[Mechanical Equipment Technology Edition] Daily Question 20191118: Basics of Refrigeration – Refrigeration Pressure-Humidity Diagrams – Refrigeration Cycles (3)
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This post was last edited by Zhang Xinlin from Binglun Environment on 2019-11-21 at 00:05. [Daily Question] is divided into three sections: fundamentals of refrigeration, equipment selection options, and maintenance of refrigeration equipment. [Reward Rules] Those who comment on this post will receive 1–3 wealth points, while those who provide accurate answers will get 10–15 points; the rewards are valid for two days, and the answers will be announced after those two days. Fundamentals of Refrigeration section – Pressure-enthalpy diagram – Refrigeration cycle (3) I. Overview Question: What is the physical meaning of enthalpy? For a flowing fluid, enthalpy is equal to the work of flow plus internal energy. Enthalpy has an energy meaning; it represents the part of the total energy transferred by the flowing fluid in the direction of flow that is determined by its thermodynamic state. If the kinetic and potential energies of the working fluid are ignored, enthalpy represents the total energy transferred along with the flowing working fluid. ============================== High-quality promotion: Daily questions on mechanical equipment – refrigeration sector, covering its value and functions: https://bbs.hcbbs.com/thread-2848974-1-1.html. Internal training materials for manufacturers of screw refrigeration compressors related to mechanical equipment: https://bbs.hcbbs.com/thread-2850090-1-1.html
There is a simple formula that shows that the internal energy of a substance plus its kinetic energy equals its enthalpy
The physical meaning of enthalpy is a form of energy that is the thermodynamic energy in a system plus the PV energy. Enthalpy has the dimension of energy; when a certain mass of matter changes from one state to another through a reversible process at constant pressure, the increase in enthalpy is equal to the heat absorbed during this process. Enthalpy is defined as H=U+pV, where U is the internal energy of the substance, p is the pressure, and V is the volume. Enthalpy is a physical quantity related to internal energy; whether a reaction absorbs or releases heat under certain conditions is determined by the difference in enthalpy values between the products and reactants, that is, the enthalpy change (ΔH).
An energy in the system that is the thermodynamic energy plus this PV energy component
Enthalpy is a concept artificially defined to facilitate the description of energy changes in chemical reactions； For a constant-pressure system where H=U+pV, enthalpy is equal to the internal energy of the system plus the energy required to maintain its volume. The enthalpy change is equal to the release/absorption of internal energy in the system, plus the energy released/absorbed due to changes in the system’s volume
In thermodynamics, it is a state function that represents the energy of a material system, commonly denoted by the symbol H. Numerically, it is equal to the system’s internal energy U plus the product of pressure p and volume V, that is, H=U+pV. The change in enthalpy is a measure of the heat absorbed by a system during a reversible process at constant pressure.
An energy in the system that is the thermodynamic energy plus this PV energy component
The physical meaning of enthalpy should be that when a working substance enters a thermodynamic system through a certain interface, it not only brings in the internal energy u stored within it, but also the work pv obtained from being pushed into the system.
The physical meaning of enthalpy should be that when a working substance enters a thermodynamic system through a certain interface, it not only brings in the internal energy u stored within it, but also the work pv obtained from being pushed into the system
This post was last edited by “Hasty Passerby” on 2019-11-18 at 21:42. The physical meaning of enthalpy is a form of energy that represents the sum of the thermodynamic energy within a system and the PV term. Enthalpy has the dimension of energy; when a certain mass of matter changes from one state to another through a reversible process at constant pressure, the increase in enthalpy is equal to the heat absorbed during this process. Enthalpy is defined as H=U+pV, where U is the internal energy of the substance, p is the pressure, and V is the volume. Enthalpy is a physical quantity related to internal energy; whether a reaction absorbs or releases heat under certain conditions is determined by the difference in enthalpy values between the products and reactants, that is, the enthalpy change (ΔH).
Enthalpy is a concept artificially defined to facilitate the description of energy changes in chemical reactions； For a constant-pressure system where H=U+pV, enthalpy is equal to the internal energy of the system plus the energy required to maintain its volume. The enthalpy change is equal to the release/absorption of internal energy in the system, plus the energy released/absorbed due to changes in the system’s volume