中文摘要：

摘要：通过对CO2的物理特性及水平光管与不同螺纹管管外沸腾传热进行实验研究，得出了传热系数随蒸发压力和热流密度的变化关系。拟合得出CO2在蒸发压力为2．6～3．6MPa、热流密度为10～50kW·m^-2的简化关联式h=A·q^n。与Cooper预测值的偏差在士15％以内，与Jabardo等关联式预测值的偏差在士7％以内，与叶天震实验关联式预测值的偏差在±9％以内。在CO2在光管管外沸腾传热的基础上进一步研究其在螺纹管营外沸腾对传热的强化效果，为CO2强化传热进一步发展提供依据。

英文摘要：

CO2 physical characteristics and boiling heat transfer at the outer surface of of smooth and screwed tubes are experimentally studied. The relationship between heat transfer coefficient, evaporating pressure and the heat flux is obtained through experimental analysis of CO2 boiling heat transfer outside a horizontal smooth tube. The fitting correlation is derived from the experimental data when CO2 evaporating pressure range is 2.6 ~ 3.6 MPa and heat flux range is 10 ~ 50 kW/m^2. The calculated deviation of the new correlation with predicted value of Cooper correlation is within ± 15%, with Jabardo correlation is within ± 7 % and with Ye correlation is within ± 9 %. Based on the analysis of CO2 boiling heat transfer outside a horizontal smooth tube, a further study on CO2 boiling heat transfer outside screwed tubes is conducted. The results provide a basis for promoting the development of CO2 heat transfer enhancement, and also provide a support for engineering problems.