Research For Effect Of Heat Transfer Under Rolling Motion

Experiment investigation and theory analysis of the heat transfer characteristics of flowboiling in a vertical narrow rectangular channel were conducted. The experimental loop isinstalled on a platform which can roll around the axle in order to simulate ocean condition,and deionized water was used as the work fluid. Experiments were carried out both inmotionless conditions and different rolling conditions.The typical phenomena appeared in the experiments were studied and analyzed, theresult showed that the parameters keep steadiness in vertical conditions. Under low heat flux,the phenomena of rolling motion and non-rolling motion seems to be the same. As the heatflux increased, when the outlet mass quality reach to a certain value, the various experimentalparameters under rolling motions begin to fluctuate periodically, the fluctuate cycle isconsistent with the rolling period. Rolling period has no effect on boiling heat transfercoefficient, while the amplitude of boiling heat transfer coefficient increases with the rollingangle.According to the analysis of flow boiling experimental data under vertical condition,itwas found that flow boiling heat transfer in the test section based on this size has no obviousheat transfer enhancement. Mass flow rate, inlet pressure, the mass quality are found to havesignificant effects on the flow boiling heat transfer coefficient. The inlet subcooling is almostno effect on the saturated boiling heat transfer. Further, several empirical correlations for thecalculation of two-phase heat transfer coefficient are evaluated against the test data, the resultshowed that Lee-Lee correlations, Liu-Winteron correlations and Kandlikar correlationscompare the results relatively better within an accuracy of±25%, while the classical empiricalcorrelation of Chen that based on the macro channels is no longer applied to calculatetwo-phase heat transfer coefficient in narrow channels.Finally, the experimental data under vertical and rolling motion were analyzed andcompared, the results showed that: Rolling motion almost has no effect on the averagedtwo-phase heat transfer coefficient against the vertical state. The amplitude of the heattransfer coefficient is dominated by inlet pressure, while the oscillation of mass flux has noeffect on instantaneous heat transfer coefficient. Special position change of the system due tothe rolling motion results in the period of the steam in the loop, which cause the fluctuation of inlet pressure. The heat transfer coefficient fluctuates in phase with the inlet pressure.