褐煤自燃倾向测定及其低温氧化反应过程研究

褐煤的自燃是一个缓慢的低温氧化过程,搭建煤自燃倾向测定实验台,采用篮热法测定不同煤种的自燃倾向,求得不同煤自燃的动力学参数,并采用热重和傅里叶红外光谱(FTIR)揭示其低温氧化反应机理,分析褐煤自燃倾向的影响因素。实验发现,水分含量的高低会影响自燃发生的时间,但不影响煤种最终的自燃倾向。褐煤的自燃倾向性是与煤的低温氧化反应性直接联系的:褐煤在低温氧化反应过程中,主要发生烷基侧链断裂,然后氧化反应放热,造成热量的积累。煤中烷基侧链基团含量越高,芳香烃含量越低,其氧化反应性越强,更易发生自燃;煤样比表面积决定了对氧的吸附能力,吸附能力越强,其低温氧化反应性越高,越容易发生自燃。     

太阳能-空气源热泵耦合式沼气池加温系统设计

针对8 m3沼气发酵池设计了一套空气源热泵-太阳能耦合式加温系统,可以根据不同天气切换运行太阳能、太阳能空气源热泵和空气源热泵3种热源模式,以满足沼气池内的加温需求。计算了沼气池加温系统的热负荷,将该系统与电热膜加温系统和地源热泵系统进行了比较,可以分别增加投资效益净现值11866.9元和4726.7元,多投资部分的投资回收期分别为8年和4年。可见,对于小型沼气池工程,采用空气源热泵辅助太阳能热水系统,从节能性与经济性来讲,是一种适宜推广的热源形式。     

洗衣机安装板热流道注射模具的设计与计算

基于Pro/E Wildfire 4.0进行热流道注射模具的设计,介绍了热流道模具的结构特点,详细论述热流道模具浇注系统的结构设计和尺寸计算、热流道板加热功率计算、热流道板线膨胀量计算及在设计时应注意的一些问题.     

水循环泵节能控制方法在冬季供暖中的应用

介绍了冬季供暖水循环泵节能控制方法,采用了传统PID结合温度模糊控制和PWM的方法。可预设转折频率、转折延时、不同温度段脉冲频率上、下限值,节能控制柜根据出水管和回水管两者温差通过PID算法调节水泵运转频率,当水泵运转频率低于转折频率,转折延时后,采用PWM方式;若水泵运转频率高于转折频率,则进入模糊PID调节。PWM技术的应用,使得供暖温度能够结合室外大气温度进行实时调控。该方法在满足用户的温度需求前提下,可使水泵电机节能30％以上。     

Design of an individually controlled system for an optimal thermal microenvironment

Individually controlled microenvironment has potential to satisfy more occupants in a space compared to a total volume uniform environment typically used at present. The performance of an individually controlled system comprising a convection-heated chair, an under-desk radiant heating panel, a floor radiant heating panel, an under-desk air terminal device supplying cool air, and a desk-mounted personalized ventilation as used and identified by 48 human subjects was studied using a thermal manikin at room temperatures of 20 °C, 22 °C and 26 °C. At a room air temperature of 20 °C, the maximum whole-body heating effect of the heating chair, the under-desk heating panel, and the floor heating panel corresponded to the effect of a room temperature increase of 5.2 °C, 2.8 °C, and 2.1 °C, respectively. The effect was 5.9 °C for the combination of the three heating options. The higher the room air temperature, the lower the heating effect of each heating option or heating combination. The maximum whole-body cooling effect of the tested system was only −0.8 °C at a room air temperature of 26 °C. The heating and cooling capacity of the individually controlled system were identified. These results, analyzed together with results obtained from human subject experiments, reveal that both the heating and the cooling capacity of the individually controlled system need to be increased in order to satisfy most occupants in practice.     

Heat emission from thermal skirting boards

The performance of three hydronic skirting heating systems was investigated. The main focus of the study was to ascertain whether thermal skirting boards served by low-temperature supply flow were able to suppress strong downdraught. The evaluation was made for a two-person office room with mechanical ventilation. Computational Fluid Dynamics (CFD) simulations and three different draught rating models were employed to predict the level of thermal discomfort inside the room. CFD results were validated against several analytical calculations and four sets of experimental data presented in previous studies. Numerical simulations showed that all three skirting heating arrangements were able to cover transmission and ventilation thermal losses of the office room. Horizontal and vertical heat distribution inside the room was uniform for all heating systems. CFD simulations also showed that thermal skirting boards served by 40 and 45 °C supply flow had difficulty in reducing the velocity of the downdraught at ankle level. Consequently the draught rating in this region was around or slightly above 15% for these cases. In contrast, heat-emitting skirting boards supplied by 55 °C hot water showed a better ability to suppress downdraught, and the proportion of people sensing draught at 0.1 m above the floor was low. The conclusion of this study was that thermal performance of hydronic skirting heaters with low-temperature water supply must be improved in order to counter strong downdraughts, in particular where such systems may be combined with heat pumps of other low-valued sustainable energy sources.     

甩丝法制备多晶氧化铝纤维

使用溶胶-凝胶法制备氧化铝质量分数为80%的多晶氧化铝纤维。以结晶氯化铝、铝粉和硅溶胶为主要原料制备出不同粘度的胶体,采用甩丝法制备纤维。研究了胶体粘度、甩丝盘转速对纤维直径和拉伸强度影响。并对热处理过程中升温制度对纤维拉伸强度的影响进行了研究。结果表明：当胶体粘度为20,Pa·s、甩丝盘转速为6,000,r/min、升温速度为240,℃/h时得到的纤维拉伸强度较高,该纤维经1,200,℃烧成后,平均单丝拉伸强度超过1,100,MPa,是一种性能较优异的氧化铝纤维。     

液体降膜中Marangoni效应的研究进展

降膜过程中的Marangoni效应是当前流体传递过程与非线性理论研究领域中的热点,对产品质量具有重要影响。回顾了近几年国内外关于Marangoni效应的最新研究进展,重点介绍了有关热Marangoni效应的实验及理论研究成果,并进行了比较和分析。结果发现,Marangoni效应与体系温度和浓度变化等有关,并会影响降膜稳定性。同时,针对目前研究中存在的一些不足,提出了今后研究工作的一些建议。     

焦炉蓄热室阻力减小的措施及效果

长期使用杂质含量很高的加热煤气,导致焦炉蓄热室堵塞严重,格子砖阻力升高。通过清扫处理,减小了蓄热室格子砖的阻力,杜绝了煤气的泄漏,节省了煤气资源,也消除了影响安全生产的隐患。     

2009显示周回顾：触控技术

在2009显示周上,触控技术取得了令人惊讶的突破,触控屏数目剧增,并且性能也得到提升。