The objective of this dissertation is to conduct on theorical analysis and calculation upon flow boiling heat transfer inside horizontal smooth and microfin tube of r290 and r404a , which are newly environmental replacements of r22 研究了文献中的几个通用性较好的光管、内螺纹管沸腾换热系数计算关联式，并深入分析了各内螺纹管沸腾换热系数关联式的联系与区别。
The type of heat transfer inside the pipes belongs to single - phase compulsive turbulent flow of inner pipe . inner trachea is a kind of special pipe compared by smooth pipe , which can strengthen heat transfer inside pipe 空预器烟气侧的换热类型是管内单相强迫紊流换热，论文在查阅了相关文献的基础上，比较了几种不同的管内强化换热措施，在其中选择内螺纹管代替光管，来改造管式空气预热器。
Abstract : this paper analyzes theoretically the effect of the reversed cone angle and length of the plug on restraint and elimination to the distortion of the internal spiral ribs , and put forth the design methods of the plug in drawing rifled tube 文摘:从理论上分析了芯棒倒锥角和芯棒长度对内螺旋凸筋形状畸变的抑制和消除作用，提出了采用倒锥形等螺距芯棒拉拔内螺纹管时芯棒几何参数的设计方法。
Besides , our company also produce " mech " brand malleable iron , gray iron , ductile iron , bronze threaded pipe fittings with american standard , din standard and british standard , steel pipe nipples , red brass nipples , stainless steel nipples and other casting products , with annual output of 70 , 000 tons . the sales revenue in year 2002 reaches rmb430 million , including export revenue usd40 million and profit rmb120 million which has created a miracle in china " s casting industry 我公司还生产迈克牌英美和德制玛钢灰铁球铁和青铜螺纹管件，钢管接管接头，铜接管接头，不锈钢接管接头，和其他铸造产品，年生产能力7万吨2002年度实现销售收入4 . 3亿元，其中自营出口4000万美元，利税1 . 6亿元，利润1 . 2亿元，在中国同行业中创造了奇迹。
Thome correlation has good precison in calculating heat transfer coefficients of r404a inside horizontal microfin tube . 3 . the analyses on different empirical formulations of in - tube boiling heat transfer coefficients indicate that r404a can be treated as pure refrigerant during calculating its the in - tube boiling heat transfer coefficients 对近共沸混合工质r404a ，通过对光管和内螺纹管沸腾换热系数关联式的分析计算得出结论：在计算r404a的光管和内螺纹管沸腾换热系数时可以被作为纯质来处理。
There are a lot of advantages when inner trachea applied in air pre - heater , such as the improvement of the temperature of pipe , the low consumption of metal , except for the increment of flow resistance . according to many related papers , it is more proper inner trachea with the structure of short distant between two whorls and shallow depth of whorl . it can enhance heat transfer with smaller flow loss 内螺纹管是一种异形管，和光管相比，管内侧的换热系数大大增强了，应用于空气预热器可以起到提高总传热系数、节约受热面金属消耗量的目的；同时提高了管壁温度，能够减轻低温腐蚀的程度和速度；不足之处是带来了更大的阻力损失。
Taking some tubular air pre - heater used in one boiler whose capacity is 130 t / h as an example , new blue print with inner trachea is completed by means of computer program . several key design variables may be changed , such as diameter of pipe and velocity of flow of gas . these cases have been considered , and their results have also been compared with each other 比较了几个重要的设计变量，如外管径、烟气流速等参数变化时，总传热系数和空预器本体管子总重量，阻力损失以及最低管壁温度等几个重要设计结果的变化趋势，对内螺纹管空气预热器的设计具有借鉴意义；其间还分析了内螺纹管与光管在设计时的不同之处；最后，初步分析了内螺纹管的优化设计问题，提出了一些建议。
Besides , our company also produce " mech " brand malleable iron , gray iron , ductile iron , bronze threaded pipe fittings with american standard , din standard and british standard , steel pipe nipples , red brass nipples , stainless steel nipples and other casting products , with annual output of 70 , 000 tons . the sales revenue in year 2002 reaches rmb430 million , including export revenue usd40 million and profit rmb120 million which has created a miracle in china " s casting industry . " mech " brand products sell well all over the world and enjoy an excellent reputation among our customers 我公司还生产迈克牌英美和德制玛钢灰铁球铁和青铜螺纹管件，钢管接管接头，铜接管接头，不锈钢接管接头，和其他铸造产品，年生产能力7万吨2002年度实现销售收入4 . 3亿元，其中自营出口4000万美元，利税1 . 6亿元，利润1 . 2亿元，在中国同行业中创造了奇迹。
Lockhart & martinelli pressure drop correlation is studied , and at the same time , based on the experimental data collected , the accuracy of this formulation is examined . 6 . the evaluating method on intensifying heat transfer performance in microfin tube is provided , and by this method the performance of r290 and r404a is investigated 研究了通用性较好的lockhart & martinelli摩擦压降关联式，同时将r290和r404a的管内沸腾换热压降实验数据与关联式计算值进行了比较，结果显示：此关联式对r404a的光管和内螺纹管沸腾换热摩擦压降有良好的预测精度，而且对于r290的光管沸腾换热摩擦压降有良好预测精度。
Various successive partial plastic forming methods for processing groove , including thread rolling , cross rolling and skew rolling , splitting , rolling of spline shaft , split rolling , open - die extrusion of spline shaft / gear , extrusion of internal screwed tooth socket parts with large helical pitch , integral cold forging for slot commutator , extrusion - ploughing for outside fin tube , drawing of tube with spiral internal / external ribs etc . have been introduced briefly 摘要介绍了用于加工槽的各种连续局部塑性成形方法，包括螺纹轧制、横轧与斜轧、分劈、花键轴滚轧、劈分轧制、花键轴齿轮开模挤压、花键套挤压、槽型换向器整体冷锻、外翅片管挤压一犁削、内外螺纹管拉拔等。
