“The meaning of \"yong\" in exergy
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I have a question: “Fire function” is a state function; it consists of the character for fire followed by the character for \"use\" – what does this mean? Could you explain it in more detail? Where can it be used?
There is a detailed explanation in physical chemistry; it refers to free energy
It is mentioned in books on chemical thermodynamics; it refers to useful work
The formula I found is E=H-H*-T*(S-S*), and I want to understand its specific physical and chemical meaning.
Useful energy, useful work: A system possesses a certain amount of energy at a given state. When the system state changes, some energy is released in the form of work or heat; depending on the process the system undergoes, its capacity to do work also varies. Therefore, the energy of the system depends both on the initial and final states as well as on the process undergone. If one wants to compare the functional capabilities of two systems, it is necessary to specify that they have the same final state and undergo the same process. Thermodynamically, it is generally stipulated that the final state corresponds to the environmental conditions (T0, p0), and the process undergone is completely reversible. In this way, the work capacity of the resulting system is the maximum available energy when the system’s state changes. It should be noted that the environmental state (T0, p0) is thermodynamically referred to as the ground state or thermodynamic dead state. In this state, the system usually no longer has the ability to function. In summary, in order to measure the availability of energy or compare the amount of energy that can be used for work in different states, the concept of \"useful energy\" was defined. The effective energy of a system in a certain state is the ideal work done by the system as it changes from that state to the ground state. Expressed as Ex. This concept was first proposed by Keenen; it is referred to as Available Energy in foreign textbooks, and it is also called “exergy” in China.
The use of (effective energy) is a concept from the second law of thermodynamics, introduced to determine the maximum capacity of a system to perform work when it is in a certain state. The amount of yong contained in a unit of energy is called the energy level (or concentration). Theoretically, energy that can be completely converted into work has an energy level of 1, while energy that cannot be converted into work at all has an energy level of 0. Forms of energy include: kinetic energy, potential energy, mechanical energy, chemical energy, etc.