Study on Thermal Performances of a Small Loop Heat Pipe

Nagano, Hosei; Nagai, Hiroki; Fukuyoshi, Fuyuko; Ogawa, H.

doi:10.1299/jtst.3.355

Cited by 8 publications

(5 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is clear that the thermal performance in the previous model (cal. Previous model) [18] was not agreed with that in experimental results when the wick with small number of the grooves were used, while they agreed well as the number of the grooves increases. In the conventional model, the vapor generated on the surface of the wick flows into the grooves immediately without any pressure loss.…”

Section: Test Resultsmentioning

confidence: 59%

“…The key technologies of the loop in the design in order to produce high heat transfer performance are (1) to have higher capillary force, (2) to have lower system pressure loss in the loop, (3) to reduce heat leak from the evaporator to the CC, and (4) to reduce thermal resistance between the wick surface and the evaporator case for higher evaporation efficiency in the evaporator [13][14][15]. The mathematical model of the LHP is being studied and developed [16][17][18][19]. However, detailed model for micro-scale thermo-fluid character in the evaporator has not been developed.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermofluid Characteristics in Microporous Structure With Different Flow Channels for Loop Heat Pipe

Nagano

Kuroi

Nishikawara

2016

Heat Transfer Engineering

Self Cite

View full text Add to dashboard Cite

The use of two-phase heat transfer devices using capillary action in a microscale porous structure such as a loop heat pipe (LHP) is a promising heat transport technology. It is because they have characteristics of higher heat transfer power and longer heat transport distances with no electrical power compared with conventional heat pipes. The thermal performance of an LHP is governed by the thermo-fluid behavior in a microscale porous structure called the wick. In this research, high-performance wicks made of polymer has been developed, and its pore distribution and permeability were evaluated. The effects of the vapor channel's shape on the loop's thermal performance have been investigated by calculation and experiment to enhance evaporator performance. A mathematical model of the evaporator considering super heat in the channel, pressure drop across the wick, and two-phase pressure loss on the boundary face between the wick and the evaporator case was newly developed. The experiment was also conducted as a function of the groove shapes. From calculation and test results, it was found that in order to increase the maximum heat transport capability and decrease the operating temperature, the groove should be well distributed.

show abstract

Section: Test Resultsmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Thermofluid Characteristics in Microporous Structure With Different Flow Channels for Loop Heat Pipe

Nagano

Kuroi

Nishikawara

2016

Heat Transfer Engineering

Self Cite

View full text Add to dashboard Cite

show abstract

“…The MLHP was designed by using mathematical model for a single evaporator LHP [10]- [12], on condition that both evaporators are heated and heat is transferred in forward direction, that is, the heat is transferred from each evaporator to the common vapor line, the condensers, and the common liquid line. To reduce the heat leak from the evaporators to the CCs and to lower the operating temperature, PTFE porous media is used as primary wicks which have lower thermal conductivity than traditional metal wicks [9].…”

Section: Experiments Systemmentioning

confidence: 99%

Operating Characteristics of Multiple Evaporators and Multiple Condensers Loop Heat Pipe with Polytetrafluoroethylene Wicks

Okutani¹,

Nagano²,

Okazaki³

et al. 2014

JECTC

Self Cite

View full text Add to dashboard Cite

This paper presents fabrication and testing of a multiple-evaporator and multiple-condenser loop heat pipe (MLHP) with polytetrafluoroethylene (PTFE) porous media as wicks. The MLHP has two evaporators and two condensers in a loop heat pipe in order to adapt to various changes of thermal condition in spacecraft. The PTFE porous media was used as the primary wicks to reduce heat leak from evaporators to compensation chambers. The tests were conducted under an atmospheric condition. In the tests that heat loads are applied to both evaporators, the MLHP was stably operated as with a LHP with a single evaporator and a single condenser. The relation between the sink temperature and the thermal resistance was experimentally evaluated. In the test with the heat load to one evaporator, the heat transfer from the heated evaporator to the unheated evaporator was confirmed. In the heat load switching test, in which the heat load is switched from one evaporator to another evaporator repeatedly, the MLHP could be stably operated. The loop operation with the large temperature difference between the heat sinks was also tested. From this result, the stable operation of the MLHP in the various conditions was demonstrated. It was also found that a flow regulator which prevents the uncondensed vapor from the condensers is required at the inlet of the common liquid line when one condenser has higher temperature and cannot condense the vapor in it.

show abstract

“…To get the saturation temperature T CC of the liquid, which cannot be measured by the thermocouples, convergence calculation is performed to maintain the relationship of the eq. (4) [4]. Q HL is calculated by using the saturation temperature T CC .…”

Section: Prototype Modelmentioning

confidence: 99%

Experimental study on thermal performance of loop heat pipes with flat evaporator for LSI package

Shioga

Ogata

Mizuno

2012

2012 2nd IEEE CPMT Symposium Japan

View full text Add to dashboard Cite

Thermal performance of a loop heat pipe (LHP) equipped with a flat evaporator and a compensation chamber integrated onto the evaporator and separated from the evaporator was experimentally investigated. The heat leak in the flat evaporator is a critical problem as it results in the degradation of the heat transport characteristics of the LHP. In this paper, the heat leak quantity during the steady-state operation of the LHP was calculated by carrying out a thermal energy balance analysis for the flat evaporator. From the results, the heat conduction along the case sidewall of the evaporator dominated the heat leak on the evaporator, and it was found that the heat leak from the heat source to the compensation chamber decreased to 5% or less of the applied input power due to the reduced heat conduction of the evaporator casing.

show abstract

Study on Thermal Performances of a Small Loop Heat Pipe

Cited by 8 publications

References 8 publications

Thermofluid Characteristics in Microporous Structure With Different Flow Channels for Loop Heat Pipe

Thermofluid Characteristics in Microporous Structure With Different Flow Channels for Loop Heat Pipe

Operating Characteristics of Multiple Evaporators and Multiple Condensers Loop Heat Pipe with Polytetrafluoroethylene Wicks

Experimental study on thermal performance of loop heat pipes with flat evaporator for LSI package

Contact Info

Product

Resources

About