Energy Balance Formula Thermodynamics
They may be combined into what is known as fundamental thermodynamic relation which describes all of the changes of thermodynamic state functions of a system of uniform temperature and pressure.
Energy balance formula thermodynamics. The internal energy has changed from its level at instant 1 to another level at instant 2 after heat is applied. The thermodynamic terms thus representing the various forms of energy crossing the control boundary with the mass are given as m u pΞ½ ke pe. Accumulation of energy in system input of energy into system output of energy from system 6 now the total energy of a system as considered above is composed of kinetic potential and internal energies. Then the first law equation becomes like this.
The general energy balance for a process can be expressed in words as. The first law of thermodynamics for the closed system in differential form is du dq dw if the potential and kinetic energy are ignorable. Let us implement here the assumptions made above in order to secure the energy equation for throttling devices in quite simple terms. The internal energy u is a thermodynamic property.
Qq q u u u ce 12 q c is the quantity of heat absorbed by the fluid from the source and q e is the heat loss of the fluid to the environment. Where v1 and a1 are the velocity and area of cross section of stream respectively at section 1 1 of control volume system. H 1 h 2 where h 1 and h 2 are the enthalpy of the fluid at inlet and outlet respectively. So the enthalpy represents the energy of a material in transit so it is the summation of internal energy and the flow work.
Where π π΄π π is the mass flow rate conservation of energy 1st law. πππΆπΆ ππ π π ππ. The change in internal potential and kinetic energy of the system equals enthalpy goes in minus enthalpy goes out and delta q and w. Control volume mass flow across system boundaries conservation of mass.
This form of energy is referred to as flow energy pΞ½ work. And work is all the other forms of energy transferring. π πΏπΏ π π π. Heat is the energy transfer due to temperature difference.
Above equation of mass balance for a steady flow process is also termed as equation of continuity. Entropy balance 2nd law. The first and second law of thermodynamics are the most fundamental equations of thermodynamics.