石墨水泥砂浆注浆钢纤维混凝土板融雪试验

采用渗浇工艺制作了石墨水泥砂浆注浆钢纤维混凝土(GSIFCON)板.对该板的电热性能和冬季野外融雪性能进行了试验研究.结果表明:GSIFCON板通电产生的热量可有效融化积雪.在GSIFCON板的底面和侧面分别设置3 cm厚聚乙烯泡沫保温层时,其融雪热效率可达20%以上,较无保温层的GSIFCON板其融雪效率提高约5%.应用这种技术,可有效避免除冰盐对混凝土和环境带来的负面影响.     

电加热辐射地板传热特性的实验研究

本文利用组合式电热辐射板实验研究了电加热地板采暖辐射板内的传热特性。研究结果表明:辐射板的结构材料及其物性参数对表面温度分布和采暖能耗具有重要的影响。即使在实验条件下加热板内各层温度,使其呈周期性波动,但室内地板表面温度分布仍然非常均匀。在辐射板的热量损失中,通过辐射板下表面的损失热量接近辐射板全部的热量损失。     

导电混凝土应用于建筑采暖工程的计算方法

导电混凝土作为一种新型建筑材料,将其应用于建筑采暖工程中,可有效节约资源、保护环境。室内空气温度是建筑采暖的主要关注点,针对导电混凝土作为建筑采暖地面的问题,在考虑电热效应、辐射换热与对流换热等的基础上,给出了混凝土温度场、室内空气平均温度的计算方法,无需对空气建模,简化了前处理工作量。与室内试验结果对比分析表明,计算结果与试验结果相对偏差在1.34%左右,验证了所提出计算方法的正确性与可用性。针对室内采暖效率,进行了不同组合工况的数值模拟分析,说明了通电电压、混凝土厚度的可挖潜能力较弱,导电混凝土的电阻率敏感性较强,是可挖潜的重要影响因素。     

新型室内供暖板

新型室内供暖板前苏联乌兹列克共和国的建筑科学家发明了一种新型采暖墙体。它是由乌兹别克首府塔什干附近的一家实验工厂由建筑技术专家们研制的一种新型加热板。实验表明，采用这种加热板后，房间里不需要再安装暖炉或其它传统的暖气设备。经剖析，这种加热板由两块混凝...     

电热混凝土建筑采暖的功率分析

介绍了电热混凝土建筑采暖的基本原理,在考虑能量守恒定律、电热效性、室内外传热过程的基础上,分析计算了室内建筑采暖的最低功率需求以及不同升温时间与电热混凝土发热功率的关系,并提出了提高室内升温速率的建议。结果表明:电热混凝土的发热功率能满足室内采暖最低功率的需求,电热混凝土的比热容和密度是影响室内升温速率的2个重要因素,降低其比热容和密度能有效缩短室内升温时间。     

新建被动式太阳房冬季热性能的实验研究

本研究住新建成的被动式太阳房内，利用多通道计算机巡回检测系统，对室内外温度、太阳辐射强度、集热蓄热墙体温度以及通风口风速、温度进行了长期实测，研究含有Trombe墙体的新建被动式太阳房采暖季节的热性能，采暖季节的室内温度随室外气象条件以及太阳辐射强度的变化情况、室内温度在集热蓄热墙体作用下的波动情况以及住不同天气情况下Trombe墙对室内温度的影响。通过分析发现，被动式太阳房的室内平均温度晴天时有5个小时室内达到了16℃，空气热循环带入室内的热量相当于热负荷的9％。阴天被动式太阳房的室内平均温度基本达到10℃左右，连续阴天的情况下太阳房需要利用辅助热源进行采暖。通过对Ra数的计算发现，在不同的室外条件下室内空气流动状态有很大不同。另外，通过实验发现对新建被动式太阳房而言，由于墙体内含有大量的水分，会直接影响Trombe墙的集热蓄热作用。     

地面采暖方案的优点及前景

地面辐射对采暖具有室内温度均匀、稳定、热容量大、不占使用面积等优点,使用效果好,人体感觉舒适,卫生标准高。由于室内采暖主要依靠辐射方式,在相同条件下,     

风机盘管辅助地板辐射采暖的实验研究

风机盘管辅助采暖可解决低温热水地板辐射采暖预热时间长的问题,使室内较快达到热舒适性要求。为研究辅助采暖系统的热工特性,通过构建两级串联加热的实验系统和测量系统运行过程参数,分析了系统在启动阶段、稳定运行和关闭后的室内温度分布及变化情况。实验结果表明:系统稳定运行时,室内温度在水平和竖直方向分布均匀,热舒适性较好。与单独的地板辐射采暖相比,启动阶段室内温度能够快速达到热舒适度要求,缩短预热时间1倍以上。     

农村住宅夜间3种床/炕加热方式对比实验研究

提出一种新型热盘管炕作为夜间采暖方式,与村镇普遍使用的火炕、电热毯在被褥热环境和室内环境方面的差异进行对比实验。分析发现,电热毯采暖响应速度快,但被褥热均匀性差,供热能力有限,无法保障室内温度;火炕采暖响应速度较快,但被褥温度保障时间短、可调节性差,室内存在烟气,CO2浓度超标;热盘管炕采暖响应速度一般,但被褥温度分布均匀,温度稳定后人体热舒适区占比可达80%以上,且室内环境良好。     

碳纤维电热板地板辐射供暖系统热工性能测试

对碳纤维电热板在地板辐射供暖系统中的升温和稳定工况下的热工性能进行了试验研究.计算了电热板对流传热量、辐射传热量及电热转换率.碳纤维电热板热惯性小,温度响应速度快,电功率基本恒定,适用于对供暖要求灵活的场所.在室内温度要求范围内,电热板表面平均温度适宜,电热平均转换率为0.948.     

Experimental studies on the indoor electrical floor heating system with carbon black mortar slabs

A room using carbon black mortar slabs (CBMS) as the electrical floor heating element has been built in our lab. Studies showed that an electrical power of about 123.8 W/m² resulted in the indoor temperature rise of 10 °C within 330 min. Temperature distribution along the height of the room was uniform. Temperature rise was slightly higher if floor tiles rather than the wood flooring was used. In the process of heating, self-heating of CBMS has consumed more than 30% of the generated heat by Joule effect, which was advantageous for the stability of the thermal state. The indoor air absorbed over 50% of the generated heat. Results derived from repeated tests show that the electrical power of the CBMS system was stable during several cycles of heating. Further, the procedure and power consumption for the system to maintain a certain indoor temperature were studied. Continuous tests for 72 h has shown that the higher the indoor controlled temperature was, the longer the working time and the shorter the rest time in every cycle of heating were required. Accordingly, the power consumption to maintain the heat state increased with the controlled temperature increasing.     

四边简支现浇混凝土空心楼盖二次抗火性能试验研究

为探究火灾后采用聚合物砂浆加固修复混凝土空心楼盖二次火灾下的抗火性能,对四边简支混凝土组合塑料模盒空心楼盖进行两次火灾试验。介绍了试验空心楼盖第一次受火试验及火灾后构件修复情况,重点介绍了加固修复后空心楼盖第二次火灾试验,描述了试验空心楼盖在两次受火下的破坏特征、变形和温度场分布规律,并进行分析和对比。研究结果表明:采用聚合物砂浆修复的空心楼盖在二次火灾作用下,第一次火灾受损较为严重的部位易产生爆裂脱落,从而降低了耐火极限;二次受火下楼盖内混凝土的温度峰值高于一次受火,且距离板底越近,两次火灾作用中温度峰值差值越大;试件在两次火灾作用下跨中处最大竖向位移基本相同,第二次受火作用后的残余位移小于第一次;采用聚合物砂浆对火灾后的空心楼盖进行修复,修复后的楼盖仍具有一定的抗火性能。     

Modeling and simulation of under-floor electric heating system with shape-stabilized PCM plates

A model is developed to analyze the thermal performance of a room applying a new kind of under-floor electric heating system with shape-stabilized phase change material (PCM) plates, which is verified by our experimental data. This system can charge heat by using cheap nighttime electricity and discharge the heat stored at daytime. The thermal performance of the heating system and the effects of various factors on it are analyzed through simulation. The results show that the heating system can be used in various climates if its structure is properly designed. The model and the discussion are helpful to design such kind of under-floor electric heating systems.     

Fuzzy and feedforward control of an hybrid thermal energy storage system

A control model for operating a system that stores simultaneously sensible heat from solar and electric energy is proposed. The hybrid thermal energy storage system accumulates solar energy during sunny days and releases it later at night or during cloudy days. It also stores heat from an electric heater during off-peak periods so as to release it later during peak periods. The control model, which makes use of 24-h weather forecasts, comprises two types of controllers: a fuzzy logic controller for estimating the daily amount of thermal electric energy to be stored and a feedforward controller for determining the electricity consumption profile of the heating element during off-peak hours. Results indicate that the proposed control system is far superior to traditional control systems. It maintains a comfortable thermal environment at all times, i.e. the temperature fluctuations are kept within the imposed margins and overheating of the room never occurs. Furthermore, compared to a traditional electric base board heating system, it reduces the electricity consumption for the winter season by 24% and 94% of this electricity is consumed during off-peak hours.     

低聚灰比VAE聚合物水泥砂浆的性能及应用

将VAE 共聚乳液掺入水泥砂浆中,能改善其多种性能。在低聚灰比条件下,研究了VAE聚合物水泥砂浆的机械性能、耐热性、耐水性、抗掺性、耐久性及负温强度。     

砂浆与饰面砖粘结强度的试验研究

介绍了粘结强度的测试方法 ,进行了灰砂比、环境湿度及拉力反复作用对砂浆与饰面砖粘结强度影响的试验。分析认为砂浆干缩和外墙室内外温差变化是导致外墙饰面砖粘贴一段时间后出现脱落的重要原因。     

高温后砂浆的水分传输与力学性能试验研究

水泥基材料是由水泥、骨料等组成的复合材料,高温作用后材料内部产生严重的热损伤,导致其力学及耐久性能降低。通过数码显微镜观察了经过105、200、400、600、800℃温度作用后水泥砂浆的表面形貌,发现砂浆表面热损伤裂缝的宽度随着温度的升高而逐渐增大。通过称重法对高温作用后水泥砂浆的毛细吸水性能进行测试后发现:热损伤作用对于水泥砂浆的一维吸水过程有着明显影响,毛细吸水系数随着温度的升高而急剧增加,经过800℃高温作用后的砂浆样品的毛细吸水系数为105℃下烘干的砂浆样品毛细吸水系数的5.7倍。通过抗压、抗折和劈裂抗拉试验研究了高温后砂浆的力学性能,证实了砂浆的抗压、抗折和劈裂抗拉强度随着温度的升高而衰减的规律,800℃作用后砂浆样品的抗压、抗折和劈裂抗拉强度分别为20℃时的31%、61%、19%。同时,测得的试验数据表明:高温损伤砂浆毛细吸水系数与其抗压、抗折及劈裂抗拉强度间均存在着明显的线性关系,因此吸水性系数可作为高温损伤水泥基材料力学及耐久性能评价的重要指标。     

相变储能材料在地源热泵建筑中应用效果的模拟研究

地源热泵系统在建筑环境中,利用介质传输的方法,起到与环境的热交换作用。在冬季,地源热泵传输的地热能在满足使用的同时,部分能够存储在相变材料中。在夜间,关闭使用地源热泵的情况下,相变材料利用自身的结晶放热性能,为建筑物室内持续加热并保持一个较为舒适的温度,实现节约电能及提高热效率的目的。地源热泵使用雨水收集系统中净化的中水作为传输介质,能够满足日常小区住户对热水需求的同时实现节能的目的。     

Modelling of a water-to-air variable capacity ground-source heat pump

The present work aims at presenting the development of a performance-based model of a water-to-air variable capacity ground-source heat pump. The main challenge is to apply the recommended control strategy to vary the speed of the compressor for each mode of operation and to be able to switch from one mode to the other. A series of verification tests tend to confirm that the speed control strategy has been correctly implemented. The proposed model is used in annual simulations of a residential system equipped with a variable capacity ground-source heat pump. In this case, the seasonal performance factor (SPF?=?ratio of the annual energy requirement for heating, cooling and domestic hot water (DHW) over the annual total energy consumption) is 3.64. The corresponding value for a conventional system composed of a fixed capacity heat pump operating in on–off mode and a separate electric DHW tank is 2.60.     

The effects of electro slag welding on material properties of box column plates

The effects of electro slag welding (ESW) on the material properties of box column plates, which is ASTM A572 Gr. 50 steel, were investigated experimentally and numerically. The material properties of the column plates before and after ESW were evaluated by macro-etching observation, micro-structural observation, and CVN impact tests. The temperature distribution of the column plates, with the ESW heat cycle as the heat input, was simulated by using the ANSYS FEM software. It was found that: (1) The CVN values in the through thickness direction of the base metal can be as low as 14J, 8.1J, and 8.1J at 0°C for plate thicknesses of 32, 40, and 50 mm respectively; (2) During the ESW process, the measured peak temperature for a 25×50 mm column plate surface was as high as 1033, 880 and 744°C for plate thicknesses of 32, 40 and, 50 mm respectively; (3) After the ESW heat cycle, the through thickness CVN value decreased by 68% for the coarse grain heat affected zone (HAZ) of the column pate; (4) The FEM thermal conduction model developed was able to simulate the temperature distribution of the steel plate during the ESW process with reasonable accuracy; (5) To avoid welding penetration due to ESW, a minimum plate thickness is suggested; (6) The impact of ESW heat cycle is more significant for thin column plates compared to thick ones.