Volume 8 Issue 2
Leakage Evaluation by Virtual Entropy Generation (VEG) Method
Zhichao Zhang, Corina Drapaca, Zhifeng Zhang, Shuaifang Zhang, Shimei Sun and Hui Liu
1School of Municipal and Environmental Engineering, Jilin Jianzhu University, Changchun 130118, China
2Department of Engineering Science and Mechanics, Pennsylvania State University, State College, PA 16802, USA
3Department of Mechanical and Nuclear Engineering, Pennsylvania State University, State College, PA 16802, USA
*Author to whom correspondence should be addressed.
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.
Keywords:virtual entropy generation (VEG) method; leakage evaluation; micro/nano-scale crack