Heat transfer enhancement in round tube with cross over disk:experiment and simulation
Experimental and numerical methods were used to study heat transfer enhancement in a round tube with a new type of insert:cross over disk(COD).Pressure drop experiments were carried out in the round tube with maltose.The correlation of friction factor for Reynolds number was given under Re range from 2×10-4 to 4×104.The pressure drop in the round tube with COD was 7—40 times bigger than the empty tube.Heat transfer experiments were performed both in vertical and horizontal tubes with COD.The maltose was heated by steam in the tube.The heat transfer correlations were obtained.In the creeping flow,the heat transfer enhancement for the horizontal tube was about 2—3.5 times bigger than the empty tube,and about 2.5—4 times for the vertical tube.The influence for geometrical parameters,such as r/R and l/d on heat transfer and pressure drop was examined by computational fluid dynamics software Fluent and correlations to describe the effect of these parameters were obtained.These correlations could be used in optimal design of the heat transfer system using COD as insert.