The performance tests were conducted on oil–water heat transfer in circumferential overlap trisection helical baffle heat exchangers with incline angles of 12°, 16°, 20°, 24° and 28°, and com...The performance tests were conducted on oil–water heat transfer in circumferential overlap trisection helical baffle heat exchangers with incline angles of 12°, 16°, 20°, 24° and 28°, and compared with a segmental baffle heat exchanger. The results show that the shell side heat transfer coefficient h_o and pressure drop Δp_o both increase while the comprehensive index h_o/Δp_o decreases with the increase of the mass flow rate of all schemes. And the shell side heat transfer coefficient, pressure drop and the comprehensive index ho/Δpo decrease with the increase of the baffle incline angle at a certain mass flow rate. The average values of shell side heat transfer coefficient and the comprehensive index h_o/Δp_o of the 12° helical baffled scheme are above 50% higher than those of the segmental one correspondingly, while the pressure drop value is very close and the ratios of the average values are about 1.664 and 1.596, respectively. The shell-side Nusselt number Nu_o and the comprehensive index Nu_o·Eu_(zo)^(-1) increase with the increase of Reynolds number of the shell side axial in all schemes, and the results also demonstrate that the small incline angled helical scheme has better comprehensive performance.展开更多
Experimental investigation of heat transfer and flow resistance performance on heat exchanger with lozenge fin tubes supported by helical baffles was carried out. Under the experimental conditions,curves of relation b...Experimental investigation of heat transfer and flow resistance performance on heat exchanger with lozenge fin tubes supported by helical baffles was carried out. Under the experimental conditions,curves of relation between heat transfer film coefficient and flow velocity,relation between flow resistance coefficient and velocity were obtained,which provides references for industrial application of this type of heat exchanger. Experimental results indicated that within the range of diesel oil flow velocity 0.22-0.85 m·s -1,heat transfer film coefficient in shell side of heat exchanger with lozenge fin tubes supported by helical baffles was 512-1378?W·m -2·K -1,which was 54%-108% higher than that of heat exchanger with smooth tubes supported by helical baffles,while flow resistance coefficient was lower by 5%-30%,which showed that heat exchanger with lozenge fin tubes supported by helical baffles had favorable heat transfer and flow resistance performance.展开更多
Shell-and-tube heat exchangers with helical baffles are now widely used in many engineering fields,especially in chemical and petroleum refining industries.The helical lead distance is one of the important design para...Shell-and-tube heat exchangers with helical baffles are now widely used in many engineering fields,especially in chemical and petroleum refining industries.The helical lead distance is one of the important design parameters.The continuous four-sector baffle was taken as an example,and the theoretical calculation method of the helical lead distance of the shell-and-tube heat exchanger with helical baffles was deduced.Then this procedure was extended to continuous n sectors baffle,continuous baffle and staggered sectors baffle.Finally,an equation to determine the helical lead distance for any kinds of helical baffle was proposed.A short discussion of the determination methods proposed in the literatures was presented.展开更多
基金Project(50976035)supported by the National Natural Science Foundation of ChinaProject(4521ZK120064004)supported by the Science and Technology Commission Green Energy and Power Engineering of Special Fund Project of Shanghai,China
文摘The performance tests were conducted on oil–water heat transfer in circumferential overlap trisection helical baffle heat exchangers with incline angles of 12°, 16°, 20°, 24° and 28°, and compared with a segmental baffle heat exchanger. The results show that the shell side heat transfer coefficient h_o and pressure drop Δp_o both increase while the comprehensive index h_o/Δp_o decreases with the increase of the mass flow rate of all schemes. And the shell side heat transfer coefficient, pressure drop and the comprehensive index ho/Δpo decrease with the increase of the baffle incline angle at a certain mass flow rate. The average values of shell side heat transfer coefficient and the comprehensive index h_o/Δp_o of the 12° helical baffled scheme are above 50% higher than those of the segmental one correspondingly, while the pressure drop value is very close and the ratios of the average values are about 1.664 and 1.596, respectively. The shell-side Nusselt number Nu_o and the comprehensive index Nu_o·Eu_(zo)^(-1) increase with the increase of Reynolds number of the shell side axial in all schemes, and the results also demonstrate that the small incline angled helical scheme has better comprehensive performance.
文摘Experimental investigation of heat transfer and flow resistance performance on heat exchanger with lozenge fin tubes supported by helical baffles was carried out. Under the experimental conditions,curves of relation between heat transfer film coefficient and flow velocity,relation between flow resistance coefficient and velocity were obtained,which provides references for industrial application of this type of heat exchanger. Experimental results indicated that within the range of diesel oil flow velocity 0.22-0.85 m·s -1,heat transfer film coefficient in shell side of heat exchanger with lozenge fin tubes supported by helical baffles was 512-1378?W·m -2·K -1,which was 54%-108% higher than that of heat exchanger with smooth tubes supported by helical baffles,while flow resistance coefficient was lower by 5%-30%,which showed that heat exchanger with lozenge fin tubes supported by helical baffles had favorable heat transfer and flow resistance performance.
文摘Shell-and-tube heat exchangers with helical baffles are now widely used in many engineering fields,especially in chemical and petroleum refining industries.The helical lead distance is one of the important design parameters.The continuous four-sector baffle was taken as an example,and the theoretical calculation method of the helical lead distance of the shell-and-tube heat exchanger with helical baffles was deduced.Then this procedure was extended to continuous n sectors baffle,continuous baffle and staggered sectors baffle.Finally,an equation to determine the helical lead distance for any kinds of helical baffle was proposed.A short discussion of the determination methods proposed in the literatures was presented.
