High-temperature Thermal Properties and Wear Behavior of Basalt as Heat Storage Material for Concentrated Solar Power Plants

The microstructures,components,thermal stability,specific heat capacity and thermal conductivity of basalt sample were studied.Besides,as a comprehensive result of thermal expansion and contraction process,both the friction coefficient and wear rate of the basalt sample were also characterized.Our results indicate that basalt is an excellent candidate to be used as thermal energy storage material for concentrated solar power plants,and also provide a strategy for solar energy utilization in volcanic area with excellent geographical environment.

Feasibility Study of Solar Energy Steam Generator for Rural Electrification

In Middle East region, where there are plentiful amounts of solar radiation and great desert areas, solar energy can play a potential role in replacing conventional fuel-operated electricity generation methods with a cost-effective, sustainable solution. This paper presents a feasibility study of a low-cost solar energy steam generator for rural areas electrification. The proposed system is based on the use of trough concentrator which converts solar radiation into thermal energy in its focal line (where a receiver pipe is installed with a fluid flowing in its interior). The aim of the paper is to predict the feasibility and potential for steam generation using a stand-alone solar concentrator with a small dimension for domestic and small-scale electricity generation. The study presented here is based on modelling of the system to determine the points at which the system is expected to produce sufficient steam energy at the tube outlet to drive a steam engine for producing electricity. Results are presented in graphical forms to show the operating points and the effect of changing selected input parameters on the behavior of the system in order to set some limits (boundaries) for such parameters. Results show that among the three input design parameters selected, the tube diameter is the most dominant parameter that influences steam energy, then the tube length and finally the flow rate of the water passing through the tube. The results of this paper can provide a useful guideline for future simulation and/or physical implementation of the system.

Quantum and Classical Approach Applied to the Motion of a Celestial Body in the Solar System

According to the classical mechanics the energy of a celestial body circulating in the solar system is a constant term. This energy is defined by the masses product of the larger and smaller body entering into a mutual attraction as well as the size of the major semiaxis characteristic for the corresponding Kepler orbit. A special situation concerns the planet interaction with the Sun because of a systematic decrease of the Sun mass due to the luminosity effect. The aim of the paper is to point out that even in the case of perfectly constant interacting masses the energy of the moving body should decrease when a quantum treatment of the body motion is considered. The rate of the energy decrease is extremely small, nevertheless it gives a shortening of the distance between the interacting bodies leading to a final effect of a touch of the larger body and a smaller one.

Solar Energy Policy for India:An Overview

India’s energy crisis can be resolved by using reliable sources of renewable resources,such as solar energy with minimum adverse ecological effects.Several photovoltaic projects have been sanctioned based on rooftop models and landbased solar parks to address energy security concerns.India’s strategy focusing on increasing the installation of new solar plants,lead to the vast expansion of the renewable energy market.This paper explores the Indian government policies,current approaches,significant achievements and a scenario for solar power in India.It also summaries various technological options,research,awareness and outreach activities for the deployment of solar energy.These supportive policies provide tax exemptions,attractive tariff plans,and economic incentives which contribute to the sustainable development of the nation.

A Possible Macroscopic-Photo-Catalysis Mechanism in Solar Furnace

Based on the experimental results of Chen et al. to use the solar furnace and medium frequency induction furnace to extract boron impurity from metallurgical silicon, we propose a strong radiation catalysis mechanism to explain the difference of reaction rates in these two furnaces. The postulate assuming the photons striking on the material not only increase the thermal energy of the molecules of reactants but also lower down the energy barrier of the reaction to speed up the chemical reaction. It is believed the photon catalysis mechanism is unlversall in most of high temperature chemical reactions and looking forward to more evidences for the postulate proposed in this article.

A microfluidic all-vanadium photoelectrochemical cell with a full-spectrum-responsive Ti2O3 photoanode for efficient solar energy storage

The all-vanadium photoelectrochemical cell is one of the promising solar energy storage technologies. However, conventional photoanodes surfer from low solar energy utilization efficiency as a result of narrow spectrum response and poor mass transfer.Hence, in this study, a microfluidic all-vanadium photoelectrochemical cell with a full-spectrum-responsive Ti2O3 photoanode was proposed for efficient solar energy storage. Experimental results indicated that the Ti2O3 photoanode responded to almost the full spectrum of sunlight and exhibited excellent photoresponse and operation stability, which facilitated efficient solar energy utilization. Additionally, the effects of the light intensity, vanadium ion concentration, and electrolyte flow rate were studied. It was found that increasing the light intensity and vanadium ion concentration and reducing the electrolyte flow rate promoted photoelectrochemical reactions and thus improved the solar energy storage performance. The obtained results demonstrate the feasibility and superiority of using Ti2O3 as the photoanode for a photoelectrochemical cell to achieve efficient solar energy storage.

Effect of Initial Moisture Content on Solar Drying Ratefor Eucalyptus grandis × E. urophylla

Wood drying is one of the most important process links in wood products processing.However, the existing drying methods mainly depend on heat to desiccate wood, which makes wooddrying consume roughly 40% - 70% of the total energy in the entire wood process. Using solar energyfor drying is greatly significant in two aspects of energy conservation and environment protection. Themoisture content (MC) of lumber affects not only the target value of wood drying, but also the heattransfer properties, moisture rate of expansion, etc., affecting dried lumber quality and drying rate.Eucalyptus grandis × E.urophylla lumbers were collected from Guangdong as test materials and dried inthe solar dryer with low temperature schedule and the effect of initial moisture content were primarystudied on drying rate. Experiments showed that solar drying was suitable for timber with high MC. Interms of drying rate and dried lumber quality, solar drying was as good as traditional steam drying withthe same schedule. And the solar dryer had distinct energy-saving effect.

Experimental investigations on the heat transfer characteristics of micro heat pipe array applied to flat plate solar collector

This paper introduces a novel fiat plate solar collector （FPC） using micro heat pipe array （MHPA） as a key element. To analyze the thermal transfer behavior of flat plate solar collector with micro heat pipe array （MHPA-FPC）, an indoor experiment for thermal transfer characteristic of MHPA applied to FPC was conducted by using an electrical heating film to simulate the solar radiation. Different cooling water flow rates, cooling water temperatures, slopes, and contact thermal resistances be- tween the condenser of MHPA and the heat exchanger were tested at different heating powers. The experimental results in- dicate that MHPA-FPC exhibits the enhanced heat transfer capability with increased cooling water flow rate and temperature. Total thermal resistance has a maximum decline of approximately 10% when the flow rate increases from 180 to 360 L h-1 and 38% when the cooling water temperature increases from 20~C to 40~C. When the inclination angle of MHPA-FPC ex- ceeds 30~, the slope change has a negligible effect on the heat transfer performance of MHPA-FPC. In addition, contact thermal resistance significantly affects the heat transfer capability of MHPA-FPC. The total thermal resistances lowers to nearly half of the original level when contact material between the condenser of MHPA and the heat exchanger changes from conductive silicone to conductive grease. These results could provide useful information for the optimal design and operation of MHPA-FPC.

Use of solar PV inverters during night-time for voltage regulation and stability of the utility grid

Photovoltaic(PV)inverters are vital components for future smart grids.Although the popularity of PV-generator installations is high,their effective performance remains low.Certain inverters are designed to operate in volt-ampere reactive(VAR)mode during the night.Yet,this approach is ineffective due to the consumption of active power from the grid(as internal losses)and the regulation necessity of the direct-current(DC)bus.This paper will demonstrate the operation of a PV inverter in reactive power-injection mode when solar energy is unavailable.The primary focus is on the design of the inverter controller with respect to the synchronous rotating frame control method.The proposed novel method enables an inverter to inject the required level of reactive power to regulate the voltage levels of the utility grid within specified limits.In the process,the inverter does not absorb active power from the grid for its internal operation.The presented model has the ability to inject≤2 kVAR of reactive power at zero power factor without absorbing active power from the grid.Simulation and hardware models of the inverter were developed and tested for different reactive loads in which the hardware model represented the real-world application.The reactive power injection of the two models ran at zero power factor and produced the expected outcomes for their corresponding independent reactive loads.Henceforth,it was evident that the proposed method can enhance the efficiency of an inverter and ensure the stability of the utility grid to which it is connected.

Cost implications of increased solar penetration and time-of-use rate interactions

Electricity-grid operators are facing new challenges in matching load and generation due to increased solar generation and peak-load growth.This paper demonstrates that time-of-use(TOU)rates are an effective method to address these challenges.TOU rates use price differences to incentivize conserving electricity during peak hours and encouraging use during off-peak hours.This strategy is being used across the USA,including in Arizona,California and Hawaii.This analysis used the production-cost model PLEXOS with an hourly resolution to explore how production costs,locational marginal prices and dispatch stacks(type of generation used to meet load)change due to changes in load shapes prompted by TOU rates and with additional solar generation.The modelling focused on implementing TOU rates at three different adoption(response)levels with and without additional solar generation in the Arizona balancing areas within a PLEXOS model.In most cases analysed,implementing TOU rates in Arizona reduced reserve shortages in the Western Interconnect and,in some cases,very substantially.This result is representative of the interactions that happen interconnection-wide,demonstrating the advantage of modelling the entire interconnection.Production costs were decreased by the additional solar generation and the load change from TOU rates,and high response levels reduced the production costs the most for high-solar-generation cases.Load change from TOU rates decreased locational marginal prices for a typical summer day but had inconsistent results on a high-load day.Additional solar generation decreased the usage of combustion turbines,combined cycles and coal-fired generation.

Sustainabilty of Rice Processing in Rural Sub-Saharan Africa

Energy and environmental sustainability are important considerations for increased rice production. This study examined the energy utilization and sustainability of rice processing in sub-Saharan Africa. The community of Gadan Loko village in the song local government of Adamawa State, Nigeria was selected as the focus of study. Rice parboiling, the most energy intensive process in rice processing is carried out usually by women in small quantities of about 13.2 kg using traditional pots on tripod support stoves. The parboiled rice is sun dried on mats before it is taken to the milling stalls where it is milled using milling machines driven by single cylinder diesel engines. There were large variations in the quality of milled rice due to lack of consistency in processing parameters. Accumulation of rice husk in the community created important environmental issues. In this study, methods of improving sustainability of rice processing were investigated. The areas included： the utilization of waste heat from the diesel engines for improved drying and efficient pre-soaking; the utilization of solar energy for pre-soaking; the utilization of rice husks as alternative fuel to firewood; and the optimization and redesign of the stoves and parboiling vessels to minimize heat loss to the environment. The results showed that the utilization of rice husk as alternative fuel and the redesign of the stoves and parboiling vessels will increase the sustainability of rice processing and can be easily adopted by the community. While solar energy pre-soaking was not economical and the utilization of waste heat from the diesel engines for drying and pre-soaking would be difficult to implement at the rural scale, because most of the parboiling is done far away from the milling stalls. The study showed that research, development of appropriate technology, and education （RATE） of the rural community is an important way of increasing sustainability.

商场冷凝水耦合光伏/光热系统在不同气候区的适宜性研究

光伏光热技术是太阳能的主要利用方式之一,太阳能光伏光热一体化(solar photovoltaic-thermal,PV/T)系统可实现系统产电和热量的双重效益。基于不同气候区的气候特征,以商场冷凝水耦合光伏/光热系统为研究对象。在确定制冷季冷凝水量的基础上,计算分析系统一次能源节约率及环境效益,研究该系统在不同气候区的适宜性。结果表明:在寒冷地区、夏热冬冷地区和夏热冬暖地区,PV/T系统比光伏(photovoltaic,PV)系统更加高效节能。在整个制冷季中,PV/T系统的发电量均高于PV系统,海口的发电效率提升了0.53%,拉萨的发电效率提升了0.11%;PV/T系统在海口地区一次能源节约率最高,达到59.62%;青岛CO_(2)减排量最高,总减排量达到5.5 t。

料液输运对太阳能界面蒸发过程的影响

太阳能是一种清洁、环保的可再生能源,将太阳能应用到海水淡化系统中是解决淡水资源短缺和能源危机的有效措施。针对太阳能界面蒸发海水淡化系统,为了探究基底宽度以及料液浓度对蒸发性能的影响,本文搭建了界面蒸发实验平台,开展了组合式蒸发结构的界面蒸发过程实验研究。研究发现:对于同一种料液浓度,基底结构上水量小于界面蒸发需求时,随着基底宽度的增大,蒸发速率增大;当上水量满足界面蒸发需求后,随着基底宽度增大,蒸发速率下降,蒸发速率存在最大值点;对于同一种基底宽度,当料液浓度增大时,蒸发速率减小;随着料液浓度的增大,蒸发速率最大值向基底宽度增大的方向偏移。

太阳能干化煤泥实验研究

针对煤泥热值低、干化成本高且污染严重等问题,利用太阳能为热源,进行了煤泥干化实验研究,考察了太阳光辐照度、煤泥层厚度等因素对煤泥干化效果的影响;探究了煤泥层厚度、太阳光辐照度对干化室内温度的影响规律。研究结果表明:太阳光辐照度为500 W/m^(2)即能达到理想的干化效果;提高煤泥层厚度对煤泥的干化有利。

不同用能模式对太阳能-空气源热泵互补供热系统的影响研究

太阳能-空气源热泵互补供热系统在农村地区得到了应用,而农村人员的用能模式与城市居民具有较大差异。为定量探讨不同用能模式对系统的影响,以全生命周期费用和碳排放量为目标函数,利用TRNSYS软件构建了系统仿真优化模型,优化了不同用能模式下的系统设备容量,定量评价了不同用能模式下的系统COP、太阳能保证率、全生命周期费用和碳排放量。结果表明,与固定室温模式相比,采用动态室温控制模式下的集热器面积和水箱体积明显减少,而用能模式的不同对系统碳排放量的影响最大。研究成果揭示了不同用能模式对太阳能-空气源热泵互补供热系统的显著影响,可为今后农村地区系统的应用及优化研究提供参考依据。

Photothermal materials for efficient solar powered steam generation

Solar powered steam generation is an emerging area in the field o f energy harvest and sustainable technologies.The nano-structured photothermal materials are able to harvest energy from the full solar spectrum and convert it to heat with high efficiency.Moreover,the materials and structures for heat management as well as the mass transportation are also brought to the forefront.Several groups have reported their materials and structures as solutions for high performance devices,a few creatively coupled other physical fields with solar energy to achieve even better results.This paper provides a systematic review on the recent developments in photothermal nanomaterial discovery,material selection,structural design and mass/heat management,as well as their applications in seawater desalination and fresh water production from waste water with free solar energy.It also discusses current technical challenges and likely future developments.This article will help to stimulate novel ideas and new designs for the photothermal materials,towards efficient,low cost practical solar-driven clean water production.

Towards highly salt-rejecting solar interfacial evaporation:Photothermal materials selection,structural designs,and energy management

With the development of the industry,water pollution and shortage have become serious global problems.Owing to the abundance of seawater storage on earth,efficient solar-driven evaporation is a promising approach to relieve the freshwater shortage.The solar-driven evaporation has attracted tremendous attention due to its potential application in the seawater desalination and wastewater treatment fields.Also,the solar-driven evaporation efficiency can be enhanced by designing both solar absorbers and structures.Up to now,many strategies have been explored to achieve high solar-driven evaporation efficiency,mainly including the selection of photothermal conversion materials and structure optimization.In this review,the solar absorbers,structural designs,and energy management are proposed as the keys for high performance solar-driven evaporation systems.We report four kinds of solar absorbers based on different photothermal conversion mechanisms,substrate structure designs,and energy management methods for the purpose to achieve high conversion efficiency.And we also systematically investigate the available salt-rejections strategies for seawater desalination.This review aims to summarize the current development of efficient solar-driven evaporation systems and provide insights into the photothermal conversion materials,structural designs,and energy management.Finally,we propose the perspectives of the salt-rejection technologies for seawater desalination.

太阳能热水系统节能率与设计参数的探讨

太阳能热水系统的能耗主要为辅热系统的能耗,其节能率与系统设计保证率呈正相关。通过分析太阳辐照量与生活热水耗热量的关系可知,选取节能率变化曲线偏离点处的太阳能保证率可避免出现热量浪费和一次投资过大,保证较高的经济效益。选取了长沙地区的3种典型的设置集中热水供应系统的建筑进行分析,依据长沙地区的气象参数和此三类建筑生活热水耗热量的变化特征,得出各自节能率变化曲线偏离点处的太阳能保证率的取值。同时,根据公式计算了长沙地区平板型太阳能集热器的年平均集热效率;推导了q_(rid)值的计算方法并推荐了在长沙地区的取值。

CNT/PVA@碳布膜的光电联合驱动界面蒸发性能研究

利用电能辅助的太阳能驱动界面蒸发技术是提高淡水产量的一个有效途径,但是如何绿色高效地获取淡水仍是一个挑战。利用带有孔洞的亚克力板作为支撑装置,在碳布上喷涂碳纳米管(CNT)和无水乙醇的混合溶液作为光热电热膜(CNT/PVA@碳布),与隔热装置和供水通道组成一个高效的界面蒸发系统。蒸发性能测试结果表明,该蒸发系统在1个标准太阳光照射下净蒸发速率达到1.5 kg·m^(-2)·h^(-1),而在与2 A电流的联合作用下,净蒸发速率高达5.08 kg·m^(-2)·h^(-1),比仅在1个标准太阳光照射下和仅提供2 A电流的蒸发速率之和高出0.6 kg·m^(-2)·h^(-1)。此外,这种蒸发系统构造简单易于规模化,为绿色高效地提高淡水产量提供了一个新的思路。

“风光氢储”多能源融合系统港船综合应用适应性研究

为促进我国水路运输绿色、低碳、可持续发展,需要综合运用风、光、氢、储等多种可再生能源和技术构建港船多能源融合系统。本文从政策标准适应性、技术适应性、能源可供性、经济适应性和环保适应性五个方面分别对风力发电、太阳能光伏发电、氢能利用以及储能技术在港船多能源融合系统中的适应性进行分析,认为“风光氢储”系统的应用十分契合我国当前的能源战略和水运行业政策。