When designing a heat pipe mounting plate there are many approaches to where and how to install the heat pipes. Direct contact, soldering a heat pipe into a mounting plate, then machining it flat, yields the best performance. However, this method has trade-offs. Note – choices are limited to soldered heat pipes.
Heat Pipe Mounting Options
Figure 1 illustrated common heat pipe mounting options. Mounting options A-D use a copper base plate to which the heat source is attached. For options E-G, the heat source directly contacts the heat pipe. In the following test setups, red arrows represent the location of the heat source/input.
Figure 1: Common Heat Pipe Mounting Options
Test Setup
Figure 2 shows the test setup. Th is thermocouple in the heater. Tc is thermocouple through the heater and touching the base.
Figure 2: Heat Pipe Mounting Test Set
CFD Performance Results Using Different TIMs
Figure 3 shows how TIM material affects delta-T figures by as much as 10%.
Figure 3: Comparison of Different TIM Materials Used in Each Mounting Configuration
Comparing CFD and Bench Test Results
On average, bench testing resulted in delta-T differences versus CFD of 3.1C. or within 6% of the CFD predictions using a grease TIM.
Figure 4: CFD vs Bench Test
Performance & Cost Implications
As the design changes from A to G (Figure 5): manufacturing process time goes up, secondary operations may become necessary, yield rate drops, and price increases. Here’s a summary of the performance and cost tradeoffs.
Figure 5: Performance and Cost Implications of Each Heat Pipe Mounting Option
