Decolorizing textile wastewater with Fenton's reagent electrogenerated with a solar photovoltaic cell

In this work it is demonstrated that Fenton's reagent can be electroproduced with abundant and cheap feedstock: oxygen saturated wastewater and solar energy. Experiments were carried out in a divided electrochemical flow cell using two electrodes: a three dimensional reticulated vitreous carbon cathode and stainless steel anode. Fenton's reagent is produced by oxygen reduction on the cathode in the presence of 1 mM Fe²⁺. The influence of electrolyte nature and its concentration and potential difference on the current efficiency, as well as the rate of Fenton's reagent electroproduction is discussed and it is concluded that over this extended range of conditions the current efficiency, for Fenton's reagent production, fell within the range 50-70%. It is possible to electroproduce a stoichiometric amount of Fenton reagent for the oxidation of 0.061 mM Reactive Black 5 (in tap water + 0.05 M Na₂SO₄, ≈pH 2.8). Similar results were obtained for solutions containing 0.1 mM Acid Green 25. Some practical applications in the field of water treatment are included. The energy required for drive electrochemical reaction is supplied to the flow cell by means of a commercial solar panel.     

Enhancing Smart Grid realisation with accurate prediction of photovoltaic performance based on weather forecast

The energy conversion efficiency of photovoltaic (PV) panels depends on solar irradiance and cell temperature. The cell temperature is affected by ambient and sky temperature, wind speed and direction, in addition to solar irradiance. This study summarises relevant relationships in the literature and describes a method of calculating cell temperature and efficiency, based only on field-measured solar irradiance, ambient temperature and wind speed. These equations have been applied to a 500?kW PV site on a typical spring day and all results were within 1.6% of measured values, with an average error of 0.05%. This provides a predictive capability for solar PV to be efficiently integrated into a Smart Grid.     

Development of a solar water distillation system with a mechanical sun tracker

This paper presents the design, construction and experimental study of a pure mechanical parabolic trough sun tracking device for solar distillation systems. It describes a novel design that uses a typical mechanical clock sun tracking system. A special mechanical weight-driven automated solar tracking system is achieved by a water float linked through a tow pulley to the gearbox. The gearbox is connected to a pulley on the shaft that connected to the dish. In estimating the driving weight required by the solar tracking collector system, the value of the summation of all loads is chosen as the driving load, resulting in a total mass of 1.5?kg with a force of 14.7?N. The results of water distillation yield show high percentage output of distillation of about 63% and consumes zero electrical energy, thereby increasing the overall efficiency of the system.     

Performance analysis of sloped solar chimney power plants in the southwestern region of Iran

The sloped solar chimney power plant (SSCPP) has significant capability to fulfil a part of the forthcoming energy requirements of villages located in the southwestern region of Iran. This paper presents the performance analysis of SSCPP which was expected to fulfil the urgent need for electric power in the southwestern region of Iran. However, to investigate the SSCPP performance and power generation throughout the southwestern region of Iran, five different regions across the Persian Gulf were considered. A mathematical model was developed to estimate the power output of solar chimneys. The performances, such as rate of air mass flow, system efficiency and solar collector efficiency, of the SSCPP were studied. The obtained results show that SSCPPs can produce from 2.98 to 5.91?MW of electricity power in the selected regions during different months of the year.     

A novel water heater using injected hydrogen combustion exhaust

With the aim of mitigating the necessity of water storage when using electric heaters and the losses and pollutant emissions produced by natural gas heaters, this article proposes a water heater based on a gas turbine system, fed with hydrogen and oxygen obtained by electrolysis within the same unit.By applying a thermodynamic analysis to the whole process, a global energy efficiency of 100% can be obtained. This high efficiency makes sense because the electrolysis losses occur in the form of heat losses, which can be used by the cold water. Because the potential of the electrolysis increases, the heat generation due to the electrolysis heat losses increases and, although the electrolysis efficiency is reduced, the global energy efficiency of the water heater remains at 100%. However, the increase in the electrolysis potential also reduces the response speed of the heater, because of the switch in both convection and conduction heat transfer. Convection heat transfer takes place when the combustion exhaust is injected directly in the cold water flow, downstream of the turbine, avoiding the losses associated with a heat exchanger and a high-temperature exhaust. The electrolysis heat losses are transferred to the water by conduction through the electrolyser walls.     

太阳能-地源热泵系统的运行模拟

以济南市某工程为例,使用DeST软件对该工程进行年逐时负荷模拟,得到冷负荷峰值为313.3 kW,热负荷峰值为293.7 kW,累计年排热量为166 451 kW·h,累计年提热量为210 380 kW·h,热不平衡率为20.88%。利用TRNSYS软件建立了太阳能-地源热泵系统动态模型,并进行模拟分析。当地土壤初始温度均为15.3℃,复合系统的模拟结果显示系统运行20年,地温均值一直保持在14.8~16.4℃的稳定范围内。研究表明:太阳能-地源热泵复合系统具有良好的蓄热能力,提高了太阳能利用率,可有效解决寒冷地区地源热泵的冷热不平衡问题,是解决严寒地区供暖问题的一个重要途径。     

郑州地区高层住宅节能优化量化研究

寒冷地区居住建筑供暖能耗占建筑总能耗很大比例,降低供暖能耗是实现建筑节能的关键之一。以郑州地区高层住宅为例,从与供暖能耗密切相关的体形系数、外围护结构热工性能和气密性三方面进行了优化设计,并利用建筑能耗模拟软件Design Builder对优化前后的供暖能耗进行了量化分析。结果表明通过体形系数、外围护结构和气密性的优化,建筑供暖能耗可分别降低2.29%、16.05%和15.14%;优化后供暖总能耗由257 917 k W·h降低至178 967 k W·h,单位供暖能耗由44.89 k W·h/m2降低至31.15 k W·h/m2,降低了30.60%。研究成果为我国寒冷地区高层住宅的节能设计提供了参考。     

Development and performance test of a low-cost hybrid solar air heater

A hybrid energy system named as SAH embraces the features of solar and thermal devices to generate electrical and thermal energies simultaneously. Recently, some SAH has developed with higher efficiency but less feasible to the developing countries due to higher installation cost. Here, a cheaper SAH with more capability of utilising the solar energy and enhanced efficiency by incorporating fin with the SAH has developed. SAH performances have been analysed experimentally by varying the air mass flow rate from 0.0132 to 0.02166?kg/s for the both fin and without fin attached condition. During mass flow rate of 0.02166?kg/s, maximum efficiency for the collector, photovoltaic cell and the overall efficiency of the system has been recorded as 34.25%, 6.48%, and 35.26% with fin and 28.07%, 4.10%, and 29.37% without fin, respectively. This study would assist the researcher for further improvement of the SAH and guide the consumer to select the appropriate SAH.     

Feasibility and techno-economic assessment of stand-alone and hybrid RE for rural electrification in selected sites of south eastern Nigeria

The study assessed the feasibility and economic viability of solar and wind energy resources as sustainable electrical source for rural communities unconnected to the grid. Rural communities made up of 200 homes, a school and health centre were conceived. Specific electric load profile of 358?kWh per day, with 46?kW primary peak load and 20?kW deferrable peak load, was formulated to match the rural communities. The assessment of the design that will optimally meet the daily load demand with a loss of load probability of 0.01 was carried out by considering three stand-alone applications of photovoltaic (PV), wind, diesel, and a hybrid design of wind-PV. The result showed that a cost-effective alternative for power generation at the different sites surpassed the conventional diesel stand-alone system. Also, the embedded generation analysis showed that 5 of the 6 configurations yielded profits for a 10-year project life in line with the present national tariff order.     

上海地区独立住宅分布式光伏发电系统的后评估研究

基于上海一独立住宅光伏发电系统运行一年的数据,从发电量、光伏系统效率、光伏能源替代率、光伏系统效率影响因素等方面进行后评估。结果表明:过去一年度理论预测年发电量为5 738 k W·h,实际发电量为4 109 k W·h,全年度光伏系统效率为73%。为研究光伏系统效率的影响因子,在系统运行期间未对光伏组件表面实施人工清洁维护,对此条件下的运行数据进行分析发现,光伏系统效率总体呈现逐渐降低的趋势。其中在近水平安装角度的情况下,组件光电转换效率最大降低达2.08%。在该住宅按照现行理想的设计条件运行(冬季连续采暖确保室内20℃、夏季连续空调确保室内26℃)的前提下,过去一年度的总用电量为12 054 k W·h,其中空调用电量为9 332 k W·h,占到总用电量的77.4%。全年光伏能源替代率为34%,过渡季节可实现光伏能源替代率最高达180%。独立住宅上存在较大的节能空间和光伏能源替代率提升空间。     

Design, construction and performance testing of a new system for energy saving in rural buildings

Drying fruit, heating residential buildings and providing a hot water supply in villages all consume energy. Using fossil fuel for these purposes creates pollution and costs too much. In contrast, the use of solar energy in these applications leads to a noticeable decrease both in pollution and investment costs. In this study, a new solar system was designed and tested in order to reduce energy usage in rural residential buildings and the food drying industry. As the peaks of energy consumption in the proposed system are not simultaneous, this new system is very effective in reducing energy consumption, controlling energy peaks and reducing environmental pollution. This system has the ability to provide the required energy in both summer and winter modes. In the summer mode, the energy supply is used for providing hot water and drying agricultural products, while in winter mode it is used for rural residences heating and hot water supply. Drying time has been varied between 51.23 and 42.45 h according to type of application, and average temperature difference between room and ambient is almost nearly 10 °C with different air heaters. The system includes energy supply and storage equipment, solar dryers, water collectors and rectangular, triangular, trapezoidal and double-pass with longitudinal fins air heaters. The system was tested in Iran for drying apricots, heating rural residential buildings and supplying hot water for domestic use, meanwhile, the energetic and exergetic efficiency of the system was calculated 37.3-61.3 and 3.2-9.7 respectively for different types of installations.     

Study on the performance of a solar assisted air source heat pump system for building heating

This paper proposed a new solar assisted air source heat pump system with flexible operational modes to improve the performance of the heating system. A mathematical model was established on the solar assisted air source heat pump system for building heating with a heating capacity of 10 kW, and an air source heat pump unit was developed to validate the model. The effect of the solar collector area on the performance of the system running in Nanjing was studied. The results showed that the COP of the heat pump unit was enhanced with the increase of the solar radiation density during the typical sunny day in the heating season. In addition, the COP also increased in proportion to the solar collector area. Compared with the case when the solar collector area was 0 m², the COP increase of the heat pump and the energy-saving rate were 11.22% and 24% respectively when the solar collector area was 40 m². Meanwhile, the solar equivalent generation power efficiency could reach 11.8%.     

The financials of constructing a solar PV for net-zero energy operations on college campuses

The LACCD has a goal of establishing net-zero energy operations across its nine campuses. The project faces many challenges, including limited open areas for installing solar PV, increasing energy consumption challenges associated with campus energy growth and the high cost of installing solar PV. A previous study by Kwan and Hoffmann (2010) found that the LACCD would need to install a 9.5 MW solar PV array in order to meet total campus energy demand on a college campus through the year 2020. This paper attempts to evaluate the financial feasibility of such a project, taking into account the current local, state and federal renewable energy incentives available. We find that despite the availability of financial incentives by local municipal utility companies including installation rebates and net metering, the cost of electricity generated by solar PV still remains approximately 30% higher than electricity generated by fossil fuels. We also find that the optimal solar PV array size from a financial standpoint is one that is sized to generate and meet all electrical demand during sunlight hours. Any array larger than this yields diminishing returns. Finally our analysis examined the influence of per kW installation cost and found that only when prices dropped to $3.00 per installed watt did a net-zero energy solar PV array have an NPV of 0.     

Description and performance of an active solar cooling system,using a LiBrH2O absorption machine

The report describes the design, modelling and performance of an active solar cooling system in northern Italy. Various aspects related to active solar cooling, like energy storage, room comfort, modelling and the LiBrH₂O absorption cycle are discussed.The cooling system consists essentially of: an array of 36 m² of flat plate collectors with a black chrome selective surface; a LiBrH₂O absorption machine with a refrigerating power of 4 kW; and two storage devices of 0.3 and 2 m³ water. The system is installed in the JRC Solar Laboratory in Ispra.The results of one summer of operation are presented together with the results of the simulation model. The overall system efficiency, defined as the fraction of the solar irradiation which is converted into cooling effect, is calculated for the whole cooling season and is found to be 11%. This value lies close to the measured values for this parameter.     

Thermo-economic analysis of an ocean thermal power plant for a Nigerian coastal region

This paper presents a thermo-economic analysis of an ocean thermal energy conversion (OTEC) power plant for a Nigerian coastal region at latitude 4°00′–4°16′N, and longitude 7°16′–7°19′E, whose energy potential is at 22 and 24?K across 1?km from the sea water surface during rainy and dry seasons, respectively. An ammonia closed cycle OTEC plant was designed to constantly supply 100?MW of electricity all year round to the region. The results of the analysis compared favourably with those for similar plants. The plant’s unit cost of energy was found to be 0.11US$/kWh when compared to 0.1US$/kWh for the municipal energy supply. The break-even point was also found to be 12 years. However, as a result of the high initial installed capital cost of 7954.37US$/kW and life cycle cost of 1.30bUS$, only very large organisations would be able to venture into this project.     

Exergoeconomic analysis of the Gonen geothermal district heating system for buildings

This paper presents an application of an exergoeconomic model, through exergy and cost accounting analyses, to the Gonen geothermal district heating system (GDHS) in Balikesir, Turkey for the entire system and its components. This exergoeconomic model is used to reveal the cost formation process and the productive interaction between components. The exergy destructions in the overall Gonen GDHS are quantified and illustrated for a reference temperature of 4 °C. The results indicate that the exergy destructions in the system occur primarily as a result of losses in the cooled geothermal water injected back into the reservoir, pumps, heat exchangers, and pipelines. Total exergy destruction and reinjection exergy of the cooled geothermal water result in 1010 kW (accounting for 32.49%), 320.3 kW (accounting for 10%) of the total exergy input to the Gonen GDHS, respectively. Both energy and exergy efficiencies of the overall Gonen GDHS are also investigated to analyze the system performance, as these efficiencies are determined to be 42% and 50%, respectively. It is found that an increase of the load condition leads to a decrease in the overall thermal costs, which will result in more cost-effective energy systems for buildings.     

Annual performance analysis of a single-basin passive solar still coupled with evacuated tubes: comprehensive study in climate conditions of Mahesana,Gujarat

A solar still is very simple device to convert available brackish or saline water into drinkable water by use of solar energy. But due to its lower distillate output, it is not used widely for industrial and domestic potable water application. In the present research paper, annual performance analysis of a single-basin passive solar still with vacuum tubes (SBSWVT) is carried out in climate conditions of Mahesna, Gujarat, India, during July 2011–June 2012. From constant research work of 1 year, energy payback time of 176 days and cost of water produced of around 0.716?Rs per litre have been found.     

Solar integrated energy system for a green building

Shanghai is characteristic of subtropical monsoonal climate with the mean annual temperature of 17.6 °C, and receives annual total radiation above 4470 MJ/m² with approximately 2000 h of sunshine. A solar energy system capable of heating, cooling, natural ventilation and hot water supply has been built in Shanghai Research Institute of Building Science. The system mainly contains 150 m² solar collector arrays, two adsorption chillers, floor radiation heating pipes, finned tube heat exchangers and a hot water storage tank of 2.5 m³ in volume. It is used for heating in winter, cooling in summer, natural ventilation in spring and autumn, hot water supply in all the year for 460 m² building area. The whole system is controlled by an industrial control computer and operates automatically. Under typical weather condition of Shanghai, it is found that the average heating capacity is up to 25.04 kW in winter, the average refrigerating output reaches 15.31 kW in summer and the solar-enhanced natural ventilation air flow rate doubles in transitional seasons. The experimental investigation validated the practical effective operation of the adsorption cooling-based air-conditioning system. After 1-year operation, it is confirmed that the solar system contributes 70% total energy of the involved space for the weather conditions of Shanghai.     

Way forward in meeting energy challenges in Pakistan

In this review the energy potential of Pakistan from hydro, coal, wind, solar and nuclear sources has been discussed. The new projects that are being commissioned on coal, wind, solar, hydel and nuclear-based technologies have also been mentioned. The review has also explored the future prospects of the country’s energy requirements. Pakistan has potential to produce 100,000?MW of electricity from Thar coal for 20 years, 56,000?MW of hydroelectricity, 150,000?MW of wind energy and ～50,000?MW from solar sources. The coal-fired power generation is expected to 11,500?MW in period 2017–2019. The country is moving in the right direction to cater its energy needs. However, there is a need to find local and foreign investment in the country to meet high energy demands in the country in future.