Abstract

An industrial furnace with a thermochemical heat recuperation (TCR) system by steam methane reforming is considered. A method for determining the TCR systems efficiency is proposed. The methodology is based on the determination of the heat recuperation rate. A distinctive feature of the method is taking into account the work losses due to flow-dynamic drag in a packed bed of a thermochemical recuperator. The total recuperated heat and the recuperated heat in the steam generator and the reformer as well as work losses due to flow-dynamic drag are calculated. It is established that the efficiency of the TCR system depends on the methane conversion and with increasing temperature, the efficiency of the TCR system increases. It is shown that work losses due to flow-dynamic drag do not have a significant effect on the energy balance in the TCR systems. It is established that the maximum recuperation rate is for 700°C and H2O:CH4=2.

Abstract

Energy structure is gradually transforming from a traditional coal-based structure to a diversified supply model in China, forming a multi-wheel drive, associated and interactive energy supply system. In this context, the integrated energy supply system will have a profound impact on the traditional energy planning, operation, management and other external systems. Therefore, it is necessary to research the connotation and characteristics of regional integrated energy systems, and to deeply analyze the interactions and mechanisms among energy subsystems. This paper establishes a system of comprehensive benefit evaluation indicators in four dimensions of basic function, clean development, energy security and energy efficiency, which are applied to the typical scenario of regional integrated energy development and provide a scientific tool of quantitative analysis and evaluation of synergic development of the regional integrated energy supply system.

Abstract

The main objective of the present study is to perform simulation, and modeling analysis for the optimized design of grid connected solar photovoltaic (PV) and proton-exchange membrane fuel cell (PEM FC) hybrid energy system for reverse osmosis desalination plant. The goal is to integrate renewable and clean energy technologies for seawater desalination. Grid (baseline), and grid-tied hybrid solar PV/fuel cell power systems are designed and tested. The performance of the renewable power system, the cost of energy and CO2 emissions are determined. The simulation data show that the grid connected photovoltaic and fuel cell hybrid energy system meet the energy demand of the desalination plant without shortage. The proposed grid connected hybrid renewable power system offers the best overall performance compared to the grid: High power generation from renewable source (31%), good cost of energy (110 $/MWh – 13% cost reduction), and low CO2 emissions (430 kg CO2/MWh – 32% CO2 emissions reduction).

Abstract

The introduction of the fourth-stage fuel limit standard and the national VI emission standard has accelerated the development of more energy-efficient and environmentally friendly new energy vehicles by Chinese automakers. Currently, the 48V mild-hybrid system is one of the most effective technical solutions for the easy technology development, low cost, short development cycle, energy saving and emission reduction. In this paper, the 48V mild-hybrid vehicle is taken as the research object. Through the comparative analysis, the architecture of the 48V mild-hybrid system, the type of the battery and motor are determined. The external characteristics of motor are obtained by bench experiment and the battery model parameters are obtained by offline identification. Aiming at the research focus of the thesis, a single-target optimization strategy based on threshold is proposed, including engine startstop, power assisting, brake regeneration and SOC balance and the strategy model is built in Simulink. The 48V mild-hybrid vehicle model and the original vehicle model are built in the Cruise software. The co-simulation of the vehicle model and strategy model is achieved by calling the strategy model’s DLL file. The results show that compared with the original vehicle, the ratio of fuel economy improvement of the 48V mild-hybrid vehicle is more than 10%, the acceleration performance is increased by 9.7%, the climbing performance is improved by 23%, and the emission performance improvement effect is remarkable. Also, the proposed control strategy is better in reducing vehicle fuel consumption and maintaining battery SOC balance compared with the control strategy based on logic threshold.

Abstract

The analysis developed investigates the minimum cost of transporting hydrogen for various delivery distances and demands. The calculations are modelbased and estimate the minimum transport cost via road infrastructure using three different methods, i.e. a comparative analysis, and two optimization models. For that, different states of aggregation are chosen for transformation processes, transport and storage options ranging from compressed hydrogen at different pressure levels to liquid hydrogen and liquid organic hydrogen carrier. Key findings from the modelling results reveal that low and medium compressed gas are used at low hydrogen demand and transport distance, while the share of liquid based options increases with the transport distance. The results show as well the importance of the modeling method to reduce the cost, and its impact on the choice of the state of aggregation for hydrogen transport. Thus, a more elaborate optimization model estimated daily reduces the cost by privileging flexible storage option as liquid and increases the share of liquid organic hydrogen carrier at low demand.

Abstract

Aiming at the defects of high harmonic distortion in input current and big volume of filter inductance of single pulse width modulation (PWM) for active power factor, a double peak PWM for active power factor corrector (active PFC) is proposed, and the working mode of which is analyzed. Input current harmonic characteristics with the single and double peak PWM are comparatively analyzed, theoretical analysis shows that the double peak PWM can significantly decrease input current harmonic. Simulation results indicate that the input current THD with the double peak PWM is lower than that of the single PWM, and the volume of the filter inductance is reduced. Simulation results verify that theoretical analysis is right and the proposed double peak PWM is feasible.

Abstract

Demand response (DR) has becomes one of the tools mostly used in adjusting users’ electricity consumption pattern and behavior on the electricity market. In this paper, a single-objective optimization model with multiple constraints is established. Based on the electricity demand-price elasticity and the credit mechanism, further consider the impact of factors such as income, environmental awareness, family member and age, a more realistic subsidy mechanism is developed by taking into account the heterogeneity of users. The actual electricity load and price data are used for numerical simulation, and the results of economic index and load factor show that this model is more effective than the model which only considers the demand-price elasticity and the results show that the model is practical and effective.

Abstract

Utilizing heat pumps (HPs) is recognized as a promising approach to promote the flexibility of the combined heat and power (CHP) units for better wind power integration in the combined heat and power system (CHPS). This paper investigates the coordinated operation of the CHP units with the HPs which are distributed at heat exchange stations (HES). We propose the method for controlling the on-off status and running power of the HPs considering the thermal inertia of the district heating system (DHS). Finally, the optimal dispatch model of the CHPS is established. The effectiveness of the distributed HPs on reducing wind power curtailment is verified with numerical studies.

Abstract

Nowadays, the environmental problem is becoming more and more serious, attracting the attention of most people. Automobiles emission pollution has a great influence on environment, so the development of vehicles requires more efficient and cleaner. Regenerative braking is an effective method for hybrid electric vehicle (HEV) to improve fuel efficient. In this paper, firstly, the dynamics of the target vehicle was verified according to the selected parameters, including acceleration and climbing conditions. Then, a control strategy based on the parallel hybrid electric vehicle was proposed. Finally, in order to verify the control strategy’s effectiveness and real-time performance, a driver-in-the-loop real-time simulation platform for HEVs was built up based on the Development to Production (D2P) product-level controller, which can reduce development costs and is easy to implement. The results show that the proposed regenerative brake control strategy has good real-time performance.

Abstract

The thermal striping can generate fast random temperature fluctuation in fluid and will transfer it to structure. It will induce high cycle thermal fatigue in several components particularly in central column and should be concerned is for Sodium Cooled Fast Reactor(SFR). However, the recent research focus on the flow and temperature characteristics of fluid. The transient temperature distribution inside the solid structure is not comprehensive enough, which is important for analyzing cyclical thermal stresses and eventually the fatigue cracks of structure. In this study, coaxial jet model and large eddy simulation(LES) were used to simulate the fluid flow of upper plenum of SFR. The transient temperature distribution inside structure were studied by Heat-fluid-solid coupling analysis. The results show that thermal fluid-solid coupling simulation is feasible and accurate to analyze the temperature distribution of structure. The temperature fluctuation from the fluid to the structure surface is significantly attenuated. It can only be transferred to limited depth inside the structure. The results contribute to the high frequency thermal fatigue life prediction of nuclear component.