Core Insights - The economic landscape of the North China region is undergoing significant transformation driven by the dual engines of coordinated development in the Beijing-Tianjin-Hebei area and an energy revolution, with the total GDP of the top 15 cities surpassing 7.8 trillion yuan, reflecting a year-on-year growth of 5.6% [1] Group 1: Economic Performance - Tangshan ranks third in North China with a GDP of 420.8 billion yuan, continuing its strong development as an industrial hub [2] - Handan has surpassed the provincial capital of Taiyuan with a GDP of 312.6 billion yuan, challenging the traditional notion that provincial capitals lead regional development [2] - Lüliang has achieved an impressive growth rate of 19.8%, emerging as a significant winner in the energy revolution [2] Group 2: Economic Structure and Growth Rates - The 15 leading cities exhibit a clear three-tiered structure, with Beijing (1.98 trillion yuan) and Tianjin (1.14 trillion yuan) in the first tier, while Tangshan and Shijiazhuang (368.2 billion yuan) are in the second tier [3] - Seven cities have outpaced the national average growth rate, with Lüliang (19.8%), Ordos (18.2%), and Baotou (15.6%) leading the way [3] - Four cities are experiencing growth rates below 4%, highlighting regional disparities [3] Group 3: Industrial Transformation - Tangshan's economic strength is attributed to the upgrade of traditional industries and the cultivation of emerging sectors, with significant projects like the high-end automotive sheet production line and hydrogen metallurgy project contributing to a 22% profit increase in the steel industry [4][6] - Handan's economic resurgence is driven by deep optimization of its industrial structure, with projects like the Great Wall Motors engine project and the "retreat to the park" strategy enhancing product value and boosting manufacturing tax revenue by 18% [9][12] - Lüliang's growth is fueled by a reevaluation of its energy sector, with projects in hydrogen energy and new materials significantly increasing the value added of strategic emerging industries by 67% [13][15] Group 4: Future Outlook - The GDP rankings of the top 15 cities in North China reflect new trends in regional economic development, with Beijing maintaining its lead but experiencing a slowdown in growth to 4.1% [16] - The "Hebei Iron Triangle" formed by Tangshan, Shijiazhuang, and Handan showcases strong potential for coordinated development [16] - The competition among cities is intensifying, with energy cities like Ordos and Baotou achieving rapid growth, while Taiyuan needs to accelerate its industrial transformation to remain competitive [16][19]

市面上销售的民用车发动机技术路线可以说五花八门，如自吸发动机有的是缸内直喷，而有的是歧管喷射，有的带VVT，有的只有可变进气阀 门。另外还有如涡轮增压、水冷中冷、EGR等不同技术的机型。那么EGR是什么技术，有什么好处呢？ 什么是EGR，为什么需要EGR？ EGR全称Exhaust Gas Recirculation，翻译过来叫作废气再循环，其作用是把发动机排出的一部分废气重新送到进气道，并在汽缸内进行二次燃 烧。 为什么需要EGR呢，其原因在于排放法规的限制以及发动效率的提升。人为活动排放的NOx，大部分来自化石燃料的燃烧过程，如汽车、飞机内 燃机的排放。由于内燃机在工作时，缸内及排气管均为高温高压富氧的环境，会产生较多的氮氧化物（NOx）。常见的包括一氧化二氮（N2O）、一 氧化氮（NO）、二氧化氮（NO2）、三氧化二氮（N2O3）、四氧化二氮（N2O4）和五氧化二氮（N2O5）。而NOx对环境的损害作用极大，它既是 形成酸雨的主要物质之一，也是形成大气中光化学烟雾的重要物质。 EGR大致分为内部EGR和外部EGR实现废气再循环。内部EGR系统利用凸轮轴与可变气门，通过提前开启进气阀，将废气巧妙地引入进气 ...