Leakage Evaluation by Virtual Entropy Generation (VEG) Method

Abstract

Leakage through microscale or nanoscale cracks is usually hard to observe, difficult to control, and causes significant economic loss. In the present research, the leakage in a pipe was evaluated by the virtual entropy generation (VEG) method. In virtual entropy generation method, the "measured entropy generation" is forced to follow the "experimental second law of thermodynamics". Taking the leakage as the source virtual entropy generation, a new pipe leakage evaluation criterion was analytically derived, which indicates that the mass leakage rate should be smaller than the pressure drop rate inside a pipe. A numerical study based on computational fluid dynamics showed the existence of an unrealistic virtual entropy generation at a high mass leakage rate. Finally, the new criterion was used in the evaluation of leakage available in the literature. These results could be useful for leakage control or industry criteria design in the future.

New Method Proving Clausius Inequality

“…, where, ΔS g is called the entropy generation [9] [10] [11]. In a spontaneous or realistic process, we can gain 0 g S ∆ ≥ .…”

Non-Equilibrium Thermodynamics of Micro Technologies

“…This special issue consists of nine articles that report on investigations dealing with heat and mass transfer and thermodynamic analysis of thermofluidic systems [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. Most of these investigations are analytic or numerical [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. Two of the investigations include experiments [ 36 , 39 ].…”

“…Other areas that have been explored include the analysis and optimization of microreactors [ 33 ], simulation and thermal analysis of micro circular Couette flow [ 37 ], and thermodynamic analysis of various-shaped micro-scale thermoelectric coolers [ 38 ]. Moreover, an interesting concept named virtual entropy generation method has been elaborated by Zhang et al [ 35 ], which provides a path for the evaluation of leakage in channels using the concept of entropy generation.…”

Numerical analysis reliability control for a double‐pipe heat exchanger with virtual entropy generation method

“…Entropy generation can be inaccurate due to measurement and operational errors. To evaluate the error of indirect measurement, one parameter called heat balance error (HBE) was used . This criterion is a powerful tool for heat exchanger experiment quality control.…”