Virtual entropy generation (VEG) method in experiment reliability control: Implications for heat exchanger measurement

Abstract

Heat exchangers are widely-used heat recovery devices. To evaluate their performance, reliable experimental data are necessary and important. In the present paper, a “virtual entropy generation (VEG)” method is developed to control the quality of heat exchanger measurement. Different from the real entropy generation caused by the process irreversibility, virtual entropy generation (VEG) is defined as the difference between the measured entropy generation and the theoretical entropy generation caused with no measurement error and uncertainties. The results of this paper illustrate the existence and restrictions of VEG in two forms: the error form and the uncertainty form. Based on the new analytical approach (VEG method), new techniques are developed (1) to derive a second-law obeying measurement error criterion, and (2) to regulate the measurement uncertainties with four kinds of calibration techniques. Finally, the virtual entropy generation (VEG) are illustrated and clarified by existing experimental results. Our new framework of analysis demonstrates a more reasonable way to develop the criterion of any irreversible process measurement and provides a promising way to improve experiment reliability.