考虑多能互补和负荷不确定性的区域综合能源系统优化定容与资产利用效率分析

电、气、热等多种能源的耦合使得区域综合能源系统能够通过多能互补协同利用,提高运行的灵活性和经济性。通过投资能源供给和转换设备能够提升区域综合能源系统运行灵活性,但其与投资成本、设备利用情况通常是对立的。在充分考虑多能互补和负荷水平不确定性的前提下,对区域综合能源系统进行优化定容和资产利用效率分析。首先,基于能源集线器模型构建了区域综合能源系统的多能互补协调优化模型。考虑在长时间尺度内多能互补的执行及负荷不确定性对资产利用效率的影响,建立了区域综合能源系统设备的双层鲁棒优化定容模型。接着,通过定义与量化多能互补策略所实现的收益,评估其资产利用效率。最后,通过测试案例验证,在多能互补策略的实施与优化定容的共同作用下,区域综合能源系统设备资产利用效率能够维持在较高水平。

固定资产全过程管理探讨

固定资产是企业组织生产的物质基础,由于它投资金额大,持续使用时间长,对企业的生产经营影响大,加强固定资产管理具有重要意义。本文通过对企业固定资产的投资、现状、变动情况及有效使用情况等有关方面的分析,提出要加强固定资产投资与使用全过程管理。

Estimating regional coal resource efficiency in China using three-stage DEA and bootstrap DEA models

Based on three-stage data envelopment analysis(DEA) model estimates of resource utilization efficiency of coal,we selected 29 provinces from China's 2012 input-output data and used the bootstrap DEA model to correct the bias.The results show that the mean overall technical efficiency,pure technical efficiency,and scale efficiency was 0.833,0.998,and 0.711 in 2012,respectively.Moreover,the comprehensive technical efficiency score indicates that the scale is invalid.Area utilization efficiencies for the eastern,central,and western regions were 0.917,0.731,and 0.629,respectively.The results prove that there are significant differences in the distribution of coal resources utilization efficiency across regions.

Urban Water Resource Utilization Efficiency in China

The efficient use of water resources directly affects environmental, social, and economic development; therefore, it has a significant impact on urban populations. A slacks-based measure for data envelopment analysis （SBM-DEA） has been widely used in energy efficiency and environmental efficiency analyses in recent years. Based on this model, data from 316 cities were examined and a category method was employed involving three different sorting techniques to empirically evaluate the efficiency of urban water re- source utilization in China between 2000 and 2012. The overall efficiency （OE） of urban water resource utilization in China was initially low, but has improved over the past decade. The scale efficiency （SE） was higher than the pure technological efficiency （PTE）; PTE is a major determining factor of OE, and has had an increasingly significant effect. The efficiency of water resource utilization varied ac- cording to the region, urban scale, and economic function. The OE score for the eastern China was higher than for the rest of the region, and the OE score for the western China was higher than for the central China. The OE score for urban water resource utilization has improved with urban expansion, except in the case of small cities. The SE showed an inverted U-shaped＇ trend with increasing urban expansion. The OE of urban water utilization in comprehensive functional cities was greater than in economic specialization cities, and was greater in heavy industry specialization cities than in other specialization cities. This study contributes to the field of urban water resource management by examining variations in efficiency with urban ~ezle

Efficiency analysis of trilateral-cycle power systems for waste heat recovery-to-power generation

Numerous innovative heat recovery-to-power technologies have been resourcefully and technologically exploited to bridge the growing gap between energy needs and its sustainable and affordable supply.Among them,the proposed trilateral-cycle(TLC) power system exhibits high thermodynamic efficiency during heat recovery-to-power from low-to-medium temperature heat sources.The TLCs are proposed and analysed using n-pentane as working fluid for waste heat recovery-to-power generation from low-grade heat source to evaluate the thermodynamic efficiency of the cycles.Four different single stage TLC configurations with distinct working principles are modelled thermodynamically using engineering equation solver.Based on the thermodynamic framework,thermodynamic performance simulation and efficiency analysis of the cycles as well as the exergy efficiencies of the heating and condensing processes are carried out and compared in their efficiency.The results show that the simple TLC,recuperated TLC,reheat TLC and regenerative TLC operating at subcritical conditions with cycle high temperature of 473 K can attain thermal efficiencies of 21.97%,23.91%,22.07% and 22.9%,respectively.The recuperated TLC attains the highest thermodynamic efficiency at the cycle high temperature because of its lowest exergy destruction rates in the heat exchanger and condenser.The efficiency analysis carried out would assist in guiding thermodynamic process development and thermal integration of the proposed cycles.

An Experimental and Numerical Analysis of Daylighting Performance for an Office Building

The urgency of increasing energy efficiency in new building design and retrofits has pushed lighting simulation to play a central role in sustainable lighting design. The shape of the building and its orientation, the reflectances of building surfaces and glazed areas are important parameters in the daylighting design of buildings. Glazing systems can cut energy consumption and associated pollution sources, reduce peak demand, enhance daylighting performance and improve occupant comfort. This paper presents the results of a numerical and experimental comparison between the performances of an office building with and without external sunscreens. The aim was to analyse the illuminance distribution and some investigations have also been made with regards to the effect on daylight in rooms when sunscreens are used. The experimental results were obtained using an office building scale model and sky simulator. The numerical results were obtained through radiance, the ray-tracing program, to accurately predict the light levels and produce photo realistic images of the architectural space in all sky conditions： Illuminance values were obtained respectively through reference point measurements. The daylighting performances of the office building model with and without the sunscreens have been compared and analysed.