The first thing I did after receiving these kits from this supplier:
https://www.stirlinghobbyshop.com/
was to replace the steel bolts that came with the engine with nylon bolts, as steel conducts heat about 300X better than nylon and in these engines, heat conducted apart from the air inside the engine is energy lost, or waste heat.
The next project was to add the regenerative displacer with the steel wool inserted into holes cut in the displacer. The reason for that is an additional increase in efficiency.
An explanation of why that is can be found here: http://www.solarheatengines.com/2008/06/09/simple-stirling-1-performance-with-and-without-regenerator/
Briefly, by having the air in the engine pass through the steel wool, much of the "waste heat" is captured within the engine internally and then "reused" to heat the air in the engine over and over again rather than all of the "waste heat" going directly to the sink, In that way more of the heat is utilized and the engine runs more efficiently. The results can be seen in the previous video.
Normally, an engine of this kind operating on a cup of boiling hot water, in an 85 degree fahrenheit environment (as was the case in the following video), would have a "Carnot efficiency" efficiency of at the absolute best 18.9% according to the laws of thermodynamics.
That would mean, according to all the thermodynamics courses I've studied or viewed, that for every 1000 joules of heat introduced to the engine, 811 joules would have to be discharged through the ambient side of the engine to the environment.
To see if this was actually true for these engines, first I insulated the cold side of the engine without a regenerator. In theory, according to the laws of thermodynamics, the engine should not be able to operate at all without rejecting that 81.1 percent of waste heat to the environment, through the ambient side of the engine.
In operating the engine on boiling hot water, the "sink" did not actually feel warm to the touch at all. It felt about room temperature.
Ten years ago I had made a post on the Stirling Engine forum that I thought, from my observations of Stirling engines that:Quote It seemed to me that if the engines heat exchanger or "sink" was at room temperature, that could be because the engine just happened to cool the heated air inside down to exactly room temperature, OR, it could mean that the engine was refrigerating itself BELOW room temperature, or trying to, but that the ambient heat from the room was actually heating the engine and heat was flowing backward through the sink into the engine.
This pretty much goes against how heat engines are SUPPOSED to work, according to the so-called "Laws" of thermodynamics, but as far as I had been able to find, no one had ever conducted this simple test. It is just an assumption that the "sink" cools the engine rather than adding more heat.
If heat was flowing into the engine "in reverse" as I suspected it might be, then insulating the sink to prevent this infiltration of heat would allow the engine to reach a colder than ambient temperature and run more efficiently then when exposed directly to the ambient heat of the room.
Anyway, this is my first experiment with the engine's "heat sink" insulated:
https://youtu.be/fFByKkGr5bE
The engine was running at a steady 162 RPM before adding the final piece of insulation to completely cover the "sink".
After placing the insulation over the top of the engine the RPM increased to 180 RPM.
I repeated the experiment using the engine with the regenerator.
This time the engine speed increased from 270 RPM to 295 RPM.
Normally, when running on a finite heat source like a cup of hot water, the only way to increase the speed of the engine would be to cool the sink with an ice cube of something.
My conclusion is, that in spite of what is supposed to be true according to the "second law of thermodynamics", these engines are cooling down internally by adiabatic expansion of the air inside the engine, converting heat into mechanical motion or "work".
To find out objectively, if this is actually true, I've sent away for this four channel thermometer so that I can put some temperature probes under all that insulation and measure the temperature of the hot and cold side of the engine as well as the ambient room temperature.
https://www.stirlinghobbyshop.com/
was to replace the steel bolts that came with the engine with nylon bolts, as steel conducts heat about 300X better than nylon and in these engines, heat conducted apart from the air inside the engine is energy lost, or waste heat.
The next project was to add the regenerative displacer with the steel wool inserted into holes cut in the displacer. The reason for that is an additional increase in efficiency.
An explanation of why that is can be found here: http://www.solarheatengines.com/2008/06/09/simple-stirling-1-performance-with-and-without-regenerator/
Briefly, by having the air in the engine pass through the steel wool, much of the "waste heat" is captured within the engine internally and then "reused" to heat the air in the engine over and over again rather than all of the "waste heat" going directly to the sink, In that way more of the heat is utilized and the engine runs more efficiently. The results can be seen in the previous video.
Normally, an engine of this kind operating on a cup of boiling hot water, in an 85 degree fahrenheit environment (as was the case in the following video), would have a "Carnot efficiency" efficiency of at the absolute best 18.9% according to the laws of thermodynamics.
That would mean, according to all the thermodynamics courses I've studied or viewed, that for every 1000 joules of heat introduced to the engine, 811 joules would have to be discharged through the ambient side of the engine to the environment.
To see if this was actually true for these engines, first I insulated the cold side of the engine without a regenerator. In theory, according to the laws of thermodynamics, the engine should not be able to operate at all without rejecting that 81.1 percent of waste heat to the environment, through the ambient side of the engine.
In operating the engine on boiling hot water, the "sink" did not actually feel warm to the touch at all. It felt about room temperature.
Ten years ago I had made a post on the Stirling Engine forum that I thought, from my observations of Stirling engines that:
If more heat is extracted as work than what actually reaches the heat sink, then theoretically, insulating the cold end of the displacer chamber against the external ambient temperatures would improve engine efficiency.
https://stirlingengineforum.com/viewtopic.php?f=1&t=478
This pretty much goes against how heat engines are SUPPOSED to work, according to the so-called "Laws" of thermodynamics, but as far as I had been able to find, no one had ever conducted this simple test. It is just an assumption that the "sink" cools the engine rather than adding more heat.
If heat was flowing into the engine "in reverse" as I suspected it might be, then insulating the sink to prevent this infiltration of heat would allow the engine to reach a colder than ambient temperature and run more efficiently then when exposed directly to the ambient heat of the room.
Anyway, this is my first experiment with the engine's "heat sink" insulated:
https://youtu.be/fFByKkGr5bE
The engine was running at a steady 162 RPM before adding the final piece of insulation to completely cover the "sink".
After placing the insulation over the top of the engine the RPM increased to 180 RPM.
I repeated the experiment using the engine with the regenerator.
This time the engine speed increased from 270 RPM to 295 RPM.
Normally, when running on a finite heat source like a cup of hot water, the only way to increase the speed of the engine would be to cool the sink with an ice cube of something.
My conclusion is, that in spite of what is supposed to be true according to the "second law of thermodynamics", these engines are cooling down internally by adiabatic expansion of the air inside the engine, converting heat into mechanical motion or "work".
To find out objectively, if this is actually true, I've sent away for this four channel thermometer so that I can put some temperature probes under all that insulation and measure the temperature of the hot and cold side of the engine as well as the ambient room temperature.