Automakers such as Hyundai, Kia, and Toyota, are adamant that combustion engines that burn hydrogen instead of gas or diesel are a viable clean alternative to fossil fuels and EVs. However, fuel-injector performance is critical in hydrogen-burning engines, and it’s difficult to keep them clean, lubricated, and properly cooled. To that end, Hyundai recent filed a patent with the European Patent Office that proposes a new way to lubricate and cool hydrogen injectors.
The Problem With Hydrogen Injectors
In normal gas engines, fuel injectors atomize the fuel by injecting it into the combustion chamber at high pressure. Typically, the flow of the fuel helps cool the injector, keeping it within operating temperature, while a little bit of oil can be introduced to lubricate it. Combustion engines that burn hydrogen also have injectors, but it’s more difficult to keep them cool and lubricated.
Increased friction accelerates wear and generates heat, reducing the injector’s service life. Introducing oil is perilous, because it causes carbon deposits in the injector, particularly around the injector tip. This is a problem in a hydrogen engine, which is more sensitive to the precise operation of the injectors, and even tiny coking deposits due to oil droplets can lead to engine-damaging pre-ignition because of the low ignition limit of hydrogen fuel.
Solution: Self-Contained Nitric-Acid Injector Lubrication
Hyundai’s patent solves this problem based on the deposit-removing and lubrication qualities of nitric acid. The system has an extraction and separation device that collects a portion of two of the combustion byproducts – water and nitrous oxide, or NOx. A reactor connected to the extraction and separation device generates nitric acid by combining the water and dried exhaust gasses, creating nitric acid that’s introduced into the injector to lubricate and cool it.
Advantages
- Self-contained, using continuously generated onboard resources
- Not dependent on any external lubrication
- Keeps the injectors thermally stable and clean
- Maintains precise and efficient hydrogen injection and combustion
- Prevents pre-ignition
Disadvantages
It requires various parts:
- Separator
- Extractor
- Reactor with heating elements
- Condenser
- Water and nitric acid pumps
- Water tank
- Flow-control valve
It is, therefore, a fairly complex system, and the parts add weight and cost, but if Hyundai can scale the technology and ensure reliable operation, it can permanently solve a perennial hydrogen-combustion problem.
