Stand-by generator

[chim]

If my "figgers" are correct, here's what the values are AT 100% EFFICIENCY. Caps because I have no idea what the efficiency will be. Could be anything.

Anyway, 6.5KW = 8.72 HP = 22,190 BTU/Hr = 4 Hrs 9 minutes of run time per gallon.

If it is 50% efficient, it will still run for 2 hours on a gallon................chim

 

[Ronbo]

how did you mate your generator to your engine? I see the plate, but how about some close up pictures and how about the shaft?

ron

 

[Mickey_Fx]

If my "figgers" are correct, here's what the values are AT 100% EFFICIENCY. Caps because I have no idea what the efficiency will be. Could be anything.

Anyway, 6.5KW = 8.72 HP = 22,190 BTU/Hr = 4 Hrs 9 minutes of run time per gallon.

If it is 50% efficient, it will still run for 2 hours on a gallon................chim

Internal combustion engines are only about 25% thermally efficient. Diesels about 10% higher.

 

[BobRip]

Internal combustion engines are only about 25% thermally efficient. Diesels about 10% higher.

They are at best 25% efficient. This is generally at some moderate load (I believe). Lightly loaded they are less efficient. At idle they are even less efficient. If you run a 100 HP engine with a 1 HP load, it still has to turn the alternator, water pump, and oil pump, push the pistons against the rings and overcome bearing friction, open and close valves etc. So efficiency drops drastically. Run down a 20 pound tank at about 1/2 electrical load and see how long it takes or not.

 

[Bob_Skurka]

Interesting project.

 

[BobRip]

I just thought of a couple of other factors with propane. When it is cold outside, there will be a lower vapor pressure and if there is not enough surface area of the tank to evaporate the propane, then the pressure will drop and the engine will be starved of fuel. I don't know the conditions where this occurs, but it should be checked. You may find it runs OK for a while, but as the propane evaporates it will get colder inside the tank and pressure will drop. There will not be enough surface are on the outside of the tank to let enough heat in to keep the propane warm enough to maintain adequate pressure.

 

[Olmike]

how did you mate your generator to your engine? I see the plate, but how about some close up pictures and how about the shaft?

ron

Ronbo,I made A flat plate to bolt where the pressure plate bolted.I welded a
1" stub shaft in the center & used A lovejoy type coupler to hook em together.The front mount plate of the gen almost centered perfectly in the bellhousing.I machined A shaft for the gen input cause it was mounted directly to the crank & block of the onan engine.

Mike

 

[Olmike]

I just thought of a couple of other factors with propane. When it is cold outside, there will be a lower vapor pressure and if there is not enough surface area of the tank to evaporate the propane, then the pressure will drop and the engine will be starved of fuel. I don't know the conditions where this occurs, but it should be checked. You may find it runs OK for a while, but as the propane evaporates it will get colder inside the tank and pressure will drop. There will not be enough surface are on the outside of the tank to let enough heat in to keep the propane warm enough to maintain adequate pressure.

Bob, I think you're right about the evap rate.I'll have to figure A way to heat the bottle.Hot water maybe?

 

[sandman2234]

How about hot water from the heater core lines coming from the engine? Seems letting it heat itself might be the best way, or build an enclosure for the whole thing?
David from jax

 

[Olmike]

Yep,Thats what I was thinkin.Wrap the bottle with 1/2" copper or 5/8" heater hose & it would also help cool the motor.I have the heater lines routed through the vaporizer now so would'nt be a big job to heat the bottle.
Mike