Isolated cold hole

[VincentG]

Imagine air conditioning a building. The ambient heat within the building is the hot side and the evaporator is the cold side, all within the building.

The "waste heat" from the room is sinking to the evaporator, as it would anyway, but if ambient heat is converted to work, the load on the air conditioner is reduced.

Further, now we have work output to generate electricity and feed back into the air conditioner, or whatever floats your boat.

[Fool]

No. :)

[VincentG]

Is that your final answer?


Btw, don't think I'm proposing self sustainability. Just higher overall efficiency.

[Fool]

The second law of thermodynamics states heat spontaneously flows from hot to less hot, and to force it to go the other way requires input of work energy. Most heat pumps are quite a bit lower than predicted Carnot efficiency. Probably close to half. There is room for improvement. When combining heat pumps with Stirling engines the real world factors compound to make the processes more inefficient.

Cooling a building to 68 F, 20 C, 293 K, Tc by pumping heat out to 104 F, and 40 C, 313 K, Th, would ultimately have a Carnot COP of 14.65 . Yes that's 1465%.

A real Stirling cooler would have to run at a lower Tc and higher Th. Say 280 K and 320 K. That extra is needed to get effective cooling per time and power. It reduces the COP to 7, or about half.

To run a Stirling engine to produce power it would have a maximum Efficiency of (293-280)/293=0.0444, or 4.44%. A real engine running on those two temperatures will more likely have an efficiency of 2%. This would mean, depending on engine, return a lot of heat back to the room on top of only supplying 2% of the power. Probably well in excess of the 2.44 percent difference.

In other words it will make it slightly worse. To investigate this look for the specifications for heat pumps and Stirling Engines. Be sure to compare the operating temperatures. If you find ones cheap enough, buy them and interconnect them for a test.

Stirling Engines appear to have a lot of room for improvement, and, as is, plenty of places they may help. Such as home remote power by homemade versions of them. We are here to explore those engines, not likely that we will solve the planet wide power crisis looming in our future. If we succeed we just might help reduce that crisis a little bit.

[VincentG]

To run a Stirling engine to produce power it would have a maximum Efficiency of (293-280)/293=0.0444, or 4.44%. A real engine running on those two temperatures will more likely have an efficiency of 2%. This would mean, depending on engine, return a lot of heat back to the room on top of only supplying 2% of the power. Probably well in excess of the 2.44 percent difference.

I think you are missing the point. The low efficiency of the Stirling cycle is exactly the point here.

The Tmin would be more like 30F(temp of evaporator) and the Tmax would be the warmest section of the room closer to 80F.

Heat will flow into the evaporator anyway, we are not trying to reverse the flow of heat, nor cool the building entirely through a Stirling engine.

How will the heat be returned to the room if the work is exported out of the room, including the working buffer pressure?

[Tom Booth]

Imagine air conditioning a building. The ambient heat within the building is the hot side and the evaporator is the cold side, all within the building.

The "waste heat" from the room is sinking to the evaporator, as it would anyway, but if ambient heat is converted to work, the load on the air conditioner is reduced.

Further, now we have work output to generate electricity and feed back into the air conditioner, or whatever floats your boat.

Sounds like a plan to me.

But why not also have another engine outside the building running between the condenser and the outside ambient as well?

[VincentG]

Because impeding the heat flow at the condenser would decrease system efficiency.

I don't think it works both ways here.

[Tom Booth]

I mean, by converting some of the heat in the room to work before it reaches the exploratory you are reducing the load on the air conditioner

AND

By converting some of the heat at the condenser to work you are also taking the heat away from the condenser which also assists the air conditioner.

So you have two heat engines running and the load on the air conditioning system is reduced by both.

Because impeding the heat flow at the condenser would decrease system efficiency.

I don't think it works both ways here.

You aren't impeding the heat flow, you're augmenting it.

What the engine doesn't use you just discard in the usual way (with a smaller fan since there is less heat left over to be removed)

If the engine isn't removing enough heat fast enough use a bigger engine!

Typically the compressor discharge temperature approaches 200°F then there is tubing going between the compressor and condenser.

That hot transfer tubing could run a Stirling engine then proceed on to the condenser.

[Tom Booth]

But basically, imagine the condenser coil inside the bottom (hot) section of a large LTD engine.

The displacer wafting air across the coils serves as the "fan" to cool the condenser coils.

In effect the engine IS the condenser, but instead of discarding the heat it converts the heat into useful work output

I don't really see any need for an additional condenser, but there could always be one in case the engine doesn't remove enough heat fast enough for some reason. But probably an improved design would eliminate the need for that, at least most of the time.

(The "fool" pulls out his hair screaming No!!!! No no!)

[Tom Booth]

I mean, by converting some of the heat in the room to work before it reaches the exploratory ...

exploratory?

Sorry, I forgot to check my auto-correct LOL

Should be evaporator of course

I just love the way technology turns a simple typo into something completely ridiculous.

[VincentG]

If the engine isn't removing enough heat fast enough use a bigger engine!

Thats true lol. But it's challenging enough to get my point across already.

It was said that heat is converted to work, but Fool is now saying that won't reduce the load on the evaporator.

I'm just attempting to get to the bottom of all this.

[Tom Booth]

If the engine isn't removing enough heat fast enough use a bigger engine!

Thats true lol. But it's challenging enough to get my point across already.

It was said that heat is converted to work, but Fool is now saying that won't reduce the load on the evaporator.
...

Yes, well fool says a lot of foolish things.

He's talking above about "Stirling cooler". Who's talking about a Stirling cooler?

Did you say anything about a Stirling cooler in your proposal?

He's talking about the heat engine putting heat back into the room?

Never mind that he's using what I consider "obsolete" mathematics, making repeated reference to the Carnot efficiency calculations, which are crap through and through.

He doesn't understand that an LTD Stirling is not "inefficient" because it can operate on a lower ∆T, in reality is generally MORE efficient than a high temperature Stirling. It takes in and utilizes more heat due to increased surface area.

Fool is living in the 1800's Carnot water wheel world.

Personally I think he KNOWS your idea would work and he is getting paid to derail and sabotage such discussions. It's his JOB.

Here is an interesting post:

The system proposed is entirely workable and would provide "Free Energy" from the environment until the end of the World as we know it.
The Oil companies do not want you to know this and so post disinformation about free energy.

https://www.stirlingengine.com/forums/v ... b1af#p3031

[Fool]

Please could you draw a block diagram and heat flow chart of what you are proposing. I could guess. There are a lot of possibilities. You now have my attention and I'm thinking about it.

It just seems that the Stirling Engine will cover over an area of the evaporator that is at 30 F and replace it with a hot plate that is at 80F. Or 68 F. The lower that temperature Th is, the less work the engine will produce. The higher the temperature is the more it blocks the evaporator.

In other words if the hot plate is at 30 F and the cold plate is 30 F, the evaporator is not blocked, but the engine does zero work. And has zero efficiency.

Any temperature higher than 30 F will block the heat by the same amount or more than the energy generated.

You might be able to find a happy medium where you supply 2% of the power and reduce the coolers effectiveness by 2%. The way to tell that is by the specifications.

It just sounds like you are trying to get energy by pumping heat to the hot outdoors. If it blocks it outdoors, it would block it indoors, wouldn't it? Rule of machines in series, so to speak.

[Tom Booth]

...

It just seems that the Stirling Engine will cover over an area of the evaporator that is at 30 F and replace it with a hot plate that is at 80F. Or 68 F. The lower that temperature Th is, the less work the engine will produce. The higher the temperature is the more it blocks the evaporator.

You don't seem to comprehend (as usual) that between the hot plate at room temperature 80° or whatever, and the cold plate at the evaporator, the heat from the 80° side is being taken away by being CONVERTED to work.

That converted heat never reaches the evaporator, so the air conditioner has that much LESS heat it needs to remove, so has less work to do moving whatever little heat might be left over, if any

In other words if the hot plate is at 30 F and the cold plate is 30 F, the evaporator is not blocked, but the engine does zero work. And has zero efficiency.

What are you talking about? The hot plate is at room temperature

Any temperature higher than 30 F will block the heat by the same amount or more than the energy generated.

The heat is not "blocked". The heat is taken out of the equation by the engine., by CONVERTING the heat into work.

Where heat is converted to work, the result is a drop in temperature.

You might be able to find a happy medium where you supply 2% of the power and reduce the coolers effectiveness by 2%. The way to tell that is by the specifications.

It just sounds like you are trying to get energy by pumping heat to the hot outdoors. If it blocks it outdoors, it would block it indoors, wouldn't it? Rule of machines in series, so to speak.

Your reasoning, and apparently your understanding of air conditioning is so muddled and confused who could hope to untangle your mental derangement?

It just sounds like you are trying to get energy by pumping heat to the hot outdoors.

No, you get energy, or save energy by NOT pumping the heat outdoors.

Instead of pumping it out you are converting it.

But you have a mental block. You still think heat is conserved as in the caloric theory.

If that were true, (caloric theory) then you would be "trying to get energy by pumping heat to the hot outdoors". But it is not true

Heat is ENERGY. As such it can be CONVERTED. In the process "heat" disappears, leaving behind "cold" and "WORK" appears in its place

But I don't think the "fool" will ever manage to wrap his head around that concept, for some reason. It's just incomprehensible and gives him a headache trying to think about it.

[Fool]

You don't seem to comprehend (as usual) that between the hot plate at room temperature 80° or whatever, and the cold plate at the evaporator, the heat from the 80° side is being taken away by being CONVERTED to work.

How much is an 80 degree hot plate going to cool an 80 degree room? Zero. It takes a temperature difference.

How much is a temperature difference going to reduce power converted and efficiency? The room will not be cooled as fast as long as the hot plate is above the temperature of the cooler evaporator.