Experimental Study on External Condensation Heat Transfer Characteristics of Bellows

Flow model and heat transfer of condensation flow outside of bellows have been theoretically and experimentally studied.The formula for calculation of condensation heat transfer coefficient was deduced,and corrected through experiment.The calculation results are accordant with the experimental ones,and the errors is less than 10%.The effect of bellows structure parameters and pipe diameter on the enhancement heat transfer has been investigated.It is found that in the steady flow region,the average condensation heat transfer coefficient in a bellows is 3~5 times than that in a straight tube under the same conditions,and when considering the increasing in heat transfer area,the effectiveness of enhancement heat transfer is 5~7 times than that in a straight tube.To facilitate the engineering design and application of bellows,the formula for the calculation of the average heat transfer coefficient of a fluid in a bellows was also given.