In this paper, a special lifetime testing apparatus is installed for dropwise condensation heat transfer on polymer-coated surfaces. Film and dropwise condensations are simultaneously carried out in the same condensing chamber to get rid of any containments. The discontinuous experimental results demonstrate that one surface has sustained dropwise condensation for about 1000 hours. The condensation heat transfer characteristics tend toward stability. In addition, the experiments prove that a polymer film prepared by the dynamic ion-beam mixed implantation (DIMI) method has good adhesion with the metal substrate.

Abrief state-of-the-art reviewis presented on research progress on dropwise condensation heat transfer in China. During the past 10 years, Chinese researchers have put forward some new proposals on the mechanism of dropwise condensation, and developed some new surface materials for promoting dropwise condensation. In particular, successful applications of dropwise condensation heat transfer surfaces in industrial condensers have provoked interest around the world and inspired the further investigation on the dropwise condensation. Since much of the work had been published in Chinese, it was considered appropriate to give a review in English. This review includes: (1) micro mechanisms and heat transfer characteristics for dropwise condensation; (2) methods for promoting dropwise condensation and (3) industrial applications of dropwise condensation.

This paper reports the test results of the first industrial-scale absorption heat transformer (AHT) equipment in China, to recover the waste heat released from mixture of steam and organic vapor at 98 C in coacervation section, synthetic rubber plant of Yanshan Petrochemical Corporation, Beijing, China. The recovered heat is used to heat hot water from 95 to 110 C, feeding back to the coagulator as the supplementary heating source. The AHT system is operating with H2O/LiBr solution with heat flow of 5000kW. The coefficient of performance (COP), the thermal efficiency and the temperature lift of the AHT system are presented. The heat transfer characteristics of the AHT components, i.e. absorber, generator, evaporator, condenser and the liquid-liquid solution heat exchanger, are also illustrated by comparison of experimental data and the model calculated results. The results show that the mean COP is 0.47, the gross temperature lift of 25 C can be realized and the payback period is 2 years.

The present paper reports an experimental investigation of film condensation in a vertical, internally finned tube with a wire insert. The finned tube and wire insert were chosen as the best performing from a series of tubes and inserts tested separately in previous investigations. Compared with previous results for the finned tube, it was found that only for ∆T>10K did the addition of the insert somewhat improve the heat transfer performance. However, the pressure drop for the finned tube with insert was increased. Empirical correlations for friction factors for the three tube configurations are proposed based on the present data.

The plasma polymerization method and dynamic ion-beam mixed implantation method were employed to coat ultra-thin polymer films on copper plates. Experiments indicated that steady dropwise condensation of steam at atmospheric pressure occurred. The condensation heat transfer coefficients increased by approximately 3 and 5-7 times for the polytrimethylvinylsilane film and polytetrafluoroethylene film respectively, compared with the value for film condensation under the same experimental conditions. The temperatures on the condensing surface and inside the test block were found to be rapidly and randomly fluctuated. The properties of the coated films and advantages of the methods used in this investigation were discussed briefly.