10 HP engine - refrigerant working fluid

fluwoebers

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I am looking for plans for an engine. Probably an organic rankine cycle engine. I want to use it for power generation in the 10KW range.
This is bigger than the typical model/hobby engine, but much smaller than an industrial engine.

I want to use low grade heat (geothermal, solar, waste) to heat a refigerant (R134 etc) as the working fluid. (I plan to use a heat pump to get a high enough temp)
Can anyone direct me to such a plan? Thanks in advance.
 
For a long time, I have had that concept in the back of my mind, but talking with a good friend of mine about different Freons I haven't come up with the right combination yet to make it work. I had geothermal in mind for mine. I'll be watching with much interest this thread. I believe I was focusing on a variant of a Stirling cycle though. Hadn't considered a Rankine.
 
I've found links to a lot of small startups claiming they have working prototypes doing amazing things. I even spoke with one of them (power verde / endless energy). They wanted $40k for the whole system (provides heating, cooling, and electric for the whole house). That is a non-starter for me. Plans have proven illusive.

As far as the working fluid: I just read an article that discusses the merits of different fluids http://eprints.utm.my/6515/1/solar(cheng-jilid20).pdf
 
Harvesting energy from low grade heat is the holy grail of renewable energy. I've also considered a freon engine. Basically a steam engine; steam engines operate via the expansion of water into steam when it boils - so why not do the exact same thing, except with a fluid that boils at a much lower temperature?

It's been a long time since I did any research on it, but IIRC what I found was that all the freons that boil in viable range of temperatures, would require some kind of active cooling to condense again. If I'm not mistaken, the active cooling would take more energy than what you can get out of the engine - no such thing as a free lunch.

It is an intriguing idea, and I intend to pursue it fully when I have time, but I suspect it's a dead end.
 
I don't think it is a dead end at all. If you cool a large building could you not run the hot gas freon to a sterling type engine that would maybe power a compressor for a few freezer cases?

Over the last 20 years innovations that didn't seem economical became more economical as energy cost increased. It used to be that each freezer was a separate unit. Now they are all driven by a central compressor/evap unit that releases the heat outside so it isn't costed off 2X. Coming to a house near you soon.

It seems that if you come up with a pipe dream plan in a spigot to make power from wifely vapors, or childley truculence you could get a grant for a few million just so you could say "gee I thought it was proven out but there just isn't so much energy in it"


Steve
 
I don't think it is a dead end at all. If you cool a large building could you not run the hot gas freon to a sterling type engine that would maybe power a compressor for a few freezer cases?

What you describe here sounds viable to me, as you'd be recovering otherwise wasted heat energy from the system (building). Like a turbo on a car. but the way I see it, its not exactly the same thing as fluwoebers is suggesting. He's referring to tapping geothermal or solar energy, which requires more effort. I don't know - It does seem to me like it should work, but it also seems too good to be true. My hunch that it's a dead end, comes from a long line of "bright ideas" over the years - I always find out that hundreds of other fools had the same idea and have been trying to make it work for 100 years with no success, or that someone's done it 100 years ago, it was inefficient, and has now evolved into something much much better.
 
What you describe here sounds viable to me, as you'd be recovering otherwise wasted heat energy from the system (building). Like a turbo on a car. but the way I see it, its not exactly the same thing as fluwoebers is suggesting. He's referring to tapping geothermal or solar energy, which requires more effort. I don't know - It does seem to me like it should work, but it also seems too good to be true. My hunch that it's a dead end, comes from a long line of "bright ideas" over the years - I always find out that hundreds of other fools had the same idea and have been trying to make it work for 100 years with no success, or that someone's done it 100 years ago, it was inefficient, and has now evolved into something much much better.

I know all the components of the system work. What I don't know is if they will work well enough together to make it worth the $/effort.
Low grade geothermal is used very widely to heat and cool homes. It relies on a heat pump (very much like an AC unit).
Organic Rankine Cycle (ORC) engines work. They are typically powered by biomass, solar, waste heat etc.
The only question remaining is will the components work well enough together to generate enough power to run the heat pump and have enough left over for anything useful.
I don't think this will ever become main stream, because the time for the system to pay for itself is probably longer than the useful life of the system. But there are other motivations besides money...

Geothermal has a pretty steep overhead cost. ORC turbines are also extremely expensive (unless I build my own?). Infinity Turbine sells one for $15K.
If I only get enough juice out of the system to offset 10% of my utility needs, it won't be especially useful.
I haven't studied it enough to know if it's a good idea. I don't want to waste all that effort if I can't even find an engine blueprint.
 
If you can't find a specific Freon engine, try a steam engine. Its the exact same thing in my mind. Never heard of of a rankine but that might work as-is as well. Don't forget about the condensing cycle though. Steam engines work well because of the open loop - water comes from the atmosphere and when the engine is done with it, it simply releases it back to the atmosphere with no need to attempt condensing it. Freon however has to be a closed loop your system will either need to contain some huge quantity of it, such that there is enough of it cycling through to have time to condense on its own, or have active cooling. With our current heating/cooling technologies, It takes more energy to remove heat than to create it.

I served on a nuclear submarine. The sub uses the same closed loop system, but has an infinite source of coolant - the sea. Maybe if you run your Freon through a heat exchanger with pond water it will work, but then you have to power the pump (active cooling). This is barely a consideration with a nuclear reactor because, well, its a nuclear reactor. For your little Freon engine it may be a huge load though. Can you see yourself with a cooling pond in your back yard, like what's outside nuclear power plants? ;)
 
In reading this post, it brought a thought to my mind. If you have heat that needs to be cooled such as the need to condense the freon being talked about. How about using a water/ammonia solution just like the old refrigerators from the past (or the new reefers in today's RVs) uses, this is a very simple setup and has good cooling capabilities.

Just a thought!
 
The system would already require a heat pump. Basically it pulls the heat out of the water. You would end up with a hot side (powers the engine) and a cold side (condensor?).
Right now, geothermal systems installed in houses use the hot side for the hot water heater and radiant heating, and the cold side for air conditioning.
In my imaginary system, you would simply use the hot and cold to run your steam engine and generate electricity. A significant portion of the electricity would have to be used to run the heat pump, but I would think there would be enough left over to charge a battery bank.

A turbine is the most efficient steam engine. The turbine itself is probably beyond my ability to create, but the rest of the parts probably are not. I'm guessing, since I haven't seen a blueprint.
 
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