes no sense to me. The radiator only blows off whatever heat the engine block/head and the exhaust manifold put into it, no more no less.
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Old 01-26-2018, 10:51:17 AM
BergmanJ BergmanJ is offline
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Default Re: Combined Heat and Power use, Kohler 10RY62?

Birken,

The radiator pusher fan is spec'd at 1.7 H. P.; that is equivalent to 4,328 BTUH, which is in the "accounted-for" column.

"6." "...radiator does not make heat..."; yes, I know; that is why it was stated as "heat rejection".

As stated, there is a total known BTUH "input" to the system as a whole; and, there are multiple known BTU "outputs" from the system as a whole. When the known "outputs" are subtracted from the known "input", there is the leftover BTUH total "output", of which I need to find-out how much of that "split" goes out the exhaust; and, how much of that "split" is added to the radiator "heat rejection".

Regards, JLB
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