水平蛇形管内传热特性实验研究
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摘要
煤矿是我国主要的能源之一,但是每年在采煤过程中会向大气中排放出大量的甲烷。煤矿乏风的主要成分是甲烷,对环境有很大污染,因此有必要采用乏风氧化装置对甲烷加以收集利用。当甲烷浓度较高时,多采用换热器将多余的能量取出用于供暖,本文采用蜂窝陶瓷内置水平蛇形管实现能量的再利用。
本课题首先自行设计和搭建煤矿乏风瓦斯取热实验台,包括换热系统、汽水循环系统、烟风加热系统及数据采集与控制系统。实验选取相关的元件进行采集,对各元器件进行校核,通过反复的调试验证,保证各实验数据的准确性。此外,对水平蛇形管的换热特性进行研究,重点研究壁温及换热系数随外部烟温、质量流速及干度的变化规律。
通过对单相和两相流壁温特性的研究得出：无论在单相还是两相状态下,沿管长的壁温分布在弯头后都略有降低；沿周向分布的壁温特性有所不同,单相流时,内侧壁温低于外侧壁温,上侧壁温最低,下侧壁温最高,而在分层流和环状流状态下,内侧壁温高于外侧壁温。通过对两相流换热系数特性的研究得出：分层流和环状流的换热系数都随质量流速的增加而增大；分层流状态下随着干度的增加,管内换热得到强化,换热系数呈现增加趋势。但当干度增加到0.8～0.9时,由于两相流质量流速较低,壁温飞升出现恶化,换热减弱,换热系数随着干度的增加反而降低。此外,本课题还对各种工况下的实验数据进行了拟合,通过将实验值与计算值的对比,证明拟合情况良好。
China is in rich of coal mines, but a great much of methane is discharged into the atmosphere through coal mining every year. The methane is the main component of VAM (Ventilation Air Methane). However, VAM is harmful to the environment. Therefore, it is necessary to collect and recycle the energy released by VAM oxidation. A heat exchanger is used to recycle the excess energy to heat when methane concentration is high. In this paper, a horizontal serpentine tube placed in honeycomb ceramic regenerators was presented to recycle the energy.
VAM heating experiment platform is firstly designed and built, including heat exchange system, steam-water circulation system, smoke wind system and data acquisition and control system. All of the experimental equipments should be calibrated and adjusted before experimenting. The accuracy of the experiment data is ensured by repeated tests. The research of heat transfer for a horizontal serpentine tube focused on the correlation between wall temperature, heat transfer coefficient and smoke temperature, mass velocity and vapor fraction under about conditions.
Several runs of experiments were conducted to test the wall temperature of both single-phase and two-phase flow, The results show that the wall temperature along the tube's length slightly decreases after the return bend. The circumferential distribution of wall temperature is different in single phase flow, the inter wall temperature is lower than the outer, the top wall temperature is the lowest whereas the bottom is the highest. However, the inner wall temperature is higher than the outer under certain conditions of stratified and annular flow patterns. The results of experiments on characteristics of two-phase flow heat transfer coefficient show that the coefficient increases with the increase of mass flow in stratified or annular flow. The heat transfer coefficient increases with the increase of vapor fraction as the latter improved the convection effect. But the heat transfer coefficient decreases after the vapor fraction increased to 0.8～0.9, because the low two-phase mass flow and anomaly high temperature lead to a low convection efficiency. The experimental data showed great agreement with the calculation.
本课题首先自行设计和搭建煤矿乏风瓦斯取热实验台,包括换热系统、汽水循环系统、烟风加热系统及数据采集与控制系统。实验选取相关的元件进行采集,对各元器件进行校核,通过反复的调试验证,保证各实验数据的准确性。此外,对水平蛇形管的换热特性进行研究,重点研究壁温及换热系数随外部烟温、质量流速及干度的变化规律。
通过对单相和两相流壁温特性的研究得出：无论在单相还是两相状态下,沿管长的壁温分布在弯头后都略有降低；沿周向分布的壁温特性有所不同,单相流时,内侧壁温低于外侧壁温,上侧壁温最低,下侧壁温最高,而在分层流和环状流状态下,内侧壁温高于外侧壁温。通过对两相流换热系数特性的研究得出：分层流和环状流的换热系数都随质量流速的增加而增大；分层流状态下随着干度的增加,管内换热得到强化,换热系数呈现增加趋势。但当干度增加到0.8～0.9时,由于两相流质量流速较低,壁温飞升出现恶化,换热减弱,换热系数随着干度的增加反而降低。此外,本课题还对各种工况下的实验数据进行了拟合,通过将实验值与计算值的对比,证明拟合情况良好。
China is in rich of coal mines, but a great much of methane is discharged into the atmosphere through coal mining every year. The methane is the main component of VAM (Ventilation Air Methane). However, VAM is harmful to the environment. Therefore, it is necessary to collect and recycle the energy released by VAM oxidation. A heat exchanger is used to recycle the excess energy to heat when methane concentration is high. In this paper, a horizontal serpentine tube placed in honeycomb ceramic regenerators was presented to recycle the energy.
VAM heating experiment platform is firstly designed and built, including heat exchange system, steam-water circulation system, smoke wind system and data acquisition and control system. All of the experimental equipments should be calibrated and adjusted before experimenting. The accuracy of the experiment data is ensured by repeated tests. The research of heat transfer for a horizontal serpentine tube focused on the correlation between wall temperature, heat transfer coefficient and smoke temperature, mass velocity and vapor fraction under about conditions.
Several runs of experiments were conducted to test the wall temperature of both single-phase and two-phase flow, The results show that the wall temperature along the tube's length slightly decreases after the return bend. The circumferential distribution of wall temperature is different in single phase flow, the inter wall temperature is lower than the outer, the top wall temperature is the lowest whereas the bottom is the highest. However, the inner wall temperature is higher than the outer under certain conditions of stratified and annular flow patterns. The results of experiments on characteristics of two-phase flow heat transfer coefficient show that the coefficient increases with the increase of mass flow in stratified or annular flow. The heat transfer coefficient increases with the increase of vapor fraction as the latter improved the convection effect. But the heat transfer coefficient decreases after the vapor fraction increased to 0.8～0.9, because the low two-phase mass flow and anomaly high temperature lead to a low convection efficiency. The experimental data showed great agreement with the calculation.
引文
[1]陈宜亮,马晓钟,魏化兴.煤矿通风瓦斯氧化热利用方式[J].中国煤层气,2007,(6)：27-30
[2]王鑫阳,杜金.浓度低于1%的矿井瓦斯氧化技术现状及前景[J].煤炭技术,2008,27(9)
[3]刘永启,刘瑞祥,高振强.矿井乏风瓦斯热氧化装置[P].中国专利：ZL 2008 10249860.3,101464062，2010-3-10
[4]胡千庭,蒋时才,苏文叔.我国煤矿瓦斯灾害防治对策[J].矿业安全与环保,2000,1
[5]Liu Rui xiang, Liu Yong qi, Gao Zhen qiang. Zheng Bin. Simulation of inner cooling of a reverse flow reactor for lean methane thermal oxidation. Proceedings of the IASTED International Conference Modeling, Simulation, and Identification, Beijing China:2009,658-665
[6]Liu Rui xiang, Liu Yong qi, Gao Zhen qiang. "Methane emission control by thermal oxidation in a reverse flow reactor,"2nd International Conference on Bioinformatics and Biomedical Engineering, ICBBE 2008, 3952-3955
[7]郑斌,刘永启,刘瑞祥等.煤矿乏风的蓄热逆流氧化[J].煤炭学报,2009,34(11)：1475-1478
[8]SalomonsS, HavesR E, PoirierM, et al. Flow reversal reactor for the catalytic combustion of lean methane mixtures[J].Catalysis Today,2003,83(4):59-69
[9]Gosiew sk ik, Wamuzin sk ik. Effect of the mode of heat with drawl on the asymmetry of temperature profiles in reverse-flow reactors[J]. Chemical Engineering Science,2007,62(1):2679-2689
[10]鲁钟琪.两相流与沸腾传热[M].北京：清华大学出版社,2002.
[11]J.G. Collier. Convective Boiling and Condensation[M]. New York:McGraw-Hill,1972
[12]林宗虎.气液两相流和沸腾传热[M].西安：西安交通大学出版社,1987
[13]W.R. Dean, Mote on the motion of fluid in a curved Pipe[J]. Philos. Mag.,1927,20:208-223
[14]S.V. Patankar, VS. pratap and D.B. Spalding J. Fluid Mech.,1974,62(3):539-551
[15]Y Mori, W Nakayama. Study on Forced Convective Heat Transfer in Curved Pipes[J]. Heat and Mass Transfer,1967,10(2):37-59
[16]Y Mori, W Nakayama. Study on Forced Convective Heat Transfer in Curved Pipes[J]. Heat and Mass Transfer,1967,10(3):681-695
[17]李斌,何安定,周芳德.窄缝环形管内流动与传热实验研究[J].化工机械,2001,28(1)：43-47
[18]李隆键.螺旋管内对流传热过程及其强化[D]：[博士学位论文].重庆：重庆大学,2000
[19]孟勐,彭晓峰.蛇形管流动沸腾弯头处传热的非均匀性[J].工程热物理学报,2009,30(3)：448-500
[20]X.Chen, F.Zhou. Critical Heat Flux in Helical Coils. Heat Transfer Sump, Beijing,1985
[21]Xue-Jun Chen, Fang-De Zhou. Forced Convective Boiling and Post-Dry out Heat Transfer in Helical Coiled Tubes[J]. Heat Transfer,1986,5(8):2221-2226
[22]Haitao Hu et al. Heat transfer characteristics of refrigerant-oil mixtures flow boiling in a horizontal C-shape cured smooth tube[J]. International Journal of Refrigeration,2010,2
[23]H. Takamatsu et al. A correlation for forced convective boiling heat transfer of pure refrigerants in a horizontal smooth tube[J]. Heat Mass Transfer,1993,36(13):3351-3360
[24]崔文智,廖全等.R134a在螺旋管内的流动沸腾传热[J].重庆大学学报,2001,24(4)：118-121
[25]张小力.水平管内环状流动核心沸腾换热模型[J].工程热物理学报,2000,21(5)：633-636
[26]张小力.HFc-134a水平管内流动沸腾换热研究进展[J].华东工业大学学报,1996,18(2):19-26
[27]Koyama Sh, Yu J, Momoki S, et al. Forced convective flow boiling heat transfer of Pure refrigerants inside a horizontal micro fin tube.1995 International Conference on Convective Flow Boiling.137-142
[28]Lie jin Guo, Xue jun Chen, et al. Forced Convection Boiling Heat Transfer and Dry out Characteristics in Helical Coiled Tubes with Various Axial Angles[J]. Heat Transfer,1998,2(11):261-266
[29]陈剑波.低沸点工质水平管内流动沸腾传热研究[D]：[博士论文].上海：上海机械学院,1991
[30]纪海维.纯工质在水平管内流动沸腾换热特性的实验研究[D]：[硕士论文].西安：西安科技大学,2006
[31]孙宗保.R134a螺旋管内流动沸腾换热特性研究[D]：[硕士论文].山东大学,2007
[32]陈听宽,陈宣政.近临界压力两相流沸腾传热特性的研究[J].西安交通大学学报,2006,6(4)：45～50
[33]陈听宽,张文清,顾亚平等.垂直U型沸腾管传热恶化特性研究[J].工程热物理学报,1985,6(2)：154-159
[34]陈听宽,杨志华,王芊等.垂直U型管两相流流型和传热研究[J].化工学报,1985,36(4)：426-443
[35]毕勤成,陈听宽,田永生等.螺旋管内高压汽水两相流传热恶化规律的研究[J].西安交通大学学报,1996,30(5)：30-35
[36]陈听宽,李遏龙,郑建学等.水平放置U型管及V型管传热特性的试验研究[J].西安交通大学学报,1990,24(1)：65-72
[37]陈如冰,罗林,姚寿广.采用IPSA法对水平管内流动沸腾传热特性的分析[J].华东船舶工业学院学报,2003,7(1)：24-27
[38]王跃社,白博峰,Hiroshi HONDAZ水平微肋管内基于气液环状流流型的沸腾传热理论模型[J].工程热物理学报,2007,28(1)：177-180
[39]锅炉机组热力计算标准方法[M].北京锅炉厂设计科,译.北京：机械工业出版社,1976,47-75
[40]杨世铭,陶文铨.传热学[M].高等教育出版社,2007
[41]J.A. Grindley, A.H. Gibson. On the frictional resistance to the flow of air through a pipe[J]. Proc. R. Soc. London Ser. 1908,80:114-139
[42]J.Eustice. Flow of water in curved pipes[J]. Proc, R. Soc. London Ser.1910,84:107-118
[43]Shah R K, Joshi S D. Handbook of single-phase convection heat transfer [M]. New York: Wiley-Interscience,1987
[44]G. Hetsroni. Hand book of Multiphase System[M]. New York:Mc Graw-Hill Book Company,1982
[45]徐济錾主编.沸腾传热和气液两相流[M].北京：原子能出版社,1993
[46]顾红芳,孙丹,陈听宽.煤油和空气的混合流体水平管内沸腾换热实验研究[J].工程热物理学报,2001,22(5)：622-625
[47]陈听宽.两相流与传热研究[M].西安：西安交通大学出版社,2004,151-154
[48]Chen J C. A correlation for boiling heat transfer to saturated fluid in vertical flow[J]. Process Design and Development,1966,5(3):322-339
[49]Gungor K E, Winterton R H S. A general correlation for flow boiling in tubes and annuli.[J]. Heat Mass Transfer,1986,29(3):351-358
[50]Gungor K E, Winterton R H S. Simplified general correlation for saturation flow boiling and comparisons with data[J]. Chem. Eng Res. Des 1987,65(2):48-56
[51]Lin Z Winterton R H S. A general correlation for saturated two phase flow boiling in tubes and annuli, based on a nucleate pole boiling equation.[J]. Heat Mass Transfer,1991,34(11):2759-2766
[52]Wattelet J P. Evaporation characteristics of R112, R134a and a mixture at low mass flexes[J]. ASHRE Trans,1994,100(1):603-615
[53]Shah M M. Chart correlation for saturated boiling heat transfer:equation and further study[J]. ASHRE Trans,1982,88(1):185-196
[54]Shah M. A new correlation for heat transfer during boiling flow through pipes[J]. ASHRE Trans,1976, 82(2):66-86
[55]N. Kattan, J.R. Thome, D. Favrat. Flow boiling in horizontal tubes:Development of new heat transfer model based on flow pattern[J]. Trans. of the ASME, J. Hear Transfer,1998,120(3):156-165
[2]王鑫阳,杜金.浓度低于1%的矿井瓦斯氧化技术现状及前景[J].煤炭技术,2008,27(9)
[3]刘永启,刘瑞祥,高振强.矿井乏风瓦斯热氧化装置[P].中国专利：ZL 2008 10249860.3,101464062，2010-3-10
[4]胡千庭,蒋时才,苏文叔.我国煤矿瓦斯灾害防治对策[J].矿业安全与环保,2000,1
[5]Liu Rui xiang, Liu Yong qi, Gao Zhen qiang. Zheng Bin. Simulation of inner cooling of a reverse flow reactor for lean methane thermal oxidation. Proceedings of the IASTED International Conference Modeling, Simulation, and Identification, Beijing China:2009,658-665
[6]Liu Rui xiang, Liu Yong qi, Gao Zhen qiang. "Methane emission control by thermal oxidation in a reverse flow reactor,"2nd International Conference on Bioinformatics and Biomedical Engineering, ICBBE 2008, 3952-3955
[7]郑斌,刘永启,刘瑞祥等.煤矿乏风的蓄热逆流氧化[J].煤炭学报,2009,34(11)：1475-1478
[8]SalomonsS, HavesR E, PoirierM, et al. Flow reversal reactor for the catalytic combustion of lean methane mixtures[J].Catalysis Today,2003,83(4):59-69
[9]Gosiew sk ik, Wamuzin sk ik. Effect of the mode of heat with drawl on the asymmetry of temperature profiles in reverse-flow reactors[J]. Chemical Engineering Science,2007,62(1):2679-2689
[10]鲁钟琪.两相流与沸腾传热[M].北京：清华大学出版社,2002.
[11]J.G. Collier. Convective Boiling and Condensation[M]. New York:McGraw-Hill,1972
[12]林宗虎.气液两相流和沸腾传热[M].西安：西安交通大学出版社,1987
[13]W.R. Dean, Mote on the motion of fluid in a curved Pipe[J]. Philos. Mag.,1927,20:208-223
[14]S.V. Patankar, VS. pratap and D.B. Spalding J. Fluid Mech.,1974,62(3):539-551
[15]Y Mori, W Nakayama. Study on Forced Convective Heat Transfer in Curved Pipes[J]. Heat and Mass Transfer,1967,10(2):37-59
[16]Y Mori, W Nakayama. Study on Forced Convective Heat Transfer in Curved Pipes[J]. Heat and Mass Transfer,1967,10(3):681-695
[17]李斌,何安定,周芳德.窄缝环形管内流动与传热实验研究[J].化工机械,2001,28(1)：43-47
[18]李隆键.螺旋管内对流传热过程及其强化[D]：[博士学位论文].重庆：重庆大学,2000
[19]孟勐,彭晓峰.蛇形管流动沸腾弯头处传热的非均匀性[J].工程热物理学报,2009,30(3)：448-500
[20]X.Chen, F.Zhou. Critical Heat Flux in Helical Coils. Heat Transfer Sump, Beijing,1985
[21]Xue-Jun Chen, Fang-De Zhou. Forced Convective Boiling and Post-Dry out Heat Transfer in Helical Coiled Tubes[J]. Heat Transfer,1986,5(8):2221-2226
[22]Haitao Hu et al. Heat transfer characteristics of refrigerant-oil mixtures flow boiling in a horizontal C-shape cured smooth tube[J]. International Journal of Refrigeration,2010,2
[23]H. Takamatsu et al. A correlation for forced convective boiling heat transfer of pure refrigerants in a horizontal smooth tube[J]. Heat Mass Transfer,1993,36(13):3351-3360
[24]崔文智,廖全等.R134a在螺旋管内的流动沸腾传热[J].重庆大学学报,2001,24(4)：118-121
[25]张小力.水平管内环状流动核心沸腾换热模型[J].工程热物理学报,2000,21(5)：633-636
[26]张小力.HFc-134a水平管内流动沸腾换热研究进展[J].华东工业大学学报,1996,18(2):19-26
[27]Koyama Sh, Yu J, Momoki S, et al. Forced convective flow boiling heat transfer of Pure refrigerants inside a horizontal micro fin tube.1995 International Conference on Convective Flow Boiling.137-142
[28]Lie jin Guo, Xue jun Chen, et al. Forced Convection Boiling Heat Transfer and Dry out Characteristics in Helical Coiled Tubes with Various Axial Angles[J]. Heat Transfer,1998,2(11):261-266
[29]陈剑波.低沸点工质水平管内流动沸腾传热研究[D]：[博士论文].上海：上海机械学院,1991
[30]纪海维.纯工质在水平管内流动沸腾换热特性的实验研究[D]：[硕士论文].西安：西安科技大学,2006
[31]孙宗保.R134a螺旋管内流动沸腾换热特性研究[D]：[硕士论文].山东大学,2007
[32]陈听宽,陈宣政.近临界压力两相流沸腾传热特性的研究[J].西安交通大学学报,2006,6(4)：45～50
[33]陈听宽,张文清,顾亚平等.垂直U型沸腾管传热恶化特性研究[J].工程热物理学报,1985,6(2)：154-159
[34]陈听宽,杨志华,王芊等.垂直U型管两相流流型和传热研究[J].化工学报,1985,36(4)：426-443
[35]毕勤成,陈听宽,田永生等.螺旋管内高压汽水两相流传热恶化规律的研究[J].西安交通大学学报,1996,30(5)：30-35
[36]陈听宽,李遏龙,郑建学等.水平放置U型管及V型管传热特性的试验研究[J].西安交通大学学报,1990,24(1)：65-72
[37]陈如冰,罗林,姚寿广.采用IPSA法对水平管内流动沸腾传热特性的分析[J].华东船舶工业学院学报,2003,7(1)：24-27
[38]王跃社,白博峰,Hiroshi HONDAZ水平微肋管内基于气液环状流流型的沸腾传热理论模型[J].工程热物理学报,2007,28(1)：177-180
[39]锅炉机组热力计算标准方法[M].北京锅炉厂设计科,译.北京：机械工业出版社,1976,47-75
[40]杨世铭,陶文铨.传热学[M].高等教育出版社,2007
[41]J.A. Grindley, A.H. Gibson. On the frictional resistance to the flow of air through a pipe[J]. Proc. R. Soc. London Ser. 1908,80:114-139
[42]J.Eustice. Flow of water in curved pipes[J]. Proc, R. Soc. London Ser.1910,84:107-118
[43]Shah R K, Joshi S D. Handbook of single-phase convection heat transfer [M]. New York: Wiley-Interscience,1987
[44]G. Hetsroni. Hand book of Multiphase System[M]. New York:Mc Graw-Hill Book Company,1982
[45]徐济錾主编.沸腾传热和气液两相流[M].北京：原子能出版社,1993
[46]顾红芳,孙丹,陈听宽.煤油和空气的混合流体水平管内沸腾换热实验研究[J].工程热物理学报,2001,22(5)：622-625
[47]陈听宽.两相流与传热研究[M].西安：西安交通大学出版社,2004,151-154
[48]Chen J C. A correlation for boiling heat transfer to saturated fluid in vertical flow[J]. Process Design and Development,1966,5(3):322-339
[49]Gungor K E, Winterton R H S. A general correlation for flow boiling in tubes and annuli.[J]. Heat Mass Transfer,1986,29(3):351-358
[50]Gungor K E, Winterton R H S. Simplified general correlation for saturation flow boiling and comparisons with data[J]. Chem. Eng Res. Des 1987,65(2):48-56
[51]Lin Z Winterton R H S. A general correlation for saturated two phase flow boiling in tubes and annuli, based on a nucleate pole boiling equation.[J]. Heat Mass Transfer,1991,34(11):2759-2766
[52]Wattelet J P. Evaporation characteristics of R112, R134a and a mixture at low mass flexes[J]. ASHRE Trans,1994,100(1):603-615
[53]Shah M M. Chart correlation for saturated boiling heat transfer:equation and further study[J]. ASHRE Trans,1982,88(1):185-196
[54]Shah M. A new correlation for heat transfer during boiling flow through pipes[J]. ASHRE Trans,1976, 82(2):66-86
[55]N. Kattan, J.R. Thome, D. Favrat. Flow boiling in horizontal tubes:Development of new heat transfer model based on flow pattern[J]. Trans. of the ASME, J. Hear Transfer,1998,120(3):156-165