Heat transfer simulation of heat source with fins using Comsol

How to Simulate a Heatsink Effect on a Computer Chip

Introduction to Simulation

• The tutorial focuses on simulating the effect of adding a heatsink, specifically a fin, to a heat source like a computer chip.

• A parameter 'l' is defined for the length of both vertical and slanting segments of the fin before starting geometry construction.

Geometry Construction

• The first vertical segment is created with length 'l', followed by constructing a slanting segment at an angle of 5 degrees.

• A mirror operation is used to reflect three line segments, which are then converted into solid geometry.

• The solid can be duplicated six times using an array transformation, ensuring proper spacing between each segment.

Material Selection

• Aluminum is chosen for the fin due to its high thermal conductivity, while silicon represents the computer chip material for simplification.

• Thermal grease is introduced as an interface material between the chip and fin to enhance heat transfer efficiency.

Physics Setup

• A heat source simulating 10 watts dissipation from the chip is established along with thermal contact settings between the chip and fin.

• Boundary conditions are set up for convection; external natural convection coefficients are applied based on surface orientations (vertical vs. inclined).

Mesh Creation and Study Configuration

• A user-controlled mesh with extra fine sizing nodes is implemented, followed by sweeping operations along the geometry's length.

• Finally, a stationary study setup utilizes direct solvers for computational analysis.

Investigating the Effect of Fin Length on Computer Chip Temperature

Parametric Sweep for Fin Length

• The process begins with a parametric sweep to analyze how varying fin lengths affect temperature. The defined parameter is in millimeters, ranging from 2.5 mm to 20 mm in increments of 2.5 mm.

• A total of eight solutions will be computed, allowing observation of temperature distribution changes as fin segment lengths are adjusted, highlighting their impact on maximum chip temperature.

Convergence and Solution Computation

• As computations progress, the current value of the fin length (l) is displayed alongside a convergence plot due to the nonlinear nature of the problem stemming from empirical formulae used for average heat transfer coefficient calculations.

• After computing four solutions, users can visualize how fin length affects maximum chip temperature by generating plots that represent these derived values.

Analyzing Temperature Distribution

• Users can create a table and plot group to visualize data effectively; selecting 'parametric solutions' ensures all parameters are considered rather than just the last one.

• Initial findings show that shorter fins lead to significant drops in temperature; however, as fin length increases further, efficiency levels off indicating diminishing returns.

Determining Optimal Fin Length

• To select an optimal fin length based on maximum allowable chip temperature (e.g., 80 degrees Celsius), it is suggested that a minimum length of approximately 16 mm is necessary for effective cooling.

• Additional visualizations such as 3D plots can illustrate temperature distributions across different sections of the fins and chips, revealing that the top part of the fin remains cooler while the computer chip itself reaches higher temperatures.