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Research Papers: Experimental Techniques

# Experimental Study of a Curved Rotating Heat Pipe

[+] Author and Article Information
T. A. Jankowski1

Mechanical and Thermal Engineering Group (AET-1), Los Alamos National Laboratory, MS J580, Los Alamos, NM 87545jankowski@lanl.gov

F. C. Prenger

Mechanical and Thermal Engineering Group (AET-1), Los Alamos National Laboratory, MS J580, Los Alamos, NM 87545

A. Razani

Department of Mechanical Engineering, University of New Mexico, MSC01 1150, Albuquerque, NM 87131

1

Corresponding author.

J. Heat Transfer 130(10), 101601 (Aug 08, 2008) (8 pages) doi:10.1115/1.2953303 History: Received August 10, 2007; Revised March 13, 2008; Published August 08, 2008

## Abstract

A curved rotating heat pipe for use in motor and generator applications is studied experimentally. The heat pipe is built so that both the condenser and evaporator sections are parallel to the axis of rotation. The condenser section is close to the axis of rotation while the evaporator section can be placed in contact with off-axis heat sources in the rotating machine. The geometry is achieved by incorporating an S-shaped curve between the on-axis rotating condenser section and the off-axis revolving evaporator section. The curved rotating heat pipe allows for a direct coupling of the rotating condenser section to an on-axis stationary refrigeration system, while allowing the revolving evaporator section to intercept off-axis heat sources in the rotating machine. An experimental rotating heat pipe test apparatus was built and operated. The test data indicate that the working fluid continued to circulate, resulting in heat transfer with a high effective thermal conductivity, with the curved rotating heat pipe operating under the influence of centrifugal accelerations approaching $400g$. Furthermore, the experimental results were used to validate a heat pipe thermal model that can be used in the design of rotating machines that rely on the curved rotating heat pipe as part of the thermal management system.

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Topics: Heat pipes

## Figures

Figure 2

The experimental apparatus used to test the rotating heat pipes. A picture is shown in (a) and a solid model of the components mounted to the frame is shown in (b).

Figure 1

The curved rotating heat pipe. The layout of the rotating heat pipe in (a) shows the on-axis rotating condenser section and the off-axis revolving evaporator section, while the cross-sectional view in (b) shows the annular gap wick structure.

Figure 10

Comparing heat transfer coefficients in the evaporator. Data labeled (measured) were measured heat transfer coefficients in the experiments performed here, and data labeled (calculated) are calculated values from the heat pipe thermal model described in Sec. 3. The dashed error bars are for the 74W data and the 198W error bars are solid.

Figure 3

Stationary dryout tests with the heat pipes installed in the rotating test apparatus

Figure 4

Low-speed dryout tests

Figure 5

Example data file for a rotating test with a 150W heat load and a condenser temperature of 25°C

Figure 6

Measured temperature difference across the evaporator liquid film for the rotating tests. All uncertainties are the same as the 38W case.

Figure 7

Conductance across the liquid film in the evaporator section of the rotating heat pipe. The 74W case gave the largest (dashed) error bar and the 198W case gave the smallest (solid) error bar when calculating the conductance.

Figure 8

Nusselt number for heat transfer across the evaporator film in the rotating heat pipe

Figure 9

Comparing measured temperature difference across the evaporator liquid film to the numerical model. Model predictions are shown as lines and experimental data as points.

## Errata

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