Car motor as generator?

[jtbo]

Lot of you smart blokes have much of knowledge from various areas so I thought that I present here one wet dream of mine, uhm, that does not sound quite way I intended to

In our world up here winters are long and harsh, houses need heating, water needs heating, where I live here most don't have even water pipe, I'm lucky to have cold water pipe, but hot water I need to warm myself, summer is not a problem, sun does everything during summer time.

For winter house needs heating and of course I need electricity for my precisious know machines, cats like warm too.

As power company is ever rising prices and power outtages are increasing every winter, I'm thinking of starting one project that would provide me electricity and heating of water, which I could use to heat the house too.

Of course costs must be kept at minimum as fuel prices are not what they used to be few years ago, so to get build even somehow economical it must be almost with zero budget.

What do you think that would be best way to get heat from exhaust and engine block into water tank?

Heat losses are perhaps something like 30% from exhaust and 40% from cooling including heat dissipating from side of motor? Cooling system is easy one, just make copper spiral and put that to tank, but motor sides and exhaust is bit more challening.

For exhaust maybe some spiral exhaust pipe in a bucket of water?

I'm not a engineer, my ideas are typically bit weird, but sometimes right out from Monty Python

For electricity generation I believe huge electric motor would be possible to bolt after clutch, motor should be ran at near full load at max torque rpm for best fuel economy, so electric motor would need to be something that closely matches torque figure of motor used?

If I take motor from 240, it would be free, that is diesel too so I could use variety of fuels in it.

Anyway I think that if I can get all heat into tank it will not be very long perioids which motor needs to be running as there is huge amount of energy in diesel.

Ideas?

[Chris_C]

I'd say that an IC engine isn't the best way to go about it bud. For hot water generation, I'd go for something like a 1930's steam engine boiler but open so as not to build pressure. They are designed to get maximum heat transfer in minimum time though, so I'd think about working on the maths to get an optimum tube length for heat generation and sustaining. That way you can still run a diesel burner to power it too.

For electric, is there no stream nearby you can power a wheel from? From some initial calcs I've done to see if I can run a solar powered water storage system in my house (think mini dam) it's not scaleable to our sizes, but with constant flowing water it's possible to get some *very* usable energy. If thats not possible, I'd work out how much of your house can be run from 12V (phone and laptop chargers normally can, kettle from the hot water gen instead of electric) and just run an uprated alternator (uprating the rectifier diodes to give you better heat sinking for higher currents).

The key to all of it is being efficient with whatever energy you make, i.e. don't convert it where you don't have to. 12V->240 converters are horribly inefficient and you mostly don't need that voltage. Same with the kettle, use waste heat from the boiler or fuel stove etc.

[volvosneverdie]

^

[jtbo]

With IC motor mechanical losses are of course what is lost and with low power 6 cylinder motor losses are indeed great, however it is free.

Actually my lights are 12 Volt leds already, only thing needed is just to plug in wires with 12VDC coming to them.

There are no streams that I could use, there is stream at neighbourg's property, but he is too greedy and would try to profit from usage rights to that so much that it would be lot cheaper to just buy electricity

Around 6500kWh per year including direct electric heating of water and rooms part of the year, 8m3 of firewood burned with bit less than 50% efficiency (fireplace weights only 100kg or so and blows gases straight out to chimney), that was last 12 month's consumption, so it is not much that I need compared to average finn.

System also needs to be such that it is very easy to automate and it should be possible to operate automatically for a week, also kWh price should be under 10 pences, which is adding a lot of challenge.

Also boiler can't reside indoors, there is no space, only outside temp space is available, so that limits greatly my options.

When I have work I'm away for week so that also limits things a bit.

Best way to store energy currently is containers with argon gas and some gravel, it is British invention actually:
http://www.guardian.co.uk/environment/2 ... gy-storage

Of course I do have property on hill so I can make a stream, but -35C during winter is not really helping at all

Some problems, if we would live at equator we would not need powercompanies or even goverment, it would be so easy to make all energy needed and grow food at own backyard, maybe simple solution is to move, buy one of those tiny islands and live like a king?

[Chris_C]

Hmmm, this is worth some thought.... that's a heck of a set of problems!

[jtbo]

Some say there is no problems, we just like to make simple complicated, or something like that

But yet alone ambient temperature extremes are between -40C and +35C, which does make water alone impossible and storing 10 000 litres of water / glycol mixture is perhaps not the best idea there is.

I know about sterling motors too, but out of budget.

However I at least like from problems, trying to solve them most efficiently is what I consider fun

[Chris_C]

However I at least like from problems, trying to solve them most efficiently is what I consider fun

I have a similar affliction. It's probably why I havn't thrown away Fake when it started breaking things.

Stirling engines are awesome pimp (I have one on my internet router and one on the mantel piece) but they won't have the torque I'd imagine. I really really want to see one work with a low overhead alternator, I think that would be a hugely elegant solution

[CBA]

your diesel engine can run on cooking oil as you know. cost = zero

Now, if you can find a generator with a ruined engine but good generator.. bolt that onto your propshaft. 20KVA/KWH should do, but higher powered generators are better and can be more efficient at low-load.

Remember to take the control-box from the generator and the governor-system whatever it might be and wire/bolt it to your engine for on-demand auto-revving as the original engine would have been hardwired to do.


Check ebay for broken genny's


And yes, fred would be proud

[CBA]

Use electric immersion heater at 7KW for your water heating.
Use another 7KW immersion heater + pump that water round your radiators.

14KW => engine should last a ridiculous amount of time with such a low load.

[jtbo]

There is about 9kWh energy in 1 litre of diesel if my memory serves me correctly. Internal combustion motor wastes somewhere around 70% of that to heat and mechanical losses, making electricity and using that electricity to generate heat would not be best way as there is more than plenty of heat generation with IC motor.

Getting heat from motor and exhaust + then make some electricity from mechanical work would mean that motor need to run only 10 minutes a day at most of year, only coldest days might see even 45minutes of operation per day, 240 motor can produce some 60kW of mechanical work and some ~130kW heat that is a lot more than plenty for my needs, least consumption happens when running at full load and at max torque rpm, so it would produce needed energy rather quick, but how do you put that energy to battery or hot water boiler in such short time?

[CBA]

I'll do a diagram.. no idea how to figure this.. but here goes nothing

[CBA]

diagram hard...

To fill a water tank with hot water ->

Engine hot water output goes to top of water tank.
Cold water to cool engine comes from bottom of tank.

Leave engine thermostat in place, engine only draws cold water when running temp is reached.
Once op. temp reached engine pumps 80 degree (ish) water to (insulated with jacket) water tank (that is in place of the original car radiator).

Instead of radiating the heat it stores it.

Water in tank should reach 70 degrees or so - how long it takes is anyones guess.


With the temps of -35 you experience you will have to run the engine every few hours to stop the clean water freezing. (cant really have a shower in 70/30 methanol )

The more you insulate the engine, tank and pipes the more efficient the heating will be.
Obv. you want ALL the heat to go to the tank.

What I was saying about the cooking oil is that it is practically free, so the efficiency really isn't an issue.

[CBA]

To get the engine to full-load a generator running some immersion heaters also in the hot water tank would be most efficient.
Then you have 80-90% of the energy (or better) going to the hot water - you can also use electricity if you need it.

As for the hot exhaust gases - Look at old boiler designs - basically a hot water tank with some copper pipes running through it, run the exhaust through the pipes.

I'll watch some fred dibnah till I find the part where he explains the working behind this copper pipe firebox heat-transfer engineerage.

[CBA]

Diagram.

[CBA]

Everything should be insulated - Glass fiber, foil and wire to lagg the exhaust pipes. Tubular foam insulation for the water pipes coated with more shiny foil.

Pipes through boiler should be copper- 10mm pipes should be ok, you need enough of them so as not to restrict the exhaust flow too much, and they need to be wide enough so as not to clog with soot (especially if burning cheap and nasty fuels)
Welding the pipes together to make the exchanger will be a challenge..