Study on convective heat transfer coefficient on vertical external surface of island-reef building based on naphthalene sublimation method

Abstract

The island-reef areas located in southern China have a unique climate—high temperature, high humidity, high concentrations of salt mist, strong solar radiation, small diurnal/annual temperature range and perennial sea breeze, and it is exceedingly diverse with the climate in Chinese inland. In order to prove the simple naphthalene sublimation method for measuring convective heat transfer coefficient (CHTC) is feasible in extreme climate conditions and obtain CHTC recommended value in island-reef areas, the study adopted the research methods to combine field measurement and data statistics. According to taking the measured data from naphthalene sublimation experiment as strong support, predictive formula of CHTC on vertical external surface of island-reef building under low wind velocities was raised to provide convenience for engineering design and validated feasible by comparing with ASHRAE recommend formula based on error analysis. Subsequently, the CHTC predictive formula and the specific wind characteristics in Xisha Islands of China were analyzed together. The results showed that CHTCs had a wide range from 6.22W/m2·Kto 54.66W/m2·K, and the average CHTC of all measured points was 17.30W/m2·K. Additionally, CHTCs on windward were greater than those on leeward. Furthermore, the CHTC predictive formula under low wind velocities raised by this study was precise and reliable, and could guarantee to be applicable for island-reef building more than 55% time no matter which season it was. Consequently, CHTC on vertical external surface of island-reef building under low wind velocities was recommended as 21.51W/m2·K in terms of average level of the whole year. This study can provide convenience for popularizing the simplified method in extreme climate conditions and lay a solid foundation for the design of low energy consumption building in island-reef areas.