The world's first! Hydrogen powered

On September 21, a large blue mining vehicle was being tested at the South Open-pit Coal Mine of the State Power Investment Corporation's Inner Mongolia Company (hereinafter referred to as "South Open-pit Coal Mine"). This "giant" marked with the code "NTH150" is a new type of hydrogen fuel and lithium battery hybrid mining vehicle (hereinafter referred to as "hydrogen fuel mining vehicle") that will be delivered for use.

Standing next to the two-person-high tire of the mining vehicle, Guo Yuanyuan, project manager of the hydrogen fuel mining vehicle of Inner Mongolia Northern Heavy Duty Truck Co., Ltd. (hereinafter referred to as "Northern Shares") and chief designer of "NTH150", told Science and Technology Daily: " This is the world's first hydrogen fuel mining vehicle that meets industrial standards such as quality, safety, environment and service. "

"From East to West of Inner Mongolia", cooperation to solve problems

The South Open-pit Coal Mine is located in Holingol City, Tongliao, Inner Mongolia, near 45 degrees north latitude. In Holingol in winter, the temperature can drop to minus 30 degrees Celsius.

Such low temperatures pose a huge challenge to fuel vehicles. Drivers add antifreeze to the fuel tank and sometimes have to install a fuel heater to get the vehicle started and running normally. For new energy vehicles that rely on batteries, the rapid power loss caused by low temperatures is an even more difficult problem to be solved.

Because of its simple reliance on resource development, Holingol City once had many ecological and environmental risks. In 2018, the Central Ecological and Environmental Protection Inspectorate sounded the alarm for Holingol City's ecological environment. Subsequently, Holingol City was determined to vigorously rectify the ecological environment of the mines.

As the first large-scale open-pit coal mine with a capacity of tens of millions of tons designed and constructed by itself in my country, Nanlucky Coal Mine has been working hard to build a "green mine". In the face of the transformation task of Holingol City, Nanlucky Coal Mine took the lead in shouldering the burden.

If the mine wants to reduce emissions, it must "cut" the mining vehicles, which are the major carbon emitters. Mining vehicles have high fuel consumption and high emission density. A 136-ton mining vehicle emits more than 1,800 tons of carbon dioxide per year, which is equivalent to the emission of 600 passenger cars.

"It can not only meet the needs of heavy-duty transportation, but also have long driving range and use clean energy." Guo Yuanyuan said, "In this case, hybrid mining vehicles become a reasonable choice."

However, the local low temperature conditions pose serious problems for the application of clean energy - without technological innovations to combat the severe cold, hybrid mining vehicles would not be able to run in mines.

"The news that the technological gap needed to be filled spread from eastern Inner Mongolia to western Inner Mongolia," Guo Yuanyuan recalled.

In March 2022, Northern Shares and Nanlutian Coal Mine signed a cooperation agreement. The two parties decided to jointly develop 100-ton hydrogen fuel mining vehicles, and planned to establish a comprehensive application demonstration scenario including hydrogen fuel mining vehicles, hydrogen storage and transportation, and hydrogen refueling in Nanlutian Coal Mine.

“Negation and denial, optimization and optimization”

As soon as he received the task, Guo Yuanyuan, who has many years of experience in vehicle design, felt the pressure.

"Take the air filtration solution for example, we have done a lot of experimental work. Before this, the design and application of hydrogen fuel mining vehicles were blank, and there was no ready-made experience to refer to." Guo Yuanyuan said that the research and development team designed a "physical + chemical" dual filtration system to meet the challenges of mine dust and sulfides.

"The complex pipeline layout is the result of the hard work of R&D personnel." Pointing to the tightly packed and orderly pipelines at the bottom of the mining vehicle, Liu Qiang, head of the electrical system of the hydrogen fuel mining vehicle, told reporters.

"As a hydrogen fuel mining vehicle, its pipelines mainly include hydrogen pipelines, high-voltage cables, low-voltage wiring harnesses, hydraulic pipelines, cooling pipelines, etc. The number of pipelines is twice that of traditional fuel vehicles." Liu Qiang said, "How to reasonably arrange all pipelines in the limited vehicle space while taking into account safety and convenient maintenance is a very challenging task."

After repeated research and analysis, the R&D personnel proposed the overall direction of hydrogen-electric isolation and layered layout, that is, hydrogen pipelines and cables are isolated and arranged to ensure safety; high-voltage cables, low-voltage harnesses, hydraulic and cooling pipelines are arranged in layers, with cables on top and pipelines on the bottom to avoid electrical short circuits caused by oil leakage. In order to achieve a reasonable structural layout, the R&D team tried dozens of versions of the plan.

"The research and development process is about negation and optimization. Staring at the densely packed pipeline layout diagram on the computer screen for a long time makes my eyes sore and dry every day. We have also found several versions of 'acceptable' solutions, but as long as we find that there is room for improvement in safety or room for optimization in the layout, we will continue to study and polish..." Liu Qiang recalled.
In September 2022, six months after the project was launched, the R&D team completed the design of various aspects including power calculation and matching, high-voltage architecture, key components, three-dimensional engineering drawings, and processes.

"Ice and Fire" - Overcoming the Battery Challenge

If the electrical system is the "blood vessels" of mining vehicles, then the battery is the "heart" of mining vehicles. Research and development of battery technology is the top priority of research and development.

Song Liming is the person in charge of the project's power system. Faced with the "toughest nut to crack" of batteries, he and his colleagues tried many solutions.

The battery is divided into two parts: the fuel cell and the power battery. After repeated research, Song Liming noticed that the two parts have different environmental requirements: the fuel cell can withstand an operating temperature of nearly 100 degrees Celsius; the operating temperature of the power battery needs to be controlled within the range of 0 degrees Celsius to 30 degrees Celsius, neither too high nor too low.

"We have to create an operating environment that is both ice and fire," said Song Liming. "The two parts of the battery have different operating temperatures and different heat dissipation requirements, but they have to be placed in the same system. We thought that water is a good medium for heat conduction and can be used for both cooling and heating. If we can use this property of water and make it circulate, then perhaps we can achieve the "ice and fire" environment."

This is easier said than done. To accurately control the water temperature, the water and thermal management systems and even other systems of the vehicle need to work together, which requires repeated simulations and experiments. Song Liming recalled with a smile that during the research and development process, in order to keep himself awake at all times, he often had to wash his face with cold water to "cool down".

Finally, the R&D team selected a "water heating + water cooling" distributed thermal management system. With the help of a high-power heater, the battery was finally able to start smoothly and run smoothly in severe cold conditions. Guo Yuanyuan told reporters, "This hydrogen fuel mining vehicle has 'driven' from traditional energy to green energy, adding a green background to the energy industry in Inner Mongolia. In the future, we also hope that it will go abroad and allow Chinese technology to advance to a higher level in the world!"