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02 September 2014

Speculations, ventures and predictions on cold fusion

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Vai alla versione in italiano pubblicata il 20 Agosto 2014

People usually think at the hydrogen atom as a planetary system in which the electron is a satellite that revolves around the planet nucleus that in this particular case is constituted by a proton.
The description of the electron with a probability distribution obtained from the solution of the Schroedinger equation is a little less coarse and no doubt more complex.
For the 1s orbital of the hydrogen atom how much is the probability that the electron is inside the nucleus? Is it null or greater than zero?
It is small, very small, but it can not be null.
This means that there is a certain probability that the hydrogen nucleus (a proton) looks electrically neutral. May the impossible becomes possible?
The above applies to an isolated hydrogen atom.
What happens to the hydrogen in a metal matrix? What does the Schroedinger equation say?
Stuff to theoretical chemists (of the smart ones), supercomputers and long days of waiting.
Maybe one day in the future you might find the conditions that raise the probability of finding the electron within the nucleus.

08 December 2012

Information to the reader

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This blog collects the English translations of the posts published on the blog titled "Scienza Laterale". Since the Author does not know when new translations will be posted again, if you are interested in the matter, you can stay updated reading the Italian version. In the Italian blog, the Google traslation in your language is readily available by clicking on the control at the top/right position on the web page and choosing the desired language.

19 April 2012

The free piston Cayley engine - Episode 06

Vai alla versione in italiano pubblicata il 04 Febbraio 2012

In previous post we saw that the relationship between the hot piston surface and cold piston surface (Shot/Scold) determines efficiency and net work of the Cayley cycle.
Among other things we have found that pushing the ratio Shot/Scold to the value of the ratio Thot/Tcold, the yield approaches to the Carnot efficiency, but simultaneously the net work will reduce to zero.

Now let us see what happens when the hot temperature is varied keeping constant the ratio Shot/Scold, ie by changing the warm operating temperature on the same machine.

The following image shows some Cayley cycles at various temperatures for Shot/Scold equal to 1.5.

First we consider the extreme case in which Thot=450K.
In the image it corresponds to the red horizontal line.
This hot temperature match the ratio Thot/Tcold at the ratio Shot/Scold.
We have already seen that in this case the gas performs an isobaric process and the engine does not work.
If the ratio between the hot surface and the cold surface is equal to 1.5 and the cold temperature is 300K (about 27°C), the motor can operate only if the hot temperature exceeds 450K (about 177°C).

The other cycles in the figure show that over the 450K is present a real Cayley cycle.
From the graph it can be extrapolated that maximum and minimum pressure of the cycle depends on the hot temperature.
As the temperature rises, the maximum pressure increases, the minimum pressure decreases.

The image also highlights another very important thing.
The area of ​​the cycle (and therefore the net work) grows if the hot temperature increases: the specific power of the engine depends on the hot temperature.

Now that our ideas are a bit clearer about what happens to the power density by varying the hot temperature, we are ready to analyze what happen to the yield.

The image shows the efficiency and net work trend for hot temperature ranging from 450K, about 177°C (lower limit of operation), to 900K (about 627°C).

The graph shows that the yield is Thot independent (horizontal blue line).
In the Cayley cycle, the engine construction (ie the ratio between the hot surface and the cold surface) determines the yield.
This behavior appears as an anomaly in the context of the exothermic engines.
The following formula provides the relationship between yield and ratio between the surfaces

yield = 1 - ( Scold / Shot )

This relation in the case where

Shot/Scold = Thot/Tcold


yield = 1 - ( Tcold / Thot )

which is the Carnot efficiency formula.

Do not forget that the surface ratio is also limiting the minimum hot temperature for operating

Thot, minimum > Tcold * Shot / Scold

Conversely, if you are interested in a machine with a defined efficiency you can simply adjust the ratio between the surfaces on the value given by the following relation

Shot / Scold = 1 / ( 1 - yield )

For example, if you are interested in a machine with an efficiency of 20%, the ratio between hot surface and cold surface must be

Shot / Scold = 1 / ( 1 - 0,20 ) = 1 / 0,80 = 1,25

If the cold temperature is equal to 300K, the motor can run when the hot temperature exceeds the value of

Thot, minimum > Tcold * Shot / Scold = 300 K * 1,25 = 375 K

In proximity of this temperature the specific power will be low, but it can be increased by operating at higher Thot.

This post concludes the first part of the chapter devoted to the exothermic Cayley engine.
At a constructional level the more evident weak point of this engine is the need of the seal at the hot piston.
In the next post we will see how you can elegantly solve this problem while maintaining all the performance benefits achieved with the introduction of thermal regeneration.
Versions submitted so far are simple on paper but difficult to achieve in practice. Future proposals will have all the credentials to be built.