共查询到18条相似文献,搜索用时 156 毫秒
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搭建了以泡沫铜翅片换热器为核心的烟气水分回收实验台,研究了冷却水进口温度、烟气雷诺数及烟气中水蒸气体积分数对该换热器水回收特性和换热特性的影响,基于实验数据,利用多元回归拟合得到对流换热的关联式,其预测值与实验值误差在6%以内。结果表明:水蒸气体积分数增大可以显著提升水回收特性,而冷却水进口温度及烟气雷诺数对其影响很小;冷却水进口温度与烟气雷诺数对换热效率的影响较大,冷却水进口温度与换热效率成反比,烟气雷诺数与之成正比,而水蒸气体积分数对其影响较小;实验获得的最大冷凝水产率为7.68 kg/h,最大冷凝率为56.94%,最大换热效率为96.95%。 相似文献
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天然气锅炉极限热效率及排烟热损失分析 总被引:4,自引:0,他引:4
以陕北天然气为例,在对锅炉各项热损失进行分析的基础上,给出了不同排烟温度下,水蒸气汽化潜热在锅炉排烟热损失中所占的份额大小。并指出,若采取措施将烟气中的潜热加以回收利用,可大幅度提高锅炉的热效率。对于陕北天然气,如果排烟温度降到40℃,烟气中水蒸气汽化潜热的70%可得到回收,锅炉热效率将比排烟温度为180℃~250℃的传统锅炉提高13.5%~16.6%。冷凝式锅炉的热效率提高潜力主要取决于燃料种类、锅炉本体的排烟温度、工艺流体的温度、所需的低品位热能的数量、过量空气系数等。 相似文献
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烟气对流凝结换热强化和换热表面防腐是天然气热能动力设备烟气余热回收利用关键技术。不同防腐表面耐腐蚀性能不同,且换热性能也不同。采用CCD高速摄像仪,对烟气在新型复合防腐表面上的凝结形态和凝结过程进行了可视化观测和换热实验研究,采用对图像边缘提取法,获得凝结液的边缘曲线。研究表明,烟气在新型复合防腐表面上的凝结为珠状凝结,凝结液珠最大粒径为0.2~0.28 mm,与其他表面形成的膜状凝结相比,在实验范围内,珠状凝结换热可提高约7倍。为增强烟气对流凝结换热和开发烟气冷凝余热回收利用技术提供了参考和依据。 相似文献
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燃气锅炉烟气余热回收实验分析 总被引:10,自引:2,他引:8
通常燃气锅炉的排烟温度较高 ,一般在 16 0~ 2 4 0℃。所排烟气中含有不凝结气体和水蒸气 ,过热状态的水蒸气是烟气中热量的主要携带者。文章分析了烟气成分、换热机理 ,通过实验证明了降低锅炉的排烟温度回收烟气中水蒸气的显热和潜热 ,不仅提高了锅炉的热效率 ,同时凝结液也回收了烟气中部分酸性气体 ,因此具有节能与环保的双重功效 相似文献
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高水分烟气对流冷凝换热模拟实验研究 总被引:9,自引:2,他引:9
针对冷凝式燃气锅炉,利用加湿热空气模拟燃气锅炉尾部烟气,通过实验研究了不凝性气体占多数时的水蒸气冷凝换热,研究了不同水蒸气分压比(3%—20%)、不同温度下(100—200℃),加湿空气的冷凝换热特性。实验表明,不凝性气体(空气)占多数时,其对流冷凝复合换热系数可以达到无冷凝时干空气对流换热系数的1.5-3倍。复合换热系数的影响因素主要有水蒸汽分压力Pv、Pe、Pr以及壁面温度Tw和混合气体主流温度Tg,在此基础上建立一个新的准则数Ln并拟合了冷凝换热Nu数的准则关系系。 相似文献
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《节能技术》2018,(6)
为了研究烟气中水蒸气在陶瓷膜管内的热、质传递规律,通过烟气在单根陶瓷膜管内的对流凝结换热实验,研究了不同烟气参数(流量、温度和相对湿度)和冷却水流量对烟气对流凝结Sherwood数、烟气对流凝结Nusselt数和烟气显热、潜热换热量的影响。实验结果表明:烟气对流凝结Sherwood数、Nusselt数随烟气流量、温度和相对湿度的增加而上升,Sherwood数随冷却水流量增加基本不变,Nusselt数随冷却水流量增加显著上升;烟气潜热换热量与烟气对流凝结Sherwood数呈相同变化趋势,烟气显热换热量随烟气相对湿度、冷却水流量增加而上升,烟气流量大于10 L/min时,烟气显热换热量增长趋于平缓,烟气温度对烟气显热换热量没有影响。研究结果对于陶瓷膜在电厂实际烟气中应用具有指导意义。 相似文献
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Kyudae Hwang Chan ho Song Kiyoshi Saito Sunao Kawai 《Applied Thermal Engineering》2010,30(17-18):2730-2737
In general, latent heat recovery is usually accompanied by the corrosion of the heat exchanger, which is caused by the strongly acidic condensate when the temperature of the flue gas is lowered below the acid dew point. The present study has been conducted to investigate the heat and mass transfer characteristics in a titanium heat exchanger with excellent corrosion resistance used for waste heat recovery with the condensation arranged in a gas fired water heater. In addition, the thermal efficiency of the gas fired water heater was evaluated based on the net calorific value at the maximum rated output during latent heat recovery from the exhaust flue gas. Parametric studies were conducted for the flue gas flow rate, inlet temperature and mass flow rate of the supplied water, respectively. Different arrangements of the tubes of the heat exchanger including in-line and staggered configurations were investigated. The experimental results indicate that the thermal efficiency of the gas fired water heater with a latent heat recovery (LHR) heat exchanger was enhanced by about 10% compared with conventional instantaneous water heaters, i.e., water heaters without heat recovery. In addition, in terms of the Nusselt number and the Sherwood number, the heat and mass transfer performance of the staggered tube bank type were approximately 50% and 10% higher than that on the in-line tube bank type when the Reynolds number of the flue gas was 103. 相似文献
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A heat pipe heat exchanger (HPHE) was used to investigate the heat transfer performance of steam-air mixture condensation, analogous to the dew condensation of flue gas, when the steam volume fraction ranged from 0 to 20%, and the inlet temperature of steam-air mixture varied from 70 to 120°C. Self-assembled monolayers (SAMs) treatment with n-octadecyl mercaptan was adopted to modify the condensation surface of the heat pipe. The comparisons were conducted to examine the influence of SAMs on condensation heat transfer of steam-air mixture vapor. The results indicate that the convection condensation heat transfer coefficient increases with the increase of steam volume fraction and Re number of the steam-air mixture. As the inlet temperature increases, the heat transfer coefficient decreases accordingly. The heat transfer performance can be improved by the SAMs surface, with a heat transfer enhancement ratio up to 1.6 at a condition of 20% of the steam volume fraction and 1500 Re number. 相似文献
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锅炉高温对流受热面进出口烟温软测量方法 总被引:3,自引:0,他引:3
在已知高温对流受热面进出口平均工质温度的条件下 ,基于锅炉局部热量平衡的原理 ,提出并验证了一种计算该段受热面进 (出 )口平均烟温方法 ,对计算误差进行了分析。在不具备测量高温烟气温度的可靠手段时 ,能够比较准确地估算对流烟道中的高温烟气温度。 相似文献
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Kwangkook Jeong Edward K. Levy 《International Journal of Heat and Mass Transfer》2012,55(25-26):8010-8019
Prediction of acid condensation has a critical role in designing heat exchangers to recover water vapor from power plant flue gas. Rates of mass transfer for condensation of sulfuric acid vapors onto heat exchanger tubes were theoretically investigated and a computer program for numerical simulations of sulfuric acid (H2SO4) condensation in a flue gas condensing heat exchanger was developed. Governing equations based on mass and energy balances for the system were derived to predict variables such as flue gas exit temperatures, cooling water outlet temperatures, and molar fractions and condensation rates of water and sulfuric acid vapors. The associated equations were solved using an iterative solution technique and a one dimensional finite difference method with forward differencing. The Controlled Condensation Method (EPA Method 8B) was applied to experimentally obtain concentration profiles of sulfuric acid vapor in flue gas along downstream in the system. Predicted results of sulfuric acid vapor condensation were compared with empirical data for model validation, and the discrepancy is analyzed in terms of measurement and computation uncertainties. It is found that from both modeling and test results sulfuric acids as well as water vapors are reduced and separated in condensing heat exchanger due to mass transfer with condensation in flue gas. The modeling methodology described here is applicable to theoretical prediction of sulfuric acid and water condensation in full scale flue gas condensing heat exchanger applications. 相似文献
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An experimental system investigating condensation heat transfer of wet flue gas was set up, and the heat transfer performance of vapor‐gas mixture with vapor condensation was discussed. The experimental results of laminar flow in a plastic longitudinal spiral plate heat exchanger were obtained and are in good agreement with the modified classical film model. It is shown that the plastic air preheater can avoid acid corrosion in the low‐temperature field for the boiler using fuel containing sulfur and recover latent heat of the water vapor of the wet flue gas. Also some SO2 was scrubbed during the vapor condensing process in the heat exchanger. © 2001 Scripta Technica, Heat Trans Asian Res, 30(7): 571–580, 2001 相似文献
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针对果蔬预冷设备应用场合,提出并设计了一套以冰浆作为载冷介质的湿冷热湿交换器,并搭建单体性能测试台架,以出风温度和相对湿度为指标,通过改变填料类型(金属、纸质填料)、载冷介质种类(冰浆、冷水)和喷淋流量进行了性能实验研究。结果表明:实验工况下,金属填料的换热性能较纸质填料好;以冰浆作为载冷介质相比以冷水的情况,可以获得更低的出风温度,但出风相对湿度也有所降低;随着进风干球温度的降低,出风温度明显降低,而出风相对湿度变化并不明显;在一定范围内,提高载冷介质的喷淋流量,有利于湿冷热湿交换器出风温度的降低和出风相对湿度的升高;低浓度的冰浆可以在湿冷热湿交换器中稳定运行,且降温效果较冷水湿冷热湿交换器更加明显,虽然相对湿度略有下降但仍然可保持在90%左右,适用于果蔬预冷和保鲜。 相似文献