Research On The Influence Of Structural Parameters On Heat Transfer Performance Of Tubular Fin Oil Cooler

The tubular fin oil coolers are widely used in the field of injection moulding machinery and so on.It is of great practical significance to study the heat transfer performance of tubular fin oil cooler.In the MA thesis,the influence of tube pitch and other parameters on heat transfer performance of tubular fin oil cooler are studied experimentally and theoretically,which expects to provide reference for energy saving and consumption reduction,greening and lightweight manufacturing in related industries.Firstly,the effects of different tube pitch on heat transfer and resistance performance of tubular fin oil cooler are experimentally studied.It is found that the heat transfer coefficient of tubular fin oil cooler with tube pitch of 12.04 mm is the largest.And comparison with tubular fin oil coolers with tube pitch of 14.72 mm,16.45 mm,17.32 mm and 18.19 mm,its shell-side heat transfer coefficient is on average improved by 18~26%,16~25%,14~23% and12~22%.The shell-side pressure drop of tubular fin oil cooler decreases with the increase of tube pitch.Taking tube pitch of 12.04 mm as a reference,the comprehensive heat transfer performance of four other tubular fin oil coolers with different tube pitch is evaluated based on PEC comprehensive heat transfer factor.It is found that PEC factor is negatively correlated with shell-side Re and positively correlated with tube pitch.When Re is between351 and 467,the comprehensive heat transfer performance of tubular fin oil cooler with 18.19 mm tube pitch is the best.When Re is greater than 467,the comprehensive heat transfer performance of the tubular fin oil cooler with 12.04 mm tube pitch is obviously better than that of the other four tubular fin oil coolers with different tube pitch.Then the experimental data are fitted and the correlation formulas of heat transfer and resistance in shell side with different tube pitch are obtained.Secondly,the three-dimensional models of tubular fin oil cooler with different tube pitch are established for numerical simulation.It is found that the flow shape of the shell side hydraulic fluid of the tubular fin oil cooler is continuous “N” shape,and the flow state is close to the ideal cross-flow.At each sharp corner of the “N” shape,the velocity of fluid flow is the highest,and the velocity of fluid flow between two adjacent baffles is low.There are dead zones near the windward side of each baffle,and the area of dead zones decreases withthe increase of tube pitch.The heat transfer mechanisms of tubular fin oil coolers with different tube pitch are analyzed by the field synergy principle.The results show that the order of synergy between shell-side velocity field and shell-side temperature field is 12.04 mm,18.19 mm,17.32 mm,16.45 mm and 14.72 mm.Finally,according to the problems of dead zone and large pressure drop on shell side,it is proposed that the holed-baffle structure be introduced into the tubular fin oil cooler.The heat transfer enhancement mechanism of holed-baffle structure is obtained by analyzing the changes of shell-side velocity field,shell-side temperature field and shell-side pressure field of tubular fin oil coolers with holed-baffle and without holed-baffle.It is found that the holed-baffle structure can produce jet fluid,which can effectively reduce the dead zone area and improve the uniformity of the flow field on the shell side and the fluid transmission ability.Comparison with the tubular fin oil cooler without holed-baffle,the shell-side heat transfer coefficient and pressure drop of tubular fin oil cooler with holed-baffle are reduced by 2.5~28% and 43~58% respectively.The shell-side pressure drop of tubular fin oil cooler with holed-baffle is negatively correlated with the opening rate.The order of heat transfer coefficient of fin oil cooler with different opening rate is 0,0.182,0.199,0.229,0.217,0.264.The drag coefficient f of tubular fin oil cooler with holed-baffle decreases with the increase of baffle spacing,and the nusselt number Nu of tubular fin oil cooler with holed-baffle increases with the increase of baffle spacing.From the point of views of comprehensive heat transfer performance and field synergy,it is found that when the opening ratio is 0.229 and the baffle spacing is 85 mm,the comprehensive heat transfer performance of tubular fin oil cooler is the best.