China’s Electricity Market Reform and Power Plants Efficiency

In the past three decades, Chinese electricity industry has experienced a series of regulatory reforms serving different purposes at different stages. In 2002, the former vertically integrated electricity utility - the State Power Corporation (SPC) – was divested and the generation sector was separated from the transmission and distribution networks in an effort to improve production efficiency. In this paper we study the impact of the reform on efficiency of fossil-fired power plants using plant-level data during 2000-2008. Our results from the data envelopment analysis (DEA) and panel regressions show that: 1) the total factor productivity (TFP) growth mainly comes from technological change; 2) the technical efficiency of previously SPC-managed power plants is converging to that of better-performing independent power producers (IPPs); 3) capacity utilization and unit size are significant factors affecting changes in technical efficiency and the pattern of converging technical efficiency between the two kinds of power plants; 4) most plants operate at increasing returns to scale indicating further cost savings could be achieved through increasing output.Efficiency, DEA, Malmquist Index, China, Electricity, Industrial Organization, Productivity Analysis, Resource /Energy Economics and Policy, D24, L11, L51, L94, L98,

Residential Energy Consumption in Urban China

Residential energy consumption (REC) is the second largest energy use category (10%) in China and urban residents account for most of the REC. Understanding the underlying drivers of variations of urban REC thus helps to identify challenges and opportunities and provide advices for future policy measures. This paper applies the logarithmic mean Divisia index (LMDI) to a decomposition of China’s urban REC during the period of 1998-2007 at disaggregated product/activity level using data collected from a wide range of sources. Our results have shown an extensive structure change towards a more energy-intensive household consumption structure as well as an intensive structure change towards high-quality and cleaner energy such as electricity, oil, and natural gas, which reflects a changing life style and consumption mode in pursuit of a higher level of comfort, convenience and environmental protection. We have also found that China’s price reforms in the energy sector have contributed to a reduction of REC while scale factors including increased urban population and income levels have played a key role in the rapid growth of REC. We suggest that further deregulation in energy prices and regulatory as well as voluntary energy efficiency and conservation policies in the residential sector should be promoted.Residential Energy Consumption, Index Decomposition Analysis (IDA), China, Consumer/Household Economics, Resource /Energy Economics and Policy, Q32, Q43,

Global existence of the harmonic map heat flow into Lorentzian manifolds

We investigate a parabolic-elliptic system for maps $(u,v)$ from a compact Riemann surface $M$ into a Lorentzian manifold $N\times{\mathbb{R}}$ with a warped product metric. That system turns the harmonic map type equations into a parabolic system, but keeps the $v$-equation as a nonlinear second order constraint along the flow. We prove a global existence result of the parabolic-elliptic system by assuming either some geometric conditions on the target Lorentzian manifold or small energy of the initial maps. The result implies the existence of a Lorentzian harmonic map in a given homotopy class with fixed boundary data.Comment: to appear in J. Math. Pures App

Experimental investigation on performance of fabrics for indirect evaporative cooling applications

© 2016 Indirect evaporative cooling, by using water evaporation to absorb heat to lower the air temperature without adding moisture, is an extremely low energy and environmentally friendly cooling principle. The properties of the wet channel surface in an indirect evaporating cooler, i.e. its moisture wicking ability, diffusivity and evaporation ability, can greatly affect cooling efficiency and performance. Irregular fibres help to divert moisture and enlarge the wetted area, thus promoting evaporation. A range of fabrics (textiles) weaved from various fibres were experimentally tested and compared to Kraft paper, which has been conventionally used as a wet surface medium in evaporative coolers. It was found that most of the textile fabrics have superior properties in moisture wicking ability, diffusivity and evaporation ability. Compared with Kraft paper, the wicking ability of some fabrics was found to be 171%–182% higher, the diffusion ability 298%–396% higher and evaporation ability 77%–93% higher. A general assessment concerning both the moisture transfer and mechanical properties found that two of the fabrics were most suitable for indirective evaporative cooling applications

Towards a systematic understanding of community in online learning

Distance education has become an integrated part of higher education, and online learning communities (OLCs) show promises to promote learning in distance education. However, many issues regarding OLCs remain unclear in literature: OLC is not well defined, its key elements are not identified, and its relationship with learning has not been fully explored. In order to build a systematic understanding of OLCs for supporting distance learning, this dissertation reviewed the existing literature to develop a conceptual model of OLCs that identified OLC\u27s key elements and the interactions among these elements. After identification of such elements, the study tested this model by developing and validating an instrument to measure community, an OLC element. The validation process of the instrument revealed community to have four factors: student-student interaction, student-instructor interaction, perceived benevolence of others, and relationships. With the instrument, the dissertation then explored the relationships between community and learning in online courses of different interaction patterns, which serves as an early step to understand how communities and OLCs affect learning in different online learning contexts

Experimental investigation of the energy performance of a novel Micro-encapsulated Phase Change Material (MPCM) slurry based PV/T system

© 2015 Elsevier Ltd. As a follow-on work of the authors' theoretical study, the paper presented an experimental investigation into the energy performance of a novel PV/T thermal and power system employing the Micro-encapsulated Phase Change Material (MPCM) slurry as the working fluid. A prototype PV/T module of 800mm×1600mm×50mm was designed and constructed based on the previous modelling recommendation. The performance of the PV/T module and associated thermal and power system were tested under various solar radiations, slurry Reynolds numbers and MPCM concentrations. It was found that (1) increasing solar radiation led to the increased PV/T module temperature, decreased solar thermal and electrical efficiencies and reduced slurry pressure drop; (2) increasing the slurry Reynolds number led to the increased solar thermal and electrical efficiencies, decreased module temperature, and increased pressure drop; and (3) increasing the MPCM concentration led to the reduced module temperature and increased pressure drop. The experimental results were used to examine the accuracy of the established computer model, giving a derivation scale ranging from 1.1% to 6.1% which is an acceptable error level for general engineering simulation. The recommended operational conditions of the PV/T system were (1) MPCM slurry weight concentration of 10%, (2) slurry Reynolds number of 3000, and (3) solar radiation of 500-700W/m 2 ; at which the system could achieve the net overall solar efficiencies of 80.8-83.9%. To summarise, the MPCM slurry based PV/T thermal and power system is superior to conventional air-sourced heat pump systems (ASHP) and solar assisted heat pump systems (ISAHP), and has the potential to help reduce fossil fuel consumption and carbon emission to the environment

Micro-encapsulated phase change material (MPCM) slurries: characterization and building applications

© 2017 Micro-encapsulated Phase Change Material (MPCM) slurries, acting as the heat transfer fluids or thermal storage mediums, have gained applications in various building thermal energy systems, significantly enhancing their energy efficiency and operational performance. This paper presents a review of research on MPCM slurries and their building applications. The research collects information on the currently available MPCM particles and shells, studies of the physical, structural and thermal stability, and rheological properties of MPCM slurries, and identification/determination of the critical parameters and dimensionless numbers relating to the MPCM slurries’ heat transfer. The research suggests possible approaches for enhancing the heat transfer between a MPCM slurry and its surroundings, while several controversial phenomena and potential causes were also investigated. Furthermore, the research presents mathematical correlations established between different thermal and physical parameters relating to the MPCM slurries, and introduces a number of practical applications of the MPCM slurries in building thermal energy systems. Based on such extensive review and analyses, the research will help in identifying the current status, potential problems in existence, and future directions in research, development and practical application of MPCM slurries. It will also promote the development and application of cost-effective and energy-efficient PCM materials and thus contribute to achieving the UK and international targets in energy saving and carbon emission reductions in the building sector and beyond