Abstract
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.
Highlights
The results show that hybrid mining truck (HMT) with a coupled hydro-pneumatic energy storage system (ESS) gained the largest economic profit in the heavy load and longdistance work cycle, whereas in light load and short-distance or middle-distance situations, hydraulic-ESS-based HMTs achieve better economic performance
Based on the above thermodynamic and heat transfer model, this section introduces the working cycle of mining trucks. It analyzes the thermal characteristics of improved hydraulic energy storage system (IHESS) in the actual and simplified cycle with the cited dynamic model (Chun, et al, 2019) corresponding to the target vehicle, a 110 t HMT, as well as the influence of the system structure and working condition parameters
About 90% of the generated heat is converted into the internal energy of nitrogen and oil
Summary
Mining trucks work at fixed routes (Newman, et al, 2010), which is different from other onroad trucks They are driven along a 4–5-km and 9–12% grade slope uphill with load and downhill. Due to the limitations of the current technology (Ding et al, 2020), this amount of electricity cannot be stored but fed into the braking resistance and transformed into heat (Dagdougui, et al, 2020). This is a promising way to bring beneficial results to the mining industry
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