Kender Solar Engine

[mikedmonds]

Dear Forum,

 

I have run across a very interesting machine that I was wondering if someone might could comment on. It is a version of the Sterling Engine, that uses a turbine instead of a piston. They have just completed phase I testing, and say it was successful. Here is a link:

 

http://www.kendersolar.com/

 

This describes the technology:

 

http://www.kendersolar.com/index.php/The-solar-technology-of-the-Kender-Engine-Phase-1.html

 

They claim that the energy extracted by the solar panel produces more energy than what it takes to drive the compressor to circulate the helium, and results in: "The system produces 39 kW of power (47 kW by the turbine, less 8 kW for the compressor). That is equivalent to 53 horse power, or enough energy to supply energy for 12 homes."

 

Does this sound theoretically possible? Any comments would be appreciated; or please forward to anyone who might could comment.

 

Thank you, and have a blessed day!

 

Sincerely,

Thomas M. Edmonds

Christiansburg, VA

 

[baxtonduglonn]

I just googled Kender and found a list of sites with "news" stories suspiciously similar to those of Patriot Energy Corp, who claimed to be replacing catalytic converters with "H2O Oxygenators" and appear to have been a scam. Based on this and the ridiculous claims made for this generator, I am convinced that this is also a scam. The "Make Money With Us" button on the homepage does nothing to persuade me otherwise.

[CaptainPanic]

Ok, Monday morning, it's a bad idea to do thermodynamics before finishing my first coffee, but here it goes.

 

It's certainly a scam (coffee or not, I can recognize stupidity). Kender Solar Energy is a scam (<-- remark for Google hits).

 

The system is essentially an open system with a turbine and a compressor. That simply means that the system has 2 areas with a different pressure. There is the entire heat exchanger and Helium storage, which should be entirely at 200 atm. And the little part between the turbine and the compressor is apparently at 20 atm.

 

Now, laws of thermodynamics (before or after coffee) say that even in an ideal case, the turbine will generate at best the same amount of energy as the compressor needs. There is no heat exchanger between the turbine and the compressor... so, the two steps (expansion and compression) are two equal but opposite steps.

 

They seem to suggest that the pressure after the compressor is not yet 200 atm (the pressure "builds up in the heat exchanger"). That means it would not work. If the heat exchanger is an open system (in its essence it's just a pipe), then the pressure is the same along the entire heat exchanger.

 

This idea might just work if you have a set of valves which are controlled by a measuring system that can open them and close them. As a continuous system, I fail to see how this can work.

 

You also will need a cold sink (a place to dump your heat). Carnot says that no cycle will run at 100% efficiency. That means that every Joule that isn't converted to electricity will become waste heat. Waste heat must be dumped.

 

Finally, if this is a continuous process... why do they add this helium storage (the storage won't become mre or less full... so why not leave it out altogether)? And why don't they just use nitrogen, which is more dense and (I believe) will carry heat a bit easier?

 

I'll read this again later. Feel free to correct my early morning thermodynamics. I got a feeling that it's correct though

 

[edit]

39 kW from a (0.8*2.5 = 2 m2 area???). The sun provides about 10 times less even in the best circumstances. Just forget about this scam...

 

If you want to make electricity from the sun, use either a solar cell, or go with a simple steam cycle (invented by Mr. Watt in 1745). Here's a picture of it. Just replace the boiler by a solar boiler.

 

[edit 2] I finished my first coffee, and I still think it's a scam.

Edited September 7, 2009 by CaptainPanic
Kender Solar Energy is a scam.

[J.C.MacSwell]

Looks like it could work...

 

 

for one cycle, since you start off with helium at 200 atm, possibly a second cycle at lesser output, using the room temperature air as a heat source and the cooled helium as a sink, maybe a third or fourth at less and less power and less and less efficiency.

 

After that, from room temperature air as the energy source, and no sink ...not so much, it will come to halt.

 

Something like this could work from solar energy, but not at the efficiencies or outputs implied

[CaptainPanic]

Looks like it could work...

 

for one cycle, since you start off with helium at 200 atm, possibly a second cycle at lesser output, using the room temperature air as a heat source and the cooled helium as a sink, maybe a third or fourth at less and less power and less and less efficiency.

 

After that, from room temperature air as the energy source, and no sink ...not so much, it will come to halt.

 

Something like this could work from solar energy, but not at the efficiencies or outputs implied

 

And from the (scam) website:

The full helium cycle runs in 0.22 seconds.

Adding the two quotes together: according to J.C.MacSwell, this process would come to a halt in about 1 second.

 

Which is 1 second longer than I predicted.

 

I'm not sure that I understand the principle of the process that J.C. explained there though. What is 1 cycle? (Because my point is that the cycle isn't a true cycle: there is just a proposed heat input, but no output, therefore no Carnot cycle, and no spinning turbine).

[J.C.MacSwell]

And from the (scam) website:

 

Adding the two quotes together: according to J.C.MacSwell, this process would come to a halt in about 1 second.

 

Which is 1 second longer than I predicted.

 

I'm not sure that I understand the principle of the process that J.C. explained there though. What is 1 cycle? (Because my point is that the cycle isn't a true cycle: there is just a proposed heat input, but no output, therefore no Carnot cycle, and no spinning turbine).

 

Take with a grain of salt my estimate as to how many cycles it would last. I was being facetious in my claim that it could work, due to the small, temporary and really insignificant energy source it had available to work using ambient temperature.

 

I just looked for an energy source and sink. Since there is a small one that is not replaced, it will be very short lived. I made no attempt to calculate it, as it was clear it would not really work as claimed, for the reasons you stated in your original post.

[mikedmonds]

Thanks Guys!

I'll be looking for an exit on this stock; and will post your comments on the message board. Your expert analysis will save many people a lot of hard earned finances.

Best regards!

Sincerely,

Cburg

[sunshine]

The kender engine does not use surrounding air temperature. It uses a thermal

solar panel to heat the helium. What you are left with is some very cold air with trace amounts of helium which would be refilled annually as it would exhaust itself in one and a half years. The amount of helium will cost around $2.00. The exact specifications as to how it works are not revealed on the website. This is only a guideline as the guts of this is a trade secret. The unit will be demonstrated in the new year with both a CE & UL mark. As for the 'make money with us' web page it is only implying a homeowner with this unit will be making extra energy to sell to the grid in places where they currently allow for this. Watch for big changes to come across North America allowing for this. Please save your criticisms until the actual unit has been demonstrated and then there will be more then speculation to converse about.

[lancelot21]

Like sunshine, I feel it a bit unfair to judge whether Kender Solar works based on the limited info available on their web site, as I don't think they should make available all their secrets anyway.

 

Moreover, I'm more concerned here about whether a company could in theory succeed in doing a similar engine, rather than knowing whether this particular company (Kender) will.

 

My understanding is that what they are trying to achieve can also be compared to heat pumps as far as thermodynamics are concerned:

 

In heat pumps, the cold air from outside the house becomes colder while the warm air inside the house becomes warmer. A small amount of electricity is used, but doesn't consume as much as a normal heater or else nobody would bother installing heat pumps in their house. Another way to see this is that some energy was taken from stored solar heat outside the house and converted into heat.

 

The (small?) new step taken by Kender is to take some energy from stored solar heat outside the house and convert it into electricity instead of heat.

 

This is not to say that they will achieve the efficiency they claim or even that they will produce electricity at all (as electricity is needed to run heat pumps in the first place), just that I don't see why their claim should be impossible according to the laws of thermodynamics.

[Mr Skeptic]

They claim that the energy extracted by the solar panel produces more energy than what it takes to drive the compressor to circulate the helium, and results in: "The system produces 39 kW of power (47 kW by the turbine, less 8 kW for the compressor). That is equivalent to 53 horse power, or enough energy to supply energy for 12 homes."

 

Does this sound theoretically possible? Any comments would be appreciated; or please forward to anyone who might could comment.

 

Sort of, but I wouldn't trust their numbers.

 

It is possible to run a heat engine powered by the sun, but at most you get a fraction of the amount of solar energy hitting your panels. The waste heat must be dumped somewhere, and the energy produced will be at most equal to the energy collected by the solar panel times (1 minus the temperature of the heat sink divided by the temperature of the solar panel), then minus internal losses. These temperatures are measured in Kelvin, so in freezing conditions your heat sink would be 273 K or so. Note that the easiest way to tell whether they are a scam is to see whether they are powering themselves with their device, or selling their device to solar power plants. There is no conspiracy, solar power plants will buy the best systems they can.

 

---

 

Yup, Kender Solar is a scam. They allow the air to expand to cool to -240 C so they can work magic with the numbers, and then use a pump to compress it. If they were being honest, they could bypass the pump and simply not expand it as much. There is no point in allowing it to expand and immediately compressing it again.

[NuclearError]

Dear Mr Skeptic,

 

I have been reading this board for some time and remain intrigued by your comments. Perhaps have you seen the video on the Kender Website.

 

the way I understand the technology is the following:

 

Indeed, the total energy extracible at most, is equal to the energy collected by the solar panel times (1 minus the temperature of the heat sink divided by the temperature of the solar panel), then minus internal losses.

 

Indeed, also, these temperatures are measured in Kelvin. But here is where I believe that you are wrong: I understand that the temperature of the heat sink is 60K, a temperature obtained by expanding the helium in the closed circuit.

 

So what I understand is this: Energy out = 1 - (60K / 293K) * Energy in

This gives a COP of 79%, excluding the losses.

It is somehow the same type of calculation as for an air-air heat pump.

 

Also, the size of the panel is irrelevant. What is important for calculating the energy coming out, as for a heat pump, is how much air you can shoot through that panel (or heat exchanger)...

 

As you know, the COP for a heat pump can be in the range of 300% (which is a nonsense number, as long as you don't add the thermal capacity and volume of the air going through the exchanger).

 

I believe we have here a simple heat pump with something new attached to it...

[Mr Skeptic]

Indeed, also, these temperatures are measured in Kelvin. But here is where I believe that you are wrong: I understand that the temperature of the heat sink is 60K, a temperature obtained by expanding the helium in the closed circuit.

 

It is not. There is no heat sink. You can't transfer heat from -240 C gas unless the surrounding air is even cooler than that (hint: it's not), so they don't transfer any heat in what should have been the heat sink. Hence, not a heat engine. Steps 2 and 3 can safely be ignored (after subtracting the losses due to the compressor), since the only effect they have is to lose energy due to the compressor -- there is no point in expanding the gas and then compressing it if you don't do something in between. At step 4, the gas is at over 200 atm and above 20 C, since compressing it heats it and some heat is added from the compressor (they ignore that the same law of physics that they previously used to cool the helium by expansion will heat the helium when compressed).

 

What you have is a heated pipe with a fan blowing air into a turbine. It is literally a bunch of hot air.

 

Furthermore, it is not an innocent mistake -- these people know what they are lying about and it is definitely a scam.

[SH3RL0CK]

Moreover, I'm more concerned here about whether a company could in theory succeed in doing a similar engine, rather than knowing whether this particular company (Kender) will.

You cannot bypass the laws of physics, specifically the law of conservation of energy. So, no, it is not even theoretically possible to do this as has already been mathematically shown...the solar energy present isn't sufficient.

[lancelot21]

You cannot bypass the laws of physics, specifically the law of conservation of energy. So, no, it is not even theoretically possible to do this as has already been mathematically shown...the solar energy present isn't sufficient.

 

My understanding is that the stored energy present in the atmosphere is huge, as it would take a huge amount of energy to heat the same quantity of air as contained in Earth atmosphere from 0K up to the average air temperature (293K?).

 

Thus, a device that could hypothetically extract heat from the Earth atmosphere and produce electricity from it would not need to bypass the law of conservation of energy to be able to produce massive amounts of electricity before running out of "fuel", ie when outside air temperature would be so low (below -70C according to Kender home page) that it wouldn't work properly any longer.

[insane_alien]

but you need a place to dump that heat that is colder than the atmosphere. without a refridgeration cycle you aren't going to get that.

[NuclearError]

It is not what, Mr. Skeptic ?

 

Not a heat pump ? What do you mean, there is no heat sink ?

 

When you create a cold, such as in a refrigerator, and you pull the plug of the refrigerator, keeping the door closed, what happens to the air inside the refrigerator ?

1. Does the outside air drop in temperature, to finally meet the temperature inside the refrigerator ?

2. Or does the air inside the refrigerator move up in temperature to finally reach the temperature of the surrounding air ?

 

I say that it is the second version, which is correct. In a heat pump, a cold is created inside the nitrogen circuit (usually in the range of -15 C). The outside air (usually at -5 C in a cold environment) is sucked through the heat exchanger and what happens ?

 

The air is dropping in temperature inside the heat exchanger and then, when it comes out, it rises in temperature again, as it is blown away into nature. And what happens to the nitrogen, which was brought to -15C in the circuit ? Its temperature rises back to -5C, the same temperature as the outside temperature.

 

So here you have an example of the temperature of the gas in the closed circuit "rising spontaneously" to the surrounding air temperature.

 

What you are saying in your text is that a heat pump cannot work. But indeed it does. Unless you have a different explanation on how a heat pump works ?

 

I say that if you pull the plug of a refrigerator, the air inside the refrigerator rises back to the outside temperature. A small portion of the air in contact outside the refrigerator might drop in temperature (due to the exchange), but that air is blown away and ultimately will rise back in temperature to the surrounding original temperature.

 

What you are saying goes against the heat pump...

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

[insane_alien]

we know what heat pumps are and how they work. just that the kender one is utter crap not only at pumping heat but its not trying to function as a heat pump but a way of generating electricity.

 

the stuff proposed on the website is rubbish.

[NuclearError]

I don't think it is rubbish. And I don't think you understand the working of a heat pump. For me it is a heat pump, a heat pump throwing out mechanical energy instead of heat...

[insane_alien]

i do know how heat pumps work, and i should do. i've designed a couple.

 

its complete crap for reasons already described in this thread. it would require thermodynamics to be thrown out of the window for it to work as claimed.

[Mr Skeptic]

It is not what, Mr. Skeptic ?

 

Not a heat pump ? What do you mean, there is no heat sink ?

 

That's right, it is not a heat engine because it has no heat sink.

 

When you create a cold, such as in a refrigerator, and you pull the plug of the refrigerator, keeping the door closed, what happens to the air inside the refrigerator ?

1. Does the outside air drop in temperature, to finally meet the temperature inside the refrigerator ?

2. Or does the air inside the refrigerator move up in temperature to finally reach the temperature of the surrounding air ?

 

Neither. The temperature both inside and outside will remain approximately unchanged. Note that their cycle time is supposed to be 0.22 seconds, so that is not much time. Note also that on part 2 of their cycle, there is no heat transfer stated so it is not a heat sink. At no part in their cycle do they transfer heat to the air, hence no heat sink.

 

What you are saying in your text is that a heat pump cannot work. But indeed it does. Unless you have a different explanation on how a heat pump works ?

 

A heat pump works just fine, as does a heat engine (they just function in reverse). Both have a section where there is heat transfer from the fluid and a section where heat is transferred to the fluid. I assume you can figure out what constraints that places on the temperature of the fluid at either of these points compared to the outside.

 

Look all you like, but you will find no mention of heat being transferred from the fluid of this supposed heat engine. Hence, a heated tube with a fan blowing a turbine, not a heat engine.

---

Merged post follows:

Consecutive posts merged

I don't think it is rubbish. And I don't think you understand the working of a heat pump. For me it is a heat pump, a heat pump throwing out mechanical energy instead of heat...

 

A heat pump that violates the second law of thermodynamics? Those don't exist. It's always funny when someone who has no clue about what they are talking about accuses knowledgeable people of the same.

[SH3RL0CK]

My understanding is that the stored energy present in the atmosphere is huge, as it would take a huge amount of energy to heat the same quantity of air as contained in Earth atmosphere from 0K up to the average air temperature (293K?).

 

Thus, a device that could hypothetically extract heat from the Earth atmosphere and produce electricity from it would not need to bypass the law of conservation of energy to be able to produce massive amounts of electricity before running out of "fuel", ie when outside air temperature would be so low (below -70C according to Kender home page) that it wouldn't work properly any longer.

 

Indeed, there are geothermal heat pumps which create energy. But as previously and repeatedly stated by others, where is your heat sink? There is none. You cannot generate electricity without moving the heat somehow to harness the temperature difference. Of course you could consume electricity by shuffling heat around and making a temperature difference, but that isn't what has been claimed and isn't newsworthy at all.

 

There are many, many various other problems with this idea. Helium is almost the worst possible choice (efficiency wise) for a refrigerant. The solar power is clearly insufficient. The apparatus inserts various inefficient processes for no apparent reason. And on and on...

 

I'm starting to believe some of the proponents of this idea here are simply trolling...

Edited December 2, 2009 by SH3RL0CK

[NuclearError]

You say that is has no heat sink ? How can you say that ?

 

In a heat engine, you have a hot source (say 500 K, inside) and a cold sink (293K, outside). This temperature differential allows for mechanical energy. Mechanical energy makes electrical energy. Here you have 210K in differential, therefore you can extract mechanical energy.

 

I see 2 different temperatures in the Kender engine. One is at 293 K (outside) and one is at 60K (inside). A temperature differential means that you can extract mechanical energy. This is what you have here also. Call one temperature the sink and one the source, it is the same. You have a differential in temperature, therefore you can get mechanical energy.

 

I don't see how you can say that there is no source and sink.

---

Merged post follows:

Consecutive posts merged

Your justification for the Kender engine not to work is that "you" don't see the source and the sink. That is not a lot of an argument. I say that there "is" a temperature differential. Therefore a source and a sink. And therefore mechanical energy.

[SH3RL0CK]

You say that is has no heat sink ? How can you say that ?

...

 

I see 2 different temperatures in the Kender engine. One is at 293 K (outside) and one is at 60K (inside). ...

 

Ok. lets call the 60K part your heat sink. How exactly do you get 60K without using a lot of energy? Haven't you just spend a very considerable amount of energy (in an inefficient process, b.t.w.) to get a heat sink? And now it is proposed that bringing this heat sink up to 273K is going to produce more energy than it took (in an inefficient process, b.t.w.) to create it in the first place?

 

I think you really need to look at the whole picture here, not just a small part...

Edited December 2, 2009 by SH3RL0CK

[NuclearError]

It takes much less energy to create a temperature differential going downwards (say 293K to 60K) than going upwards (say 293K to 526K). I have to go back to my formulas to show you the difference. I don't have them with me right now. But I will get these when I get back soon.

[insane_alien]

actually, its harder to go down than up. this is why we got good at making really hot things faster than really cold things.

 

your sink is not at 60K because there is no heat transfer there. you're just giving your compressor more work to do.