| 摘要: | 現今電子元件發展迅速，其效能日益精進同時追求縮裝輕薄短小之產品導向，儼然肇生因質量體積漸減與單位密度功率提升所導致熱集中現象，容易致使關鍵元件過熱而失效損毀與影響壽期等問題，並且由於散熱空間與面積之限制，高密度熱能之傳導技術研究成為關鍵之議題。為確保產品壽期與功能穩定性，探討熱傳導路徑執行專案熱流分析，以設計適合研發測裝與產製之實務為方針，採用階段性標準化流程建構模型，搭配實驗數據修正參數驗證模型可靠度，進一步提出設計優化方案，針對產品功能特性與使用場景擬定改善目標，期望精進原構型整體散熱性能及降低產品成本。
本研究採用CFD方法，運用COMSOL模擬軟體進行共軛熱傳模擬分析，本文模型主要架構與熱傳導路徑，分別由四個相同機匣所組立而成之模組，其中內部核心熱源經由機匣本體由上至下直接接觸熱傳導至水冷板，再以水冷板充填工作流體為純水進行水冷式內循環作為散熱方案，因此水冷板內部流道設計成為關鍵熱源溫度影響控制幾何因子。
水冷板內流場經由計算雷諾數，判別流動為紊流狀態，考量不可忽略邊界黏性層高梯度準確流場，選擇SST作為本研究紊流模型，依序加入邊界層網格與y+設定層厚及數量用以觀測黏性層流速變化，並且適度調修模型保持網格品質同時提升網格離散收斂性，再執行網格獨立性測試定義熱源溫度與流場平均線流速作為模擬實驗特性，藉以縮短模擬分析時間成本。
此外，於模型各介面之接觸熱阻設定值根據實驗測試數據所定義，熱源部分同步視網格生成收斂性適度以薄層設定條件取代，在不影響結果真實性情況下節省冗長計算時間，由此得到符合實驗之初始設定，奠定優化內部流道設計有效模型基礎，並進行內部流道設計變更。透過分析熱源位置調整流道方向與幾何形態，另加入各式型態渦流產生器產生擾動，助於熱傳導路徑之間邊界層混合效應，研究熱源溫度變化與探討壓降及製程規劃評估性能效益，以探討研發精進構型可行性。
;In recent years, electronic components are developing rapidly, and their efficacy is becoming more and more sophisticated while pursuing the product orientation of shrinking, light, thin, and short. The decrease in mass and volume and the increase in power per unit density bring heat concentration. The accumulated heat causes key components to overheat, failing and damaging the components and affecting the life span. Due to the limitation of heat dissipation space and area, research on high-density thermal energy transport technology has become essential. To ensure the product life cycle and functional stability, mastering the heat transfer path to perform heat flow analysis, with the guideline of designing a practice suitable for research and development, testing, assembly, and production cannot be overlooked. It is also vital to adopt a standard process to build a model and use experimental data to verify the reliability of the model. Based on the model, one can propose a design optimization plan, formulate improvement goals for product functional characteristics and usage scenarios, and expect to improve the overall heat dissipation performance and ease of production.
In this study, the computational fluid dynamics method is used to simulate the conjugate heat transfer using the COMSOL simulation software. The four modules composed of identical casings are the main structure and heat transfer path. The internal core heat source in each module directly contacts and transfers heat to the cold plate from top to bottom through the casing body. The cold plate is filled with pure water as the working fluid for water-cooled internal circulation as a heat dissipation solution. Therefore, the design of the internal flow channel of the cold plate becomes a critical controlling factor that affects the heat source temperature.
The flow field in the cold plate is judged to be turbulent by calculating the Reynolds number. Considering the high-gradient flow field of the viscous boundary layer that cannot be ignored, SST(shear stress transport) model is selected as the turbulent flow model in this study. By refining the grids size and retaining the y plus as small across the boundary, the flow velocity gradient is resolved in the boundary layer. The model is moderately adjusted to maintain the grid quality while improving the numerical convergence. The grid independence test is performed. The temperature of the heat source and the average velocity are adopted as the characteristics of the simulation experiment to shorten the simulation analysis time cost.
In addition, we apply the contact thermal resistance at each interface of the model defined according to the experimental test data. The mesh of each heat source is moderately replaced by the thermal resistance, which saves computational time without reducing the resulting
authenticity, which conforms to the experiment. We use the model as the foundation for optimizing the effectiveness of the cold plate, testing various flow channel designs, and adjusting the flow direction and geometry by analyzing the heat source′s position. In addition, multiple types of vortex generators are tested to generate flow disturbance, which helps the boundary layer mixing effect between heat transfer paths. We study the temperature change of the heat source and discuss the pressure drop and the manufacturing process to evaluate the performance and explore the feasibility of developing advanced configurations. |
