Li Shi, Wu Xin, Du Yiwei, Liu Daojie, Sun Li, Li Junhui
2018, 32(1): 1-6.
To research the heat-transfer performance of different plated/coated pipes during flue gas heat recovery, experimental studies were conducted on the vertical copper pipe, Ni-P-plated pipe and PTFE-coated pipe, with steam-air mixtures longitudinally flowing over their surfaces (w(H2O)=6%~16%). Results show that the heat-transfer coefficient increases with rising mass fraction of steam and with rising flow rate of steam-air mixtures, and the PTFE-coated pipe has the best heat-transfer effect. Film-wise condensation occurs on copper pipe surface, while drop-wise condensation forms on PTFE-coated pipe surface, and for Ni-P-plated pipe surfaces, both the film-wise condensation and the drop-wise condensation can be observed simultaneously. Based on multiple linear regression analysis of the experimental data, experimental correlations about convection and condensation heat transfer of above three pipes are obtained respectively, and the relative errors between theoretical values and experimental data are within ±15%, indicating that the experimental correlations have high accuracy.
