Sensitivity analysis and numerical experiments on transient test of compact heat exchanger surfaces

Abstract

A single-blow transient testing technique considering the effect of longitudinal heat conduction is suggested for determining the average convection heat transfer coefficient of compact heat exchanger surface. By matching the measured outlet fluid temperature variation with similar theoretical curves, the dimensionless longitudinal conduction parameter ?_l, the time constant of the inlet fluid temperature ?⁺, and the number of heat transfer units N_tu can be determined simultaneously using the Levenberg-Marquardt nonlinear parameter estimation method. Both sensitivity analysis and numerical experiments with simulated measurements containing random errors show that the method in the present investigation provides satisfactory accuracy of the estimated parameter N_tu, which characterizes the heat transfer performance of compact heat exchanger surfaces.

References

1. Kays W M, London A L . Compact Heat Exchangers. 3rd ed . New York: McGraw-HillBook Co, 1984
2. McDonald C F . Low-cost compact primary surface recuperator concept for microturbines. Applied Thermal Engineering, 2000, 20(5): 471–497. doi:10.1016/S1359-4311(99)00033-2
3. Liang C Y, Yang W J . Modified single-blow techniquefor performance evaluation on heat transfer surfaces. Journal of Heat Transfer, 1975, 97(1): 16–21
4. Ren Hesheng, Cai Zuhui . A modified single-blow transienttesting technique including the effect of longitudinal conduction. Journal of University of Shanghai for Science andTechnology, 1981, 3(2): 1–18 (in Chinese)
5. Cai Z H, Li M L, Wu Y W, et al.. A modified selected point matching techniquefor testing compact heat exchanger surfaces. International Journal of Heat and Mass Transfer, 1984, 27(7): 971–978. doi:10.1016/0017-9310(84)90113-3
6. Luo X, Roetzel W, Lüdersen U . The single-blow transient testing technique consideringlongitudinal core conduction and fluid dispersion. International Journal of Heat and Mass Transfer, 2001, 44(1): 121–129. doi:10.1016/S0017-9310(00)00089-2
7. Ren Hesheng, Hua Guixian, Cui Xiaoyu, et al.. Nonlinear parameter estimation method for transienttest of compact heat exchangers. Journalof University of Shanghai for Science and Technology, 2006, 28(5): 473–478 (in Chinese)
8. Beck J V, Arnold K J . Parameter Estimation in Engineeringand Science. New York: John Wiley, 1977
9. Woodbury K A, Ke Quanpeng . An inverse algorithm fordirect determination of heat transfer coefficients. In: Proceedingsof NHTC'00 34th National Heat Transfer Conference. Pittsburgh, Pennsylvania, 2000, 663–669