gas engine/evolution?

[LowGear]

The sickness spreads:

https://www.washingtonpost.com/news/morning-mix/wp/2017/04/06/the-coal-mining-museum-in-harlan-county-ky-switches-to-solar-power/

A pretty good overview example of power generation evolution but is just WRONG.

[glort]

I don't think it would be such a trick to get or excede the efficency of commercial units. They have a lot of paramarters they have to work to we don't. Emissions for one, weight and packaging for another, autonomy- set and forget operation that a DIYer is not going to be as concerned about as somone that just wants heat/ power and doese not want to know about it.

With your Changfa's,  before getting too excited about something new and different, Have you considered gas fumigation?  Run the thing as a diesel but have an amount of gas entering the airstream  which is combusted with the diesel to lower it's consumption. This can be very easy in the setup you are chasing, can just be a fixed amount of gas and the govenor on the engine will add more or less diesel as required. It works on power output/ RPM not mixture.  Probably not that hard to stage the injection high and low if one had the need.

I think my suggestion on using the low value heat from the engine with an AC pump has merit in chasing max efficency. You could be using the exit temp of the exhaust through the HE and pulling a LOT more heat out of that which would bump your Numbers. You could build the condenser at the end of the enclosure of an engine and draw air past the engine so all the heat from the engine block itself and accessories even like the alternator was pulled through the AC condenser and put to use. The colder the weather the more effective this could be.

The exhaust could go through some pipe work after the water heater as there is still a lot of energy in that and have air blowing across the pipes much like a modern gas furnace which pulls the the exhaust down to 40oC or less so much more heat was extracted or maybe put it through another  Condenser on it's own that could be blocked off or disconnected in Summer. With that you would be able to use all the Cooling heat, all the exhaust heat and all the low grade heat emitted from the engine and your alternators as well. That should push the efficiency numbers well up indeed.

The one thing I see that would need to compliment a setup of the type you describe is cooling. I don't it's cold everywhere all year so having a system that could use the heat to make cold Like an absorption system would also bump the numbers the right way.  I Can't get my head exactly around how absorption systems work but obviously they do and that's it.  It seems those that can understand them could build one in a DIY application as well.  That would be able to make use of all the heat which would otherwise be not needed in summer and should make for a potential powerful cooling system in addition to the pump.  Furthermore, which it might be easy to store heat in water, other problems come up with storing cold. They could be over come with large tanks of salt water.  Ice is a VERY efficient cold storage however there are a Lot of difficulties with that especially in getting the cold back.
There are ice based AC systems commercially available which can be studied to se how they do it but again to yours truly show the difficulties more over than DIY solutions.

I looked at this a while back and concluded that 2X 1000L  drums of salt water that would be buried in my yard surrounded by coolroom panel which is available free and fairly readily would be a worthwhile system for my home.  1 Tank would do it by 2 allowed for miscalculations and rather have to much than run short.  I could cool the Brine at night when the temps were low using a spray of water on a condenser for low grade cooling which would be enough at certain times of the year and use excess solar to drop the temp some more during the day even when the house was being cooled. I would have plenty of power to do this.  In winter the plan was to heat the water using an engine which, at the time of planning , would also give me the ability to make power I could use.  Now I have that covered, the power could simply be used in  resistance heating or with an AC pump setup.

The other alternative was to heat the tanks using an oil burner.  One useful side effect I saw to this was the heat that leaked from the setup would warm the soil and give me a great spot for a small greenhouse that I could grow vegetables in winter. I have learned it's not keeping the Plants warm thats the trick but rather keeping the soil warm.  This would be a real Coup in efficiency if the heat leakage could even be utilised.  It was proposed by some that insulation would not even be needed on the top of the tanks for this reason and that the correct depth would be workable for keeping cold in but allowing enough heat for the plant roots.

Perhaps low Grade exhaust heat and the exhaust itself in small amounts could be used in a greenhouse as commercial greenhouses do admit an amount of Co2 in order to double the atmospheric concentrations that make plants grow better. The exhaust after the water heater could be run through some pipes with air being blown across for home heat ( wouldn't be hard to design Vertically with small condensation pipes on the bottom of the runs for draining that off if needed or run the exhaust through soil or into a greenhouse to use what was left.

Using the heat in winter is easy. Making the setup seriously efficient in summer I see as the real trick and where the real numbers could be gained. Without it, you basically do have a Furnace in summer that's going to be of limited use thermally and go back to the mechanical energy being the only real useful component.

[mobile_bob]

yes i did testing with fumigation, and pilot injection, works just fine.
did it with propane, but did not have natgas to work with at that location

here where i am currently i have enough nat gas capacity on site to support a few hundred hp, so it would be my fuel of choice

with the high compression of the changfa being what it is, nat/gas would be the way to go.

under the scheme example given, i don't see long runs times being needed or desirable in the summer months
running long enough to make the needed domestic hot water and not much else, do the rest with solar.

however a small diesel such as the r165 water cooled (which were once available and cheap) might still be useful in the summer months, to drive an A/C compressor for space cooling of a small super insulated house, and still be relatively efficient as the amount of hot water might be in range of what is useful.

years ago, i read about an african village that used a trough reflector/concentrater using rock salt as the absorbent in a batch fired ammonia system, it made 20lbs of ice per day, and required frequent cover to cycle the thing in the summer sun... they had lots of help and even 20lbs of ice to folks that had never seen ice was most welcome.

batch firing with low value heat would be doable and i could see a significant amount of refridgeration  and maybe some space cooling using the waste heat in summer.

my problem is, as much as i would like to work with an ammonia system, you have to have a license to get the stuff, and finding a licensed refrigeration guy that is ammonia certified is about as rare as hens teeth around here.... much easier to find that sort of guy around fisheries and big ice house/cold storage buildings/units.

the day comes i find that guy around here, is the day i really get excited and go to work.... as to me it would be the holy grail of cogeneration, making use of the waste heat in summer to cool with.

bob g

[glort]

under the scheme example given, i don't see long runs times being needed or desirable in the summer months.

The difference in our Conditions.
Here AC is essential .  It literally gets hot enough to be a health risk not to mention the problem of not sleeping. Luckily the night temps do Drop a Lot but it's also not unusual to have one that stays well above 30oC.  By the same token, a lot of nights can drop below 20oC after a 40+ Day.  There were 3 days here last year where the temp did not fall below 40oc ( 100f) till after 9 pm.
Even when the outside temps drop, the house is heat soaked and that's when insulation works against you. Open windows aren't enough.  I have put fans in windows and it helps but still a lot of nights where the temps are still too warm.

running long enough to make the needed domestic hot water and not much else, do the rest with solar.

I keep getting confused as to what the goal is here with regards to the heat/ cooling source. :0)
I have an aircooled  165 and it is without a doubt my favourite and smallest diesel engine. The thing is rated at 3 Kw I think it is and will out pull my 6 Hp engines, all of them, all day everyday with out smoking, overloading or anything else. It's the little train that could.

If we are talking about an over all practical system, I would suggest that if one had enough solar to run an AC, one also has enough solar to heat the domestic water.  In the example, a 165 is going to supply 3 Kw of combined energy at best, twice a day in an hour run.
6 Kwh of solar where I am would be a walk in the park with anything that was capable of driving a small AC, say 2-3 Kwh of panels.  You could easily have the hot water taken care of before there was any need for running the AC unless one lived in virtual Dessert conditions.

Solar has a ramp up and ramp down before making full power but the power it does make could easily be channelled to a water heater. I would Imagine that a 3 Kw system at the latitude I am at least would have no trouble generating 3 Kwh or more before 9am when the total output was probably never above 2 Kw or less. Even though the solar hasn't come on a whole lot, in the case of water you can still " bank" and accumulate that energy.

Friend and I are working on a small, cheap and very easy built controller for this exact purpose.  It stores the available power from the panels in a capacitor or bank thereof and acts like a voltage switch. Instead of the panels being dragged off their curve by being over loaded by an element, (even a low voltage one will still pull them down at less than optimum output) it gives the panels a low loading which keeps them on their  optimum power curve and then when the cap is charged to the full voltage, that power is dumped into the element l It can Cycle at 100Hz or more with ease  and the thing is it lets the panels develop the full power they can at the current lighting condition ( even if only a few watts) and transfer that into the element.

It will work with any element at all.  One could plug an unmodified electric kettle or frypan into an array and run that off DC because the controller creates an AC like Zero crossing wave form that would stop any arcing, maybe even better than a regular AC output.  We have proper Circuit Boards printed and are just running tests now. We have over engineered everything after seeing how electronically weak some of the far more expensive ( Ridiculous for what they are) boards are built and to give this thing virtually unlimited within practicality ( and not so) power handling capabilities.  5 Kw wouldn't faze it and if you wanted to go 10, change a couple of mosfets, make sure you have adequate heat sinking for what you want and off you go. Built it yourself in an hour or less and cost will be $50-100 depending where you get components.

You could run this with other loads at the same time as well. Just set the voltage limiting resistors according to the " Left over"  power and to leave adequate for the AC or whatever and  it will run when there is sufficient generation and turn off when there is not.

years ago, i read about an african village that used a trough reflector/concentrater using rock salt as the absorbent in a batch fired ammonia system, it made 20lbs of ice per day, and required frequent cover to cycle the thing in the summer sun... they had lots of help and even 20lbs of ice to folks that had never seen ice was most welcome.

I read of something similar. It was a bigger system in the middle of no where. They had water and from memory they lit a camp fire for energy.  The difference it made to that village and surrounding was incredible. The village with the setup earned money from selling the ice and the people that bought it took it back to their village and could preserve their food supply so they had far less feast and famine. Something so simple was quite an advantage to them.

my problem is, as much as i would like to work with an ammonia system, you have to have a license to get the stuff, and finding a licensed refrigeration guy that is ammonia certified is about as rare as hens teeth around here.... much easier to find that sort of guy around fisheries and big ice house/cold storage buildings/units.

Reading more on absorption systems, I think I get the picture a bit better.  They are basically Cyclic for the most part.

I'm wondering if something like LPG couldn't be used or some thing with similar properties.  Use the heat to Boil/ superheat it and raise the pressure then allow it to depressurise if not condense through another line that does the chilling. LPG may be the wrong Medium, maybe something like Alcohol would be better where it could be phase changed and re condensed.

One thing with LPG, I have used it in a number of AC units and it works well. Real well.  Given the cost of refrigerants here and the over the top rules for environmental concerns for venting it, LPG is a great alternative.  It runs about half the weight of R134a so I just charge the pressures watching the high and low sides with Gauges.  When the pressures are correct, the system is properly charged.

The day comes i find that guy around here, is the day i really get excited and go to work.... as to me it would be the holy grail of co generation, making use of the waste heat in summer to cool with.

I wonder how physically large an absorption system would have to be to use say 3 Kw of heat in terms of Physical size and amount of ammonia and water etc?

Do and why would they still use absorption systems in commercial applications over Compressed systems?  What would be the heat source?

[glort]

Been thinking a bit more about this in practical terms to my own situation.

I made 102 Kwh yesterday with my solar. Very respectable figure and OK wile I can grid back feed but with the legislation that we all have to go to smartarse meters here, that will end my party.
If I went off grid, a practical battery pack would not cover my needs.

My problem will really be heating. I need that mainly at night. Running an engine may be difficult to get it quiet enough as even though I am on acreage, neighbours are only about 20M away on one side.  Cooling wont be so bad, I could run the AC during the day with the solar and cool the place down and I'd ask mate to help me with a solution  for a chiller for cold storage for night use.

The solution would be thermal storage.
A cheap , easy and practical way of achieving that would be with water heater tanks. They seem very plentiful at my local scrap yard and I have picked up a few for nothing in exchange for what I leave.  I sometimes pick up scrap now just so I have something to take there just to keep them on side and give something back.

400L tanks are common here. They usually have 3.6 and 4.8 KW elements in them, on occasion you see the pick of the bunch, the ones with an upper and lower element . But not often. 
In any case, these could be used for thermal storage.  Plumb the engine into the tank and let it heat it up from the heat energy and if one were charging a battery pack, once that was full, then the heating elements could be kicked in.

2x 400L tanks heated up to 90oC  and taken down to 30oC would store 55kwh of heat.  That would be sufficient for my needs. If it were not, a 3rd tank could be added.
I would think that the solar alone would cover the 2 tranks on sunny days, May take a decent run time on an engine for the crappy ones though.
As for fuel consumption, 7L would cover the requirement with reasonable efficiency.  With a 12 HP motor, about 9 Kw could be produced so call that again 6 Hours run time.

I have a 12 Kw Induction motor up the back  which would be a good match for this setup.  Having a fixed load like a resistive heater is the perfect application for one of these IMAGs which can be VERY finicky with varying loads.  For battery charging, alternators could be used ( I'd go 24V for simplicity ) and the load on the Imag dialled in with a PWM controller on the element and some tweaking of the caps.

This would be a fairly simple heating system with the benefit of being a battery charger or power supply as well.  Would be nice to have a larger engine.  I have a 30 HP twin Diesel but that is aircooled and the other is my om 617 5 cyl merc motor which is probably a bit over kill.  A 20 -30 Hp watercooled would be ideal. Plenty of heat and power with much shorter run times.