Differences Between LNG and CNG Engines
2 Answers
The differences between LNG and CNG engines are as follows: 1. Different methods of storing natural gas fuel: CNG is stored under high pressure, while LNG is stored at low temperatures. CNG is stored in high-pressure steel cylinders or steel-lined hoop-wrapped cylinders with a working pressure of 20 MPa, whereas LNG is stored in vacuum-insulated cryogenic containers at -162°C. The different storage methods result in different usage scenarios. 2. Different safety precautions: The primary protection for CNG cylinders is to prevent explosions caused by stress corrosion, while for LNG, the focus is on preventing collisions in accidents that could lead to explosions of low-strength cryogenic tanks. Additionally, precautions must be taken to avoid frostbite from leaks and to prevent excessive pressure buildup in storage tanks during prolonged parking, which could cause the safety valve to release natural gas. Measures should also be taken to address the potential decline in vacuum effectiveness over long-term use of storage tanks.
From a technical perspective, the main difference between LNG and CNG engines lies in fuel storage. LNG stands for liquefied natural gas, which requires a temperature of -162 degrees Celsius to maintain its liquid state. It has a smaller volume but more complex storage tanks, making it suitable for long-distance vehicles like trucks, as one tank can cover a greater distance. CNG is compressed natural gas, stored simply as a high-pressure gas, with simpler tanks, making it ideal for urban cars or bus systems. The engines themselves both operate by igniting natural gas, with similar working principles, but LNG systems include additional cooling units, making maintenance more troublesome and prone to failure points. In terms of safety, LNG's low-temperature tanks pose leakage risks, while CNG's high-pressure tanks must guard against explosions, each presenting its own challenges. Personally, I believe these differences significantly impact vehicle range and power output, and the choice between them depends on the intended driving distance.
