Abstract

Switching to electricity for road transport is considered as a promising solution to energy transition and CO2 emission reduction. In this paper, an integrated assessment model, which contains an elaborate transport module for detailed behavioral and technological descriptions, is employed to investigate how the energy use and emission profiles would be altered by the electric vehicle (EV) adoption. A set of scenarios is created according to policy interventions for the promotion of electric mobility. The results show that the EV financial incentives will significantly boost the market shares and reduce effectively the CO2 emissions produced by the light-duty vehicle, while carbon pricing only exerts a moderate influence. The regional heterogeneity of emission trajectories across various countries indicates that incentives for EV adoption require more attention in developing counties. Policy Instruments to promote electric mobility would entail considerable costs, which should be considered in the policymaking.

Abstract

As a promising linear energy conversion system, the free piston internal combustion powertrains system (FPICPS) has many advantages such as compact structure, short energy transmission chain and high fuel flexibility. The main parts of FPICPS consists of a two-stroke combustion engine, a permanent magnet linear synchronous machine system (PMLSMS) and a gas spring chamber. However, FPICPS has special structure of no mechanical constraints, and the extra degree poses a huge technical challenge for a series of operation processes such as start-up, continuous stable generation, emergency braking, overcoming misfire and unstable operation caused by potential disturbance. This paper concentrates on research on the precise, controllable and instant response characteristics of force of PMLSMS. It was found that the power adjustment controller on PMLSMS side can switch the operating mode under generation and motorized state with negligible delay compared to relay. So technically feasible control variable of force for PMLSMS was chosen and coupled with a force of PMLSMS controller design to implement a series of operation processes by identifying current operating status and different types of system mode, which could be applied in future FPICPS control system designs for different operating modes. The controller performance was seen to be satisfactory for switching between different operating modes without delay and of great significance in improving the robustness of FPICPS and improving the combustion efficiency by MATLAB/SIMULINK. Therefore, it may be beneficial to the application of FPICPS as range extenders in the way that synergize advantages of the free piston engine and functional control logic of the stable operation, promising in hybrid vehicles.

Abstract

Natural gas combined cycles are expected to operate in a flexible manner in the future energy markets to complement the increasing variable renewable electricity generation. Stresses in thick-walled components and gas turbine load ramps are the main limitations in the dynamic operation of NGCCs. This work presents two different modelling approaches of the thermal and mechanical stresses originated in the high-pressure drum and steam turbine rotor, and compares four different formulations, two linear and two nonlinear, of the optimization problem included in the model predictive control strategy. A case study shows the capability of the proposed control methodology to optimally operate the NGCC without exceeding the maximum allowable stress in the critical components.

Abstract

Parabolic trough collectors (PTCs) harvest high temperature heat and are widely applied in solar thermal utilization. The key parts of the parabolic trough collectors are the solar receivers, the thermal performance of the solar receivers has significant impacts on the PTCs. However, the high temperature incurs considerable radiative heat loss of the solar receivers. A structural optimized solar receiver with an inner radiation shield was proposed for reducing the heat loss and improving the thermal performance. The indoor heat loss and the outdoor thermal efficiency testing were conducted in Electricity Engineering of China Academy to validate comprehensive thermal performance of the novel solar receivers. The experimental results show that the heat loss of novel solar receiver can be reduced by 28% at absorber temperature of 550 °C, and the thermal efficiency can be enhanced by 4.9 % at 350 °C inlet temperature.

Abstract

In this paper, a novel hierarchical power management strategy is proposed for a plug-in hybrid electric vehicle with multiple energy sources. In the first level, dynamic programming is used to distribute the power between the energy storage system and the engine. Then, the hybrid energy storage system is composed by adding a supercapacitor to the energy storage system. In the second level, the low-pass filtering algorithm is researched to distribute power between the battery and the supercapacitor of the hybrid energy storage system. To control the battery and the supercapacitor working within the energy range, the limit management approach is proposed to redistribute power among the battery, the supercapacitor and the engine. Simulink results show that the final distributed powers of battery, supercapacitor and engine are within the reasonable power and energy ranges.

Abstract

In this paper, a novel system integrating direction reduction iron (DRI) production, H2 production, and CO2 capture has been proposed. The novel polygeneration system avoids excessive CH4 conversion rate, and the chemical energy of CH4 is cascade converted. Besides, the system realizes gradual enrichment of CO2 in the CH4 conversion process. This paper presents the exergy analysis of the novel system. It shows that the energy saving ratio of the polygeneration system could reach up to 12.3%, and the performance improvements are mainly attributed to three aspects: cascade utilization of chemical energy, cascade utilization of physical energy, and lower separation penalty. For the polygeneration system, the CO2 concentration could reach up to 65%, and the energy consumption for separation is only about 30% of the general post-combustion separation process. At this point, the CO2 recovery ratio of the system is about 70%.

Abstract

The network strength and resilience resource allocation are the most important guarantees for the safe operation of distribution network, which also reflects the capability to resist disasters. To fully evaluate the network strength and resilience resource allocation, the evaluation indexes are proposed from perspectives of the grid robustness, emergency power supporting ability and failure repair capability. Meanwhile, an evaluation method is built to calculate the index weight by analytic hierarchy process-entropy method-grey relational analysis (AHP-EM- GRA), so as to overcome the impact caused by different physical significance and types of indexes. The result of case study indicates the validity and rationality of the proposed indexes and methods.

Abstract

Traditional climatic zoning method divides China into 5 building thermal design zones by taking average temperatures of the coldest and hottest months, as well as accumulated temperature days in a year as the key indices. The method may not properly reflect the real building thermal characteristics. This paper therefore proposes a novel building thermal design zoning method based on the clustering of building indoor thermal performances of a typical commercial building model under different climates across China. K-Means method is adopted for clustering process. Three representative cities are selected to analyses the dynamic characteristics of thermal loads. Meanwhile, a new building thermal design zoning map is eventually developed, and thermal load patterns of the selected cities are also identified.

Abstract

Enormous amounts of low-grade heat 60-90 °C are available from industrial processes that can be converted into electricity by Adsorption Reverse Electrodialysis. This study assesses the concept by using experimental data from an adsorption desalination system at 60 °C. The experimental energy consumption of the adsorption regeneration is used to determine the energy and exergy efficiency of the overall system based on the results of a thermodynamic analysis. The system can achieve exergy efficiencies up to 12 % with solutions that can be used in current membranes. Advanced solutions increase the exergy efficiency to 30-40 % highlighting the great potential of the technology.

Abstract

A physical model of multi-layer hydrate reservoir contained free gas was established for gas hydrate reservoir at W17 site in Shenhu area of South China Sea, and the effects of multi-vertical well patterns and inter-well distance on the production characteristics of hydrate reservoir by depressurization were investigated by numerical simulation. The results indicated that the production is affected by inter-well interference. The cumulative amount of dissociated gas and gas production for each well in multi-vertical well patterns are always less than that in single well alone after 36 days. For the hydrate produced by multi-vertical well patterns, the cumulative amount of water for each well can be effectively reduced compared to that by single well alone. From the percentage of hydrate dissociation and gas liquid ratio RGW perspectives, the 40 m well distance is more conducive to the exploitation of the hydrate reservoir.