Thermal Behavior of a Double-Condenser Design LHP for Monitor of All-sky X-ray Image

Muto, Miki; Murakami, Masahide; Nagai, Hiroki; Ueno, S.; Matsuoka, M.

doi:10.4271/2002-01-2505

Cited by 3 publications

(2 citation statements)

References 4 publications

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“…Furthermore, the evaporator and condenser can be independently designed for a particular application. Multipleevaporator LHPs have been developed for aerospace applications to cool several heat sources to the same temperature, and multiple-condenser LHPs have also been developed for a greater heat removal capacity [11][12][13][14]. Thus, the LHP configuration promises greater flexibility in application than that of traditional heat pipes and is utilized in this study to increase the surface area available at the condenser.…”

Section: Introductionmentioning

confidence: 99%

“…When flooded, less surface area is available for condensation, and therefore the thermal resistance of the system increases. While dual-condenser LHPs have been developed in the past, most studies investigated operating conditions with the condensers at equal height or did not compare the performance of the individual condensers [11,12,14].…”

Section: Introductionmentioning

confidence: 99%

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Development and Characterization of an Air-Cooled Loop Heat Pipe With a Wick in the Condenser

Kariya¹,

Peters²,

Cleary³

et al. 2013

Journal of Thermal Science and Engineering Applications

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Thermal management of modern electronics is rapidly becoming a critical bottleneck of their computational performance. Air-cooled heat sinks offer ease and flexibility in installation and are currently the most widely used solution for cooling electronics. We report the characterization of a novel loop heat pipe (LHP) with a wick in the condenser, developed for the integration into an air-cooled heat sink. The evaporator and condenser are planar (102 mm Â 102 mm footprint) and allow for potential integration of multiple, stacked condensers. The condenser wick is used to separate the liquid and vapor phases during condensation by capillary menisci and enables the use of multiple condensers with equal condensation behavior and performance. In this paper, the thermal-fluidic cycle is outlined, and the requirements to generate capillary pressure in the condenser are discussed. The LHP design to fulfill the requirements is then described, and the experimental characterization of a single-condenser version of the LHP is reported. The thermal performance was dependent on the fan speed and the volume of the working fluid; a thermal resistance of 0.177 C/W was demonstrated at a heat load of 200 W, fan speed of 5000 rpm and fluid volume of 67 mL. When the LHP was filled with the working fluid to the proper volume, capillary pressure in the condenser was confirmed for all heat loads tested, with a maximum of 3.5 kPa at 200 W. When overfilled with the working fluid, the condenser was flooded with liquid, preventing the formation of capillary pressure and significantly increasing the LHP thermal resistance. This study provides the detailed thermal-fluidic considerations needed to generate capillary pressure in the condenser for controlling the condensation behavior and serves as the basis of developing multiplecondenser LHPs with low thermal resistance.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development and Characterization of an Air-Cooled Loop Heat Pipe With a Wick in the Condenser

Kariya¹,

Peters²,

Cleary³

et al. 2013

Journal of Thermal Science and Engineering Applications

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Low Frequency High Amplitude Temperature Oscillations in Loop Heat Pipe Operation

2003

SAE Technical Paper Series

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This paper presents a theory that explains low frequency, high amplitude temperature oscillations in loop heat pipe (LHP) operation. Oscillations of the CC temperature with amplitudes on the order of tens of degrees Kelvin and periods on the order of hours have been observed in some LHPs during ambient testing. There are presently no satisfactory explanations for such a phenomenon in the literature. It is well-known that the operating temperature of an LHP with a single evaporator is governed by the compensation chamber (CC) temperature, which in turn is a function of the evaporator heat load, sink temperature, and ambient temperature. As the operating condition changes, the CC temperature will change during the transient but eventually reach a new steady temperature. Under certain conditions, however, the LHP never really reaches a true steady state, but instead displays an oscillatory behavior. The proposed new theory describes why low frequency, high amplitude oscillations may occur when the LHP has a low evaporator power, a low heat sink temperature (below ambient temperature), and a large thermal mass attached to the evaporator. When this condition prevails, there are some complex interactions between the CC, condenser, thermal mass and ambient. The temperature oscillation is a result of the large movement of the vapor front inside the condenser, which is caused by a change in the net evaporator power modulated by the large thermal mass through its interaction with the sink and CC. The theory agrees very well with previously published test data. Effects of various parameters on the amplitude and frequency of the temperature oscillation are also discussed.

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On-Orbit Performance of the TES Loop Heat Pipe Heat Rejection System

Rodriguez¹,

Na-Nakornpanom²,

Rivera³

et al. 2008

SAE Technical Paper Series

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Thermal Behavior of a Double-Condenser Design LHP for Monitor of All-sky X-ray Image

Cited by 3 publications

References 4 publications

Development and Characterization of an Air-Cooled Loop Heat Pipe With a Wick in the Condenser

Development and Characterization of an Air-Cooled Loop Heat Pipe With a Wick in the Condenser

Low Frequency High Amplitude Temperature Oscillations in Loop Heat Pipe Operation

On-Orbit Performance of the TES Loop Heat Pipe Heat Rejection System

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