不锈钢表面多孔换热管制备与传热性能试验研究

发布时间：2018-03-16 01:22

  本文选题：304不锈钢粉末　切入点：粉末烧结　出处：《华东理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：304不锈钢管由于具有优良的耐腐蚀性能而被广泛应用于沸腾传热设备中,其换热效率对热交换器的工作效率有着很大影响。表面沸腾强化管能够有效提高沸腾传热系数、降低沸腾所需过热度,这为沸腾传热设备的性能升级带来巨大潜力;碳钢管以及铜合金表面沸腾强化管工在业上较为常见,而不锈钢材质的表面多孔管却很少见到,因而对不锈钢表面多孔管进行研究开发具有十分重要的科研以及工程价值。本文将从以下两个方面展开:(1)提出制备不锈钢表面多孔换热管并制定其烧结方案,通过试验优化不锈钢内表面多孔烧结结构以确定最佳制备工艺:为确定不锈钢表面多孔层烧结工艺参数,通过改变粉末类型、粒径、以及烧结气氛等因素,在不同烧结温度下分别进行了烧结试验,实验结果表明:烧结气氛是决定烧结结构以及母材性能的关键因素,真空烧结可以保证烧结过程的顺利进行;随着烧结温度的升高,烧结时间的延长,烧结结构的结合强度升高,而孔隙率呈现急剧下降趋势;粉末粒径不是影响孔隙率的主要因素,但是孔隙的当量直径随着粒径的增大有变大的趋势,而混合粒径的粉末得到的烧结结构能够得到孔隙当量直径分布较宽的烧结结构;确定了不锈钢表面多孔管最佳烧结工艺:采用真空烧结,在烧结温度1000℃～1020℃下保温15min左右,得到的烧结结构孔隙率约在30%～60%,剪切结合强度不低于1.5 KN/mm;(2)制备工业用不锈钢表面多孔换热管并对其传热性能进行分析:自主搭建了沸腾传热试验试验设备,采用表面张力较小的甲醇水溶液作为管内沸腾工质对在最佳烧结工艺下得到的烧结多孔管进行了沸腾试验,试验结果表明:在相同的沸腾温差下,烧结强化管的沸腾传热系数可达光管的1.6～2倍左右;相同的总温差下,烧结强化管的热流密度是光管的1.4～1.6倍;相同温差下,烧结强化管的总传热系数为光管的1.4～1.6倍,这说明烧结多孔管能够有效提高换热性能。
[Abstract]:304 stainless steel tube is widely used in boiling heat transfer equipment because of its excellent corrosion resistance. The heat transfer efficiency of 304 stainless steel tube has great influence on the working efficiency of heat exchanger. Reducing the superheat required for boiling has great potential for upgrading the performance of boiling heat transfer equipment. Surface boiling enhancement of carbon steel pipes and copper alloys is more common in industry, but porous tubes with stainless steel surfaces are rarely seen. Therefore, the research and development of the porous tube on the surface of stainless steel has very important scientific research and engineering value. In order to determine the sintering parameters of the porous layer on the stainless steel surface, the powder type, particle size and sintering atmosphere were changed to determine the optimum preparation process by optimizing the porous sintering structure of the inner surface of the stainless steel. The sintering experiments were carried out at different sintering temperatures. The results show that the sintering atmosphere is the key factor to determine the sintering structure and properties of the base metal, and vacuum sintering can ensure the smooth sintering process with the increase of sintering temperature. With the prolongation of sintering time, the bonding strength of sintered structure increases, while the porosity decreases sharply, the particle size of powder is not the main factor affecting porosity, but the equivalent diameter of pore increases with the increase of particle size. The sintered structure of the powder with mixed particle size can obtain the sintered structure with wide pore equivalent diameter distribution, and the optimum sintering process of the porous tube on the surface of stainless steel is determined as follows: vacuum sintering is adopted, and the sintering temperature is 1000 鈩，

本文编号：1617711