共查询到19条相似文献,搜索用时 125 毫秒
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在以(BsSrPb)TiO3为基的PTCR材料中适量掺杂TiCN能提高和改善材料的温度系数α、PTC效应;降低室温电阻率2ρ5;增强耐压强度Vm ax. 相似文献
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束义福 《中学物理教学参考》2000,29(12):25-25
题目 家用电热灭蚊器中电热部分的主要元件是PTC.PTC元件是由钛酸钡等半导体材料制成的电阻器,其电阻率与温度的关系如图1所示,由于这种特性,因此,PTC元件具有发热、控温双重功能.对此,以下判断中正确的是[ ] 相似文献
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采用固相法制备了施主杂质Nb和受主杂质Mn共掺的BaTiO3基半导体复合陶瓷.通过对比实验结果,详细地分析了施主杂质和受主杂质的参杂效应对于BaTiO3基PTC陶瓷的室温电阻率和升阻比的影响,得到了充分利用BaTiO3基半导体复合陶瓷PTC效应较为理想的掺杂浓度范围.同时,比较Heywan与Ihring模型对于PTC效应的不同解释,根据原子价控理论和铁电效应补偿理论措一步分析了PTC效应的微观机制.较为完备地解释了PTC效应. 相似文献
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采用固相法制备了施主杂质Nb和受主杂质Mn共掺的BaTiO3基半导体复合陶瓷.通过对比实验结果,详细地分析了施主杂质和受主杂质的参杂效应对于BaTiO3基PTC陶瓷的室温电阻率和升阻比的影响,得到了充分利用BaTiO3基半导体复合陶瓷PTC效应较为理想的掺杂浓度范围.同时,比较Heywan与Ihring模型对于PTC效应的不同解释,根据原子价控理论和铁电效应补偿理论进一步分析了PTC效应的微观机制,较为完备地解释了PTC效应. 相似文献
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刘渠 《数理天地(初中版)》2008,(10)
1.电热灭蚊器例1 PTC是一种新型的半导体陶瓷材料,它以钛酸钡为主,渗入多种物质后加工而成.目前家用的陶瓷暖风器、陶瓷电热水壶等就是用这种材料做成的.PTC有一个根据需要设定的温 相似文献
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高中物理教材中指出:有的半导体,在温度升高时电阻减小得非常迅速,利用这种材料可以制成体积很小的热敏电阻。因此不少师生认为,热敏电阻的阻值总是随温度的升高而减小。果真如此吗?其实热敏电阻是电阻值随温度变化的半导体传感器,按其温度特性分为三类:负温度系数热敏电阻(NTC)、正温度系数热敏电阻(PTC)、临界温度系数热敏电阻(CTR),三类热敏电阻的特性曲线如图1所示,下面对其作一具体介绍。1PTC热敏电阻PTC(PositiveTemperatureCoeffiCient)是指随温度上升电阻急剧增加、具有正温度系数的热敏电阻现象或材料。该材料是以钛酸钡、… 相似文献
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为了介绍方便先对PTC元件的特性给以说明。PTC元件是在钛酸钡(BaT_1O_3)的固溶体中掺合微量稀土元素,用制造陶瓷工艺制成的半导体电阻元件。它具有正温度系数,即Positive Temperature Cofficient.简称PTC,这种元件的电阻——温度特性曲线如图(1)。在温度较低时,即小于居里点温度范围内,具有很小的负温度系数,大于居里点温室时,这种元件具有很大的正温度系数,即PTC特性。电阻会发生几个数量级的突变,也就是说它在高温时的电阻值是低温时的许多倍。元件温度一定时, 相似文献
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分析PTC电阻的原理和特性,建立PTC的短路限流开关模型,通过直流短路仿真实验,得出了PTC电阻的部分极限参数和在短路系统中的特性。提出了基于PTC电阻和MOV过压保护的限流方案,并对其过压保护原理和工作特性做出简要分析。 相似文献
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相同PTC元件,高的发热功率及高的加热器表面温度,极大程度取决于加热器的热阻.表面发热的方式使PTC发热元件及其它表面型加热器低热阻化.表面型PTC加热器具有许多优点,其应用与开发具有一定的意义. 相似文献
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Design and preliminary experimental investigation of a 4 K Stirling-type pulse tube cryocooler with precooling 总被引:1,自引:0,他引:1
A Stirling-type pulse tube cryocooler (PTC) with precooling was designed and manufactured to investigate its performance at 4 K. Numerical simulation was carried out based on the well-known regenerator model REGEN with an emphasis on the performance of a 4 K stage regenerator of the Stifling-type PTC as influenced by the warm end temperature, pressure ratio, frequency and average pressure with helium-4 and helium-3 as the working fluid respectively. This study demonstrates that the use of a cold inertance tube can significantly improve the efficiency of a 4 K Stirling-type PTC. A preliminary experimental investigation was carried out with helium-4 as the working fluid and a refrigeration temperature of 4.23 K was achieved. The experimental results show that the operating frequency has a significant influence on the performance of the Stirling-type PTC and a relatively low average pressure is favorable for decreasing the loss associated with the real gas effects of a 4 K Stirling-type PTC. 相似文献
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黄秀 《合肥联合大学学报》1999,(3)
自动加浓阀主要由PTC、石蜡体和针阀组成。改变PTC与石蜡体的配方,可以使化油器在各种环境下都能提供给发动机起动与暖机过程中所需的理想空燃比的混合气,提高化油器的综合性能。 相似文献
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A. VALAN ARASU T. SORNAKUMAR 《浙江大学学报(A卷英文版)》2008,9(3):416-422
Parabolic trough collectors (PTCs) are employed for a variety of applications including steam generation and hot water generation. This paper deals with the experimental results and an economic analysis of a new fibre reinforced plastic (FRP) based solar PTC with an embedded electronic controlled tracking system designed and developed for hot water generation in a restaurant in Madurai, India. The new collector performance has been tested according to ASHRAE Standard 93 (1986). The performance of a new PTC hot water generation system with a well mixed hot water storage tank is investigated by a series of extensive tests over ten months period. The average maximum storage tank water temperature observed was 74.91℃, when no energy is withdrawn from the tank to the load during the collection period. The total cost of the new economic FRP based solar PTC for hot water generation with an embedded electronic controlled tracking system is Rs. 25000 (US$ 573) only. In the present work, life cycle savings (LCS) method is employed for a detailed economic analysis of the PTC system. A computer program is used as a tool for the economic analysis. The present worth of life cycle solar savings is evaluated for the new solar PTC hot water generation system that replaces an existing electric water heating system in the restaurant and attains a value of Rs. 23171.66 after 15 years, which is a significant saving. The LCS method and the MATLAB computer simulation program presented in this paper can be used to estimate the LCS of other renewable energy systems. 相似文献
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本文报道了在几种不同季铵盐存在下,采用氟化钾氟化钠混合氟化剂<对氯硝基苯与混合氟化剂的比为1:1.5(mol),其中对氯硝基苯与氟化钾的比为1:1(mol)>合成对氟硝基苯的方法;探讨了催化剂,反应时间和反应温度对产率的影响。 相似文献
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在相转移催化奈件下合成了1-环己基吖丁啶3基取代苄基醚这类具有潜在生理活性的新化合物,该法操作简便,收率高,经^1H NMR、IR、MS确认了产物的结构,同时讨论了合成这类化合物的最佳反应条件. 相似文献
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报导了邻苯二酚二(ω-氯代二甘醇)醚的相转移催化合成,探讨了催化剂、氢氧化钠浓度对产率的影响,并与KoplowS法作了比较 相似文献