在柴油机试验车间设计中,高温废气流的排放形式,已直接影响到产品的出厂试验、车间的劳动保护、工人的健康。因此,如何合理地进行排气系统的设计,已成为工艺和通风设计人员面临的一个重要课题。柴油机制造厂试验车间进行产品出厂试验时,由于产量大,同时试验的台位可多达十几个以上,车间规模就较为庞大。所产生的大量高温废气流,必须通过一个排气系统汇集后排入室外高空,才能保证试验工作的顺利进行。对于一台四冲程柴油机来说,它的排气过程,是在排气阀从下死点前35～70度时开启直到上死点后20～30度时关闭这一段时间间隔内完成的。整个排气过程可以分为下述三个阶段。从排气阀打开时起,到活塞达到下死点时为第一阶段排气。这时,柴油机气缸内的压力达到3～ In the diesel engine test shop design, the discharge form of high-temperature exhaust gas has directly affected the product’s ex-factory test, workshop’s labor protection, and worker’s health. Therefore, how to reasonably design the exhaust system has become an important issue faced by process and ventilation designers. When the diesel engine factory test factory carries out the product ex-factory test, due to the large output, the number of benches that can be tested at the same time can be as many as a dozen or more, and the workshop scale is relatively large. The large amount of high-temperature exhaust gas flow generated must be collected and discharged into the outdoor sky through an exhaust system to ensure the smooth progress of the test work. For a four-stroke diesel engine, its exhaust process is completed when the exhaust valve is opened from 35 to 70 degrees before bottom dead center and closed at 20 to 30 degrees after top dead center. The entire exhaust process can be divided into the following three stages. From the time when the exhaust valve is opened, the first stage of exhaust is performed when the piston reaches the bottom dead center. At this time, the pressure in the cylinder of the diesel engine reaches 3~