共查询到18条相似文献,搜索用时 187 毫秒
1.
10 kV配电线路带电作业过程中,为避免作业人员发生触电事故,需采用绝缘毯等绝缘遮蔽用具对带电体进行包裹遮蔽。通过温度—流体场耦合方法模拟了10 kV配电线路带电作业时绝缘毯的温升和散热过程,分析了绝缘毯的材料、长度、厚度、风速和日照强度等对绝缘毯温度分布的影响。结果表明,相同条件下,树脂绝缘毯的温升低于橡胶绝缘毯;绝缘毯包裹厚度的减小和风速的增大对绝缘毯的散热具有一定的促进作用;日照强度升高100 W/m2时,橡胶和树脂绝缘毯的温度分别升高0.9、0.8 K左右,日照是绝缘毯温度过高的主要因素之一;虽然树脂绝缘毯的散热性能更好,但其熔点较低,在高温重负荷环境下应避免树脂绝缘毯的温度过高。 相似文献
2.
以带电更换直线绝缘子为例,针对配电线路带电作业中绝缘遮蔽罩的使用安全问题,分析了在配电线路带电作业中简化遮蔽流程、提高作业安全性和绝缘遮蔽材料热熔现象,提出了采用绝缘操作杆远距离操作、增大绝缘遮蔽罩内部空间等解决办法;并从绝缘遮蔽罩的结构(包括遮蔽罩遮蔽范围和遮蔽罩体积)、绝缘遮蔽罩材料和颜色三个方面,提出了增加裙边、采用回形设计等思路。实践结果表明,该优化设计可改善绝缘遮蔽罩使用的方便性和安全性。 相似文献
3.
通过建立几何、计算模型,对不同环境风速、温度和热负荷进行了塔烟内换热器换热性能的数值计算,得到了不同场的变化规律,并根据换热器出口面的风量和风温的变化,对影响换热性能的因素进行了分析。结果表明:换热器的换热性能与风速、布置位置、环境温度及热负荷等因素的有关。随环境风速增加,各换热器通风量下降;迎风布置的换热器通风量最少,背风侧的最大;环境温度高,热负荷小,各换热器通风量少;环境温度低,热负荷大,换热器通风量增加。换热器通风量越多,其换热性能越好,反之亦然。因此,换热器布置在烟囱内外筒间的夹层空间内,能够满足冷却一定的热负荷的要求。 相似文献
4.
间接空冷系统空冷散热器运行特性的数值模拟 总被引:5,自引:0,他引:5
以某6×1000 MW间接空冷电厂主要建筑物和空冷塔平面布局为例,通过CFD模拟,得到了冷却空气流场、温度场,分析了机组热负荷、环境气温、风速、风向对空冷散热器进口空气流速的影响.结果表明:处于环境风上游的空冷散热器单元,其迎面风速最大,空气温度最低,冷却效果最好;而处于侧面的空冷散热器单元,迎面风速最小,空气温度最高,冷却效果最差.随机组热负荷增加,空冷散热器冷却空气流量增加,随环境气温、风速增加,空冷散热器冷却空气流量减小.风向的改变也会影响散热器的运行特性. 相似文献
5.
6.
7.
对于大电流的传输电设备而言,发电机出口母线的发热、温升和散热问题是影响发电机工作稳定性的一个非常重要的因素之一。针对一种采用固体绝缘结构的发电机管型封闭母线,研究其在不同工作条件下的温升和散热特性。文中采用ANSYS软件建立封闭母线的温度场分析二维模型,并结合传导、对流及辐射等热传递模式,进行温度场仿真。在此基础上分析环境温度、气体压强以及不同负荷电流下的母线发热现象,分析出具有良好温升特性的发电机固体绝缘母线绝缘结构参数和运行条件。 相似文献
8.
9.
选取了高、中、低负荷的3个典型工况,研究了进气节流及喷油策略对柴油机缸内燃烧过程、排放性、经济性及柴油机催化氧化器(diesel oxidation catalyst,DOC)入口温度的影响,得到全工况区域的DOC入口温度的升温策略。试验结果表明:随进气节流阀开度减小,进气流量降低,压缩压力下降,燃烧始点滞后,最高燃烧压力下降,循环指示功降低;HC排放得到抑制,其他排放恶化;DOC入口温度得到有效提升,负荷越小,温升效果越显著。喷油规律耦合进气节流发现,主喷提前角的推迟使得滞燃期缩短、后燃加重,DOC入口温度小幅度提升;近后喷油量增加可提高DOC入口温度,推迟近后喷,DOC入口温度先增大后降低,存在最佳的近后喷时刻。依据样机全工况排温分布特征,提出了不同工况区域DOC入口温度升温控制策略。 相似文献
10.
11.
以新型变桨距风力机为研究对象,针对其独特的变桨调节机构,通过风洞试验的方法,采用IMC载荷测试系统,对其关键部件进行载荷测试。试验结果显示:随着桨距角增大,叶根所受弯矩降低,但叶根挥舞弯矩较摆振弯矩减小更明显;塔筒俯仰方向的受力大于侧弯方向,当风轮转速约为243.5 r/min时,塔筒侧弯受力出现突增;不同桨距角下,变桨调节机构的齿条与齿条同步盘测点载荷大小随风速变化趋势一致,但随着桨距角的增加,表现为先增加后减小再增加的趋势。 相似文献
12.
不同海拔条件下喷油参数对柴油机性能的影响 总被引:1,自引:0,他引:1
通过内燃机高原环境模拟试验台,研究了不同海拔条件下高压共轨柴油机在最大转矩转速点(1500 r/min)全负荷(2300 N·m)和部分负荷(500 N·m)工况下喷油提前角、共轨压力及循环喷油量(全负荷)对柴油机燃烧特性与性能的影响规律.结果表明:全负荷工况下,随着喷油提前角增加,柴油机滞燃期增加,最高燃烧压力和最大压力升高率增大,增大趋势随海拔增加而降低,柴油机转矩在0 km和3 km海拔先增加后减小,在5 km海拔时逐步增加.随着共轨压力增加,柴油机燃烧相位提前,最高燃烧压力、最大压力升高率和转矩均增加,排温降低;部分负荷工况下,有效燃油消耗率随共轨压力增加而降低.随循环喷油量增加,转矩、排温和缸内压力均逐渐增大,最大压力升高率在3 km海拔范围内逐渐增加、在5 km海拔时逐渐减小.海拔每升高1 km,柴油机在全负荷工况下,最佳循环喷油量平均降低5.81%,最佳喷油提前角和共轨压力在全负荷和部分负荷工况下平均分别增加了1.2°,CA、0.8°,CA和4 MPa、3 MPa. 相似文献
13.
为研究全向导叶作用下不同实度对垂直轴风力机气动性能的影响,通过改变叶片数及弦长调整实度并分析其对全向导叶垂直轴风力机气动性能的作用。结果表明:全向导叶使垂直轴风力机周围流体提速效果显著,最大风能利用率和力矩系数较原始垂直轴风力机分别提高41.6%和25%;随实度增大时,全向导叶垂直轴风力机最佳尖速比降低;改变弦长时,风能利用率峰值随弦长增大呈现先增后减的趋势,且在小尖速比工况下,高实度全向导叶垂直轴风力机力矩系数较高,最大可达0.192;改变叶片数时,风能利用率峰值随叶片数增多而降低,且大尖速比下的低实度全向导叶垂直轴风力机力矩系数较大,但不同实度的全向导叶垂直轴风力机最大力矩系数相差较小。 相似文献
14.
从现有风能直驱式热泵系统存在的突出问题入手,利用软连接管路突破了风能直驱热泵系统硬连接的瓶颈问题,提出新型风力机直驱蒸汽压缩式热泵系统,并对该系统进行了实验研究。实验结果表明,热泵机组制热量随压缩机转速呈近似线性规律,热泵机组COP随转速呈近似指数变化规律,机组存在最佳转速;金属软管阻力损失对制冷剂焓值影响可以忽略,但是对冷凝温度有较显著影响,如需要保证热水温度,则需要提高冷凝压力,相应COP会降低,机组运行稳定,初步证明系统可行。 相似文献
15.
16.
A. A. El-Haroun 《国际可持续能源杂志》2013,32(1):9-18
Energy generated from wind turbine depends to a great extent on the wind speed at its inlet. The use of thermosyphon solar tower is an attempt to increase the air velocity at inlet of the wind turbine and of course to increase its power. The wind speed in a certain location changes always with time and with the height above ground surface. In this work, the effect of wind speed at the top of the tower on the performance as well as on the energy generated from thermosyphon solar turbine was studied theoretically. One location in Egypt was chosen for this study. The calculations were achieved mainly with the solar turbine located at tower bottom. For the purpose of comparison, the energy generated from the solar turbine was compared with that generated from free wind turbine at tower height with the absence of solar tower. It was found that, the wind speed at the top of the tower results in a pressure drop which affects the performance of the thermosyphon solar turbine. This pressure drop increases with the rise in wind speed and will be zero only when the wind speed at the top of the tower reaches zero. It was found also that, there is an increase in friction losses through the tower and a decrease in both temperature difference between inlet and outlet of the tower and in heat losses from tower walls with the rise in wind speed in location. The inlet air velocity to the solar turbine and consequently its specific power were found to be increased with the increase in wind speed at the top of the tower. Therefore, the effect of wind speed at the top of the tower must be taken into account during thermosyphon solar tower calculations. By comparing the performance of solar turbine and the free wind turbine located at tower height with the absence of thermosyphon solar tower, it was found that the mean inlet air velocity to the solar turbine located at tower bottom and consequently its specific power are higher than these values for free wind turbine. The mean inlet air velocity to the solar turbine is found to be 117% of its value for a free wind turbine. The yearly specific energy generated from solar turbine is expected to be 157% of its value for free wind turbine. 相似文献
17.
18.
Energy storage is often seen as necessary for the electric utility systems with large amounts of solar or wind power generation to compensate for the inability to schedule these facilities to match power demand. This study looks at the potential to use building thermal energy storage as a load shifting technology rather than traditional electric energy storage. Analyses are conducted using hourly electric load, temperature, wind speed, and solar radiation data for a 5-state central U.S. region in conjunction with simple computer simulations and economic models to evaluate the economic benefit of distributed building thermal energy storage (TES). The value of the TES is investigated as wind and solar power generation penetration increases. In addition, building side and smart grid enabled utility side storage management strategies are explored and compared. For a relative point of comparison, batteries are simulated and compared to TES. It is found that cooling TES value remains approximately constant as wind penetration increases, but generally decreases with increasing solar penetration. It is also clearly shown that the storage management strategy is vitally important to the economic value of TES; utility side operating methods perform with at least 75% greater value as compared to building side management strategies. In addition, TES compares fairly well against batteries, obtaining nearly 90% of the battery value in the base case; this result is significant considering TES can only impact building thermal loads, whereas batteries can impact any electrical load. Surprisingly, the value of energy storage does not increase substantially with increased wind and solar penetration and in some cases it decreases. This result is true for both TES and batteries and suggests that the tie between load shifting energy storage and renewable electric power generation may not be nearly as strong as typically thought. 相似文献