Abstract

The co-pyrolysis of lignocellulosic wastes with plastic has been found to improve the both the yield and quality of pyrolysis oil and gas products. In this study, the co-pyrolysis of corn stover (CS) with plastic (low-density polyethylene, and polypropylene) were studied through thermogravimetric analysis. The parameter “change in weight loss rate” denoted by ΔW was used to quantify the synergistic effects on the yield during co-pyrolysis. The ΔW values were fitted using a combined mixture design to generate an RSM model relating the factors mixture component proportions, plastic type, and temperature to the response Δ W. From numerical optimization, the obtained optimum co-pyrolysis conditions are: (a) 0.60 CS proportion, 0.40 LDPE proportion, and 481.73 ℃ temperature for CS-LDPE, (b) 0.68 CS proportion, 0.32 PP proportion, and 492.15 ℃ temperature for CS-PP. The activation energy, and preexponential factor of the reactions in the co-pyrolysis process were also obtained using direct solution method. The activation energy of the thermal decomposition of plastic was found to be lower in the co-pyrolysis of corn stover and plastic than in the pyrolysis of pure plastic.

Abstract

Owing to the limitation of single objective optimization configuration of the distributed combined cooling heating and power (DCCHP) system, the multi-objective optimization configuration of the system was carried out from the aspects of energy efficiency and economy. Taking the maximum primary energy saving (PES) and minimum annual cost (AC) as the objective functions, three key parameters of gas turbine capacity, absorption refrigeration ratio and gas turbine minimum load rate were selected as decision variables. Nondominated sorting genetic algorithm II (NSGA-II) was used to optimize the system with multi-objective, and subsequently Pareto optimal solutions were obtained. With the aid of ideal point method, the optimal capacity configuration of the system was selected. For the case of an energy supply system of a hotel, optimized results show that under the given parameters, the optimal PES is 0.6788 and the minimum AC is 2.1309 million yuan in consideration of both energy efficiency and economy.

Abstract

Environmental computable general equilibrium (CGE) models have been widely used to support policy analysis of climate change mitigation and adaptation at different scales. The simulation results highly rely on the model structure, assumptions as well as parameter value inputs. Most single-region CGE models follow the traditional model settings, such as the agent-identical specification for import demand and price taker for exports pricing. This study aims to explore the importance of CGE model specifications on the simulation results and policy implications by means of alternative agent-specific specification for import demand and partial price pass-through for exports price, respectively. Singapore is chosen as the case study as its economic circumstance does not completely support the standard settings. It is found that, under both the carbon tax and border carbon adjustment scenarios, economic performance, emission reduction and average abatement cost vary substantially with different specifications. Policy implications are consequently discussed and compared.

Abstract

The objective of this research is to explore the potential of high temperature aquifer thermal energy storage (HT-ATES) to enhance the techno-economic performance of district heating systems in the Netherlands. Two case studies have been performed for the city of Utrecht and Den Haag. By using modelling tool EnergyPRO, multiple scenarios have been developed for the year 2017 and 2030. This research underlines the importance of local conditions in heat-related projects. First of all, the applicability of HT-ATES depends on the suitability of the underground, which could be different for any locations. Secondly, the local availability of heat sources with low operational costs is crucial for making a successful business case for HT-ATES.

Abstract

A distribution strategy of relief and repair materials for distribution network in typhoon scenarios is proposed in this paper. Firstly, the typhoon process is simulated by Batts model and the failure rate of electric poles is obtained based on the wind load theory. Secondly, the failure rate of overhead lines is obtained by tandem model of poles. Thirdly, a multi-timescale distribution method of relief materials before typhoon landing is proposed as the first step of the distribution strategy, through which wind-proof cables and generator cars are allocated based on the vulnerability index of overhead lines. The failure frequency of lines and the importance of loads are included in the vulnerability index, where the failure frequency of lines is related to the failure rate of lines. The weights of the two factors are determined by the Analytic Hierarchy Process (AHP). Finally, a distribution method of repair materials after typhoon is proposed as the second step of the distribution strategy, which is based on the priority index of lines to allocate the repair materials. The line integrity and load importance are included in the priority index and the weights of the two factors are determined by AHP. Simulation results show that the proposed distribution strategy can allocate the limited materials more effectively in typhoon scenarios.

Abstract

In this study, a three-dimensional numerical analysis has been done to investigate the heat transfer, pressure drop in the shell side and vortex shedding, tubes deformation due to fluid induced vibrations in the shell and tube heat exchanger (STHX). Three-dimensional CFD and two-way FSI has performed with the commercial software ANSYS. To examine the thermo-hydraulic performance and induced vibrations in shell-and-tube heat exchangers with segmental/ helical/ clamping anti-vibration baffles and cylindrical/twisted tubes, numerical simulations are carried out. The numerical models show the thermo-hydraulic performances for the heat exchangers with segmental, helical and novel clamping anti-vibration baffles with cylindrical and square twisted tubes. The result shows that the use of square twisted tubes result in higher heat transfer rate as compared to cylindrical tubes. As far as pressure drop is concerned, it is also greater in the shell and tube heat exchangers with square twisted tubes for segmental, helical and anti-vibration baffles. The deformation in the tubes, velocity of the tubes and vortex shedding formation is minimum in STHX with clamping anti-vibration baffles than in STHXs with helical and segmental baffles.

Abstract

The extension of power supply radius of every single substation by technology has become a primary task of electric power construction in western China. This paper proposes a new scheme to extend the power supply radius in sparse areas, simultaneously realizing voltage boosting and unified power quality compensation through two smart parallel power electronic subsystems. Dynamic voltage regulating technique is used to compensate voltage loss while three phase unbalance compensation, reactive power compensation and filtering are solved in one topology. After simulated by Matlab/Simulink and field-tested in Guoluo State, the result shows great changes in lifting voltage and improving power factor (to above 0.95), which utterly solves the problem of power supply radius extension and lays a foundation for further construction of smart grid in west area.

Abstract

A simulation and experimental study is conducted on a natural gas fuel injection system. The injection system includes a rail tube, a solenoid gas injector and an electric pressure regulator (EPR). The purpose of this study is to examine the operating characteristics of the injection system such as EPR control voltage, EPR plunger displacement, gas pressure in the rail tube, and injection flow rate. Mathematical models are established to describe the operation of solenoid gas injector and EPR. Besides, a control model is built to examine the response as well as injection pressure controlled by EPR. These models are solved in MatlabSimulink. Effects of EPR design parameters such as spring stiffness and plunger mass on the operating characteristics of the gaseous fuel injection system are investigated. The simulation results show that the operating performance of the gaseous fuel injection system can be improved if EPR spring stiffness and plunger mass are suitably chosen. In addition, the electric pressure regulator can be successfully controlled to maintain a stable output pressure providing to the solenoid injector. The simulation results are validated with experimental results for the controlled gas pressure.

Abstract

Current technologies for capturing carbon from flue gas are plagued by high capital, energy and chemical costs, etc. Here, we report a composite supported liquid membrane containing mimic enzyme that may provide a possible solution to these issues. This composite membrane has two highly permeable silicone layers which immobilize the mimic enzyme (Zn-cyclen complex) solution in the pores of a cellulose acetate nanofiltration membrane. The schematic is showed in Fig.1. The membrane couples the selectivity of liquid sorbents and energy-efficiency of membrane separation without absorbent regeneration unit. The prepared Zn-cyclen complex was characterized by 1HNMR and dissociation constant (pKa). The contact angles of the cellulose acetate support membrane and the prepared composite membrane were tested. CO2 separation performances of the membranes were studied in a plate-and-frame membrane module system. The membrane system presents a CO2/N2 selectivity of 94 and a CO2 permeance of 1.33 [m3 (STP)/(m2 bar h)] with a very small amount of 0.0052 M mimic enzyme. This composite supported liquid membrane shows the advantages of low cost, simple production procedure and high CO2 separation performance.

Abstract

The energy transition raises a need for innovative ideas to cope with the integration of high shares of variable renewable energy sources. Across political, industrial and research audiences, the idea of electricity self-sufficiency has been gaining rising interest. It might, among others, solve questions of energy security and help to avoid short term necessary investments into the electricity grids. However, while electricity selfsufficiency can be technically feasible for a large range of user types (e.g. residential, agricultural, and industrial) and cluster sizes (e.g. individuals, districts, municipalities), it becomes rapidly unfeasible when strict regulations are considered. In this study, the feasibility of electricity self-sufficiency based on free-standing photovoltaics, wind power and storage systems was evaluated for all municipalities in Bavaria (Germany) and the Czech Republic. Main focus of this paper is the calculation of the spatially distributed electricity demand of today and the future. Methods for the technology potential evaluation and the development of an optimization model to determine necessary system sizes are shortly presented referring to previous work. Results indicate that around 20% of the German and 6% of the Czech municipalities could achieve self-sufficiency today based on the considered technologies and under current Bavarian regulatory restrictions. These figures improve enormously with milder regulations for wind power installations. Furthermore, due to an expected depopulation of rural areas, a rising trend in potentially electricity self-sufficient municipalities is visible.