Scientists from the University of Zurich have come up with a very simple device which allows the flow of heat from a cold object to a warm one without the help of any external source of power. At first glance, it seems that the fundamental law of physics is violated here. The study has been published in the Science Advances journal.
We have always known that when we keep a hot object it gradually cools down. For example, if we keep a teapot containing hot water on a table, after some time the temperature will cool down to that of the table, it would not fall farther. This is a demonstration of the second law of thermodynamics, which states that entropy of a closed system always increases. That means heat flows from a hot to a cold object, not the other way.
However, apparently, the results of the experiment conducted by Andreas Schilling, professor of Physics at the University of Zurich appears to violate the second law of thermodynamics. Researchers were able to cool the temperature of a piece of copper weighing nine grams from more than 100 degrees to much below than the room temperature without using any additional power source. Schilling says that a theoretical model of the device can transform boiling water into ice without using any amount of energy.
For getting this result, scientists used the Peltier element, which is normally used for cooling minibars. The element can act as a heat pump and transfer heat from one side to another with the help of electric current, depending on its direction. It has been previously used in experiments such as in electrical inductor for developing an oscillating heat current which keeps on changing direction. Heat flows from a cold to a hot object hence the temperature of the colder object further goes down.
Researchers have demonstrated that thermal oscillating circuit can also work in a passive manner. Without any external power supply, the flow of heat took place from a cold copper piece to a warm heat bath of temperature 22 degrees, without any transformation to other forms of energy. It did not violate the law of thermodynamics as it was shown that entropy of the entire system increased with time.
As the commercial Peltier was used, the temperature difference of only 2 degrees was recorded compared to the ambient temperature. Scientists claim that if the ideal Peltier (yet to discovered) could be used, cooling up to -47 degrees is possible. For a larger scale application, the efficiency of Peltier elements has to be increased.