Research groups at Keio University, the University of Tokyo, and Gakushuin University have discovered new fundamental limits that indicate "what can't be done" in the field of thermodynamics, which has a history of more than 200 years. "If you try to increase efficiency, the output per hour will inevitably decrease," he proved.
Thermodynamics is based on two "impossible" principles: the "first law of thermodynamics" that energy cannot be created from nothing, and the "second law of thermodynamics" that heat energy cannot be converted into 1% usable energy.The ratio of how much can be used is called "efficiency", and efficiency has an upper limit (Carnot ratio).In addition, how much energy a device that converts thermal energy such as a "heat engine" into kinetic and electrical energy can output per hour is called "power".
This time, the research group used the latest "non-equilibrium statistical physics" to derive a principle relational expression showing that the power inevitably decreases when the efficiency is increased for a general thermal engine.From this relational expression, it can be concluded that in order to increase the efficiency of the engine to the upper limit, the operating speed of the engine must be infinitely slowed down so that the available energy is scarcely obtained.The result is said to have negatively resolved the long-standing controversy "Is it possible to use a thermal engine that uses energy efficiently and obtains a lot of energy in a short time?"
This achievement will be the basis of a new theoretical system by knowing "impossible".Now that the effective use of energy resources is important, the principle limit between efficiency and power is expected to be useful as a standard for performance evaluation of thermal engines and a development guideline.
