【作者】 张志红；

【导师】 由世俊；

【作者基本信息】 天津大学 ， 供热、供燃气通风及空调工程， 2005， 硕士

【摘要】 伴随着我国能源政策与能源结构的不断调整,天然气将成为大中城市的重要能源品种,燃气型真空锅炉的应用将更为广泛。燃气型真空供热锅炉由于符合国家的环保政策,集多功能于一体,将会有广阔的应用前景。燃气型真空热水锅炉因具有热效率高、环保、运行安全可靠、安装位置不受限制、初投资少、运行费用低等优点,因而日益受到热用户的欢迎,在一些大中城市已逐渐替代传统的燃煤热水锅炉。真空热水锅炉是利用水在不同的压力下沸腾温度存在差异的特性来进行工作的,在真空锅炉的工作压力下,燃气燃烧使热媒水温度上升至饱和温度并在水面上产生相同温度的负压蒸汽,管内的冷水被管外的负压蒸汽加热成热水并通至用户处,而管外的水蒸汽则被冷却凝结成水滴落入水面,再被加热成蒸汽,从而完成整个循环过程。本课题以天大胜远中央空调有限公司开发的真空锅炉为研究对象,分析了真空锅炉的工作原理及传热特性,并通过实验测定,计算出真空热水锅炉热效率。研究内容包括燃气真空热水锅炉中燃料的燃烧过程,烟气向水的传热过程,水的沸腾传热过程,蒸汽与水通过换热器的传热过程。在这个循环传热过程中,通过对炉膛燃烧的数值模拟,再经过计算机求解控制微分方程组,便可以计算出燃烧器内部流体温度、浓度的分布及其变化,为燃烧装置的优化设计提供了计算依据。燃气真空锅炉中水的沸腾属于可润湿壁的水在大空间的沸腾换热,通过对沸腾换热基本机理的分析,给出大空间沸腾换热系数的计算式。而蒸汽与换热器中水的传热属于膜状凝结换热,可按层流膜状凝结换热公式计算出换热系数;并对管束外凝结换热的影响因素进行了分析。最后对炉膛、烟管、以及凝结换热管的传热进行了理论计算,对其结构设计进行了校核,并对真空热水锅炉热效率进行了实际测定,其热效率达到93%。更多还原

【Abstract】 With the continually innovation of the energy policy and energy structure of our country, the natural gas will become the primary source of energy in large and medium cities, the application of gas vacuum hot water boiler will be more extensive. Complying with the national environmental protection policy and having multi-functional, there will be a wide application prospect for the gas vacuum hot water boiler.Because of the high thermal efficiency, environmental protecting, safe and reliable operating, free erection site, little investment for the first time, and the low operating cost, the gas vacuum hot water boiler has gradually replaced the traditional coal-fired hot water boiler in some large and medium cities.Vacuum hot water boiler utilizes phase change principle to operate. Under the operating pressure, which is below atmospheric pressure, hot medium water is boiled. The supplying water is heated by steam in boiler, and is sent to users. Hot medium water is condensed into boiler to complete this cycle process.This thesis has researched the vacuum hot water boiler, which is developed by Shengyuan Central Air-conditioning CO., LTD affiliated with Tianjin University, analyzed the operation principle and heat transfer characteristics of it, calculated the vacuum hot water boiler thermal efficiency, and done the experimental study. This research includes the process of fuel combustion, the heating transfers process of water in boiler. Through the CFD simulation, the distribution of temperature inside the boiler was obtained. This study results will guide the design of gas vacuum hot water boiler.The heat transfer in the gas vacuum hot water boiler is large space boiling. The coefficient of heat transfer in boiling is calculated, through the analysis of principle of heat transfer in boiling. The process of water heat transfer in heat exchanger is film condensation heat transfer, and the condensation coefficient of heat transfer is gotten by the formula of laminar film condensation heat transfer. The effective factors of condensation heat transfer outside the tubes are analyzed. Finally, the process of heat transfer is calculated in the furnace, smoke tube and condensation heat transfer tube, and the design of construction is checked out. In the experiment, the thermal efficiency of this boiler is up to 93%.更多还原