|
Energy systems engineering: methodologies and
applications
Pei LIU, Efstratios N. PISTIKOPOULOS, Zheng LI
Front. Energy. 2010, 4 (2): 131-142.
https://doi.org/10.1007/s11708-010-0035-8
Energy systems are the major contributor to ever-increasing primary energy consumption and consequent greenhouse gas emissions. To tackle these critical problems, planning and design of energy systems needs to be improved towards a more efficient, cost-effective, and environmentally benign direction. However, although there are many technical choices available, they are often developed separately by their own technical communities and driven by their specific interest, thus methods and experience obtained in planning and design of a certain type of energy systems are usually not applicable to other types of energy systems. Energy systems engineering provides a generic methodological framework to facilitate the planning and design of energy systems and to produce integrated solutions to real-life complex energy problems via a systematic approach. In this paper, we present an overview of key methodologies of energy systems engineering, covering superstructure based modelling, mixed-integer programming, multi-objective optimization, optimization under uncertainty, and life-cycle assessment. Applications of these methodologies in polygeneration energy systems design, hydrogen infrastructure planning, and design of energy systems in commercial buildings are provided to demonstrate the capability of these methodologies.
参考文献 |
相关文章 |
多维度评价
|
|
MHD effect on the critical temperature differences
of oscillatory thermocapillary convection in two-layer fluid system
Hulin HUANG, Xiaoming ZHOU,
Front. Energy. 2010, 4 (2): 155-160.
https://doi.org/10.1007/s11708-009-0063-4
The effect of different directional magnetic fields on critical temperature differences of oscillatory thermocapillary convection in a rectangular cavity with differentially heated side walls filled with two viscous, immiscible, incompressible fluids is simulated in the absence of gravity. In this two-layer fluid system, the upper layer fluid is the electrically non-conducting encapsulant boron oxide (B2O3), while the lower one is the electrically conducting molten indium phosphide (InP). The interface between the two fluids is assumed to be flat and non-deformable. The computational results show that all the magnetic fields along the x, y and z directions can delay the transition from steady convection to oscillatory convection, and critical temperature differences increase with an increasing Hartmann number. Furthermore, the effect of a magnetic field along the z direction is strongest, followed by that along the y direction, and that along the x direction is the weakest for the same intensity of the magnetic field.
参考文献 |
相关文章 |
多维度评价
|
|
Evolution of composite fouling on a vertical
stainless steel surface caused by treated sewage
Cheng ZAN, Lin SHI, Xiujuan MA, Wenyan YANG,
Front. Energy. 2010, 4 (2): 171-180.
https://doi.org/10.1007/s11708-009-0068-z
Composite biological and inorganic fouling occurs in plate heat exchangers (PHEs) using treated sewage as heat transfer medium, which lowers the heat transfer coefficient and increases the frictional resistance. In order to optimize the heat exchange process and improve the anti-fouling strategies, the dynamic behavior of composite fouling at a vertical surface of stainless steel (ANSI 316L) was investigated under typical conditions of PHEs. The growth curves of composite fouling were obtained. The evolution of composite fouling was characterized by means of environmental scanning electron microscopy (ESEM). Backscattered Electron Image (BEI) and energy dispersive X-ray spectrometry (EDS) were used as aids in interpreting the results. The experimental results show that a preliminary stage of a 6-day period with a low fouling growth rate exists during the composite fouling development. A significant change of the fouling growth rate happens after the preliminary stage during which the bacterial behaviors at the surface could be recorded clearly. After the preliminary stage, a space net-shape, mainly consisting of bacteria, extracellular products (EPS) and inorganic particles, could be established on the surface of the fouling layer. The change of fouling growth rate occurs synchronously with the evolution.
参考文献 |
相关文章 |
多维度评价
|
|
On corrosion to stainless steel by calcium chloride
with different extender
Lv XU, Yuanyang HU, Liwei WANG, Ruzhu WANG,
Front. Energy. 2010, 4 (2): 181-184.
https://doi.org/10.1007/s11708-009-0065-2
A calcium chloride solution with a different extender, which is made up of either pure calcium chloride, calcium chloride with expanded graphite, or calcium chloride with activated carbon, acts differently on stainless steel. The mass ratio between calcium chloride with expanded graphite or activated carbon is almost 4∶1, which is demonstrated to be the optimum ratio. The experimental research in this paper reveals that, of the three solutions, which are pure calcium chloride, calcium chloride with expanded graphite, and calcium chloride with activated carbon, the strongest oxidation creation and pitting corrosion happened in the solution of calcium chloride with expanded graphite, the weakest oxidation creation happened in the solution of calcium chloride with activated carbon, and pitting corrosion was stronger than oxidation creation in the solution of pure calcium chloride. This paper gives the reasons for these phenomena. Furthermore, based on theory analysis, multiple means and approaches are provided to prevent stainless steel from further corroding.
参考文献 |
相关文章 |
多维度评价
|
|
Thermal performance of phase change material
energy storage floor for active solar water-heating system
Ruolang ZENG, Xin WANG, Wei XIAO, Yinping ZHANG, Qunli ZHANG, Hongfa DI,
Front. Energy. 2010, 4 (2): 185-191.
https://doi.org/10.1007/s11708-009-0079-9
The conventional active solar water-heating floor system contains a big water tank to store energy in the day time for heating at night, which takes much building space and is very heavy. In order to reduce the water tank volume or even cancel the tank, a novel structure of an integrated water pipe floor heating system using shape-stabilized phase change materials (SSPCM) for thermal energy storage was developed and experimentally studied in this paper. The thermal performances of the floors with and without the SSPCM were compared under the intermittent heating condition. The results show that the Energy Storage Ratio (ESR) of the SSPCM floor is much higher than that of the non-SSPCM floor; the SSPCM floor heating system can provide stable heat flux and prevent a large attenuation of the floor surface temperature. Also, the SSPCM floor heating system dampens the indoor temperature swing by about 50% and increases the minimum indoor air temperature by 2°C–3°C under experimental conditions. The SSPCM floor heating system has a potential of making use of the daytime solar energy for heating at night efficiently.
参考文献 |
相关文章 |
多维度评价
|
|
Framework design of a hybrid energy system by
combining wind farm with small gas turbine power plants
Nengsheng BAO, Weidou NI,
Front. Energy. 2010, 4 (2): 205-210.
https://doi.org/10.1007/s11708-009-0073-2
Owing to the stochastic characteristic of natural wind speed, the output fluctuation of wind farm has a negative impact on power grid when a large-scale wind farm is connected to a power grid. It is very difficult to overcome this impact only by wind farm itself. A novel power system called wind-gas turbine hybrid energy system was discussed, and the framework design of this hybrid energy system was presented in detail in this paper. The hybrid energy system combines wind farm with several small gas turbine power plants to form an integrated power station to provide a relatively firm output power. The small gas turbine power plant has such special advantages as fast start-up, shutdown, and quick load regulation to fit the requirement of the hybrid energy system. Therefore, the hybrid energy system uses the output from the small gas turbine power plants to compensate for the output fluctuation from the wind farm for the firm output from the whole power system. To put this hybrid energy system into practice, the framework must be designed first. The capacity of the wind farm is chosen according to the capacity and units of small gas turbine power plants, load requirement from power grid, and local wind energy resource distribution. Finally, a framework design case of hybrid energy system was suggested according to typical wind energy resource in Xinjiang Autonomous Region in China.
参考文献 |
相关文章 |
多维度评价
|
|
Modelling the dynamic response of a solid oxide
steam electrolyser to transient inputs during renewable hydrogen production
Qiong CAI, Nigel P. BRANDON, Claire S. ADJIMAN,
Front. Energy. 2010, 4 (2): 211-222.
https://doi.org/10.1007/s11708-010-0037-6
Hydrogen is regarded as a leading candidate for alternative future fuels. Solid oxide electrolyser cells (SOEC) may provide a cost-effective and green route to hydrogen production especially when coupled to a source of renewable electrical energy. Developing an understanding of the response of the SOEC stack to transient events that may occur during its operation with intermittent electricity input is essential before the realisation of this technology. In this paper, a one-dimensional (1D) dynamic model of a planar SOEC stack has been employed to study the dynamic behaviour of such an SOEC and the prospect for stack temperature control through variation of the air flow rate. Step changes in the average current density from 1.0 to 0.75, 0.5 and 0.2 A/cm2 have been imposed on the stacks, replicating the situation in which changes in the supply of input electrical energy are experienced, or the sudden switch-off of the stack. Such simulations have been performed both for open-loop and closed-loop cases. The stack temperature and cell voltage are decreased by step changes in the average current density. Without temperature control via variation of the air flow rate, a sudden fall of the temperature and the cell potential occurs during all the step changes in average current density. The temperature excursions between the initial and final steady states are observed to be reduced by the manipulation of the air flow rate. Provided that the change in the average current density does not result in a transition from exothermic to endothermic operation of the SOEC, the use of the air flow rate to maintain a constant steady-state temperature is found to be successful.
参考文献 |
相关文章 |
多维度评价
|
|
Experimental study on premixed combustion of
spherically propagating methanol-air-nitrogen flames
Xiangang WANG, Zhiyuan ZHANG, Zuohua HUANG, Xibin WANG, Haiyan MIAO,
Front. Energy. 2010, 4 (2): 223-233.
https://doi.org/10.1007/s11708-010-0016-y
The outward propagation and development of surface instability of the spark-ignited spherical premixed flames for methanol-air-nitrogen mixtures were experimentally studied by using a constant volume combustion chamber and a high-speed schlieren photography system. The laminar burning velocities, the mass burning fluxes, and the Markstein lengths were obtained at different equivalence ratios, dilution ratios, initial temperatures, and pressures. The laminar burning velocities and the mass burning fluxes give a similar curve versus the equivalence ratios. They increase with the increase of initial temperature and decrease with the increase of dilution ratio. The laminar burning velocity decreases with elevating the initial pressure, while the mass burning flux increases with the increase of the initial pressure. Markstein length decreases slightly with the increase of initial temperature for the rich mixtures. High initial pressure corresponds to low Markstein length. Markstein length increases with the increase of dilution ratio, which is more obvious when the mixture becomes leaner. Equivalence ratio has a slight impact on the development of the diffusive-thermal cellular structure at elevated initial pressures. The initial pressure has a significant influence on the occurrence of the flame front cellular structure. At the elevated pressures, the cracks on the flame surface branch and develop into the cell structure. These cells are bounded by cracks emitting a bright light, which may indicate soot formation. For very lean mixture combustion, the buoyancy effect and cooling effect from the spark electrodes have a significant impact on the flame propagation. The hydrodynamic instability, inhibited with the increase of initial temperature around the stoichiometric equivalence ratio, is enhanced with the increase of initial pressure and suppressed by mixture dilution.
参考文献 |
相关文章 |
多维度评价
|
|
Dynamic characteristics of molten droplets and
hot particles falling in liquid pool
Liangxing LI, Weimin MA, Huixiong LI, Tingkuan CHEN,
Front. Energy. 2010, 4 (2): 246-251.
https://doi.org/10.1007/s11708-009-0077-y
The dynamic characteristics of molten droplets and hot particles at the very beginning of their fall into coolant pools are presented. The falling course of a single droplet or a single hot particle was recorded by a high-speed camera and a curve of velocity vs. time was obtained. Emphasis was placed on the effects of the droplet’s size and temperature, the coolant’s temperature and properties, and the droplet’s physical properties on the moving behavior. The results for the all cases showed that the velocity of a falling droplet/particle decreased rapidly but rebounded shortly, at the beginning of droplet/particle falling in the coolant. Following such a V-shaped evolution in velocity, the droplet/particle slows down gradually to a comparatively steady velocity. An increase in either coolant temperature or droplet temperature results in a larger velocity variation in the “J-region”, but a smaller deceleration when it moves out of the “J-region”. The elevated volatility of a coolant leads to a steeper deceleration in the “J-region” and beyond. The bigger size of a particle leads to a greater velocity variation in the “J-region” and terminal velocity. A high melting point and thermal conductivity as well as lower heat capacity contribute to dramatic variation in the “J-region” and low terminal velocity.
参考文献 |
相关文章 |
多维度评价
|
20篇文章
|