By Josh Perry, Editor
[email protected]

A recent article from Advanced Thermal Solutions, Inc. (ATS), a leading-edge engineering company based in Norwood, Mass. focused on the thermal management of electronics, outlines the effect that liquid fill ration and vacuum have on the thermal performance of heat pipes.

The article explores the effect of vacuum and fill ratio on heat pipe performance.
(Advanced Thermal Solutions, Inc.)

According to the article, “The state of liquid pressure should be in the region below atmosphere (vacuum) and above the complete vacuum. To obtain lower operating temperature the heat pipe pressure should be decrease and vice versa. The state of liquid after the condenser has to be saturated liquid, so the wick can create the liquid motion.”

Maximum heat transfer in heat pipes is an exponential function of vacuum pressure, and by decreasing vacuum pressure than Qmax increases.

In terms of fill ratio, it is important to have the right amount of liquid to ensure that evaporation occurs and is not delayed as well as to avoid drying out. The article notes that the standard is the volume of the liquid should be higher than the pore volume of the wick.

The article concluded, “There is not much data in the literature about the effect of these two factors on the performance of the heat pipe. And it appears that most heat pipe manufacturers either resort to a try and error procedure or use the information from past experience. This topic needs further research.”

Read the full article at https://qats.com/cms/2018/07/17/technical-note-effect-of-vacuum-and-fill-ratio-on-performance-of-heat-pipes.