【作者】 李林；

【导师】 臧子璇；

【作者基本信息】 重庆大学 ， 供热、供燃气、通风及空调工程， 2015， 硕士

【摘要】 随着拉萨市城市燃气的发展和天然气供应工程的日益完善,越来越多的拉萨地区居民将会使用燃气灶具。但是,拉萨市位于青藏高原中部,海拔3650m,年平均大气压力65.23k Pa,空气稀薄,空气中含氧量低,特殊的使用环境将会对燃气用具的使用产生诸多影响。市面上的天然气灶具多是针对平原地区使用环境,按照额定压力为2000Pa进行设计的。通过在拉萨市当地对这类灶具的性能测试发现:按照2000Pa的额定压力供气,灶具的热负荷明显偏低,甚至无法满足居民的正常使用要求。如果简单采取改变喷嘴直径的方式对热负荷进行调整,虽然可以解决灶具的热负荷偏低的问题,但可能会造成一次空气量不足,烟气中CO含量偏高的问题。关于高海拔对燃气用具热负荷的影响,有学者提出可通过提高燃具前供气压力的方法来消除此影响。根据CJJ 12-2013《家用燃气燃烧器具安装及验收规程》,拉萨地区天然气燃具前的供气压力宜为2800Pa。本文对一台针对平原地区供气压力设计的燃气灶在拉萨当地进行实地性能测试,分析不经过结构上的任何改变,只通过提高燃具前额定供气压力,灶具直接在拉萨地区使用的可能性。通过在拉萨市的实地性能测试分析发现,针对平原地区设计的燃气灶在拉萨使用时,灶前供气压力提高到2800Pa后,灶具的实测热负荷大于3.5k W,基本能够满足居民正常使用的要求,但其低氧环境却会促使烟气中的CO生成。采取提高过剩空气系数的措施可能是解决拉萨地区燃气灶具烟气中CO体积分数偏高的主要手段。为此,本文针对拉萨地区的使用环境对不同锅支架高度下燃气灶的燃烧工况进行了数值模拟,分析了锅支架高度与灶具的热效率和烟气中CO含量的关系,给出了能够满足烟气中CO含量不超标的同时又有较高热效率的锅支架高度范围。更多还原

【Abstract】 With the improvement of the gas pipeline network construction in Lhasa, more and more local residents will use natural gas stove. But Lhasa is located in the central of Tibet Plateau, Where the altitude is 3650 m and the average atmospheric pressure is only 65.23 k Pa. With thin air, low oxygen in the air, the special geographical and climatic conditions would have a negative impact on the use of gas appliances.As gas stoves on current market mostly be designed in accordance with normal gas pressure of 2000 Pa in plain areas. Test results of gas stove in accordance with normal gas pressure of 2000 Pa in Lhasa area show that the heat load is significantly lower, and even unable to meet the daily requirements of local residents. To solve the impacts of altitude on the gas stove heat load, gas appliance manufacturers tend to adopt the way of changing the diameter of the nozzle to adjust the heat load, this approach will not only significantly increase the production cost of manufacturers, but may also affect the combustion conditions of the gas stove, resulting in a lack of air volume and high CO content in the flue gas.On the effects of altitude on gas appliances heat load, some scholars have suggested to eliminate this influence by increasing upstream gas pressure of gas stove. According to the CJJ 12-2013 "Regulation of domestic gas burning appliances installation and acceptance", upstream gas pressure of gas stove in Lhasa area is appropriate for 2800 Pa.So in this paper, a gas stove designed for the nominal pressure in plain areas has been tested to analysis the possibility that without any structural change, just by elevated gas pressure conditions, the test stove direct used in Lhasa area.The test results show that when the gas stove designed for the plain areas been tested in Lhasa, by increasing the upstream gas pressure to 2800 Pa, the measured thermal load is larger than 3.5k W, and can basically meet the requirements of local residents’ normal use. High altitude environment conducive to the improvement of the thermal efficiency of the stove, but its hypoxia environment will lead to the generation of CO in the flue gas. It’s maybe the main means by increasing the excess air ratio to solve the high volume fraction of CO in flue gas in Lhasa. For this reason, numerical simulation of combustion under different pot support height has been performed in the last part of this paper, and the relationship between pot support heights and the heat load and volume fraction of CO in flue gas have been analyzed. According to the analysis result, pot support height range that able to meet the CO content of the flue gas is not excessive and with a higher thermal efficiency has been given at the same time.更多还原