Would a wind turbine on a moving car generate energy efficiently?

[RonL]

There was https://www.physicsforums.com/showthread.php?t=180442". That thread convinced me that improving the aerodynamics of a vehicle would yield more energy savings vs. any type of fan/turbine addition.

And there would appear to be more of these threads:



They should put an index at the back of the book, as I cannot find the thread ASN was talking about.

Vehicles
...Cars
...Adding wind turbines(see also: crackpottery, but tolerated due to educational value)

Hi Om,
I went back and looked at that thread that you under lined "much more", unless I missed a post, It's interesting to me that Ranger Mike was the first to mention the thought of HEAT, a few post later the thread was locked.
Being able to recover waste heat from a hot engine but not from a mass of warm air, seems a little hypocritcal to me.

Guess I was out working and missed that thread, thanks for linking to it.

A little of what I have been trying to explain, is what I offered to try and pass on to Mike for use on his race car, figured he might be able to calculate things much better and run numbers that are far above my ability.

Thanks
Ron

 

[OmCheeto]

Hi Om,
I went back and looked at that thread that you under lined "much more", unless I missed a post, It's interesting to me that Ranger Mike was the first to mention the thought of HEAT, a few post later the thread was locked.
Being able to recover waste heat from a hot engine but not from a mass of warm air, seems a little hypocritcal to me.

Guess I was out working and missed that thread, thanks for linking to it.

A little of what I have been trying to explain, is what I offered to try and pass on to Mike for use on his race car, figured he might be able to calculate things much better and run numbers that are far above my ability.

Thanks
Ron

I'm hesitant to paraphrase what I think you are describing, but I'll do it anyways.

Are you saying that cooling the air in front of the vehicle via some sort of heat exchanger with the back of the vehicle is going to improve the efficiency of the vehicle?

In a closed system, a thermal gradient can be a source of energy, but in this open system?

If this were true, then you could propel a vehicle in this way. I seriously doubt you could get anything resembling a car to move in this manner without a [STRIKE]gigawatts[/STRIKE] terawatts worth of heat exchangers.

This idea isn't something you've transferred from hot air balloon technology is it?

 

[RonL]

I'm hesitant to paraphrase what I think you are describing, but I'll do it anyways.

Are you saying that cooling the air in front of the vehicle via some sort of heat exchanger with the back of the vehicle is going to improve the efficiency of the vehicle?

In a closed system, a thermal gradient can be a source of energy, but in this open system?

If this were true, then you could propel a vehicle in this way. I seriously doubt you could get anything resembling a car to move in this manner without a [STRIKE]gigawatts[/STRIKE] terawatts worth of heat exchangers.

This idea isn't something you've transferred from hot air balloon technology is it?

Om,
Nearly all my thoughts have evolved from the 60s' dream of a submersible, provoked by J. Cousteau, designed to be free of any surface support in any ocean or body of water that might need some kind of attention. A design that draws it's energy from the water. A design that involves no combustion of any kind that would have a polluting discharge. When R. Ballard showed us Hot Vents at close to 800F degrees, I really got a renewed fever as I had just started study about A/C and heat pumps (recharge points in any ocean who knows where).
Years of working with mechanical things has given a gift (or curse ??) of mixing and matching anything and not be concerned at the start about it being practicable or will it work in a positive way, the answer to failing conditions almost always opens a door to other lines of thought. The thermal exchanging fan is actually a spin-off idea that started as a propeller design for the submersible, A sealed system that moved refrigerant through cross flow shaft and tube, into the hub area then circulating through copper tubing curved to form a shape like a typical propeller. Only problem might be ice buildup, but under what conditions ??

I did just figure a way to phrase a question that will determine the validity of my thinking.

Without any detail of mechanics involved, if we consider a heat pump with a COP of 4:1 and the wattage input is 1,000 required by the motor and if the heat transferred is (equal ??) to 4,000, then if the coils move that heat into a second unit's cold liquid section will the pressure gain in the second unit be based on 1,000 or the 4,000 figure ?

Everything I think I understand is that the 4,000 number is now heat energy available to drive the second unit in some form of conversion.

The numbers don't have to be exact just simply put is this example close to correct ?

Thanks for your help

Ron

PS In answer to your first question, The warm air is drawn in by the spinning fan, heat is taken and adds to the driving system which is composed of several things, as air is moved from intake to cold discharge it might be pulled through even more fans until it's final discharge. The total heat that can be removed will equal the total work required to sustain motion.

 

[OmCheeto]

Cold air requires less energy to move than hot air, does anyone disagree ?

Since http://en.wikipedia.org/wiki/Density_of_air" , it seems to me it would require more energy to move.

ρ=P/(RT): if T goes down, rho goes up

F = ½ρC_dAv²

When rho goes up, so does drag force.

Hmmm... Perhaps we should put a spray mister on the end of a long tube in front of the car, bombard it with microwaves, turning the spray into steam, which when it cools, will produce a vacuum in front of the car, and atmospheric pressure at the rear of the car will provide the propulsive force.

Oh! And put a wind driven fan in there somewhere to power the whole thing. Otherwise I'll be off topic.

 

[stevenb]

There is one practical application—a turbine mounted on a stationary vehicle in the presence of a significant breeze. You could, for instance, stick one on the roof of a parked RV to power your TV or computer. In that case, there would be no parasitic losses to the vehicle.

There is also the case of going down a steep hill. This does not violate the conservation of energy.

 

[RonL]

Since http://en.wikipedia.org/wiki/Density_of_air" , it seems to me it would require more energy to move.

ρ=P/(RT): if T goes down, rho goes up


When rho goes up, so does drag force.

Hmmm... Perhaps we should put a spray mister on the end of a long tube in front of the car, bombard it with microwaves, turning the spray into steam, which when it cools, will produce a vacuum in front of the car, and atmospheric pressure at the rear of the car will provide the propulsive force.

Oh! And put a wind driven fan in there somewhere to power the whole thing. Otherwise I'll be off topic.

First let me make a most important point for any young mind reading this thread. "GET THE EDUCATION" you might have the greatest idea the world has ever seen, but if you can't articulate what's in your mind to other people, it likely will never see the light of day...Again "GET THE EDUCATION".

Om,
I think you are right, but let me see if my "mirror image, reverse logic" can make sense and you still be right.

I found a prop calculator and filled in all the numbers and at the bottom the standard air density was set at 29.92, lowering the number produced less thrust and then raising the number increased thrust, I think we will both agree that a thrust will always have an equal input requirement of power from some source.

But looking at power to compress air, each scf (standard cubic foot)compressed to 200 psi in a single stage compressor will require .250 hp, a two stage will require .230 hp, and a three stage will require .212 hp. At each stage heat has been removed and as a result horse power needs have gone down.

What I have described is a way to remove heat in a volume of air as it is continually reducing in volume in a duct that reduces in size and at the rear the same mass of air is thrusted rearward at a colder temperature than it entered. "if there had been no temperature reduction, more power would have been required to move the mass and a higher temperature discharge would have resulted".

The heat is used to produce pressure in the gases that help drive the primary "power group" that turns the fans and puts work into the motion of the car.

Did the fan design that provides thrust and at the same time removes heat (or if needed adds heat) go unnoticed ? (Russ)? anyone?

Maybe my mind has been inside that little submarine tooo long!

Ron

 

[russ_watters]

Sorry the fan design did not register in your mind, as it is critical to the operation.

A shrouded fan which you pump refrigerant through in order to allow the fan to double as an evaporator. Got it. I highly doubt that the idea would be workable as a commercial product (reliably sealing the tubes in a rotating hub would be near impossible), but even if it could be made to work, I can't see it being efficient at either heat transfer or moving air. For one thing, the vast majority of HVAC evaporator fans aren't axial, but centrifugal. Anyway...

Back to the original topic, no positive energy from air movement due to motion of a car can be obtained, unless there is a thermal reduction of that air.
Cold air requires less energy to move than hot air, does anyone disagree ?

Yes. The energy required to move air - by mass - is independent of temperature. It has to be. The kinetic energy equation is just E=.5MV^2.

Heat increase in any closed system will cause an increase in pressure ?

Temperature increase, yes.

Liquid and gas volume will define maximum energy movements within a closed system ?

That's incoherent. Word salad. Many of those words don't belong in the same sentence with each other. Volume of a closed system has nothing to do with energy movement.

Heat can be moved in and out of a closed system ?
Electricity can be moved in and out of a closed system ?
Mechanical energy can be moved in and out of a closed system with magnetic couplings?

Yes.

Kinetic energy can be stored in a flywheel, which can reside inside or outside a closed system?

No.

Without any detail of mechanics involved, if we consider a heat pump with a COP of 4:1 and the wattage input is 1,000 required by the motor and if the heat transferred is (equal ??) to 4,000, then if the coils move that heat into a second unit's cold liquid section will the pressure gain in the second unit be based on 1,000 or the 4,000 figure ?

What pressure gain? What is a "second unit"? You haven't described the thermodynamic process you are trying to drive! That's the problem that I asked about in my previous post! That said, what it looks like to me is that you think you can use a heat pump to drive power production, in a way that will produce more energy than is consumed. That would be an obvious violation of conservation of energy.

What I need is a concise, coherent description of the process, in single-sentence steps. For a gas turbine, for example, the process looks like this:

1. Incoming air is compressed (and it heats up).
2. Heat is added via a burner.
3. Energy is extracted via a turbine (and the exhaust cools).
4. Exhaust/heat rejection.

It should be possible to describe your process in that short/simple of a format. Please try! Let me help get you started by describing what I see so far:
1. Incoming air is pulled-in by a fan.
2. Incoming air is heated by a heat pump (it may be in the same device, but it is two separate thermodynamic processes).
3. Compress the air (it heats up more).
4. Cool the air using a the other side of the heat pump in #2 (pressure drops).
5. Extract electrical energy via a turbine.
6. Low temperature heat rejection.

Does this come anywhere close to what you are proposing?

 

[RonL]

A shrouded fan which you pump refrigerant through in order to allow the fan to double as an evaporator. Got it. I highly doubt that the idea would be workable as a commercial product (reliably sealing the tubes in a rotating hub would be near impossible), but even if it could be made to work, I can't see it being efficient at either heat transfer or moving air. For one thing, the vast majority of HVAC evaporator fans aren't axial, but centrifugal. Anyway... Yes. The energy required to move air - by mass - is independent of temperature. It has to be. The kinetic energy equation is just E=.5MV^2.
Temperature increase, yes. That's incoherent. Word salad. Many of those words don't belong in the same sentence with each other. Volume of a closed system has nothing to do with energy movement. Yes.
No. What pressure gain? What is a "second unit"? You haven't described the thermodynamic process you are trying to drive! That's the problem that I asked about in my previous post! That said, what it looks like to me is that you think you can use a heat pump to drive power production, in a way that will produce more energy than is consumed. That would be an obvious violation of conservation of energy.

What I need is a concise, coherent description of the process, in single-sentence steps. For a gas turbine, for example, the process looks like this:

1. Incoming air is compressed (and it heats up).
2. Heat is added via a burner.
3. Energy is extracted via a turbine (and the exhaust cools).
4. Exhaust/heat rejection.

It should be possible to describe your process in that short/simple of a format. Please try! Let me help get you started by describing what I see so far:
1. Incoming air is pulled-in by a fan.
2. Incoming air is heated by a heat pump (it may be in the same device, but it is two separate thermodynamic processes).
3. Compress the air (it heats up more).
4. Cool the air using a the other side of the heat pump in #2 (pressure drops).
5. Extract electrical energy via a turbine.
6. Low temperature heat rejection.

Does this come anywhere close to what you are proposing?

Russ,
Thanks for being patient with me and thanks for the suggestion about how to keep my thoughts in a short, simple, step by step method.

I think you have misinterpreted a few things that I have tried to imply, but that's OK for now, I'll try to address each and every one as this progresses.

Wow! the flywheel is the last thing I would have expected you to disagree with, if you can give the reason I would be thankful.

My next few days are going to be pretty full, but I will carry a note pad and try to jot down little bits at a time and maybe by Thursday of the coming week I can make a decent post.

I do hope you understand that even if I have not worded things well, I have always maintained staying within the first two laws.

Guess I better not try to say anything else, except THANKS.

Ron

 

[russ_watters]

Wow! the flywheel is the last thing I would have expected you to disagree with, if you can give the reason I would be thankful.

Actually, I'm not sure how that got in there - it must have been an editing mistake. A flywheel is a flywheel - it is an energy storage device and it has no relevance whatsoever to the discussion.

 

[RonL]

Actually, I'm not sure how that got in there - it must have been an editing mistake. A flywheel is a flywheel - it is an energy storage device and it has no relevance whatsoever to the discussion.

I might be wrong to think it's needed, but in my mind I see a need to use a storage of some kind to carry a cycle above and below it's steady state flow. Hope that's not word salad.

 

[OmCheeto]

Om,
I think you are right, but let me see if my "mirror image, reverse logic" can make sense and you still be right.

I found a prop calculator and filled in all the numbers and at the bottom the standard air density was set at 29.92, lowering the number produced less thrust and then raising the number increased thrust,

Yes.

I think we will both agree that a thrust will always have an equal input requirement of power from some source.

Power = Thrust * Velocity (according to wiki)

But looking at power to compress air, each scf (standard cubic foot)compressed to 200 psi in a single stage compressor will require .250 hp, a two stage will require .230 hp, and a three stage will require .212 hp. At each stage heat has been removed and as a result horse power needs have gone down.

This is where I start having a problem.
As soon as you start incorporating heat transfer, you are going to have to deal with the second law of thermodynamics, and the dreaded http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/carnot.html#c1".

What I have described is a way to remove heat in a volume of air as it is continually reducing in volume in a duct that reduces in size and at the rear the same mass of air is thrusted rearward at a colder temperature than it entered. "if there had been no temperature reduction, more power would have been required to move the mass and a higher temperature discharge would have resulted".

The heat is used to produce pressure in the gases that help drive the primary "power group" that turns the fans and puts work into the motion of the car.

Without ever inserting numbers into your theory, you will never know how inefficient it would really be.

And without having a clue as to what your contraption looks like, aka a schematic, we can't plug the numbers in for you.

 

[kmarinas86]

It seems like a wind turbine would be used to generate electricity.

So why not just have the wind turbine where it belongs and just plug in the vehicle to the grid to recharge?

Far better improvements can be made by making cars as aerodynamic as airplanes.

Adding windmills to cars to generate energy is a stupid idea.

 

[RonL]

It seems like a wind turbine would be used to generate electricity.

So why not just have the wind turbine where it belongs and just plug in the vehicle to the grid to recharge?

Far better improvements can be made by making cars as aerodynamic as airplanes.

Adding windmills to cars to generate energy is a stupid idea.

Everything you say is "precisely true". The question is, what if anything, can move it beyond the stupid point??

I say yes.

There is only time for this short answer.

Ron

 

[RonL]

Yes.

Power = Thrust * Velocity (according to wiki)

This is where I start having a problem.
As soon as you start incorporating heat transfer, you are going to have to deal with the second law of thermodynamics, and the dreaded http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/carnot.html#c1".


Without ever inserting numbers into your theory, you will never know how inefficient it would really be.

And without having a clue as to what your contraption looks like, aka a schematic, we can't plug the numbers in for you.

Hi Om,
Don't have time right now, but will get back later this evening.

I really have never fully understood the Carnot cycle, but isn't it describing a single machine or process cycle ?

I'm working on Russ's suggestion, so I'll throw your posts in as well.

Thanks

Ron

 

[russ_watters]

The Carnot cycle is simply the ideal thermodynamic cycle, containing the four basic processes (there are always variants of them...) in any thermodynamic cycle. Learning it is a critical part of the beginning of learning thermodynamic analysis. If you tell us what, specifically, you don't understand about it, maybe we can help...

 

[RonL]

The Carnot cycle is simply the ideal thermodynamic cycle, containing the four basic processes (there are always variants of them...) in any thermodynamic cycle. Learning it is a critical part of the beginning of learning thermodynamic analysis. If you tell us what, specifically, you don't understand about it, maybe we can help...

It just seems hard to comprehend motion of a piston movement and under different conditions not having changes of measurement, (heat or pressure). I don't for a moment doubt it's validity. I think it has more to do with not having a good recall of all terms and definitions of things associated with thermodynamics and the Carnot cycle.

My big fear is that age is beginning to show signs of memory loss and poor comprehension, not that they have ever been all that great.

Just found an area of wiki that has a lot of information about air handling equipment as used in aircraft, not a lot of overlapping systems and not very high pressure, but quite similar to what I am trying to describe.

I have made a little progress in your suggestion about presentation, but am finding it hard to make short statements about things that involve a multiple of actions happening at the same time and having positive and negative values that are conditioning different parts of each system.

I'll try to get a little more done tomorrow.

Thanks
Ron

 

[RonL]

An hour of typing, I hit the space bar and everything blinked and went away, second time in a week, does anyone know why this happens ??

Ron

 

[RonL]

Om, as you suggested.
It might be good to setup some numbers of what is being competed with in current transportation power use.
A. Conventional gasoline has a BTU value of about 125,000 per gallon.
B. 25% efficiency gives a net applied value of 31,250 BTU
C. 20 mile per gallon internal combustion engine powering the vehicle.
D. Speed of 60 miles per hour.

3 gallons used gives a total BTU rate of 93,750/60 minutes = 1562.5/42.4 = 36.85 HP

The weight of the vehicle will be determined by how efficiently the air flow drag, drive line friction, and tires in contact with road surface can be tweaked.

The question first presented has been changed to something like, "can any of those 1562.5 BTU's expended, be recovered, using a turbine or fan design?" I have stated "no...unless a thermal exchange can come into play".

Has that changed the thread to a point of starting a new thread and linking this one to it? I guess this question is directed to Russ.

I'm stopping here for now.

Ron

 

[RonL]

In an effort to draw energy from air that moves through a system, two methods are being considered.
1. A fan design that serves as a heat engine, more than one system of thermal exchange can be incorporated within a single rotating set, I have eliminated the need for seals.

2. A compressed air system that flows through the inner portions of the heat engine.

A question based on my understanding,
Would all energy used in compressing air inside the correct portion of a heat engine, be reflected in the final pressure of the air and all heat of compression normally wasted to the atmosphere, will show as an increase to a certain pressure of the heat pump gas? these TWO pressures based on volume would equal the same potential as the energy expended in the compression of the air.

One step of several.

Ron

 

[OmCheeto]

Om, as you suggested.
It might be good to setup some numbers of what is being competed with in current transportation power use.
A. Conventional gasoline has a BTU value of about 125,000 per gallon.
B. 25% efficiency gives a net applied value of 31,250 BTU
C. 20 mile per gallon internal combustion engine powering the vehicle.
D. Speed of 60 miles per hour.

3 gallons used gives a total BTU rate of 93,750/60 minutes = 1562.5/42.4 = 36.85 HP

The weight of the vehicle will be determined by how efficiently the air flow drag, drive line friction, and tires in contact with road surface can be tweaked.

The question first presented has been changed to something like, "can any of those 1562.5 BTU's expended, be recovered, using a turbine or fan design?" I have stated "no...unless a thermal exchange can come into play".

Has that changed the thread to a point of starting a new thread and linking this one to it? I guess this question is directed to Russ.

I'm stopping here for now.

Ron

This is starting to remind me of my https://www.physicsforums.com/showthread.php?t=203654" threads here at the forum. As such, I'd say we are getting way off topic.

 

[RonL]

This is starting to remind me of my https://www.physicsforums.com/showthread.php?t=203654" threads here at the forum. As such, I'd say we are getting way off topic.

Thanks Om,
I'll sit quietly for a while and follow the links in those two post, I guess one of my problems is that I can't find any words in the 1st and 2nd law that says I have to waste heat!

You now have all those phrases and no change actions cleared up in your mind?

I did find some wiki stuff that might help me work numbers into what my mind sees and I can never forget touching a hot compressor head, then a little later watch ice specks fly out of an air tool exhaust. Stuff like that just keeps me messed up:uhh:

Oh well guess I need to get ready for tomorrow, sighhh.

Ron

 

[RonL]

This is starting to remind me of my https://www.physicsforums.com/showthread.php?t=203654" threads here at the forum. As such, I'd say we are getting way off topic.

The op is asking based on a hood ornament, the discussion expanded to a larger windmill or turbine and I have jumped to thermal transfer. I see the connection all the way through, but then that's me. The point and my concern...no longer a hood ornament.

Ron

 

[OmCheeto]

Thanks Om,
I'll sit quietly for a while and follow the links in those two post, I guess one of my problems is that I can't find any words in the 1st and 2nd law that says I have to waste heat!

You now have all those phrases and no change actions cleared up in your mind?

Actually, I was just reviewing all of that 2nd law stuff, and I think I might see where you are coming from.

I did find some wiki stuff that might help me work numbers into what my mind sees and I can never forget touching a hot compressor head, then a little later watch ice specks fly out of an air tool exhaust. Stuff like that just keeps me messed up:uhh:

Oh well guess I need to get ready for tomorrow, sighhh.

Ron

I've seen the same things Ron. Though the hot compressor head and ice specks tell me that we just haven't given a hoot about throwing energy away in the past. And probably you too.

I've an out of state wedding to prepare for and go to this weekend, so I'll also be a bit late coming back analyzing where such wastes of thermal energy can be recovered in our hood ornament quest for knowledge.

 

[RonL]

Actually, I was just reviewing all of that 2nd law stuff, and I think I might see where you are coming from.


I've seen the same things Ron. Though the hot compressor head and ice specks tell me that we just haven't given a hoot about throwing energy away in the past. And probably you too.

I've an out of state wedding to prepare for and go to this weekend, so I'll also be a bit late coming back analyzing where such wastes of thermal energy can be recovered in our hood ornament quest for knowledge.

OK, hope this doesn't mess your weekend up

Instead of detailed mechanics I'll describe where my thoughts have developed, then one or two additional post just so there is no big loss if everything disappears, as has happened before.

Helped someone rod out a 50 ton system years ago, it had a 50 HP motor and a chill water cooling tower outside. The refrigeration cycle required a steady supply of electrical power to drive the 50 HP motor. What impressed me most was the 3/4 HP electric motor that pumped cool water through the water/refrigerant heat exchange unit and out to the open air cooling tower. This has always amazed me that so much heat transition can take place with such a small 3/4 HP motor.
The entire system is stationary, bolted to the concrete floor, so over time as my understanding started to grow a little, my thoughts went to "putting the system on 4 wheels at say 60 MPH".

I'm going to post and pick up the next thought on the next post. (just being safe)

 

[RonL]

OK, hope this doesn't mess your weekend up

Instead of detailed mechanics I'll describe where my thoughts have developed, then one or two additional post just so there is no big loss if everything disappears, as has happened before.

Helped someone rod out a 50 ton system years ago, it had a 50 HP motor and a chill water cooling tower outside. The refrigeration cycle required a steady supply of electrical power to drive the 50 HP motor. What impressed me most was the 3/4 HP electric motor that pumped cool water through the water/refrigerant heat exchange unit and out to the open air cooling tower. This has always amazed me that so much heat transition can take place with such a small 3/4 HP motor.
The entire system is stationary, bolted to the concrete floor, so over time as my understanding started to grow a little, my thoughts went to "putting the system on 4 wheels at say 60 MPH".

I'm going to post and pick up the next thought on the next post. (just being safe)

What changes need to take place? First look at what happens with no attempt at energy generation or recovery.

Put the car in motion at say 60 MPH, electric drive system and plenty of battery supply for a short time. If 50 HP is being expended to maintain speed, the generated apparent wind will turn the fan we have been talking about at less than the wind speed, but if a second motor is engaged to turn the fan, only a small amount of power will need to be added to bring the fan to a neutral speed in relation to the apparent wind, (maybe 5 HP) if a little more power is added (5 HP) the fan produces a very small suction in front and a very small thrust in rear, somewhere in there will be a zero point where the two motors are in balance with respect to total power needed, at that point any increase of power to the small motor will reflect an equal drop in the larger motor.
No energy recovered = a total negative expense.

 

[RonL]

What changes need to take place? First look at what happens with no attempt at energy generation or recovery.

Put the car in motion at say 60 MPH, electric drive system and plenty of battery supply for a short time. If 50 HP is being expended to maintain speed, the generated apparent wind will turn the fan we have been talking about at less than the wind speed, but if a second motor is engaged to turn the fan, only a small amount of power will need to be added to bring the fan to a neutral speed in relation to the apparent wind, (maybe 5 HP) if a little more power is added (5 HP) the fan produces a very small suction in front and a very small thrust in rear, somewhere in there will be a zero point where the two motors are in balance with respect to total power needed, at that point any increase of power to the small motor will reflect an equal drop in the larger motor.
No energy recovered = a total negative expense.

Now to extract any energy, which is the topic at hand, I have suggested a fan design that serves in multiple capacities, all in some way to contribute a thermal transfer from the heat in the air that is being pulled through and thrust out the back.
Without trying to describe the mechanics within the design, I will list some things that can be used in the conversion process. (some may not be needed)

Somewhere around 2000 BTU/minute will be needed, maybe less.
Everyone should know that heat can be extracted from air and that heat can be converted to useful work.

Work to put the vehicle in motion must be expended first and when in motion things can start to happen. Thermal conversion and energy generation inside the fan body.
First thing to consider is that no resistance is created in the fans function, if the mechanics inside the fan structure are not engaged and even the heat engine functions carried on inside the fan design will not have any affect on the fan as it turns.

A list of things inside the fan design, these can be single units or multiple interacting systems.
A. Stirling Cycle
B. Vapor Compression
C. Gas Cycle (compressed air)
D. Vapor Absorption ?

E. Vane Motors
F. Generator(s)
G. Electric Motor(s)

energy transfer
H. Slip Rings/Brushes
I. Magnetics
J. Air Pressure
K. A variety of motion control things.

With those things in mind, I say yes we can transform heat into work in an efficient manner.
Basically we are doing the same as driving a plane with no wings.
The design questions will all revolve around how many BTU can be extracted from what volume of air flow needed to pull and push the vehicle at an acceptable speed.

Using Heat engine tech, compressed air and very common energy transfer equipment, there is lots of room to exchange normally wasted heat from one unit and use it to enhance another.
Just to be clear, a main power source turns the fan and energy generated inside the fan is transferred out to assist or replenish the energy used to turn the fan.

I have tried to avoid explaining things in detail, just hope there is enough logic here to trigger some different kinds of thought in regard to energy waste.

Ron

 

[RonL]

For Russ and anyone that likes to crunch numbers, I hope this is a close and basic enough set of values to show potential of some energy recovery.

1. Vehicle weight between 4,000 and 5,000 pounds.

2. 4 wheels, traction drive for 2 or 4.

3. Main power, 2 or 3, 20 HP DC motors and a possible AC combination.

4. Battery storage ?, will depend on several things.

5. Heat engine design will involve multiple fans, (5 > 7)

6. Heat engine design will have axle tube of 12" - 18" diameter and be about 15' in length.

7. Front intake area ? I have chosen 19.625 sq ft as a start for showing airflow volume.

8. Starting power applied to both traction drive and fan system.

9. As speed increases, heat engine functions start to develop.

10. Based on vehicle motion, fan is balanced or slightly positive to eliminate any negative frontal resistance.

11. Power to sustain forward motion is kept close to equal between motors serving as drivetrain or fan drive.

12 Volume of airflow through fan system at 30 mph and 60 mph,
(a.) 30 miles per hour = 51,810 cubic feet per minute.
(b.) 60 miles per hour = 103,620 cubic feet per minute.

13. To find a 2,000 or close BTU per minute transfer rate, seems to me not to be needing a very large thermal Delta, especially on really warm days.

14. A 48" fan system might need to be enlarged a little, depending on axle diameter.


Stuffing all mechanical and heat exchange parts inside the axle tube will be a bit complicated and will result in a heavy axle tube, but is within reason.

Compressed air, electric motors and generators along with heat exchange properties taking place inside the axle tube and through the fan blades and fan rings, should provide an easy transfer of BTU from such a very large mass air flow.

I'm sure this leaves a lot to question, Russ I hope this is close to your suggested form of presentation. In trying to describe the inner working of the axle tube, I wound up with almost 10 pages of notes and descriptive wording.

There are lots of reasons that a fan driven car will not work for general transportation, but having this endless quest for better fuel mileage and cheap power needs to end. The use of Hydrogen for transportation, I think is as impractical as trying to stop global warming.

Hopeing this is a better presentation.

Ron

 

[RonL]

OK, after 4 days and 400+ views...no comments or questions, so here is my simple math, maybe someone will see the error of my thinking in regard to extracting heat from the air.

A steady speed of 60 MPH
A fan that is in balance with air flow in relation to speed.
A frontal area intake of 19.625 square feet
A mass air flow of 103,000 cubic feet per minute (not exact, but close)
Weight of a cubic foot of dry air @ 70 degrees F .07495
BTU's to raise temperature of 1 pound of air 1 degree F .240
BTU's per minute to equal 1 Horsepower...42.4

Using these numbers to raise temperature shows 43.697 HP per 1 degree

I believe the reverse would apply, dumping 43.697 HP into the heat engine.

A delta of 30 degrees would put temperature of the mass air flow at 100 degrees F
The new weight per cubic foot is .07094, the new HP figure is 41.359
Adding the two HP figures and dividing by two gives an average HP for each degree of change 42.528, multiple by 30 for a total of 1275.845 HP in a 30 degree Delta.

As I stated before, it is impossible to absorb more power than is being used, unless there is some sort of storage system in the design and then ONLY until it is full, after which the absorption will never exceed a dispersement (which is keeping the vehicle in motion)

If only 75 HP is needed then the Delta that delivers that other 1200 HP CANNOT come into play. The same as a Gasoline engine with 500 HP cannot apply more than the same 75 HP at a steady speed.

So unless someone explains why a heat pump cannot feed a heat engine and an air compressor cannot be inside said heat engine and produce two pressure values based on compression and heat of compression, Then pressure converted to work (mechanical or electric or both) satisfying R Clausius Heat/Work statement, then I will need a stronger understanding of the first two laws of Thermodynamics.

Heat being absorbed from the mass air flow, Then being converted to work, which is being directed into sustaining motion, which is producing the air flow...I can't see the violation in any of the three things above.

I think I have shown the potential of the heat in the air and to satisfy the 2nd law, ONLY the heat needed to overcome the resistance of motion can be extracted.
This is different from the electric motor driving a generator, then the generator giving the motor the power it needs...because electricity can put out heat, but not absorb heat and cannot be compressed or expanded.

So back to the question of the thread, I say yes, and this is the thinking that goes on in my head, someone speak up. My simple math and logic might have overlooked that key thing...which is?

Thanks
Ron

 

[Andrew Mason]

You are trying to create a perpetual motion machine of the second kind. You cannot run a steamship across the ocean by extracting heat from the ocean using a heat pump and then using the heat from the heat pump to run the steam engines. This would violate the second law of thermodynamics, but would not violate the law of conservation of energy.

The most amount of work you could get out of such a machine would be the amount of work done by the heat pump (in your case, that would be using a Carnot heat pump running off the car engine and Carnot heat engine supplementing the car engine's output). In reality, you could not achieve Carnot efficiency in either, so you would be wasting energy.

AM

 

[RonL]

You are trying to create a perpetual motion machine of the second kind. You cannot run a steamship across the ocean by extracting heat from the ocean using a heat pump and then using the heat from the heat pump to run the steam engines. This would violate the second law of thermodynamics, but would not violate the law of conservation of energy.

The most amount of work you could get out of such a machine would be the amount of work done by the heat pump (in your case, that would be using a Carnot heat pump running off the car engine and Carnot heat engine supplementing the car engine's output). In reality, you could not achieve Carnot efficiency in either, so you would be wasting energy.

AM

Thanks AM,
This is the same as Russ stated, when he said I need to understand the Carnot Cycle, so that will be the only mission for me, and as Halls of Ivy said to someone else in another thread this weekend "understanding every detail and word of an established law or definition" that might not be exact but I think it is close, did not go unnoticed by me.

I'm really having trouble understanding why, if normal losses are being recovered and recirculated within the heat conversion process inside the system, this represents an internal energy that keeps momentum strong and cycles moving so that only what is added can be sent out as work. Maybe that doesn't make sense.

My mind See's the 1st and 2nd law as saying, it's as impossible to sustain waste as it is to have more than 100% in a system.

Anyway I have a lot in front of me and a lot of misunderstandings to push to the side, if in fact my thinking is completely wrong.
Thanks for the answer.

Ron

PS Looking back at that statement about the ship, in essense the steam engine would be inside my heat engine (or heat pump) I think that is what makes the difference ??

 

[RonL]

Last post, I promise.

I guess I never really defined the T high and T low of the system and these can be any value based on design.
Inside the heat engine, the range might be 1200 F degrees high and -50 F low, with any number of exchange points, then if outside air is 90 F intake and 85 F discharge should equal, or be close to the needs of energy out.
Energy volume inside can be quite large and maintain a large amount of momentum.

I'll go to wiki and any books I have, and not say another word until I have this straight in my mind.

Thanks
Ron

 

[Andrew Mason]

I'm really having trouble understanding why, if normal losses are being recovered and recirculated within the heat conversion process inside the system, this represents an internal energy that keeps momentum strong and cycles moving so that only what is added can be sent out as work. Maybe that doesn't make sense.

You cannot convert all the heat energy into work. The work done by the wind on the windmill (which is really the work done by the car engine on the windmill) may result in cooling of the air (I'm not sure about that). But if it did, the amount of work you would be able to extract from a heat engine operating between the two temperatures cannot possibly be more than the amount of work done by the engine in creating the temperature difference. This is the second law of thermodynamics.

My mind See's the 1st and 2nd law as saying, it's as impossible to sustain waste as it is to have more than 100% in a system.

The first law is simply the conservation of energy. The second law is more subtle. It says that work is required to make heat flow from a colder to a hotter reservoir. The second law says that the amount of work you can get out of a heat engine that uses a heat flow between a hot and cold reservoir cannot exceed the amount of work required to reverse the heat flow from the cold to the hot reservoir.

AM

 

[RonL]

You cannot convert all the heat energy into work. The work done by the wind on the windmill (which is really the work done by the car engine on the windmill) may result in cooling of the air (I'm not sure about that). But if it did, the amount of work you would be able to extract from a heat engine operating between the two temperatures cannot possibly be more than the amount of work done by the engine in creating the temperature difference. This is the second law of thermodynamics.


The first law is simply the conservation of energy. The second law is more subtle. It says that work is required to make heat flow from a colder to a hotter reservoir. The second law says that the amount of work you can get out of a heat engine that uses a heat flow between a hot and cold reservoir cannot exceed the amount of work required to reverse the heat flow from the cold to the hot reservoir.

AM

Thanks AM,
I certainly don't want to sound too resistant, but would like to present three thoughts.

1. This is not working between two reservoirs, just one.
2. The fan, as stated further back in the thread, is both the thrust provider and at the same time the heat absorber.
3. The entire system is in motion as all this takes place, the net energy balances at 0, no need for a positive supply.

If you take the wheels off and bolt it to a foundation, it becomes no more than a pretty good heat pump or refrigerator, depending on what is desired.
I think what keeps me confused is the one reservoir I see and the two reservoirs mentioned in all thermodynamics textbooks.
If I have two reservoirs in what I have suggested, they exist inside the heat engine and are well insulated from each other, this is what I have to try and sort out, so far I have had little success as my level of education is pretty short. I do feel confident in my mechanical aptitude, just too many lose ends that I have a hard time connecting properly.

Thanks AM and anyone else that has tried to understand my thoughts.
Now back to some books.

Ron

 

[RonL]

Thanks AM,
I certainly don't want to sound too resistant, but would like to present three thoughts.

1. This is not working between two reservoirs, just one.
2. The fan, as stated further back in the thread, is both the thrust provider and at the same time the heat absorber.
3. The entire system is in motion as all this takes place, the net energy balances at 0, no need for a positive supply.

If you take the wheels off and bolt it to a foundation, it becomes no more than a pretty good heat pump or refrigerator, depending on what is desired.
I think what keeps me confused is the one reservoir I see and the two reservoirs mentioned in all thermodynamics textbooks.
If I have two reservoirs in what I have suggested, they exist inside the heat engine and are well insulated from each other, this is what I have to try and sort out, so far I have had little success as my level of education is pretty short. I do feel confident in my mechanical aptitude, just too many lose ends that I have a hard time connecting properly.

Thanks AM and anyone else that has tried to understand my thoughts.
Now back to some books.

Ron

This might be what I need to study and find the way to say what I have been trying to imply.

http://en.wikipedia.org/wiki/Fluctuation_theorem

Going down to dissipation function, I find the term "non equilibrium" to represent the state of a machine in motion, that for a period of time to operate in a positive energy mode.
Poorly worded, I have some more study time in the near future, but for the moment some that are more advanced in Thermodynamics, might throw out some insights.

Later
Ron

 

[OmCheeto]

This might be what I need to study and find the way to say what I have been trying to imply.

http://en.wikipedia.org/wiki/Fluctuation_theorem

Going down to dissipation function, I find the term "non equilibrium" to represent the state of a machine in motion, that for a period of time to operate in a positive energy mode.
Poorly worded, I have some more study time in the near future, but for the moment some that are more advanced in Thermodynamics, might throw out some insights.

Later
Ron

Well, I must admit that I do not fully understand the Fluctuation Theorem, but I don't think I'll further my studies of the subject, as you cannot utilize it for anything on the scales we are talking about.

In the article referenced by the wiki entry, the FT is only valid at the nano-scale. I believe I once heard something about all of the atoms in a pot of water having a mathematically finite possibility of all of the atoms moving in the same direction, hence having the water jump out of the pot. Unfortunately, the probability is so low that you would have to wait for a bazillion (that's the age of the universe times a gazillion) years.

http://www.newscientist.com/article/dn2572"
09:21 19 July 2002 by Matthew Chalmers

"In a typical room, for example, the air molecules are most likely to be distributed evenly, which is the overall result of their individual random motion", says theoretical physicist Andrew Davies of Glasgow University. "But because of this randomness there is always a probability that suddenly all the air will bunch up in one corner." Thankfully this probability is so small it never happens on human timescales.