The mining trucks with heavy loads are widely used in open‐pit mines, which are usually under working conditions where the recoverable potential energy accounts for more than 1/3 of the traction energy. Therefore, it is important to study the existing energy recovery technologies suitable for mining trucks. This work presents a comparative study on the economy of a mining truck by integrating four different energy storage systems (ESS): battery, supercapacitor, hydraulic accumulator, and air tank combining with the existing internal combustion engine to form a hybrid mining truck. First, recent applications and features of the four ESSs in vehicles are discussed. Next, the configurations of four types of partial hybrid mining trucks are presented. In addition, this project compares different configurations by the total benefit over 10 years of operation. The compressed‐air ESS with full capacity obtained the best benefit under medium and heavy load scenarios, which is more applicable to the actual situations. Therefore, it will be beneficial to turn the conventional electric‐driving mining truck into a compressed‐air hybrid.

The compressed air energy storage system has a better energy density, while the widely used hydraulic one is superior in power performance. Therefore, they are suitable for different hybrid vehicles, which require a comparative study on the performances and vehicle applicability of the broad pressure energy storage system layouts. In this paper, an integrated mathematical model of four basic pressure layouts is presented for characteristic analysis and applicability discus- sion. Results show that the open volume layout achieves the best power performance with the flow specific power of 13.92 MJ/m³, thus it is suitable for heavy hybrid trucks and mobile machinery. The open mass layout achieves the best energy performance with the energy density of 124.35 MJ/m³, which can be used in light new energy passenger vehicles. And the performance of the closed volume layout is close to the open volume layout with the flow specific power of 9.78 MJ/m3, so it could be applied to middle and light hybrid trucks. This research provides a basis for the hybrid method of pressure energy storage system layouts for vehicles, and could be applied in the design and research of non-electric hybrid vehicles in the near future.

In order to recover and utilize the potential energy of mining trucks efficiently, this paper proposes a nested optimization method of a novel energy storage system. By analyzing the multi-objective optimization problem of the oil-circulating hydro-pneumatic energy storage system, a nested optimization method based on the advanced adaptive Metamodel-based global optimization algorithm is carried out. Research shows that this method only requires a short time to solve the complex nonlinear hybrid optimization problem and achieves better results. The optimized energy storage system has higher system efficiency, energy density, and volume utilization rate, thus obtaining a smaller system volume and weight. Verified by the bench experiment of its powertrain, the hydro-pneumatic hybrid mining truck with the optimized energy storage system significantly reduces its fuel consumption and CO₂ emission. Thus, it lays the foundation for the practical application of hydro-pneumatic hybrid mining trucks.

The energy storage system of electric-drive heavy mining trucks takes on a critical significance in the characteristics including excellent load capacity, economy, and high efficiency. However, the existing battery-based system does not apply to harsh cold environments, which is the common working condition for the above trucks. A type of cycle hydro-pneumatic energy storage system for the trucks was proposed in this study. The dynamic model of the system, including the dynamic and thermodynamic models of hydraulic and pneumatic parts, was built to analyze the performance of the system. Subsequently, the thermodynamic characteristics were clarified during the energy storage and released through the real test condition-based simulation. The power and energy performances of the system were studied in practice based on the above characteristics. The analysis of the results showed that the system reduced 22.03% driving power at the optimal braking energy recovery rate, the energy density was nearly 12.6 MJ/m³, the maximum input power was higher than 230 kW, and the cycle efficiency was about 40.6%. The results of this study will be conducive to the application of the hydro-pneumatic energy storage system for the electric-drive mining trucks and reducing the resulting carbon emission.

The improved hydraulic energy storage system (IHESS) is a novel compact hydraulic ESS with only 10% of oil and 64.78% of installation space of the regular ones. However, its novel circulating structure and lightweight material result in poor heat dissipation. The thermodynamic and heat transfer model of IHESS with an oil-circulating layout is proposed. Based on the mining trucks’ dynamic model, thermal characteristics of IHESSs with different parameters under the actual and simplified working conditions are studied and the factors causing overheating are analyzed. Finally, a feasible thermal design is put forward, and its efficiency is analyzed. The simulation shows that more accumulators and higher recovery power lead to higher system temperature and vice versa. Under the standard simplified working condition at 40°C ambient temperature, the highest oil temperature reached is 93.13°C. About 90% of the generated heat is converted into the internal energy of nitrogen and oil. On this basis, by adopting an energy-saving passive cooling system with a cooling power of 6.68 kW, the highest temperature of the oil drops to 52.79°C and 28% of the generated heat is released through the cooling system.