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Latent Power Turbines and black swans


Until 1697, when the Dutch explorer Willem de Vlamingh discovered black swans in Australia, Europeans believed that all swans were white.

The philosopher Karl Popper used this discovery to support his argument that just because all of the evidence we can find supports a theory, this does not prove that the theory is absolutely correct. At some date in the future, we may find a new piece of evidence that contradicts the theory.

But engineers and scientists can't live their professional lives in constant doubt. So if a theory works for us time and again, we are quite entitled to use it.

The laws of thermodynamics fall into this category and have never let us down.[The author of this article has full confidence in them.]

The textbooks teach us that an inevitable consequence of these laws is that it is impossible to build a heat engine that converts heat into electricity with 100% efficiency. [And the author also agrees with this.]

The diagram below sums up this teaching.

Figure 1. All heat engines, including those found inside Latent Power Turbines are wasteful. In fact the heat engine inside an LP Turbine is particularly inefficient, because it only converts about 2% of the heat into electricity.


Now this is where it gets interesting.

Latent Power Turbines can run on very low grade heat, including heat extracted from the atmosphere and oceans. The standard textbook teaching is that this claim defies the second law of thermodynamics because heat engines must always reject some heat into a colder reservoir.

But we need to be careful here, because in addition to accepting the wisdom of the laws of thermodynamics, several additional a priori assumptions have crept into the heat engine teaching.
The textbooks assume that:

(i) In order to serve a useful purpose, heat engines must run hot,
(ii) If a compressible working fluid is involved (steam or gas), it has to expand from high to low pressure to create the kinetic energy required to drive the turbine (or do other useful work),
(iii) Recycling the rejected heat is futile because this involves re-compressing the working fluid. - And doing work to compress the fluid would consume all of the useful energy produced.

These assumptions are valid for all the important heat engines that have built over the last 300 years. But listing all known examples does not provide irrefutable proof that they are necessary.

Karl Popper’s white and black swan argument cautions us to keep an open mind.

Latent Power Turbines are ‘black swans’ that contradict the textbook assumptions

Figure 2. Latent Power Turbines contradict three textbook assumptions about how efficient turbo-generator type heat engines should work.

By placing the heat engine inside the throat of a Venturi heat pump and using the pump to extract heat from the atmosphere, the heat engine is forced to run cool, at temperatures below ambient.

[A Venturi is a tube that tapers and then broadens out again in the manner of an hour glass. The throat is the narrowest section of the taper.]

Therefore, in accordance with the second law of thermodynamics, heat must flow from the environment into the heat pump. This heat offsets most of the work done by the heat engine, with some expansion from high to low pressure still being needed to keep the working fluid moving. The Carnot efficiency of such an engine is very low (approximately 2%), but by using a closed loop heat pump the rejected heat is recycled indefinitely. In principle, this means that our ‘black swan’ can extract heat from the air anywhere on the planet and convert it into electricity. In warm environments this air cooling offers free air conditioning as a bonus.

Figure 3. The internal heat engine satisfies the second law of thermodynamics, as illustrated in Figure 1. But because it runs at a lower temperature than the air in the laboratory, it can also draw in heat from the laboratory air, to help offset the electricity output.

This arrangement creates the illusion that the outer mechanical engine used to drive the working air round the system is a physically impossible heat engine that defies the second law of thermodynamics.



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