The mathematical expression of the first law of thermodynamics is:
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Among them, q is the energy exchange form caused by the temperature difference between the system and the environment; △U is the change value of the internal energy of the system; A is the work exchanged between the system and the environment, and the work in thermodynamics includes volume work and non-volume work (such as surface work and electric work). It can be seen from the formula (4. 1) that all the heat energy obtained by the system from external exchange is converted into internal energy except the work done by the system when exchanging energy with the outside. The essence of the first law of thermodynamics is that no matter whether energy is transferred from one object to another or from one form to another, its total amount remains unchanged, which is the law of energy conservation (and energy transformation).
The mathematical expression of the second law of thermodynamics is:
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Where: η is the effective working coefficient; Q 1 total calorific value provided for high-temperature heat source; Q 1-Q2 is the heat value that can be successfully converted in the heat exchange process; T 1 and T2 are the initial absolute temperatures of high temperature objects and low temperature objects, respectively. The essence of the second law of thermodynamics is that all functions are converted into heat, but not all heat can be successfully converted. In the field of geochemical research, the second law of thermodynamics and its derived formulas for calculating various thermodynamic parameters are widely used.