**1. Discussion on the Reasons Why Natural Gas Vehicles Are Safer Than Gasoline Vehicles** Natural gas vehicles (NGVs) have long been regarded as safer alternatives to traditional gasoline-powered vehicles, and this sentiment is backed by several key factors. Firstly, the ignition point of natural gas is significantly higher than that of gasoline. Natural gas, with its ignition temperature typically above 650°C, is far more resistant to ignition compared to gasoline, which has an ignition point of around 427°C. This inherent property of natural gas makes it less prone to accidental ignition, thereby enhancing the overall safety of NGVs. Secondly, the density of natural gas, specifically methane (CH4), is significantly lower than air, with a relative density of 0.48. This low density allows any leaked gas to quickly dissipate into the atmosphere, minimizing the chances of accumulation to a hazardous level. On the contrary, gasoline is heavier than air and can accumulate in enclosed spaces, increasing the risk of an explosion or fire. Additionally, the flammability range of natural gas in air is narrow, limited to a concentration of 5% to 15%. This means that it is difficult to achieve a mixture with enough gas to sustain a fire or explosion in a typical environment. Gasoline, on the other hand, has a wider flammability range, making it more dangerous. Lastly, modern NGVs are equipped with advanced safety features such as dual fuel leak detectors and stringent quality controls for CNG cylinders. These features further reduce the risk of accidents and ensure the safe operation of NGVs. In conclusion, the higher ignition point, lower density, narrower flammability range, and advanced safety features of natural gas make NGVs a safer choice compared to gasoline-powered vehicles. **2. Discussion on the Names and Working Principles of Three Power Forms of Natural Gas Vehicles** Natural gas vehicles (NGVs) primarily operate on three main power forms: Compressed Natural Gas (CNG), Liquefied Natural Gas (LNG), and Liquid Petroleum Gas (LPG). Let's delve into the names and working principles of these power forms. Firstly, Compressed Natural Gas (CNG) involves compressing natural gas to a pressure of 200-250 bar for storage in tanks. When the engine needs fuel, the CNG is released from the tank, regulated to a lower pressure, and mixed with air before being ignited by the spark plugs. The compressed state of CNG allows for higher energy density, making it suitable for long-distance travel. Secondly, Liquefied Natural Gas (LNG) is natural gas that has been cooled to approximately -162°C, turning it into a liquid. This process significantly reduces the volume of natural gas, allowing for more efficient storage. LNG is stored in cryogenic tanks and, upon reaching the engine, is heated and vaporized before being mixed with air and ignited. LNG-powered vehicles offer longer ranges compared to CNG vehicles due to the higher energy density of LNG. Lastly, Liquid Petroleum Gas (LPG), though not pure natural gas, is often used as an alternative fuel in NGVs. LPG is a by-product of oil refining and consists mainly of propane and butane. It is stored as a liquid under moderate pressure and is vaporized for use in the engine. LPG-powered vehicles operate similarly to gasoline-powered vehicles, with LPG being mixed with air and ignited by spark plugs. LPG offers similar safety benefits to CNG and LNG due to its higher ignition point and lower density. In summary, CNG, LNG, and LPG are the three main power forms used in natural gas vehicles. Each has its unique advantages, but all offer safer and more environmentally friendly alternatives to traditional gasoline-powered vehicles.
