共查询到20条相似文献,搜索用时 234 毫秒
1.
不良导体热导率测量实验装置研究 总被引:1,自引:0,他引:1
不良导体热导率测量实验装置研究朱肖平(重庆后勤工程学院630042)在不良导体热导率测量时,主要误差来自对传热率或散热率的测得过程中,本文介绍新的实验装置研究,力求减少这类系统误差,使得测量结果稳定可靠,突出物理思想.图1为实验装置图,其中A为加热盘... 相似文献
2.
3.
4.
针对目前高校常用的稳态法良导体导热率测量装置及实验方法存在的不足,将原装置加热部分、保温材料、散热部件、待测样品结构以及测温仪表等进行改进与创新,使良导体导热率测量准确度明显提高. 相似文献
5.
6.
7.
通常将对流分为自然对流和强迫对流.在自然对流时,发热体周围流体介质的流动,主要是因为在各处温度不同情况下密度不同而引起的;在强迫对流时,热体周围介质主要凭借外加气泵成风扇的作用来维持流动.在稳态时,热体因对流而散失的热量可由下式来表示其中散热率兰表示热体在单位时间内所散失的热量,人为周围流体的温度,在空气中就是室温.E是与热体的表面积、表面状态、周围空气的状态和性质等有关的系数.m值在自然对流时为m=5/4=1.25.本文介绍一种新的实验方法,在稳态时,通过直接测量散热率,来确定m值和E值.下图为实验装置图… 相似文献
8.
9.
10.
11.
12.
利用数值模拟的方法分析了均匀冷却与非均匀冷却对传导冷却端面泵浦板条放大器波前畸变的影响,结果发现:信号光的波前畸变强烈依赖于zig-zag周期数,一定的光路可以将波前畸变减小到λ/10量级;板条长度方向散热不均匀及两块热沉之间散热能力的差异对波前畸变的影响很小,而宽度方向散热不均匀对波前畸变的影响较大;当宽度方向散热不均匀时,波前畸变主要为倾斜像差,输出光束的传输方向将发生偏折。因此,在非均匀冷却条件下,为了减小宽度方向散热不均匀性的影响,应选择反射次数较少的之字型光路。 相似文献
13.
14.
Zhiyi Zhang Gaozhi Xiao Jiaren Liu Chander P. Grover 《Fiber and Integrated Optics》2004,23(4):311-326
We analyzed stress and heat transfer in attached planar waveguides. Die attaching adhesives were known to be the key to avoiding stress buildup in and dissipating heat from waveguides. When adhesives have a shear modulus of less than 1 MPa and a thermal conductivity of 2 w/mk, a 0.1-0.2-mm-thick layer of adhesive can eliminate stress-related effects and efficiently dissipate 30-50 mW/mm2 of heat, even if aluminum is used as a substrate. Supersoft thermal conductive adhesives were thus developed and used to attach 60-mm-long AWG dies to aluminum with excellent results. 相似文献
15.
以某中等功率LED灯具为例,设计了塑料散热器的基本构型。采用数值仿真的办法对散热器的性能进行分析,并根据分析结果进行结构改进与优化。结果表明,在同样构型下塑料散热器散热性能低于铝合金散热器;与传统铝合金散热器不同,当肋片高度达到30 mm后,塑料散热器的散热能力趋于稳定;虽然导热塑料的红外发射率较高,仿真分析表明通过热辐射散出的热能只占总热很小的一部分,所以塑料散热器的设计应以增加对流换热面积为主,增加肋片与环境的视角系数是次要考虑因素。改进优化后的塑料散热器达到了和铝合金散热器相近的散热性能,总质量较铝合金散热器减轻了30%,验证了塑料散热器在降低产品重量方面的优越性。 相似文献
16.
C L Hartman S Z Child D P Penney E L Carstensen 《The Journal of the Acoustical Society of America》1992,91(1):513-516
Tests with mice show that lung tissue is not selectively heated in comparison with other soft tissues and that lung has an efficient mechanism for dissipating that heat which is produced. Temperatures measured with a fine thermocouple placed at the outer surface of the mouse lung show approximately 1 degree C total rise in temperature in the living animal for an incident intensity of 1 W/cm2 (4 MHz, unfocused sound field). 相似文献
17.
18.
In the electronic industry, dissipating the heat load becomes a critical factor for highly developed designs. These require higher power transfer in a more compact size. In the current study, a new microcooling system was developed and tested. It utilizes the enhancement in heat transfer characteristics associated with implementing a vortex promoter in the evaporator segment of a water-based heat pipe. The test evaporator was a cavity of 4-mm diameter and 23-mm length in an electrically heated aluminum block. A helical coil (of various diameters, namely 500, 300, and 250 μm) was introduced to the evaporator segment to act as a vortex promoter. Configurations of a new microcooling system based on a modified heat pipe technology were built and tested. The presented system proves to work efficiently in situations where a closed-loop thermosyphon encounters film boiling limitation. The most efficient configuration has a flow modifier diameter about one-tenth of the evaporator chamber gap, while the diameter of the return line was three-quarters of the evaporator gap. This configuration shows a stable operation characteristic and possesses high thermal efficiency. The maximum heat flux obtained by such a configuration was 305 W/cm2 when it runs at 103°C saturated temperature and 0.01°C/W thermal resistance. A uniform temperature distribution along the system was noticed. 相似文献
19.
含湿量对甲烷湿空气自热重整积碳特性的影响 总被引:1,自引:0,他引:1
微动力装置中碳氢燃料催化燃烧被认为是有效的方法,但燃烧室内燃料催化重整普遍存在由积碳导致的催化剂失活等问题.本文采用数值方法研究了微细腔中甲烷湿空气在镍基催化剂上的自热重整反应,重点分析含湿量对甲烷自热重整反应及积碳特性的影响.结果表明:含湿量将增强甲烷重整反应;自热反应散热量和表面积碳浓度均随含湿量增加而降低.混合物... 相似文献