An Experimental Investigation in the Performance of Water-Filled Silicon Microheat Pipe Arrays

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
D. K. Harris ◽  
A. Palkar ◽  
G. Wonacott ◽  
R. Dean ◽  
F. Simionescu
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Effective Thermal Conductivity ◽  
Thermal Performance ◽  
Single Channel ◽  
Baseline Measurement ◽  
Separate Study ◽  
Performance Measurements ◽  
Horizontal Orientation ◽  
Systematic Biases

This study details the fabrication and measurements of a water-filled 5 mm wide by 10 mm long silicon microheat pipe (MHP) array consisting of 22–100 μm square channels. This study is unique in that many experimental results reported in open literature are for single channel microheat pipes. The number of channels in the array and the fluid charge used here were optimized under a separate study. A number of experiments were carried out on the specimen MHPs to determine their effective thermal conductivity and comparisons were made with previous results found in literature. The testing methodology was designed to remove systematic biases and the array thermal performance measurements are reported in terms of a silicon equivalence by identically measuring an uncharged empty silicon array as a baseline measurement. Two separate water-filled specimens were made, independently tested, and are reported to have thermal conductivities of 261 W/m K and 324 W/m K, representing a silicon equivalence of 1.8 and 2.2, respectively. All testing was performed in a horizontal orientation.

Experimental Investigation of Effective Thermal Conductivity for LHP Wicks

2010 ◽  
Author(s):  
Gongming Xin ◽  
Kehang Cui ◽  
Yan Chen ◽  
Wenjing Du ◽  
Yong Zou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Effective Thermal Conductivity ◽  
Pure Copper ◽  
Pure Nickel ◽  
Loop Heat Pipe ◽  
Porosity Level ◽  
Nickel Powders ◽  
Copper Powders ◽  
Reasonable Prediction

In this study, the effective thermal conductivity (ETC) of sintered loop heat pipe wicks, with pure nickel powders, pure copper powders, Ni-10wt%Cu powders and Ni-20wt%Cu powders were experimentally investigated. The ETC of sintered Ni-Cu wicks is found less than those of sintered pure nickel wick and sintered pure copper wicks. In the same porosity level, addition of copper into nickel will reduce ETC of the sintered Ni-Cu wicks. The sintered Ni-20wt%Cu wick presents the lowest ETC among the tested wick samples. Compared to experimental results, Alexander model can provide a reasonable prediction in some wick samples.

Experimental Investigation of Thermal Conduction Performance on Silicon-Based Micro Flat Heat Pipe

2015 ◽  
Vol 645-646 ◽  
pp. 1032-1037
Author(s):  
Cong Ming Li ◽  
Yi Luo ◽  
Chuan Peng Zhou ◽  
Liang Liang Zou ◽  
Xiao Dong Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Pipe ◽  
Effective Thermal Conductivity ◽  
Thermal Performance ◽  
Axial Direction ◽  
Filling Ratio ◽  
Parallel Structure ◽  
Working Fluid ◽  
Vacuum Degree ◽  
Structure Dimension

There are several factors that affect heat transfer of heat pipe, for example, structure dimension, filling ratio and vacuum degree of charging. This paper studied the thermal conductivity of micro flat heat pipes (MFHPs) with different structure dimension and with different filling ratio, when the charging vacuum degree of MFHP was decided. When electric power was 2W or 4W, MFHPs with parallel grooves and nonparallel grooves, charged by working fluid with different filling ratio, were carried out. And the filling ratio is 30%, 40% and 50%, respectively. The better thermal performance of MFHP can be evaluated by lower thermal resistance and higher effective thermal conductivity. The experiment results show that MFHP has the highest effective thermal conductivity when the filling ratio is 40%; and the thermal performance of MFHP with nonparallel structure in axial direction is better than that of MFHP with parallel structure.

An Experimental Study on the Thermal Performance Evaluation of SCW Ground Heat Exchanger

2017 ◽  
Vol 25 (01) ◽  
pp. 1750006 ◽  
Author(s):  
Keun Sun Chang ◽  
Min Jun Kim ◽  
Young Jae Kim
Keyword(s):  
Thermal Conductivity ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Effective Thermal Conductivity ◽  
Thermal Performance ◽  
Thermal Response ◽  
High Heat ◽  
Injection Rate ◽  
Operating Parameters ◽  
Ground Heat Exchanger

In recent years, application of the standing column well (SCW) ground heat exchanger (GHX) has been noticeably increased as a heat transfer mechanism of ground source heat pump (GSHP) systems with its high heat capacity and efficiency. Determination of the ground thermal properties is an important task for sizing and estimating cost of the GHX. In this study, an in situ thermal response test (TRT) is applied to the thermal performance evaluation of SCW. Two SCWs with different design configurations are installed in sequence to evaluate their effects on the thermal performance of SCW using a single borehole. A line source method is used to derive the effective thermal conductivity and borehole thermal resistance. Effects of operating parameters are also investigated including bleed, heat injection rate, flow rate and filler height. Results show that the effective thermal conductivity of top drawn SCW (Type A) is 11.7% higher than that of bottom drawn SCW (Type B) and of operating parameters tested bleed is the most significant one for the improvement of the thermal performance (40.4% enhanced in thermal conductivity with 10.9% bleed).

Multi-scale thermal modeling of glass interposer for mobile electronics application

2016 ◽  
Vol 26 (3/4) ◽  
pp. 1157-1171 ◽  
Author(s):  
Sangbeom Cho ◽  
Venky Sundaram ◽  
Rao Tummala ◽  
Yogendra Joshi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Thermal Performance ◽  
Memory Bandwidth ◽  
Vapor Chamber ◽  
Packaging Technology ◽  
Content Type ◽  
Low Thermal Conductivity ◽  
Multi Scale

Purpose – The functionality of personal mobile electronics continues to increase, in turn driving the demand for higher logic-to-memory bandwidth. However, the number of inputs/outputs supported by the current packaging technology is limited by the smallest achievable electrical line spacing, and the associated noise performance. Also, a growing trend in mobile systems is for the memory chips to be stacked to address the growing demand for memory bandwidth, which in turn gives rise to heat removal challenges. The glass interposer substrate is a promising packaging technology to address these emerging demands, because of its many advantages over the traditional organic substrate technology. However, glass has a fundamental limitation, namely low thermal conductivity (∼1 W/m K). The purpose of this paper is to quantify the thermal performance of glass interposer-based electronic packages by solving a multi-scale heat transfer problem for an interposer structure. Also, this paper studies the possible improvement in thermal performance by integrating a fluidic heat spreader or vapor chamber within the interposer. Design/methodology/approach – This paper illustrates the multi-scale modeling approach applied for different components of the interposer, including Through Package Vias (TPVs) and copper traces. For geometrically intricate and repeating structures, such as interconnects and TPVs, the unit cell effective thermal conductivity approach was used. For non-repeating patterns, such as copper traces in redistribution layer, CAD drawing-based thermal resistance network analysis was used. At the end, the thermal performance of vapor chamber integrated within a glass interposer was estimated by using an enhanced effective thermal conductivity, calculated from the published thermal resistance data, in conjunction with the analytical expression for thermal resistance for a given geometry of the vapor chamber. Findings – The limitations arising from the low thermal conductivity of glass can be addressed by using copper structures and vapor chamber technology. Originality/value – A few reports can be found on thermal performance of glass interposers. However thermal characteristics of glass interposer with advanced cooling technology have not been reported.

Thermal Assessment and Enhancement of Molded Array (MAP) PBGA Packages for Handheld Telecommunication Applications

2000 ◽  
Author(s):  
V. H. Adams ◽  
V. A. Chiriac ◽  
T.-Y. Tom Lee
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Thermal Performance ◽  
Transfer Problem ◽  
Effective Area ◽  
Printed Wiring Board ◽  
Heat Spreader ◽  
Fine Pitch ◽  
Plastic Ball

Abstract Computational Fluid Dynamics (CFD) simulations were conducted to characterize the thermal performance of Molded Array Plastic Ball Grid Array (MAP PBGA) packages for hand-held applications. Due to size constraints, these PBGA packages tend to have fine pitch solder ball arrays and small overall size. Thermal analysis is required to assess the design risks associated with this trend toward smaller size and increasing power dissipation requirements. A conjugate heat transfer problem, in which radiative losses from the exposed surfaces of the package and the printed wiring board to the walls of the wind tunnel, was solved for horizontal natural convection cooling conditions. Thermal model assumptions and development for the MAP PBGA package are provided. The model is benchmarked with measurements obtained for a 64 I/O 0.8 mm pitch, 8 mm MAP PBGA. Predictions for junction-to-ambient thermal resistance were within 10% of measured values. Baseline simulations were conducted for 0.8 mm pitch MAP PBGA packages with substrate/die size combinations in the range of 6 to 12 mm substrate size and 3.81 to 7.62 mm die size. Junction-to-ambient thermal resistances varied over the range of 28.8 °C/W to 62.4 °C/W. Methods to improve thermal performance of these packages were investigated. Previous work indicated that effective conduction to the substrate by heat spreaders, metallic lids, mold compound, heat sinks, and their combinations promoted thermal performance. A necessary further step is to understand how effective area for heat spreading inside the package affects its thermal behavior, while varying the die size for package configurations with and without heat spreader. Studies were conducted to evaluate thermal performance improvement through the use of a copper heat spreader on the package top surface as it is affected by die size, package size, and substrate effective thermal conductivity. Substrate effective thermal conductivity is varied through the use of two and four layer substrates with thermal vias under the die. Results show a modest 1% to 15% reduction in junction-to-ambient thermal resistance for the MAP PBGA package sizes of interest.

Comparative Study on Thermal Performance of Ultrathin Miniature Loop Heat Pipes With Different Internal Wicks

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Guohui Zhou ◽  
Ji Li ◽  
Lucang Lv ◽  
G. P. Peterson
Keyword(s):  
Experimental Investigation ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Heat Pipes ◽  
Copper Plate ◽  
Loop Heat Pipes ◽  
Liquid Line ◽  
Horizontal Orientation ◽  
Cooling Mechanism ◽  
Heat Loads

Presented here are the results of an experimental investigation of two ultrathin miniature loop heat pipes (mLHPs) with different internal wicking structures: one with a primary wicking structure in the evaporator and a secondary wicking structure in the liquid line, and the other only with the same primary wicking structure in the evaporator, but no secondary wick. The systematic experimental investigation was conducted using natural convection as the cooling mechanism in order to study the heat transfer performance of the two mLHPs and fully examine the effects of the secondary wick. The results indicated that both of the test articles could effectively dissipate 12 W at all test orientations with a minimum total thermal resistances of 6.38 °C/W and 6.39 °C/W, respectively. However, the results indicated that the presence of the secondary wicking structure in the liquid line at low power loads resulted in more stable startup characteristics and a weaker dependence on the different orientations. Moreover, it was demonstrated that the steady-state evaporator temperatures of the test article with the secondary wicking structure in the liquid line were much lower than those observed for a 1-mm thick copper plate with the same geometric dimensions for all heat loads in the horizontal orientation, showing a higher thermal performance.

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