A strategy for reducing CO2 emissions from buildings with the Kaya identity – A Swiss energy system analysis and a case study

Within the general context of Greenhouse Gas (GHG) emissions reduction, decomposition analysis allows the quantification of the contribution of different factors to changes in emissions as well as the assessment of the effectiveness of policy and technology measures. The Kaya identity has been widely used for that purpose in order to disaggregate carbon emissions into various driving forces. In this paper, it is applied for the analysis of emissions resulting from energy use at three different scales. First, a decomposition analysis of the carbon emissions for the complete Swiss energy system is presented using the future projections from the Swiss Energy Strategy 2050. The Kaya identity is then applied to the Swiss building sector after it is adapted with factors that are more relatable to building parameters, such as floor area instead of Gross Domestic Product (GDP). Finally, the last level of analysis is a small scale community energy system for a unique Swiss village that aims to significantly reduce its emissions. An energy strategy is developed and its effectiveness is assessed with the adapted Kaya identity and benchmarked against the Swiss average values. The presented method demonstrates how the performance of buildings under various retrofitting scenarios can be benchmarked against future emission targets.     

Adsorption efficiency and photocatalytic activity of fly ash-based geopolymer foam mortar

Fly ash-based geopolymer foam mortar (GFM) was used as an adsorbent material to methylene blue (MB) and also the dye removal material using the photocatalytic mechanism. The GFM, containing 50 wt% river sand aggregate, was prepared to have approximately 46% open porosity, pore size distribution between 0.01 and 3.5 mm, and water permeability of 0.2 cm/s. The variation of adsorption efficiency and adsorption capacity with the contact time of the GFM was first evaluated using various GFM dosages (10, 20, 50, 80, and 100 g/L). The adsorption efficiency at equilibrium (AE_e) was found to linearly increase, while adsorption capacity (q_ae) exponentially decayed, with an increase of loading dosages. The photocatalytic removal efficiency of ~100% was obtained with 50, 80, and 100 g/L GFM loading dosages, with a shorter time at higher dosages. The GFM could be reused, without regeneration, for 5 cycles. The AE_e and q_ae for each reused cycle did not noticeably change suggesting the reusability. The photocatalytic removal efficiency, however, was found to decrease with an increase of the reused cycle. After the 5^th cycle, the highest removal efficiency was reduced to ~70%. The attempts to treat the GFMs with hydrochloric (HCl) and phosphoric (H₃PO₄) acid to reduce the excess alkaline did not give satisfactory results as expected. The photocatalytic removal efficiency had subsided after the treatment with both acids.     

A microfluidic toolbox for cell fusion

Cellular fusion is a key process in many fields ranging from historical gene mapping studies and monoclonal antibody production, through to cell reprogramming. Traditional methodologies for cell fusion rely on the random pairing of different cell types and generally result in low and variable fusion efficiencies. These approaches become particularly limiting where substantial numbers of bespoke one‐to‐one fusions are required, for example, for in‐depth studies of nuclear reprogramming mechanisms. In recent years, microfluidic technologies have proven valuable in creating platforms where the manipulation of single cells is highly efficient, rapid and controllable. These technologies also allow the integration of different experimental steps and characterisation processes into a single platform. Although the application of microfluidic methodologies to cell fusion studies is promising, current technologies that rely on static trapping are limited both in terms of the overall number of fused cells produced and their experimental accessibility. Here we review some of the most exciting breakthroughs in core microfluidic technologies that will allow the creation of integrated platforms for controlled cell fusion at high throughput. © 2015 Society of Chemical Industry     

Thermodynamic Analysis of Thermal Efficiency of HTR-10 Hydrogen Production System

This paper presents thermodynamic analysis of the thermal efficiency of the 10 MW high temperature gas cooled reactor (HTR-10) hydrogen production system. The global reaction for the equilibrium reaction model is introduced. An analytical expression for the thermal efficiency is developed using the global reaction. For the specified temperature and pressure the thermal efficiency can be computed with the solution of the equilibrium. The investigation provides a more realistic limit for the efficiency of the nuclear hydrogen production system. The influence of the temperature, latent heat, steam-to-carbon ratio and pressure on the thermal efficiency is analyzed. Varying the temperature there is a maximum thermal efficiency for the specified pressure and steam-to-carbon ratio. The latent heat influences the thermal efficiency significantly, especially at the high temperature condition. Also varying the steam-to-carbon ratio there is a maximum thermal efficiency for the specified pressure and temperature. The process should be operated with high steam-to-carbon ratio to obtain maximum thermal efficiency when the reforming temperature is low and pressure is high. The maximum value is 68.9% within the range of the pressure greater than 1 MPa and steam-to-carbon ratio greater than 2. Comparison of theoretical results to experimental data is carried out.     

What encourages local authorities to engage with energy performance contracting for retrofitting? Evidence from German municipalities

Municipalities aiming at mitigating climate change by implementing new energy efficiency technologies face budgetary and capacity constraints. Outsourcing through energy service contracting could provide a solution. This paper reports results from a survey of 1298 municipalities concerning barriers to retrofitting public street lighting and the possible role of energy service contracting to overcome these barriers. Using a logistic regression analysis, the authors investigate determinants of opting for energy service contracts in the specific context of LED retrofits. Results point to an advantage of outsourcing in a financially and capacity-constrained environment, which corresponds with the main reasons for engaging in contracting: minimising investments and financial risks. However, municipalities often do not fully grasp the risks associated with retrofitting especially using a novel technology such as LED. In relation to that they underestimate the risk reduction potential of energy performance contracts (EPC). Previous experience with outsourcing increases the probability to engage in servitization although certain existing partnerships, particularly with utilities, prevent municipalities from considering energy performance contracts. Interestingly, engaging an energy consultant has a negative propensity to use energy service contracts, while pre-negotiated standardised contracts for energy performance contracts have a positive influence.     

Effect of sol–gel MgO spin-coating on the performance of TiO2-based dye-sensitized solar cells

This paper is concerned with the improvement of dye-sensitized solar cell (DSSC) efficiency upon MgO post-treatment of the TiO₂ electrode. A simple sol–gel technique, involving magnesium acetate as precursor, ethanol as solvent and nitric acid as stabilizer, is applied to prepare a solution of suspended MgO nanoparticles. A single drop of MgO sol at 0.1 M precursor concentration was spin-coated at 3000 rpm for 30 s onto the TiO₂ electrode and sintered at 500 K for 1 h. Dye-loading using N3-dye was applied for 6 h. An increase in the average efficiency of the DSSC from 2.5% to 3.9% (over 50% enhancement) was recorded. Measurements of the dark I–V characteristics, the open circuit voltage decays, the SEM images and the dye absorbance spectra, for both uncoated and MgO-coated electrodes were examined. The improvement of the DSSC efficiency was attributed to an upward shift of the TiO₂ flat band energy and a reduction of the rate of back-transport and recombination.     

蒸汽转化炉对流段热效率低的原因分析

结合2500t/d甲醇装置蒸汽转化炉的工艺流程及运行状况,分析与探讨蒸汽转化炉对流段热效率低的原因,并制定出相应的改进措施。     

管壳式换热器壳程进出口流通面积调整方法

依据GB 151-1999附录K中壳程进出口流通面积的计算方法,推导出影响壳程进出口流通面积的3个因素,即壳程进出口接管内径、换热管的列数和壳体内径,并提出在壳程进出口流通面积不足时,如何调节这3个因素使流通面积满足要求。     

新型锥齿轮-滚轮平盘式无级变速器摩擦效率及温度场研究

针对摩擦式无级变速器摩擦生热和温度场的研究，以自行设计的新型锥齿轮-滚轮平盘式无级变速器为例，对传动过程中的滑移率、功率损失和摩擦效率进行理论研究，并用ANSYS软件对滚轮平盘摩擦生热温度场进行仿真分析。结果表明：随着转速的提高滚轮和平盘的温度上升，随着压紧力的增大，摩擦功率损失提高，摩擦效率降低；压紧力的提高，滑动速度会随之增大，产生更多摩擦热，同时也会增大接触面积，摩擦发热的面积更大，因此对温升影响更明显；新型锥齿轮滚轮-平盘式无级变速器具有较高的摩擦效率，其摩擦升温也较小。     

提高压气站运行效率的探索

通过对压气站室温高影响压缩机正常工作问题的分析,给出了避免压缩机吸入高温气体的设备布局、利于自然对流散热的厂房结构等的优化设计方案。实践表明,能提高压气站运行稳定性,效率提高约13%。