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Author Topic: exhaust/engine cooler heat recuperator  (Read 19105 times)

Creativity

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exhaust/engine cooler heat recuperator
« on: April 29, 2008, 11:35:24 AM »
Hey,
i was working lately on an idea of inexpensive/light bolt on system for heat recuperation in an internal combustion engine.It has to be inexpensive in order to become popular or used by manufacturers.It has to be light and occupy small space,because this is important for any system in a car.It has to be bolt on,so no changes should be made to the engine itself,reducing the risks of installation and level of knowledge of instalator needed to bolt it on.
As we all know about 50% or more of the fuel energy gets dispatched into the air as a heat.25%% goes into the exhaust (but also sound energy is there,so not all energy is heat there) and around 20% into water cooling of the engine.Now imagine if we could get just like 10% of all this wasted energy in say electricity,would it be nice ? :) we could take off the load on engine caused by alternator(when cruising it can be like 10% of the engine power!=>direct 10% saving in fuel costs when cruising !) i invented a small system (+7 to 10 kg) on cheap parts that can recuperate engine peripheral elements.

see the picture attached.It is only a case for a exhaust gases heat re-cuperator.Similar design operating underly low pressure and liquid to liquid exchanger can be applied for coolant heat recuperation.Exhaust gases heat manifold to high temp,sufficient to produce amounts of steam.I would use copper pipe wound up around the manifold(it could be then all insulated termically from the engine compartment,reducing ambient air temp en adding power to the engine).In this pipe water would be injected by high pressure water pump.When pressure goes low enough a pressure sensor is used to notify water pump to inject more.Blow off valve sets up upper steam pressure limit.Steam is fed into the steam turbine/engine connected to the alternator.Used steam is condensed in a condenser(cooled by ambient air) reducing the backpressure to add turbine efficiency.Condensed water can be reused by water pump.
in this system alternator would be fully driven by exhaust heat,thus disconnected from engine shaft.

Second idea was to use peltier thermo electric couples,they are small and produce electricity directly from heat.Unfortunately efficiency is very low (4,5-9%).Max temperature of operation is around 250*C.Cold side of peltier has to be cooled as efficiently as possible adding extra problems.I could see peltiers as an intermediate part of coolant system of engine.Coolant would be then cooled down via heat transfer through peltier stack to the secondary cooland circuit with engine cooler.So engine would have to transfer all its heat though peltiers into the cooler.This setup would satisfy reuse of existing car parts and producing extra electricity from waste heat.

To make the steam producing unit in a simple way is to use some copper pipes(used for sanitary installations).Inexpensive thermo couples are available to serve as temp sensor.Home water heaters are equipped with safely pressure blow off valves (in case of steam formation inside of the heater).Water condenser could be an car airco cooler(works on high pressure and easily fitted on the car).As for now i don't know where to find a water pump that can pump small amounts of water (2cc per sec,120 cc per minute with pressure of 6,3 bar -90psi).Turbine :) my latest idea is to use the pneumatic wrench,it operates on 6,3 bar pressure and allows power output up to 0,8 kW and operates on speeds up to 10 000 rpm (can be directly mounted to the alternator).This wrench is not big and inexpensive.


So that's my idea :0 hope u have some comments!

Creativity

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Re: exhaust/engine cooler heat recuperator
« Reply #1 on: April 29, 2008, 02:15:34 PM »
or maybe we can use a Stirling engine instead of the turbine? but those are very expensive i guess,no?

argona369

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Re: exhaust/engine cooler heat recuperator
« Reply #2 on: April 29, 2008, 05:13:37 PM »
yes, it's a good idea,

there's some good links in this thread.

http://tech.groups.yahoo.com/group/free_energy/message/30552

Cliff,

Creativity

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Re: exhaust/engine cooler heat recuperator
« Reply #3 on: April 29, 2008, 05:52:47 PM »
interesting:

http://www.autoweek.com/apps/pbcs.dll/article?AID=/200602170430/FREE/60213002

well once more somone was faster than i was  ;) lots of brains,the same thinking,NO ACTION  >:(
But it gets me even more mad that its not in the production yet! it would save us all like 10% of fuel costs all this years,and think about the CO2....  >:(

edit:
yeah but still if we wait untill the car developers will incorporate it we will be still loosing this years,and all the cars that are already there...it gives me new power to acctually build those sytsems myself,as chep as possible and as simple as possible to fit it on existing cars.Besides there are still areas for improvement,like engine radiant heat loses,redesign of the the intake and applaying an on-board H2 production as a fuel additive+all the changes to the engine it allows.I feel that reasonably speaking we can get like +30% on extracting of fuel power.Then incorporate it into the turbo-diesel hybrid car can yeld a big advance... a car running 100km on 2,5-3 l of diesel will be true.
« Last Edit: April 29, 2008, 10:03:12 PM by Creativity »

b0rg13

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Re: exhaust/engine cooler heat recuperator
« Reply #4 on: April 29, 2008, 11:33:38 PM »
we should have been in electric cars years ago, really need to get right away from oil/gasoline, while your idea might work and save what ? %10 ?......, go electric and save %100 and be done with it.

Creativity

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Re: exhaust/engine cooler heat recuperator
« Reply #5 on: April 29, 2008, 11:43:38 PM »
I totally argee unfortunately who around us have say 6000+ Euro to do that... otherwise i would like to go all the way to electric  :) for a lot of people it is still a dream,so i will try to concentrate on easy improvement ,awaiting electric cars.In the time we chat we still use this old ICE :|
(to be strict electric will just shift oil use to the powerplant so its not 100% gain)

b0rg13

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Re: exhaust/engine cooler heat recuperator
« Reply #6 on: April 30, 2008, 12:10:17 AM »
i fully agree with you about the price!, and also have to add if i cold afford an elec car(id like the mini to start with), i would also go off the grid( as im researching and planing to any way), there are an array of ideas and ways to do it as well, but yes it comes back down to cost, grrrr  ;D

b0rg13

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Re: exhaust/engine cooler heat recuperator
« Reply #7 on: April 30, 2008, 12:14:37 AM »
btw , i like your ideas, im looking for a way to spin a gen/alt and every idea helps. :)

Creativity

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Re: exhaust/engine cooler heat recuperator
« Reply #8 on: April 30, 2008, 12:16:13 AM »
i will stay tuned :) in the mean time i will try to save some cash for u ,me and others by posting my progress on improvement :) if we will have small savings we r one step closer to full electric  ;D.
I just bought a small pneumatic grinder for 20E :) i also have the copper tubing for a preheater .I will take grinder apart to see how it works and what would make problems with steam.I want to make closed water cycle so i will remove silencer from it for extra power.I made some fast calculations already.it would need like 2,5 cc of water per second to turn into steam (around 6kW energy absorbed).I am planning to put in on higher pressure like 8-9 bar for extra torgue.max speed rating is 10 000 rpm and its cool as alternator runs a bit faster than engine :).First run will be on an open system,then i will mount the airco cooler to condensate collected steam after the turbine.

F6Pilot

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Re: exhaust/engine cooler heat recuperator
« Reply #9 on: May 01, 2008, 03:46:58 AM »
What about using a turbo on the exhaust to turn an alternator for the energy supply to an HHO generator. This should supply enough energy for the HHO without the demand on the existing electrical system.

Creativity

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Re: exhaust/engine cooler heat recuperator
« Reply #10 on: May 01, 2008, 12:50:21 PM »
true,
1)but turbo(you only mean an exhaust turbine attached,without compressor?) introduces a pressure restriction into exhaust and creates a back pressure.Back pressure is only a good thing on low rpm's when the valve timing has a big overlap in intake and exhaust(race machines,motorbikes => see yamaha EXUP valve).In all other cases back pressure is working against the engine(engine in exhaust phase has to push against this back pressure -loosing energy)
2)turbine spins in excess of 100.000 rpm's and the speed of it is varying by as much as 60%,there is simply no gear to gear it down to max 15.000 rpm needed by a standard alternator.So high speed alternator would be required capable of fast changing in rotation speed.

maybe you could go around second problem by using turbocharger to compress the air and then to run it through the other turbine with lower rpm's to run the alternator.

Creativity

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Re: exhaust/engine cooler heat recuperator
« Reply #11 on: May 01, 2008, 01:09:24 PM »
i did some calculations yesterday,it seems that water steam is kind of tricky .It needs a lot of energy to turn water into steam (like 2,5 kW per 1 g per s) it is because of the high vaporisation heat.I will bring u a fast overview(with rough numbers):

turbine i bought will need 8cfm(250 l/min) of uncompressed air to produce 0,8 kW.But first this amount of air should be compressed to 6,5 bar (90psi).So roughly speaking i need 4,5 l of uncompressed air per s.1 g of water produce 1,6 liter of uncompressed steam,so i need let say 3g of water to be evaporated per s.
It is then 7,5 kW energy absorbed from exhaust.Alternator efficiency 60%.
7,5 kW vs 0,8 *0,6=0,48 kW produced. Quite low conversion ratio.By getting turbine to run on 30 bar(high pressure!) situation would be more beneficial.

Still! I looked around for other working gas/liquid.Best i found is methanol (unfortunately flammable).It has hear of vapourisation of an order less than water.
it takes 0,11kW to evaporate 1g of it.1 g of methanol produces 1 l of uncompressed gas=>4,5 g evaporated per s=> 0,5 kW absorbed
0,5kW vs 0,48 kW produced is a big step forward comparing to water.

but i still look to find some nonflammable gas liquid with vaporisation temp higher that 40*C (so higher than ambient air temp so i can condensate it)and vaporisation heat lower than that of water.

anyhow i see a methanol as a good working fluid for even inefficient solar heat panels (temp of vapourisation under normal pressure of 65 *C! ) to generate electricity.In the full sun u can easily get 120*C in an empty sun panel wit a lot of steam.Prefferably put is somewhere in the garden and not on the roof (still a bit concerned about the fire in case of leakege).Fortuanetely it would require a small panel and only small amount of methanol to run the thing,so fire would not be severe :).Maybe i should build first a sun panel as a proof of concept.Cold side with condenser would be in the shadow.

(i just started with steam systems so i may make some mistakes here and there)

Creativity

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Re: exhaust/engine cooler heat recuperator
« Reply #12 on: May 01, 2008, 01:34:14 PM »
in fact...to tell the truth i was a bit shocked yesterday when i did exact calculations,because even with all the loses heat to electric conversion was above 90%(for methanol).too good to be so easy ;)
I guess i still don't get some concept around  ???

Creativity

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Re: exhaust/engine cooler heat recuperator
« Reply #13 on: May 02, 2008, 11:38:06 PM »
OK i was looking around some more and found a mistake.I bring here my calculation so maybe someone could verify.
It goes about the solar heat mirror collecting the high temperature (at least 240 deg C) sun beam to evaporate the methanol.240*C is the critical point for methanol (above it no methanol can exist in a liquid form no matter how big is the pressure).Boiling point for methanol under normal pressure is 65degC.
Super heated methanol vapour ,under pressure of 6,3 bar goes through the air turbine of the grinder.Grinder exhaust 7 liters of air per second to produce 0,4 kW of mechanical power.turbine operates best at 5000 rpm (half of its max no-load speed) and runs alternator of efficiency = 60% producing around 0,24 kW electricity.(efficiency from wikipedia,grinder ratings from producent technical specifications)

now tricky part:

methanol has density of 792kg/m3 and 1,332 kg/m3 when evaporated under normal pressure so i calculated that it expands 600 times in volume.
Next i took the gas law (http://en.wikipedia.org/wiki/Ideal_Gas_Law) to calculate how much would volume increase if i heated this vapour to 250*C (isobaric).
T1=65*C,T2=250*C under normal pressure and V1=600  .V2=600*250/65= 2300.
I concluded that 1 l of methanol when evaporated at the temp of 250*C would occupy 2300 l of volume.

to get 7l/s i will need 3ml or 2,41 g of methanol evaporated per second at the temp 250*C.

methanol heat energy 2,55J/gK. to heat methanol from 60*C to 240*C(above it is just a gas and heat energy is way smaller ,so i  negated the 10*C of heating it),temp difference of 180*C:
180*2,55*2,41=1,1 kW power absorbed

methanol evaporation energy 0.11 kJ/g.To evaporate 2,41 g takes 0,265 kW

So in total 1,365 kW absorbed to create super heated vapour from liquid methanol.

Air turbine will turn it into 0,4 kW of mechanical power and alternator with efficiency of 60% will make 0,24 kW electricity.

I come to maximal efficiency of 17% not counting the mirror Sun concentrator efficiency and heat losses.

with sun rate of 1kW per 1m2 the system would put out 170W of electricity.

I think it is a great deal :) considering that we could swap alternator for a solid magnet generator (around 80% efficiency),the thermal loses will be small as only a small amount of installation would need insulation.
It is cheap too!
pneumatic grinder cost me 20E second hand,now i would need some used car airco cooler (50E+) if i want to run it in a closed cycle,some copper pipes (1meter of so),solar concentrator can be made out of a satelite dish covered with silver(i am looking for some info how to do it).
I think the whole system would cost like 150E max with second hand parts,producing 240W + heat from condensation of methanol in the airco cooler.

any suggestion folks?
« Last Edit: May 03, 2008, 11:29:29 AM by Creativity »

Creativity

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Re: exhaust/engine cooler heat recuperator
« Reply #14 on: May 06, 2008, 11:33:00 PM »
Besst for mirror would be an aluminium satelite dish.aluminium can be chemically or electrochemically put into a high reflective sufrace,with low cost :)
i made some extra calculations to see what would be the best max temperature to operate on.The lowerst temperature is around 150degC,then the vapour pressure rises to 6.5 bar and grinder can be operated on rated power.At 250degC pressure rises to 34 bar and i think i can't handle that much so easily ;)Also the temperature will rise only to the level of the pressure selected.If my setup will operate on 6.5 bar temperature will stay 150C.The higher the pressure the higher the efficiency on the turbine.Lower temperature means lower heat loses.
Good news is that some companies tried to use methanol already as a replacement for freons in home solar heaters!It is thus enough safe to use i guess.second thing is that it will use max 0.5 liter of methanol to run this baby :)