China, People’s Republic

The integration of renewable energy sources such as wind and solar power at high proportions has become an inevitable trend in the development of power systems under the new power system framework. The construction of a microgrid system incorporating hydrogen energy storage and battery energy storage can leverage the complementary advantages of long-term and short-term hybrid storage achieving power and energy balance across multiple time scales in the power system. To prevent frequent startstop cycles of hydrogen storage devices and lithium battery storage under overcharge and overdischarge conditions a coordinated control strategy for power distribution in a microgrid with hydrogen storage is proposed. First a fuzzy control algorithm is used for power distribution between hydrogen storage and lithium battery storage. Then the hydrogen storage tank’s state of health (SOH) and the lithium battery’s state of charge (SOC) are compared with the goal of selecting a multi-stack fuel cell system operating at its optimal efficiency point where each fuel cell stack outputs 10 kW. This further ensures that the SOC and SOH remain within reasonable ranges. Finally simulations are conducted in MATLAB/Simulink R2018b to verify that the proposed strategy maintains stability in the DC bus and alleviates issues of overcharge and overdischarge ensuring that both the system’s SOC and SOH remain within a reasonable range thereby enhancing equipment lifespan and system stability

This paper proposes a novel dual-fuel dual-mode dual-thermodynamic cycle aviation propulsion system for the first time and conducts theoretical research on it based on a moderately simplified mathematical model. It is specifically designed to significantly reduce carbon emissions for wide-body aircraft. A comprehensive thermodynamic model is developed for this hybrid power system which integrates a high-temperature proton exchange membrane fuel cell with a dual-rotor turbofan engine. The matching characteristics between aircraft and engine performance are analyzed by systematically varying the fuselage length of the dual-fuel aircraft configuration. Results show that the specific fuel consumption of the proposed engine is decreased by 12.6% compared with that of the traditional turbofan engine as the Mach number increases. Conversely as the relative physical rotational speed decreases the thrust of the novel engine is increased by 10%. With a 20 % extension in fuselage length the dual-fuel aircraft operating on 100 % hydrogen fuel can achieve an endurance exceeding 17 h representing a 20 % endurance improvement over conventional aviation kerosene-powered aircraft. In this case the aircraft weight can be reduced by 96.79 tons and CO2 emissions can be decreased by 301.65 tons.

Enhancing system durability and fuel economy stands as a crucial factor in the energy management of fuel cell hybrid vehicles. This paper proposes an Equivalent Consumption Minimization Strategy (ECMS) based on the Genetic Algorithm (GA) aiming to minimize the overall operating cost of the system. First this study establishes a dynamic model of the hydrogen–electric hybrid vehicle a static input–output model of the hybrid power system and an aging model. Next a speed prediction method based on an Autoregressive Integrated Moving Average (ARIMA) model is designed. This method fits a predictive model by collecting historical speed data in real time ensuring the robustness of speed prediction. Finally based on the speed prediction results an adaptive Equivalence Factor (EF) method using a GA is proposed. This method comprehensively considers fuel consumption and the economic costs associated with the aging of the hydrogen–electric hybrid system forming a total operating cost function. The GA is then employed to dynamically search for the optimal EF within the cost function optimizing the system’s economic performance while ensuring real-time feasibility. Simulation outcomes demonstrate that the proposed energy management strategy significantly enhances both the durability and fuel economy of the fuel cell hybrid vehicle.

During the development of hydrogen fuel cell systems with the augmentation of power conventional air-cooling systems which are frequently employed in portable scenarios encounter difficulties in maintaining the balance between radiator heat dissipation and power consumption. In contrast liquid-cooling systems are widely adopted in high-power applications. In this regard aiming to address the heat dissipation problem and make use of the wastewater from the stack tailpipe a novel spray cooling system integrated with the traditional air-cooling for the radiator of hydrogen fuel cell systems is put forward. Through experimental investigations based on heat transfer theory and the design principles of fuel cell systems it is discovered that under specific nozzle apertures and spray water pressures the heat dissipation rate can be enhanced by 40 % and 30 % respectively. With particular radiator internal water flow rates and fan speeds the heat dissipation rate can be increased by 30 % and 108 % respectively. And the spray angle of 60 ◦ is the best angle. In contrast to the conventional air-cooling system the spray-air cooling system exhibits a heat dissipation rate that is approximately 50 % higher. Exper imental analyses demonstrate that the new system effectively harnesses water resources and enhances the heat dissipation performance of the radiator thereby providing a technical reference for the application of spray cooling in the radiators of hydrogen fuel cell systems.

Ammonia a molecule that is gaining more interest as a fueling vector has been considered as a candidate to power transport produce energy and support heating applications for decades. However the particular characteristics of the molecule always made it a chemical with low if any benefit once compared to conventional fossil fuels. Still the current need to decarbonize our economy makes the search of new methods crucial to use chemicals such as ammonia that can be produced and employed without incurring in the emission of carbon oxides. Therefore current efforts in this field are leading scientists industries and governments to seriously invest efforts in the development of holistic solutions capable of making ammonia a viable fuel for the transition toward a clean future. On that basis this review has approached the subject gathering inputs from scientists actively working on the topic. The review starts from the importance of ammonia as an energy vector moving through all of the steps in the production distribution utilization safety legal considerations and economic aspects of the use of such a molecule to support the future energy mix. Fundamentals of combustion and practical cases for the recovery of energy of ammonia are also addressed thus providing a complete view of what potentially could become a vector of crucial importance to the mitigation of carbon emissions. Different from other works this review seeks to provide a holistic perspective of ammonia as a chemical that presents benefits and constraints for storing energy from sustainable sources. State-of-the-art knowledge provided by academics actively engaged with the topic at various fronts also enables a clear vision of the progress in each of the branches of ammonia as an energy carrier. Further the fundamental boundaries of the use of the molecule are expanded to real technical issues for all potential technologies capable of using it for energy purposes legal barriers that will be faced to achieve its deployment safety and environmental considerations that impose a critical aspect for acceptance and wellbeing and economic implications for the use of ammonia across all aspects approached for the production and implementation of this chemical as a fueling source. Herein this work sets the principles research practicalities and future views of a transition toward a future where ammonia will be a major energy player.

The transformation from a fossil fuel economy to a low-carbon economy has reshaped the way energy is transmitted. As most renewable energy is obtained in the form of electricity using green electricity to produce hydrogen is considered a promising energy carrier. However most studies have not considered the transportation mode of hydrogen. In order to encourage the utilization of renewable energy and hydrogen this paper proposes a comprehensive energy system optimization operation strategy considering multi-mode hydrogen transport. Firstly to address the shortcomings in the optimization operation of existing systems regarding hydrogen transport modeling is conducted for multi-mode hydrogen transportation through hydrogen tube trailers and pipelines. This model reflects the impact of multi-mode hydrogen delivery channels on hydrogen utilization which helps promote the consumption of new energy in electrolysis cells to meet application demands. Based on this the constraints of electrolyzers combined heat and power units hydrogen fuel cells and energy storage systems in integrated energy systems (IESs) are further considered. With the objective of minimizing the daily operational cost of the comprehensive energy system an optimization model for the operation considering multi-mode hydrogen transport is constructed. Lastly based on simulation examples the impact of multi-mode hydrogen transportation on the operational cost of the system is analyzed in detail. The results indicate that the proposed optimization strategy can reduce the operational cost of the comprehensive energy system. Hydrogen tube trailers and pipelines will have a significant impact on operational costs. Properly allocating the quantity of hydrogen tube trailers and pipelines is beneficial for reducing the operational costs of the system. Reasonable arrangement of hydrogen transportation channels is conducive to further promoting the green and economic operation of the system.

In the vehicle-to-everything scenario the fuel cell bus can accurately obtain the surrounding traffic information and quickly optimize the energy management problem while controlling its own safe and efficient driving. This paper proposes an energy management strategy (EMS) that considers speed control based on deep reinforcement learning (DRL) in complex traffic scenarios. Using SUMO simulation software (Version 1.15.0) a two-lane urban expressway is designed as a traffic scenario and a hydrogen fuel cell bus speed control and energy management system is designed through the soft actor–critic (SAC) algorithm to effectively reduce the equivalent hydrogen consumption and fuel cell output power fluctuation while ensuring the safe efficient and smooth driving of the vehicle. Compared with the SUMO–IDM car-following model the average speed of vehicles is kept the same and the average acceleration and acceleration change value decrease by 10.22% and 11.57% respectively. Compared with deep deterministic policy gradient (DDPG) the average speed is increased by 1.18% and the average acceleration and acceleration change value are decreased by 4.82% and 5.31% respectively. In terms of energy management the hydrogen consumption of SAC–OPT-based energy management strategy reaches 95.52% of that of the DP algorithm and the fluctuation range is reduced by 32.65%. Compared with SAC strategy the fluctuation amplitude is reduced by 15.29% which effectively improves the durability of fuel cells.

The combustion of hydrogen increases the water content of the combustion products affecting the aerodynamic performance of turbines using hydrogen as a fuel. This study aims to design a radial turbine using the differential evolution (DE) algorithm to improve its characteristics and optimize its aerodynamic performance through an orthogonal experiment and analysis of means (ANOM). The effects of varying water content in combustion products ranging from 12% to 22% on the performance of the radial turbine are also investigated. After optimization the total–static efficiency of the radial turbine increased to 89.12% which was 1.59% higher than the preliminary design. The study found that flow loss in the impeller primarily occurred at the leading edge trailing edge and the inlet of the suction surface tip and outlet. With a 10% increase in water content the enthalpy dropped Mach number increased and turbine power increased by 4.64% 1.71% and 2.41% respectively. However the total static efficiency and mass flow rate decreased by 0.71% and 2.13% respectively. These findings indicate that higher water content in hydrogen combustion products enhances the turbine’s output power while reducing the combustion products’ mass flow rate.

Historically it has been a challenge to simulate the experimentally observed cellular structures and marginal behavior of multidimensional hydrogen-oxygen detonations in the presence of losses even with detailed chemistry models. Very recently a quasi-two-dimensional inviscid approach was pursued where losses due to viscous boundary layers were modeled by the inclusion of an equivalent mass divergence in the lateral direction using Fay’s source term formulation with Mirels’ compressible boundary layer solutions. The same approach was used for this study along with the inclusion of thermally perfect detailed chemistry in order to capture the correct ignition sensitivity of the gas to dynamic changes in the thermodynamic state behind the detonation front. In addition the strength of transverse waves and their impact on the detonation front was investigated. Here the detailed San Diego mechanism was applied and it has been found that the detonation cell sizes can be accurately predicted without the need to prescribe specific parameters for the combustion model. For marginal cases where the detonation waves approach their failure limit quasi-stable mode behavior was observed where the number of transverse waves monotonically decreased to a single strong wave over a long enough distance. The strong transverse waves were also found to be slightly weaker than the detonation front indicating that they are not overdriven in agreement with recent studies.

Hydrogen is a key pillar in the global Net Zero strategy. Rapid scaling up of hydrogen production transport distribution and utilization is expected. This entails that hydrogen which is traditionally an industrial gas will come into proximity of populated urban areas and in some situations handled by the untrained public. To realize all their benefits hydrogen and its technologies must be safely developed and deployed. The specific properties of hydrogen involving wide flammability range low ignition energy and fast flame speed implies that any accidental release of hydrogen can be easily ignited. Comparing with conventional fuels combustion systems fueled by hydrogen are also more prone to flame instability and abnormal combustion. This paper aims to provide a comprehensive review about combustion research related to hydrogen safety. It starts with a brief introduction which includes some overview about risk analysis codes and standards. The core content covers ignition fire explosions and deflagration to detonation transition (DDT). Considering that DDT leads to detonation and that detonation may also be induced directly under special circumstances the subject of detonation is also included for completeness. The review covers laboratory medium and large-scale experiments as well as theoretical analysis and numerical simulation results. While highlights are provided at the end of each section the paper closes with some concluding remarks highlighting the achievements and key knowledge gaps.