Closed-form analytical solutions for radially rotating miniature high-temperature heat pipes including non-condensable gas effects

Abstract

The radially rotating miniature high-temperature heat pipe is a wickless heat pipe, which has a simple structure and low manufacturing cost, and can withstand strong vibrations in a high-temperature environment. In this paper, the radially rotating miniature high-temperature heat pipe having a diameter in the range of 1.5–2 mm is analyzed by employing appropriate flow and heat transfer models as well as experimental investigation. The diffuse effects of non-condensable gases on temperature distribution along the heat pipe length are investigated. Closed-form analytical solutions for the temperature distribution along the heat pipe length are obtained and extensive experimental tests are undertaken. These closed-form analytical solutions are in good agreement with the experimental data. The theoretical and experimental studies prove that the radially rotating miniature high-temperature heat pipe with sodium as the working fluid has a very large heat transfer capability and a high effective thermal conductance that is 60–100 times higher than the thermal conductivity of copper. Although the diffuse effects of the non-condensable gases would increase temperature drop along the heat pipe length, the heat pipes can still work effectively and reliably. As a result, the combination of the traditional air-cooling technology with radially rotating miniature heat pipes is a feasible and effective cooling means for the rotor blades of a high-temperature gas turbine.