{"id":1633,"date":"2010-07-12T13:03:20","date_gmt":"2010-07-12T17:03:20","guid":{"rendered":"https:\/\/wpmu2.mit.local\/?p=1633"},"modified":"2010-07-12T13:03:20","modified_gmt":"2010-07-12T17:03:20","slug":"sintered-metal-wicks-for-loop-heat-pipes","status":"publish","type":"post","link":"https:\/\/wpmu2.mit.local\/sintered-metal-wicks-for-loop-heat-pipes\/","title":{"rendered":"Sintered Metal Wicks for Loop Heat Pipes"},"content":{"rendered":"
\"Figure<\/a>

Figure 1: Sample of bi-layer wick. The wick shown consists of a 40-90-\u00b5m coarse copper powder in the bulk and a 5-15-\u00b5m fine copper powder layered on top.<\/p><\/div>\n

Loop heat pipes (LHPs) are a widely-used component in the thermal management of high-power electronics. LHPs transfer heat by utilizing the latent heat of a working fluid, which is circulated by the capillary pumping of a porous wick. A typical design consists of an evaporator and condenser connected in a closed loop.\u00a0 As the capillary wick, located in the evaporator, influences the operating characteristics and limits of the LHP, much work has been devoted to optimizing the wick\u2019s capillarity and permeability to extend the range of LHP operation [1<\/a>]<\/sup> [2<\/a>]<\/sup> [3<\/a>]<\/sup>.<\/p>\n

This work investigates the wick characteristics necessary to operate a novel, multi-condenser LHP.\u00a0 To ensure controlled condensation and full utilization of all condensers, an additional wick must be integrated into the condensers.\u00a0 Condensation occurs on the wick\u2019s surface, and the wick is used to separate the vapor and liquid phases.\u00a0 The wick must therefore have high capillary pressure at the interface to separate the phases and high bulk permeability for ease of liquid flow.<\/p>\n

To achieve high capillary pressure at the wick surface and high bulk permeability, a bi-layer sintered wick structure was fabricated in two steps (Figure 1).\u00a0 The bulk wick was first made by sintering coarse (120-140 \u00b5m) copper powder at 850 \u00b0C for 30 minutes.\u00a0 The sintering was performed in a tube furnace under a hydrogen-nitrogen atmosphere.\u00a0 A thin layer of high-capillarity wick was then fabricated on top of the bulk wick by layering fine (5-15 \u00b5m) copper powder and sintering at 650 \u00b0C for 30 minutes.\u00a0 A controlled fabrication procedure resulted in a repeatable thickness of the fine layer of approximately 100 \u00b5m.\u00a0 The bi-layer wick showed improvement over the single-layer coarse wick, matching the permeability (10-11<\/sup> m2<\/sup>) of the coarse wick in the bulk while increasing the surface capillary pressure from 100 to 680 Pa for the advancing meniscus.<\/p>\n

\r\nReferences
  1. J. Ku, \u201cOperating characteristics of loop heat pipes,\u201d SAE 1999-01-2007. [↩<\/a>]<\/li>
  2. C.C. Yeh, B.H. Liu, and Y.M. Chen, \u201cA study of loop heat pipes with biporous wicks,\u201d Heat and Mass Transfer<\/em>, vol. 44, pp. 1537-1547, April 2008. [↩<\/a>]<\/li>
  3. X. Huang and G. Franchi, \u201cDesign and fabrication of hybrid bi-modal wick structure for heat pipe application,\u201d Journal of Porous Matter<\/em>, vol. 15, pp. 635-642, July 2007. [↩<\/a>]<\/li><\/ol><\/div>","protected":false},"excerpt":{"rendered":"

    Loop heat pipes (LHPs) are a widely-used component in the thermal management of high-power electronics. LHPs transfer heat by utilizing…<\/p>\n<\/div>","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[29],"tags":[4176,4110],"_links":{"self":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1633"}],"collection":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/comments?post=1633"}],"version-history":[{"count":4,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1633\/revisions"}],"predecessor-version":[{"id":1638,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1633\/revisions\/1638"}],"wp:attachment":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/media?parent=1633"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/categories?post=1633"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/tags?post=1633"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}