内插扭带强化换热过程及最佳螺距研究
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摘要
与普通换热管相比,内插扭带传热管内由于螺旋涡的存在,使管内介质压力梯度增加、流速加快,从而提高管内传热系数。采用了FLUENT数值模拟计算,以水为管内流体介质,对内插扭带管进行传热特性分析。结果表明,随着雷诺数增大,努塞尔数呈直线增大,而摩擦阻力系数呈指数型减小;并且在相同雷诺数条件下,内插扭带管的摩擦阻力系数和努塞尔数均大于光管;通过综合因子评价方法确定了内插扭带强化换热的最佳螺距为50 mm,并且该方法适合于小雷诺数流动条件下的强化换热。
Compared with ordinary heat transfer pipes, due to the spiral vortexes in the heat transfer pipes with inserted twisted belt that increases the pressure gradient of medium in the pipes and speeds up the flow rate, the heat transfer coefficient in the insert twisted pipes can be increased. In this paper, FLUENT was used for numerical simulation calculation to analyze the heat transfer characteristics of the inserted torsional belt pipe with water as the fluid medium in the pipe. The results showed that as the Re increased, the Nu increased linearly, while the fc decreased exponentially. At the same Re, the fc and Nu of the tubes were larger than that of the bare tubes. The optimal pitch of the interpolated torsion belt was determined to be 50 mm by the comprehensive factor evaluation method, and this method can be suitable for the enhanced heat transfer under the condition of small Reynolds number flow.
Compared with ordinary heat transfer pipes, due to the spiral vortexes in the heat transfer pipes with inserted twisted belt that increases the pressure gradient of medium in the pipes and speeds up the flow rate, the heat transfer coefficient in the insert twisted pipes can be increased. In this paper, FLUENT was used for numerical simulation calculation to analyze the heat transfer characteristics of the inserted torsional belt pipe with water as the fluid medium in the pipe. The results showed that as the Re increased, the Nu increased linearly, while the fc decreased exponentially. At the same Re, the fc and Nu of the tubes were larger than that of the bare tubes. The optimal pitch of the interpolated torsion belt was determined to be 50 mm by the comprehensive factor evaluation method, and this method can be suitable for the enhanced heat transfer under the condition of small Reynolds number flow.
引文
[1]Nanan K,Thianpong C,Promvonge P,et al.Investigation of heat transfer enhancement by perforated helical twisted-tapes[J].International Communications in Heat and Mass Transfer,2014,52:106-112.
[2]WongchareeaK,Eiamsa-and S.Heat transfer enhancement by twisted tapes with alternate-axesand triangular,rectangular andtrapezoidal wings[J].ChemicalEngineering and Processing:Process Intensification2011,50(2):211-219
[3]Bhuiya M M K,Chowdhury M S U,Saha M,et al.Heat transfer and friction factor characteristics in turbulent flow through a tube fitted with perforated twisted tape inserts[J].International Communications in Heat and Mass Transfer,2013,46:49-57.
[4]Eiamsa-ard S,Promvonge P.Performance assessment in a heat exchanger tube withalternate clockwise and counter-clockwise twisted-tape inserts[J].International Journal of Heat and Mass Transfer,2010,53(7-8):1364-1372.
[5]Eiamsa-ard S,Somkleang P,Nuntadusit C,et al.Heat transfer enhancement in tube by inserting uniform/non-uniform twisted-tapes with alternate axes:Effect of rotated-axislength[J].Applied Thermal Engineering,2013,54(1):289-309.
[6]Seemawute P,Eiamsa-and S.Thermohydraulics of turbulent flow through a round tube by a peripherally-cut twisted tape with an alternate axis[J].International Communications in Heat and Mass Transfer,2010,37(6):652-659.
[7]Thianpong C,Eiamsa-and P,Eiamsa-ard S.Heat transfer and thermal performancecharacteristics of heat exchanger tube fitted with perforated twisted-tapes[J].Heat Mass Transfer,2012,48(6):881-892.
[8]Ananth J,Jaisankar S.Experimental studies on heat transfer and friction factor characteristics of thermosyphon solar water heating system fitted with regularly spaced twisted tape with rod and spacer[J].Energy Conversion and Management,2013,73:207-213.
[9]Jaisankar S,Radhakrishnan T K,Sheeba K N,et al.Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of Left-Right twisted tapes[J].Energy Conversion and Management,2009,50(10):2638-2649.
[10]Promvonge P,Suwannapan S,Pimsam M,et al.Experimental study on heat transfer in square duct with combined twisted-tape and winglet vortex generators[J].International Communications in Heat and Mass Transfer,2014,59:158-165.
[11]Eiamsa-ard S,Kongkaitpaiboon V,Nanan K.Thermohydraulics of turbulent flowthrough heat exchanger tubes fitted with circular-rings and twisted tapes[J].Chinese Journal of Chemical Engineering,2013,21(6):585-593.
[2]WongchareeaK,Eiamsa-and S.Heat transfer enhancement by twisted tapes with alternate-axesand triangular,rectangular andtrapezoidal wings[J].ChemicalEngineering and Processing:Process Intensification2011,50(2):211-219
[3]Bhuiya M M K,Chowdhury M S U,Saha M,et al.Heat transfer and friction factor characteristics in turbulent flow through a tube fitted with perforated twisted tape inserts[J].International Communications in Heat and Mass Transfer,2013,46:49-57.
[4]Eiamsa-ard S,Promvonge P.Performance assessment in a heat exchanger tube withalternate clockwise and counter-clockwise twisted-tape inserts[J].International Journal of Heat and Mass Transfer,2010,53(7-8):1364-1372.
[5]Eiamsa-ard S,Somkleang P,Nuntadusit C,et al.Heat transfer enhancement in tube by inserting uniform/non-uniform twisted-tapes with alternate axes:Effect of rotated-axislength[J].Applied Thermal Engineering,2013,54(1):289-309.
[6]Seemawute P,Eiamsa-and S.Thermohydraulics of turbulent flow through a round tube by a peripherally-cut twisted tape with an alternate axis[J].International Communications in Heat and Mass Transfer,2010,37(6):652-659.
[7]Thianpong C,Eiamsa-and P,Eiamsa-ard S.Heat transfer and thermal performancecharacteristics of heat exchanger tube fitted with perforated twisted-tapes[J].Heat Mass Transfer,2012,48(6):881-892.
[8]Ananth J,Jaisankar S.Experimental studies on heat transfer and friction factor characteristics of thermosyphon solar water heating system fitted with regularly spaced twisted tape with rod and spacer[J].Energy Conversion and Management,2013,73:207-213.
[9]Jaisankar S,Radhakrishnan T K,Sheeba K N,et al.Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of Left-Right twisted tapes[J].Energy Conversion and Management,2009,50(10):2638-2649.
[10]Promvonge P,Suwannapan S,Pimsam M,et al.Experimental study on heat transfer in square duct with combined twisted-tape and winglet vortex generators[J].International Communications in Heat and Mass Transfer,2014,59:158-165.
[11]Eiamsa-ard S,Kongkaitpaiboon V,Nanan K.Thermohydraulics of turbulent flowthrough heat exchanger tubes fitted with circular-rings and twisted tapes[J].Chinese Journal of Chemical Engineering,2013,21(6):585-593.