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By krishan arora
#10443
Harnessing the Waste Heat Energy of the Vehicle Engines

A very large part of the fuel energy that is consumed by the vehicle engines (and other combustion engines) is wasted in the form of heat which has to be removed perforce by forced cooling.

It should be possible to use this heat energy, instead of wasting it, in several innovative ways to add value to the vehicle and increase the overall fuel efficiency of the vehicles by taking over some of the functions which presently need to draw additional power from the engines.

A few examples are:

-A heat transfer liquid filled coil could draw away the waste heat from the engine and transfer it for warming up the interiors, and the wind/rear screens of the vehicles in winters/cold weather.

-The heat transfer system could be used to warm up snacks/food being carried for the journey.

-The heat transfer system could also be used to boil water, with probably some incremental heating, either for sterilizing the drinking water or for providing a hot cup of tea or coffee during the journey.

-The heat transfer system could be used to vaporize a low boiling point liquid and run a gas turbine, akin to the systems being used in the Ocean Thermal Energy Conversion method of energy generation. The power so produced could be used to run electric motors to drive the vehicles, thereby saving on fuel consumption. This of course would be possible only in fuel/electric hybrid vehicles. In other vehicles this power could be used for battery charging, heating/cooling of the vehicles, or for any other applications needing electric power.

-The waste heat energy from the engines could also be used as the main heat source for a mini Vapor Evaporative Cooling System to provide for air conditioning the vehicles. This may need a small supplemental heating up of the working fluid to achieve the minimum working temperature but the system would subsequently provide a much larger fuel savings by allowing for smaller engines to be used in the vehicles.

Reward: No reward wanted. In fact I may be able to offer several other ideas for those wanting to make use of the above ideas.
By Daryl666
#10800
-A heat transfer liquid filled coil could draw away the waste heat from the engine and transfer it for warming up the interiors, and the wind/rear screens of the vehicles in winters/cold weather.


this has existed nearly as long as the automobile has had a radiator
this peticular device happens to be called a heater core and it is essentually a mini radiator whos sole purpose is the heating of the cabin of the vehicle.

-The heat transfer system could be used to vaporize a low boiling point liquid and run a gas turbine, akin to the systems being used in the Ocean Thermal Energy Conversion method of energy generation. The power so produced could be used to run electric motors to drive the vehicles, thereby saving on fuel consumption. This of course would be possible only in fuel/electric hybrid vehicles. In other vehicles this power could be used for battery charging, heating/cooling of the vehicles, or for any other applications needing electric power.

-The waste heat energy from the engines could also be used as the main heat source for a mini Vapor Evaporative Cooling System to provide for air conditioning the vehicles. This may need a small supplemental heating up of the working fluid to achieve the minimum working temperature but the system would subsequently provide a much larger fuel savings by allowing for smaller engines to be used in the vehicles.

are currently to heavy or bulky to implement altough i will point out that thermalcouplings are solid state devices usable for the purpose of producing electric current from heat. they operate on the Peltier effect except in reverse.(you will find that the peltier effect is commonly on solid state cooling pages but they do operate in reverse, meaning that there is energy produced if heat is allowed to force its way from 1 side to the other) the only thing keeping those from showing up everywhere is $$$$$$$$$$$$ thermalcouplings are quite expensive at the moment.

I will however see what i can do about making some sort of engine heat utilising stove or teapot. it is quite possable.
By krishan arora
#10862
this has existed nearly as long as the automobile has had a radiator
this peticular device happens to be called a heater core and it is essentually a mini radiator whos sole purpose is the heating of the cabin of the vehicle.


Thanks for this information. I don't think this feature is found in Indian cars because cabin heating is normally not needed because of the climate here.

are currently to heavy or bulky to implement altough i will point out that thermalcouplings are solid state devices usable for the purpose of producing electric current from heat. they operate on the Peltier effect except in reverse.(you will find that the peltier effect is commonly on solid state cooling pages but they do operate in reverse, meaning that there is energy produced if heat is allowed to force its way from 1 side to the other) the only thing keeping those from showing up everywhere is $$$$$$$$$$$$ thermalcouplings are quite expensive at the moment.


Thermocouplings based on the Seltier/Seebeck effect have low energy conversion efficiencies and may perhaps not provide the power needed for the vehicles' transmission. I think it may be quite possible however to scale down both the low-volatility-liquid vaporization cum gas turbine system to provide the electrical output for the vehicles, and also the vapor absorption cooling system for the air-conditioning of the vehicles.

I will however see what i can do about making some sort of engine heat utilising stove or teapot. it is quite possable.


That would be very nice and I hope I can hear from you soon that you have done so.

I would like to add that besides all this heat energy that is being wasted, and awaits being used, there is also plenty of kinetic energy
in the exhaust gases which too could be used to run an auxiliary turbine to generate additional power. This is known as a turbo-alternator and I believe it is used in some places, so why can't it be used as a standard practice in vehicles too?
By coqui
#12248
if you use a turbo alternator then you would make it harder for the engine to work
By krishan arora
#12290
coqui wrote:if you use a turbo alternator then you would make it harder for the engine to work


Turbo alternators would not be linked directly to the engines but would only be installed in the exhaust gases stream and sufficiently far away from the exhaust opening to preclude any back pressure affecting the engine.

Turbochargers' turbines using the exhaust gases stream can develop RPMs of as much as 150,000 to 200,000 rpms whereas turbo alternators would be needing only about a tenth of that value. I don't think therefore that turbo alternators would adversely affect engine output. In fact we could probably think of having more than one alternator so as to get a higher electric output.
By coqui
#12348
I see your point. There are some things to consider:
First the good news:
To most engines designs, some back pressure is desirable, about 8-11psi. This is useful to avoid combustion gases from escaping too fast into the atmosphere. if gases escape "slowly" then some of them can be sucked back and burned completely so efficiency is higher and polution lower. Higher back pressures than that for wich engines are designed would probably make it work very badly.
The need of this back pressure is also the reason why exhaust valves are less in number and/or smaller than intake valves. Also, the catalytic converter and muffler and muffler contribute to build up this pressure. (aftermarket mufflers will make your car a bit more powerfull but also a bit less efficient)
I think that turbo alternators and muffler with high flow could be placed as a replacement of the standard muffle. The turboalternator would be powered and at the same time it builds up back pressure. The high flow muffler could the sound the turboalternator fails to.

The not so good news:
-electric power generated by the turboalternator is determined by the power in the flow of the exhaust gases. On one side, more and smaller turboalternators could mean more output since they are spinned with more ease. However, more and smaller (or normal sized) turboalternators could also mean that the power from the exhaust gases has to be divided among these.

-alternators vary their outputs depending on the demand for electricity con cars. If you take the alternator and place only the turboalternator then, in order to adjust power output, it could build up to much pressure on the wrong rpm range. forcing the engine to work faster could make it less efficient during those times. On the other hand if you keep the alternator then the whole turboaltenator idea is not that good.

Notice that i wrote "could" rather than "would". what i mean here is that you have the idea... however we dont know if it would actually work and if it does, if it would actually be better one or more than one turboalternator, where would be the best place to locate the turboalternators, or if it would be better to have alternator and turboalternator or just turboalternator
By krishan arora
#12376
-electric power generated by the turboalternator is determined by the power in the flow of the exhaust gases. On one side, more and smaller turboalternators could mean more output since they are spinned with more ease. However, more and smaller (or normal sized) turboalternators could also mean that the power from the exhaust gases has to be divided among these.


I suggested more than one turboalternator only because the power in the exhaust stream is high enough to generate very high RPMs of around 150,000 - 200,000 rpm whereas turboalternators run at a fraction of these values.Dividing the power of the exhaust stream among several turboalternators therefore appears to make more sense.

-alternators vary their outputs depending on the demand for electricity con cars. If you take the alternator and place only the turboalternator then, in order to adjust power output, it could build up to much pressure on the wrong rpm range. forcing the engine to work faster could make it less efficient during those times. On the other hand if you keep the alternator then the whole turboaltenator idea is not that good.


I am not suggesting that we eliminate the normal alternators but only to supplement the total power generated by tapping the energy in the exhaust stream too, which is presently being totally wasted. The additional power could be used for auxiliary loads such as air conditioning, heating etc, though ideally it should be used for power transmission in electric hybrid vehicles, to enable reducing engine sizes and fuel consumptions, and that too without adversely affecting the vehicles' performance.
By fridgeman
#13185
With regard to the use of the surplus heat for air conditioning purposes. The average A/C system in a car can use as much as 8% of the petrol used which is quite a lot and getting more expensive every day. The current rotary compressor based system has several disadvantages the main one being leakage at the rotary compressor shaft seal ( hence the DIY bottles of gas to refill the system. your idea of using heat could be applied to an absorbtion type system for cooling using amonia and water currently used in campers and caravans where the fluid driving force is a 12v heater the chain of thought continues.
By krishan arora
#13196
fridgeman wrote:The average A/C system in a car can use as much as 8% of the petrol used which is quite a lot and getting more expensive every day. The current rotary compressor based system has several disadvantages the main one being leakage at the rotary compressor shaft seal ( hence the DIY bottles of gas to refill the system. your idea of using heat could be applied to an absorbtion type system for cooling using amonia and water currently used in campers and caravans where the fluid driving force is a 12v heater the chain of thought continues.


Yes, what I had suggested, as far as the air conditioning is concerned, was to use the waste heat to run a vapor absorption cooling system for the car's interiors ( please also see my post of 24 Sep '06). Such systems are already used for industrial air conditioning and I think it should be quite feasible to scale these down to be fitted in vehicles too.

Earlier, it used to be mentioned that such systems needed a minimum heat source temperature of about 140 C ( I hope I'm not too much off the mark!) and this temperature should be readily available around the engine casing. However, I believe that such systems can now work for even much lower heat source temperatures of about 70 C, as evidenced by the claims of one company which claims to run such systems based on domestic rooftop solar water heating systems. If this is true, then the vehicles' air conditioning could be based on the waste heat from the radiator water too. Incidentally, this would also increase the radiator efficiency, and maybe allow for smaller radiator fans being used - adding to the energy savings!

Though ammonia was commonly used in earlier systems, I believe the newer systems are using lithium bromide - water as the working medium.

K L Arora
By fridgeman
#13207
Yes your close on the makr at 140C with ref to the solar panels running the system I believe that they were using evacuated tube type. They are undergoing testing at the local uni here and can achieve temps of 147o naturally this is at the top of the collector and the temp reduces significantly when the water volume of the secondary system flows. Ill have a further look at this as time here is a bit limited at the moment regards John Bearing in mind these tests are in N.Ireland not the warmest place on earth
By krishan arora
#13214
fridgeman wrote:Yes your close on the makr at 140C with ref to the solar panels running the system I believe that they were using evacuated tube type. They are undergoing testing at the local uni here and can achieve temps of 147o naturally this is at the top of the collector and the temp reduces significantly when the water volume of the secondary system flows. .......


Solar powered air conditioning units using solar reflective panels and evacuated tube heat collectors, which provide a heat source of around 140 C, are already in commercial use in many places. What I am suggesting is to replace the solar heating source ( or electric/fuel based heat source) in the vapor absorption chilling/air-conditioning method by the waste heat from the vehicles' engines. The minimum needed temperatures of around 140 C should be readily available around the engine casing.

In addition to the above it should also be possible to use the waste heat from the radiators as the heat source for he vapor absorption cooling system. I had read somewhere, early last year, that some company (probably in USA) had claimed that it had developed a vapor absorption cooling system for domestic air conditioning based on the hot water available at about 70 C as obtained from the roof top domestic solar water heating systems. I think the temperatures in vehicle radiators varies between 90 -120 C and could thus be ideally suited for vapor absorption cooling of the vehicle interiors. Further, such a method would also enhance the radiator efficiencies and probably allow for smaller radiator fans - and corresponding power savings.

Krishan
#13223
How about a direct inject ceramic block/piston engine? A ceramic engine wouldn't require any cooling at all. Many have tried but the ceramics necessary to withstand the extreme forces of combustion seem to elude ceramic engineers. Always close but no cigar.
By krishan arora
#13234
Michael D. Grissom wrote:How about a direct inject ceramic block/piston engine? A ceramic engine wouldn't require any cooling at all. Many have tried but the ceramics necessary to withstand the extreme forces of combustion seem to elude ceramic engineers. Always close but no cigar.


Sure, a ceramic engine, or one made of thermal insulating engineering plastics, would prevent heat loss from around the engine casing. However, that does not reduce the total heat generated by the fuel combustion; only this waste heat would then be channeled out through the exhaust. This too can, and should be, harnessed for heating, power generation and cooling as I had suggested in my initial posts.

Krishan
By S13240
#13932
I recomend doing some research on how the internal combustion engine functions and how modern cars and their features function first. Your first statement sounded very uneducated. Google magic is a great thing.
By krishan arora
#13970
S13240 wrote:I recomend doing some research on how the internal combustion engine functions and how modern cars and their features function first. Your first statement sounded very uneducated. Google magic is a great thing.


I am appending below an extract from Wikipedia's article on internal combustion engines:
"... Most gasoline-fueled internal combustion engines, even when aided with turbochargers and stock efficiency aids, have an average efficiency of about 20% [1][2]. The efficiency may be as high as 37% at the optimum operating point. With this point as an example, 37% of the fuel energy reaches the shaft as useful work, maybe 35% goes to the exhaust as heat, another 18% to the coolant water as heat and the rest, 10% goes to mechanical friction and essential losses like oil pump, coolant water pump, fan, altenator etc. ....."

All that I have been trying to say is that there is quite a large amount of fuel (35% + 18% = 53% at least as shown above) that is being wasted in the form of heat losses and that we should try and constructively utilize this in whatever way we can to increase the overall utilization of the fuel. I had suggested some possible ways of doing so but there certainly could be other ways too and all suggestions in this regard should be welcomed and examined objectively.

Krishan
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