The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Guang-sheng Du - One of the best experts on this subject based on the ideXlab platform.
-
Numerical study of impurity distribution in ultrasonic Heat Meter body
Journal of Hydrodynamics, 2015Co-Authors: Guang-sheng Du, Min ZhangAbstract:Based on a discrete phase model, the numerical simulation is carried out for the flow fields of different size calcium carbonate suspensions in the ultrasonic Heat Meter body. The flow characteristics and the impurity distribution in the ultrasonic Heat Meter body are analyzed. The errors of the ultrasonic Heat Meter in measuring calcium carbonate suspensions of particles of 10 microMeters and the causes are analyzed by simulation and experiment. Results show the effects of the impurities on the value of the k coefficient and the sound attenuation on the reflection path due to the particle distribution are the two main factors that influence the measurement accuracy.
-
Study of errors in ultrasonic Heat Meter measurements caused by impurities of water based on ultrasonic attenuation
Journal of Hydrodynamics, 2015Co-Authors: Min Zhang, Guang-sheng Du, Dong LiAbstract:Impurity is one of the main factors that affect the measurement accuracy of an ultrasonic Heat Meter. To study the effects of different impurity species and concentrations on the accuracy of Heat Meters, flow tests were carried out for the suspending of calcium carbonate and yellow mud. By analyzing the attenuation characteristics of the ultrasound amplitude in different impurity concentrations and species, the influence of the impurities on the Heat Meter measurement accuracy is evaluated. In order to avoid the inaccuracy caused by the sediment of the reflective bottom surface, a vortex generator is put ahead of the reflective surface. According to the test, the calcium carbonate suspension with a mass concentration of 1%, which influences the Heat Meter accuracy severely, is used as the flow media. The influence of the vortex generator on the calcium carbonate suspension flow field in the Heat Meter body is studied with numerical simulations. The results of this paper provide some theoretical guide on improving the Heat Meter measurement accuracy when the water contains impurities.
-
The analysis of flow characteristics in multi-channel Heat Meter based on fluid structure model
Journal of Hydrodynamics, 2015Co-Authors: Zheng Gang Liu, Guang-sheng Du, Li-ping LiuAbstract:In this paper, a fluid structure interaction (FSI) model is used to study the internal flow field and the measurement performance of a multi-channel flow Meter. The RNG k - ε turbulent model and the finite element model are used separately in the fluid domain and the structure domain to obtain the Meter factor K and the deformation of the structure. The Meter factor K of the flow Meter is obtained through the FSI model at temperatures of 20°C, 50°C and 80°C. The calculated results show the thermo expansion of the structure can significantly influence the measurement performance of the flow Meter. The Meter factor of the flow Meter is also measured experimentally, and the comparison between the experimental results and the calculated results shows the validity of the fluid-structure interaction model. In order to reduce the measurement error, the Meter factor K should be modified as the water temperature changes.
-
Application of Vortex Generator in Ultrasonic Heat Meter Measurement
Advanced Materials Research, 2014Co-Authors: Guang-sheng DuAbstract:Fluids in the Heat-supply pipelines have a small amount of impurities. Impurities can easily settle down on the ultrasonic Heat Meters’ reflecting faces. It caused measurement inaccuracy. Vortex generator is placed in ultrasonic Heat Meter in this paper, which can generate vortex in the reflect fields. Vortex toke away impurities on the bottom of Heat Meter. Reflecting surface keeps clean. A v-shaped ultrasonic Heat Meter is taken for example. Numerical study of the flow field near the Reflecting surface vortex generator is carried out. Results show certain strength of vortex is caused in the reflective surface, while other palaces influenced little.
-
fluid characteristics of rotary wing Heat Meter with single channel
Journal of Hydrodynamics, 2008Co-Authors: Guang-sheng Du, Li Li, Liang MengAbstract:Fluid characteristics of a rotary wing Heat Meter with single-channel were studied through theretical analysis, numerical simulation and experiments. The obtained results show that the number of vanes can obviously influence the Heat Meter, but the water temperature seldom influence the Meter, and the optimal number of vane is 6–8.
Jindou Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Heat Meter with ultra-low-power consumption Microcontroller
2008 3rd IEEE Conference on Industrial Electronics and Applications, 2008Co-Authors: Yong Zhang, Xin Geng, Jindou ZhangAbstract:The Metering principle of quantity of Heat is introduced in detail. A Metering method using k coefficient compensation function is stated, the accuracy of measurement is enhanced. The low power consumption design is implemented based MSP430 microcontroller, including hardware and software. The Heat Meter can be remotely read by means of M-BUS. The principle of system and method of decreasing power are discussed.
Bernhard Wunderlich - One of the best experts on this subject based on the ideXlab platform.
-
Methodology of interpreting thermal analysis of polymers
Journal of Thermal Analysis and Calorimetry, 2011Co-Authors: Bernhard WunderlichAbstract:The goal of the thermal analysis experiments is to extract scientifically and technological important information from measurements of “Heat.” Unfortunately, there exists no direct Heat Meter. In fact, the assessment of the quantity Heat has a colorful past and, as is a common human trait, the back-integration of successively gained knowledge into the basic teaching is lax, as in all stages of education. Thermal analysis can be taken as a prime example of this problem. A “Methodology of Interpreting Thermal Analysis of Polymers” is described in this report on the example of recent data on poly(butylene terephthalate), PBT, crystallized by slow cooling from the melt. It is shown how the simple temperature-difference or Heat-flow rate as a function of sample temperature is converted to calorimetric information. Once calorimetric data are available, the results can be interpreted using modern descriptions of phases, making use of a scheme of phase structures as well as considering molecular motion arguments and phase sizes. Using the three classical types of strong chemical bonding leads to 57 possible condensed phases and two types of transitions (glass and order/disorder transitions) necessary for the description.
Yong Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Heat Meter with ultra-low-power consumption Microcontroller
2008 3rd IEEE Conference on Industrial Electronics and Applications, 2008Co-Authors: Yong Zhang, Xin Geng, Jindou ZhangAbstract:The Metering principle of quantity of Heat is introduced in detail. A Metering method using k coefficient compensation function is stated, the accuracy of measurement is enhanced. The low power consumption design is implemented based MSP430 microcontroller, including hardware and software. The Heat Meter can be remotely read by means of M-BUS. The principle of system and method of decreasing power are discussed.
Ronald J. Warzoha - One of the best experts on this subject based on the ideXlab platform.
-
Design Considerations for Miniaturized Steady-State Thermal Characterization Instruments
IEEE Transactions on Components Packaging and Manufacturing Technology, 2018Co-Authors: Ronald J. Warzoha, Lauren Boteler, Andrew N Smith, Ashim BajwaAbstract:We use numerical simulations to design and optimize a set of miniaturized Heat Meter bars for high-resolution measurements of interfacial thermal transport across solid, contacting junctions (RT) and thermal conductivity within low-resistivity materials (κ). We find that extreme care must be taken to design both the geometry of the Heat Meter bars and the cooling technique used to drive thermal transport across the junction. To reduce measurements of RT down to 0.1 mm2·K/W, a channel Heat sink is optimized to remove Heat from the lower bar. Results suggest that in order to maintain a sufficient number of temperature measurements, the bar length can be no less than 3 mm in order to maintain a linear thermal gradient a sufficient distance away from the interface. Further reductions in Heat Meter bar length are insufficient to achieve corresponding reductions in RT. To address this limitation, a jet impingement cooling technique is assessed. We find that a 2 × 3 array of jets (D = 1 mm) is sufficient to maintain a linear thermal gradient around the interface as the Heat Meter bar length is reduced below 5 mm. Using the jet impingement cooling technique described in this paper, measurements of RT = 0.01 mm2 · K/W are found to be theoretically possible. This would represent a two-orders-of-magnitude improvement in the resolution of interfacial thermal resistance measurements made with steady-state thermal characterization techniques. The thermal challenges explored in this paper are critical to the design of instruments that can directly characterize the magnitude of Heat flow permitted across high-performance thermal interface materials in electronics packaging systems.
-
Design considerations for a miniaturized TIM tester with extremely high measurement resolution
2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm), 2017Co-Authors: Ronald J. Warzoha, Andrew N Smith, Ashim Bajwa, Lauren BotelerAbstract:This work describes relevant design considerations for the fabrication of a miniaturized thermal interface material characterization instrument that is capable of resolving interfacial thermal resistances (RT) below 1 mm2.K/W. Leveraging previous work (Warzoha et al., 2017, Smith et al. 2016), the authors propose a reduction in the length scale of the primary Heat Meter bars to below 4 mm in order to sufficiently increase the temperature difference across the interface, thereby reducing the measurement uncertainty of RT across high-performance materials. The analytical uncertainty analysis takes advantage of an increase in the number of temperature measurements that can be made across the length of each bar via infrared microscopy. In a preliminary numerical analysis, we find that extreme care must be taken to apply and remove Heat uniformly from the end points of each bar, particularly as the length of the bar is reduced below 4 mm. To do this, longitudinal fins are directly integrated into the bottom Heat Meter bar assembly and are immersed in a Heat transfer fluid that is advected within a custom cold plate assembly. We conduct a parametric study to determine the linearity of the thermal gradient along the length of each Heat Meter bar, which in turn provides us with an upper limit for the number of temperature measurements that can be made via infrared microscopy and therefore the minimum achievable measurement of RT. Finally, we use this information to design a more suitable lower Heat Meter bar cooling technique for measuring the thermal resistance across a sintered silver-copper interface with an expected value of RT = 0.1 mm2.K/W. To do this, we find it necessary to transition from a Heat sink cooling mechanism to the use of jet impingement for Heat dissipation at the bottom of the lower Heat Meter bar.
-
Improved methodology for calculating interfacial thermal resistance and uncertainty for steady-state TIM testers with embedded probes
2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm), 2016Co-Authors: Ronald J. Warzoha, Andrew N Smith, Maurice HarrisAbstract:Efforts to miniaturize electronic components within the semiconductor industry continue to intensify stresses on the primary thermal pathways that are used for Heat dissipation in electronics packaging equipment. This is particularly true for Heat flow pathways that traverse interfaces. Consequently, an increasing priority for thermal engineers is to design materials that are capable of reducing the impedance to Heat flow acrosss device junctions. However, the equipment most often used to measure the resistance to Heat flow across interfaces (ASTM D5470) is becoming increasingly insufficient for the characterization of next-generation thermal interface materials (TIMs), as evidenced by the wide variability in the reported results for current state-of-the-art TIMs. Through the use of statistical analyses, we show that one possible reason for these discrepancies is the method by which the temperature difference across the interface is calculated. Additionally, we find that there exists a lack of consideration for many potential sources of positional uncertainty that exist within the measurement system, including: 1) the thermal conductivity mismatch between the thermal probes, the Heat Meter bars and any interstitial filler material used to increase contact conductance between them, 2) drill drift during manufacturing, 3) the temperature and positional uncertainties of each probe along the length of the Heat Meter bars, 4) the tolerance associated with the location of each thermal probe's junction and 5) the number of thermal probes that are used to determine the temperature difference across the interface. We find that these factors result in an unavoidably large uncertainty in the position of the thermal probes, which produces a significant measurement uncertainty when RT is on the order of 1·10-5 m2·K/W or lower, regardless of the temperature measurement accuracy that can be achieved with the probes. Using numerical simulations, we conduct a parametric study to determine the magnitude of these effects on positional uncertainty. Results suggest that the lowest positional uncertainty is achieved when the thermal probe is significantly less thermally conductive than its surrounding filler, and that drill drift and the uncertainty associated with the location of the actual thermal probe junction account for a significant increase in the overall uncertainty of the measurement. It is expected that these results will allow for the development of steady-state TIM characterization instruments with improved measurement resolutions and for greater consistency between the results of different groups that use thermal probe-based TIM testers.
