Yeah it is probably way smaller to be able to generate some power for you. This smallest engine ever to be based on the Carnot cycle has been finally been shaped into reality two years after it was first conceptualized in the Physical Review Letters in 2014. In the paper, the authors discussed that a new nano engine able to operate on the Carnot cycle at the molecular level could be on the cards. Its efficiency was also touted to be significantly higher than the conventional Carnot cycle we are taught about in Thermodynamics 101. In a world where engines are still as lousy and huge as they are essential, this nano engine stirred quite a bit of interest from peer circles that led to this eventual build.
First we need to revisit the Carnot cycle and understand its principles as a light reminder. The Carnot cycle is an ideal thermodynamic engine in which efficiency is calculated by the Work output divided by the total number of heat input into the system. A heat engine uses the concept of the Carnot cycle to generate cyclic mechanical power for us. Here the heat is added by the combustion of fossil fuels including large amounts of molecules getting burned and producing power.
Now this nano engine is nothing like any engine that you have ever seen. It uses a Linear Paul Trap as shown in the diagram below to work with a single negatively charged Calcium atom. The Calcium atom normally produces a Cation (Ca+2) but for this nano engine, we reverse that and use it as an anion. When the atom is placed inside the trap as shown below, it is introduced to a large electrostatic force from the negative side. A Laser acts as a hot reservoir and accelerates the atom towards the negative field. The two negatives repel each other and therefore, heat energy is induced in the atom and propels it to the larger side of the engine. Afterwards, the atom is cooled through Doppler cooling with the help of another Laser which is infact, the cold reservoir of the system and brings it back to the original position. In this engine, the atom essentially is the engine and the fuel itself. The resulting cycle also makes it vibrate incredibly strongly just like any engine would do.
Although the whole engine seems pointless, it is not so in the eyes of the researchers as they have already thought of what to do next. Roßnagel puts it like this “if you imagine that you put a second ion by the cooler side, it could absorb the mechanical energy of our engine, much like a flywheel [in a car engine],” therefore harnessing the energy from the engine. It is also devoid of the Carnot’s limitation that limits the efficiency of Carnot’s conventional applications. Here it exceeds by more than a factor of two so it could spell a bright future for the engines. The increase in efficiency is caused by the atom’s varying size during different stages of the thermodynamic cycle. This size variation allows it to behave like a supercharger of sorts in which the efficiency is increased by letting more pressurized fuel into the engine.
As a result of this remarkable development, the nano engine was able to generate a power of 3.4 × 10 ^-22 joules per second, which is is quite a lot considering the mass of one Calcium atom is 6.3 x 10^-23 grams. Amazing, huh?
But just to be sure, the engine never breaks any thermodynamic law nor it will ever. Many students are confused with the laws and believe they can be bypassed or fooled around with to make better efficiency engines but that is simply not the case here. It is just an engine that changes shapes during operation and that gives it an edge that means more power according to the very own thermodynamic cycles that it is based on. The Laws of Thermodynamics are like Gravity and Nuclear forces. They are as real as they get and we can only look for loopholes to facilitate our end requirement but they are here to stay. We can’t do anything about it!