Can thermodynamic modeling be called as a more idealistic and preliminary stage than the thermal modeling? Though assumptions exist in both the modeling, what exactly distinguishes the both?
I think thermal modelling comes under Thermodynamic modelling. However, Thermodynamic simulations are not limited to the thermal modelling. It also includes the velocity, pressure, internal energy and other thermophysical parameters of the fluid/system under observation.
Hi Hakeem,
Thermodynamic modeling implies that you are examining or calculating different properties of a system under equilibrium conditions. Thermal modeling by contrast is not necessarily in equilibrium and as a matter of fact is in most cases out of equilibrium as there would typically exist thermal gradients to drive heat transfer in the system. I hope this helps.
Hi,
Thermodynamic deals with heat and other forms of energy
thermal modelling is used to establish the heating or cooling
Thermodynamics helps in describing the 'state' of the system in terms of parameters like temperature, pressure etc. and also how energy interactions (e.g. heat, work) affect the state. As pointed out above, while performing thermodynamic analysis, normally we deal with systems in equilibrium and quasi-static processes (though there does exist the more advanced domain of non-equilibrium thermodynamics). This gives us the end-states, but does not describe the time it takes for this transition. The mode of heat or work transfer is also immaterial - whether the heat transfer is by conduction/convection or work by expansion work/electric does not affect the results. These can however be accounted for in a thermal analysis. Thus we have concepts like the rate of heating, mode of heating etc. in thermal analysis. In a sense, thermodynamic analysis helps in determining the end states (say states 1 and 2) and thermal analysis fills in the gap by determining details of this transition from point 1 to 2, which usually does not occur by an equilibrium path.
I will agree with the answer given by Adib Shamin above. However, it is not necessary that you have to always resort to equilibrium thermodynamics. There is a well developed subject of non-equilibrium thermodynamics with associated concept of negentropy. I
All engin n in recent years while studying Rayleigh-Taylor instability in an isolated box, that the entropy of the system fluctuates, i.e., entropy is not a monotonic increasing function. Some reviewers found it "stressful" to accept it that entropy can decrease during instability - as has been pointed out earlier by Prigogine. Many engineers/ scientists are not familiar with this, due to their over-dependence on concepts learnt for equilibrium thermodynamics.
Thus I will think thermal analysis is generic and should be practiced by engineers. Equilibrium thermodynamics is pedagogic and should used with extreme care.
Comparison of New and Old Thermodynamics
1. Logic of the Second Law of Thermodynamics: Subjectivism, Logical Jump, Interdisciplinary Argumentation.
2. New thermodynamics pursues universality, two theoretical cornerstones:
2.1 Boltzmann formula: ro=A*exp(-Mgh/RT) - Isotope centrifugal separation experiments show that it is suitable for gases and liquids.
2.2. Hydrostatic equilibrium: applicable to gases and liquids.
3. The second and third sonic virial coefficients of R143a derived from the new thermodynamics are in agreement with the experimental results.
3.1. The third velocity Virial coefficient derived is in agreement with the experimental data, which shows that the theory is still correct when the critical density is reached.
4. See Appendix Pictures and Documents for details.
1，The second law of thermodynamics is incorrect. See figure below for details.
2，The system is isothermal and exchanges heat with a large heat source to keep the temperature constant. Only volume changes are discussed.
3，The problem here is that the actual system is balanced and the second law of thermodynamics judges it to be unbalanced.
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