Ambient heat engine

[Philip Hardcastle]

What are the hurdles that have been flogged to death?

The idea that heat pumps and heat engines can ever defeat the Carnot limit, and so as Pomodoro points out you will not scavenge free energy from ambient using such technology. Whilst home heat pumps can achieve exceptional heating efficiency yielding, say 4kW of heat output for 1kW of electrical input, the heat so scavenged from ambient is insufficient if used in a perfect heat engine (say a Stirling), to produce 1kW of electrical output so required to make a closed loop perpetual motion scheme.


This is a fact and despite 1,000s of amateurs hoping otherwise, it remains the issue that has been flogged to death for 150+ years.

[Bronepoezd]

Hello! The use of low-grade heat and transfer it into electricity is a reality today. I have developed a pattern, working on phase transition and generating 0.085 Watts of power. The device environmentally friendly and can be operated for a long time. This is only the beginning.
Here is a link to the video: https://www.youtube.com/watch?v=0rPQvTyXxqA&t=4s

[memoryman]

"The idea that heat pumps and heat engines can ever defeat the Carnot limit" think creatively and you may see something else...

[sm0ky2]

a more economical approach, if one has two reservoirs, a source of heat, and a source of cold.
would be to use the interface between the two, creating an impedance of some sort to negotiate the transfer of energy.
the heat will naturally migrate to the cold heating up the cold region in an attempt to balance out the difference.

for instance, the peltier/seedbeck effects could be used to draw usable electricity from an insulating wall.
this could provide more usable energy then the carnot cycle, but lets look at a sterling engine placed at the same interface.
approx. 50% of the potential difference in heat energy could be used as mechanical power.
by allowing the heat transfer to occur in a natural (but controlled) manner.

let's say it were hot outside, and cold at a level just under the ground.
a house in the middle could generate usable energy by maintaining a temperature somewhere in the middle.
when the inside gets too hot, generate energy by transferring the heat into the ground, when the house gets too cold
generate energy by transferring the outside heat to the inside.

a well designed heat pump will circulate fluids on it's own when there is a temperature difference.
generally such systems are implemented with a method of collecting the heat, such as a solar-thermal reflector.
but they work on their own just as well.

heat on one side of the system creates a pressure difference and the fluid circulates to balance this out.
flow control valves can adjust the rate of heat transfer, by controlling the fluid rate through the radiators.

the difference in pressure is directly related to the difference in temperature, therefore, usable energy can be taken from the interface.
in a metallic junction a similar thing can occur at the electrical interface.

you have to think in terms of potential difference,
place your house (or whatever you want to climate control) in-between the two temperature reservoirs.
the efficiency of energy conversion is extra on top of the free climate control. so whatever the % is, its' free (or renewable) energy.

[sm0ky2]

here is a drawing of two sterling engines.
what some of you may not know, is the sterling engine not only runs on Heat,
but can also run on "cold".
meaning, the engine can transfer heat from the ambient to a cold source.

The operation of a sterling engine, from hot to cold, or cold to hot
depends on the location of the Displacer. (Yellow on the picture)

In the top example, heat applied to the Heat Exchanger (Grey)
  causes the working fluid to expand, actuating the piston.
the displacer on the cold side allows for decompression and cooling of the gasses in the chamber.
this lowers the pressure on the hot side and draws the piston back, compressing the fluid and the cycle starts over.

In the bottom example, cold applied to the Heat Exchanger lowers the pressure on the Cold side, causing more pressure on the Hot side.
actuating the piston towards the cold side, actuating the displacer so the fluid does not compress and heat up.
this lowers the pressure on the hot side, drawing the piston back the other way, compressing the hot-side fluid and the cycle starts over.
in this manner, the engine absorbs heat from the surrounding air and transfers it to the cold source.

in both examples, usable work is being drawn from the temperature imbalance.

using both types of sterling engine at the interface between Hot and Cold reservoirs, respectively
allows for a central 'buffer', or middle-point between the two temperatures.
the total power is the same, because change in T = 1/2 for both engines.
increasing or decreasing the rate of heat transfer (RPM) on either engine, allows you to control the temperature of the buffer zone.
This zone could be your house, or your car... think of what we do now. we just use ambient heat from the car's engine, to heat ourselves inside.
we could be drawing off the potential between the cars engine and the outside temp. creating usable energy, maybe to power some of the car's electronics.