Solar Assisted Small-Scale Biomass District Heating System in the Northern Part of Sweden

Abstract

This article presents a case study of a projected solar assisted biomass district heating system in the north of Sweden. It is generally known that a biomass district heating system combined with solar heat brings many important benefits. The most common system solution is to install a heat store and a large solar collector field near the heating central. No plant of this type is however in operation in the northern part of Sweden. The main reason for this is that the solar irradiation at these latitudes is very low when the demand for heat is high. Solar heat could however be useful during summer in order to generate hot tap water. One problem is that the heat losses, calculated as percentage of the delivered heat, become very large during these months. This article presents the idea of allowing the connected households to generate their own hot tap water using solar collectors and heat stores installed in each house. The district heating network can therefore be closed in summer, which eliminates the heat losses outside the heating period. A case study of a projected plant has been carried out and it is shown that it is possible to reduce the heat losses by 20% compared to a conventional system. This idea also provides many other important technical and economic benefits.     

浅析锅炉水处理的必要性

锅炉给水不进行处理,必然导致锅炉的结垢和腐蚀。锅炉结垢使锅炉供暖效率降低,严重时可能会造成熔孔或爆管。     

2种改性活性炭对甲苯吸附性能的对比研究

利用微波、电炉加热对活性炭进行改性,并测定了改性前后不同种类活性炭对甲苯的吸附性能、表面酸碱官能团含量以及比表面积.结果表明,对于微波改性,随着改性温度升高,活性炭对甲苯的吸附量逐渐增大,表面碱性官能团含量也相应增加,比表面积相应减小.改性温度850℃时活性炭吸附甲苯性能最高,650℃与450℃改性后活性炭吸附甲苯的性能相差不大.电加热改性也具有类似的趋势,但对甲苯的吸附性能总体低于微波改性.扫描电镜表征显示,热改性去除了活性炭孔道内的杂质,使活性炭内部孔道更加通畅,有利于提高吸附甲苯的能力,但温度升高同样存在炭骨架收缩,孔道变窄的弊端.微波加热和电炉加热在原理和热传递方向上的不同.是导致改性结果之间差别的关键问题.     

沼气伴热研究进展

介绍了温度对厌氧发酵过程的影响,综述了解决低温发酵问题的各种措施,包括加热沼气池、优选低温菌种、添加促进剂以及改善发酵工艺,提出驯化低温发酵菌种是将来的主要研究方向。     

水中高锰酸盐指数测定全程质量控制

质量控制是环境监测赖以生存和发展的基础,加强全程质量控制才能确保监测数据的准确性和可靠性。结合环境监测工作实际,应用国标经典分析方法-酸性法／碱性法《水和废水监测分析方法》（第四版）（增补版）对水中高锰酸盐指数测定进行了全程质量控制技术探讨。简介了方法所需仪器与试剂,深入探讨了运用国标法进行水中高锰酸盐指数测定全程质量控制技术问题。指出在标准分析方法基础上,选用有效期内的质量合格的分析纯以上试剂,正确进行样品测定预处理,严格规范加热操作与滴定过程,准确进行分析结果数据处理,切实加强结果填报规定程式．能够确保大批量、成分复杂未知水样高锰酸盐指数测定精密度和准确度。     

原油加热炉对流炉管表面积灰清理技术的应用

针对鲁宁线和中洛线原油加热炉炉管穿孔现象,对加热炉积灰成分、性质及成因进行了分析,提出有效的高压蒸汽清灰技术。现场应用表明,该技术可提高炉管换热效率、减少炉管的腐蚀,确保加热炉的安全运行。     

齐齐哈尔市热电联产项目节能减排分析

以热电联产集中供热作为节能减排的重要措施,分析了齐齐哈尔市热电联产项目在节能降耗和污染减排中的作用.     

Assessing the number of users who are excluded by domestic heating controls

Space heating accounts for almost 60% of the energy delivered to housing which in turn accounts for nearly 27% of the total UK's carbon emissions. This study was conducted to investigate the influence of heating control design on the degree of ‘user exclusion’. This was calculated using the Design Exclusion Calculator, developed by the Engineering Design Centre at the University of Cambridge. To elucidate the capability requirements of the system, a detailed hierarchical task analysis was produced, due to the complexity of the overall task. The Exclusion Calculation found that the current design placed excessive demands upon the capabilities of at least 9.5% of the UK population over 16 years old, particularly in terms of ‘vision’, ‘thinking’ and ‘dexterity’ requirements. This increased to 20.7% for users over 60 years old. The method does not account for the level of numeracy and literacy and so the true exclusion may be higher. Usability testing was conducted to help validate the results which indicated that 66% of users at a low-carbon housing development could not programme their controls as desired. Therefore, more detailed analysis of the cognitive demands placed upon the users is required to understand where problems within the programming process occur. Further research focusing on this cognitive interaction will work towards a solution that may allow users to behave easily in a more sustainable manner.     

Comparative experimental analysis of the effect of convective heat losses on the performance of parabolic dish water heater

This paper reveals comparative experimental analysis of the effect of variation of natural and forced convection heat losses on the performance of prototype parabolic dish water heater with coated and non-coated receivers. With the above-described system, hot water needs in domestic applications can be fulfilled instantly. A parabolic dish collector was used for instant water heating. Design of solar parabolic dish collector consists of truncated cone-shaped helical coiled receiver made up of copper at focal point. Instantaneous efficiency of 63% and 48% has been achieved with coated and non-coated receivers. This prototype has been evaluated for its performance with water flow rate of 0.0076 kg/s during the months of April and May 2010 at Shivaji University, Kolhapur, Maharashtra, India (latitude: 16.42° North, longitude: 74.13° West).     

System dynamics modelling of hybrid renewable energy systems and combined heating and power generator

The role of energy in the present world is critical in terms of both economical development and environmental impact. Renewable energy sources are considered essential in addressing these challenges. As a result, a growing number of organisations have been adopting hybrid renewable energy system (HRES) to reduce their environmental impact and sometimes take advantage of various incentives. When a HRES is being planned, the ability to model a HRES can provide an organisation with numerous benefits including the capability of optimising sub-systems, predicting performances and carrying out sensitivity analysis. In this paper, we present a comprehensive system dynamics model of HRES and combined heating and power (CHP) generator. Data from a manufacturing company using HRES and CHP generator are used to validate the model and discuss important findings. The results illustrate that the components of a HRES can have conflicting effects on cost and environmental benefits; thus, there is a need for an organisation to make trade-off decisions. The model can be a platform to further simulate and study the composition and operating strategies of organisations that are venturing to adopt new or additional HRESs.