Technology & Engineering
Fluid Internal Energy
Fluid internal energy refers to the energy stored within a fluid due to its molecular motion and intermolecular forces. It is a measure of the fluid's thermal energy and is related to its temperature. Understanding fluid internal energy is crucial in various engineering applications, such as in the design and operation of thermal systems, including heat exchangers and power plants.
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3 Key excerpts on "Fluid Internal Energy"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
Internal Energy In thermodynamics, the internal energy is the total energy contained by a thermo-dynamic system. It is the energy necessary to create the system, but excludes the energy to displace the system's surroundings, any energy associated with a move as a whole, or due to external force fields. Internal energy has two major components, kinetic energy and potential energy. The kinetic energy is due to the motion of the system's particles (translations, rotations, vibrations), and the potential energy is associated with the static constituents of matter, static electric energy of atoms within molecules or crystals, the static energy of chemical bonds. The internal energy of a system can be changed by heating the system or by doing work on it; the first law of thermodynamics states that the increase in internal energy is equal to the total heat added and work done. If the system is isolated, its internal energy cannot change. For practical considerations in thermodynamics or engineering it is rarely necessary, nor convenient, to consider all energies belonging to the total intrinsic energy of a sample system, such as the energy given by the equivalence of mass. Typically, descriptions only include components relevant to the system under study. Thermodynamics is chiefly concerned only with changes of the internal energy. The internal energy is a state function of a system, because its value depends only on the current state of the system and not on the path taken or process undergone to arrive at this state. It is an extensive quantity. The SI unit of energy is the joule. Sometimes physicists define a corresponding intensive thermodynamic property called specific internal energy , which is internal energy per a unit of mass of the system in question. As such, the SI unit of specific internal energy is J/kg. If intensive internal energy is expressed per amount of substance, then it is referred to as molar internal energy and the unit is J/mol.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Library Press(Publisher)
Internal Energy In thermodynamics, the internal energy is the total energy contained by a thermodynamic system. It is the energy necessary to create the system, but excludes the energy to displace the system's surroundings, any energy associated with a move as a whole, or due to external force fields. Internal energy has two major components, kinetic energy and potential energy. The kinetic energy is due to the motion of the system's particles (translations, rotations, vibrations), and the potential energy is associated with the static constituents of matter, static electric energy of atoms within molecules or crystals, the static energy of chemical bonds. The internal energy of a system can be changed by heating the system or by doing work on it; the first law of thermodynamics states that the increase in internal energy is equal to the total heat added and work done. If the system is isolated, its internal energy cannot change. For practical considerations in thermodynamics or engineering it is rarely necessary, nor convenient, to consider all energies belonging to the total intrinsic energy of a sample system, such as the energy given by the equivalence of mass. Typically, descriptions only include components relevant to the system under study. Thermodynamics is chiefly concerned only with changes of the internal energy. The internal energy is a state function of a system, because its value depends only on the current state of the system and not on the path taken or process undergone to arrive at this state. It is an extensive quantity. The SI unit of energy is the joule. Sometimes physicists define a corresponding intensive thermodynamic property called specific internal energy , which is internal energy per a unit of mass of the system in question. As such, the SI unit of specific internal energy is J/kg. If intensive internal energy is expressed per amount of substance, then it is referred to as molar internal energy and the unit is J/mol.
- Allan D. Kraus, James R. Welty, Abdul Aziz(Authors)
- 2011(Publication Date)
- CRC Press(Publisher)
37 38 Introduction to Thermal and Fluid Engineering FORMS OF ENERGY Kinetic Energy is the energy that a body possesses by virtue of its motion. Potential Energy is the energy that a body possesses by virtue of its position. Internal Energy is a characteristic property of the state of a thermo-dynamic system including the intrinsic energies of individual molecules, kinetic energies of internal motions, and contributions from interations between individual molecules. FIGURE 3.1 Forms of energy. The internal energy is treated as a macroscopic quantity even though it is composed of many microscopic energies resulting from the atomic and molecular structure. Having thus observed that mass is a conserved property, we next focus our attention on the forms of energy and a general conservation of energy principle known as the first law of thermodynamics . The forms of energy are summarized in Figure 3.1. 3.2 Kinetic, Potential, and Internal Energy Macroscopic kinetic energy, gravitational potential energy (most often referred to merely as “potential energy”), and microscopic internal energy are scalar properties and we ex-amine them in some detail in the subsections that follow. 3.2.1 Kinetic Energy In Newton’s second law, F = ma , the acceleration can be represented by a = d ˆ V dt = d ˆ V dx dx dt = ˆ V d ˆ V dx where x is the displacement and ˆ V is the velocity in the direction of the applied force, F . If this form of the acceleration is substituted into F = ma where the applied force is constant, the result is F = m ˆ V d ˆ V dx or, after separation of the variables Fdx = m ˆ Vd ˆ V Integration between x 1 , where the velocity is ˆ V 1 , and x 2 , where the velocity is ˆ V 2 , gives Fs = m 2 ( ˆ V 2 2 − ˆ V 2 1 ) Energy and the First Law of Thermodynamics 39 Datum Level z ˆ V FIGURE 3.2 A projectile that possesses kinetic energy by virtue of its velocity and potential energy by virtue of its elevation, z, above the datum level.
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