Genetic Algorithm Based Optimization of PCM Based Heat Sinks and Effect of Heat Sink Parameters on Operational Time

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Atul Nagose ◽  
Ankit Somani ◽  
Aviral Shrot ◽  
Arunn Narasimhan

Using an approach that couples genetic algorithm (GA) with conventional numerical simulations, optimization of the geometric configuration of a phase-change material based heat sink (PBHS) is performed in this paper. The optimization is done to maximize the sink operational time (SOT), which is the time for the top surface temperature of the PBHS to reach the critical electronics temperature (CET). An optimal solution for this complex multiparameter problem is sought using GA, with the standard numerical simulation seeking the SOT forming a crucial step in the algorithm. For constant heat dissipation from the electronics (constant heat flux) and for three typical PBHS depths (A), predictive empirical relations are deduced from the GA based simulation results. These correlations relate the SOT to the amount of phase change material to be used in the PBHS (φ), the PBHS depth (A), and the heat-spreader thickness (s), a hitherto unconsidered variable in such designs, to the best of the authors’ knowledge. The results show that for all of the typical PBHS depths considered, the optimal heat-spreader thickness is 2.5% of the PBHS depth. The developed correlations predict the simulated results within 4.6% for SOT and 0.32% for ϕ and empowers one to design a PBHS configuration with maximum SOT for a given space restriction or the most compact PBHS design for a given SOT.

Author(s):  
D. Jaya Krishna

Abstract In the present study, the numerical investigation has been performed for a phase change material (PCM)-based longitudinal fin heat sink. The fins are taken as an integral part of the heat sink and are made up of aluminum. The PCM considered in the study is RT44HC. Heat is transferred to the heat sink through its horizontal base. In order to simulate the melting behavior of the PCM, volume of fluid model has been used. To attain the best configuration with optimum operational time, Taguchi method has been used followed by analysis of melt fraction and maximum base temperature. The optimized heat sink configuration with maximum operational time has been obtained at the critical temperatures of 54.8 °C, 63 °C, and 72.6 °C.


Author(s):  
Rajesh Akula ◽  
C. Balaji

Abstract A power surge is a frequent phenomenon that occurs in electronics. Inadequate and improper cooling during power surges results in a rapid increase in operating temperatures that may lead to failure of the electronics. In the present investigation, the thermal characteristics of a phase change material (PCM)-based heat sinks, having different configurations and orientations of fins, subject to (i) constant heat load and (ii) heat load with a power surge, are studied numerically. Preliminary investigations showed that a heat sink with PCM gets heated at a much lower temperature than an air cooled heat sink. Following this, four finned heat sinks are considered for further investigations. The heat sink with PCM, sans fins, is used for baseline comparison. The orientation of fins in the other four heat sinks is either vertical or horizontal with square and rectangular cross sections. The heat sink and fins are made of aluminum, and the PCM used is n-eicosane (C20 H42). The enthalpy-porosity method is used to model the solid–liquid phase change in the PCM. All the transient three-dimensional numerical simulations are carried out using ansys fluent 15.0. For a constant heat load of 5 W and power surges of various magnitudes at different time instants, the heat sink with vertical square fins shows superior performance. However, the performance variation among the heat sinks with different fin configurations is insignificant for constant heat load. Even so, for power surges, the location and the configuration of fins have a significant effect on the heater temperature. Cases with high power surge and shorter duration of the surge were also considered to critically examine the effect of fins in controlling the maximum temperature in the heat sink. The numerical results of the best-performing heat sink, i.e., the heat sink with vertical square fins, are finally validated against in-house experiments.


Author(s):  
Julie Pecson ◽  
Craig Perkins ◽  
Ab Hashemi

Passive heat rejection from a weapon system deployed in space is a challenging problem. This paper describes the development of a phase-change material mini heat sink to absorb the heat from a laser diode for the required operational scenario. Three mini heat sinks made of aluminum, copper, and copper tungsten were designed and manufactured. Phase change material (PCM) was selected to accommodate required heat dissipation from a laser diode. Metal fins, attached to the metal casing of the heat sink, were placed into the PCM to uniformly spread the heat and achieve effective heat transfer. Analytical models were developed to predict the performance of the heat sink. The heat sink was manufactured and initially tested in the laboratory with simulated heat load. Then, tests were carried out under prototypical conditions and the performance of the sink was demonstrated. A comparison of the analytical predictions with data also showed excellent agreement. This paper presents the design, modeling, manufacturing, testing, and comparison of the predictions with experimental results.


Author(s):  
Mohamed Emam ◽  
Ali Radwan ◽  
Mahmoud Ahmed

Concentrated photovoltaic (CPV) integrated with phase-change material (CPV-PCM) system is considered as a single module to reduce the CPV temperature rise and achieve higher solar conversion efficiency. For low concentration ratios (CRs), up to 20, a larger PCM thickness is needed to absorb much more heat and prolong the thermal regulation time of CPV systems. As a result, the heat absorbed in the PCM is not released efficiently to the ambient during the night time. Therefore, active heat dissipation from the CPV-PCM system is required during that time to attain full transition to solid state at the starting of each period of insolation. Thus, a hybrid CPV-PCM water system including various designs of the PCM heat sink is proposed. Such system provides a high-energy storage density during the daytime and enhances the heat extraction from PCM during the night time. To predict the thermal and electrical performance of the hybrid CPV-PCM water system, a comprehensive 2-D model for CPV layers integrated with both PCM, and water flow is developed. The model couples thermal models for CPV layers and thermo-fluid model that considers the phase-change phenomenon and water flow. Numerical simulations of the developed models are performed to determine the instantaneous liquid-solid interface evolution and the transient temperature distribution within the hybrid CPV-PCM water system. Results indicate that the hybrid CPV-PCM water system achieves a significant reduction in the CPV temperature during the daytime and improves the heat dissipation from PCM during the night time.


2022 ◽  
Vol 48 ◽  
pp. 103882
Author(s):  
Adeel Arshad ◽  
Mark Jabbal ◽  
Hamza Faraji ◽  
Pouyan Talebizadehsardari ◽  
Muhammad Anser Bashir ◽  
...  

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Qilong Cheng ◽  
Sukumar Rajauria ◽  
Erhard Schreck ◽  
Robert Smith ◽  
Na Wang ◽  
...  

AbstractThe microelectronics industry is pushing the fundamental limit on the physical size of individual elements to produce faster and more powerful integrated chips. These chips have nanoscale features that dissipate power resulting in nanoscale hotspots leading to device failures. To understand the reliability impact of the hotspots, the device needs to be tested under the actual operating conditions. Therefore, the development of high-resolution thermometry techniques is required to understand the heat dissipation processes during the device operation. Recently, several thermometry techniques have been proposed, such as radiation thermometry, thermocouple based contact thermometry, scanning thermal microscopy, scanning transmission electron microscopy and transition based threshold thermometers. However, most of these techniques have limitations including the need for extensive calibration, perturbation of the actual device temperature, low throughput, and the use of ultra-high vacuum. Here, we present a facile technique, which uses a thin film contact thermometer based on the phase change material $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 , to precisely map thermal contours from the nanoscale to the microscale. $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 undergoes a crystalline transition at $$\hbox {T}_{{g}}$$ T g with large changes in its electric conductivity, optical reflectivity and density. Using this approach, we map the surface temperature of a nanowire and an embedded micro-heater on the same chip where the scales of the temperature contours differ by three orders of magnitude. The spatial resolution can be as high as 20 nanometers thanks to the continuous nature of the thin film.


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