Hysteresis phenomena in flat-type loop heat pipe

Gai, Dongxing; Sun, Junying; Chen, Chen; Chen, Ting

doi:10.2298/tsci191010166d

Cited by 3 publications

(1 citation statement)

References 17 publications

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“…A LHP under test may respond to that independently from the operation history or show some sensitivity to that, denoted as hysteresis. [7] studied exactly that with a LHP of flat evaporator, but have encountered a situation when LHP evaporator temperature changed during a rather steady operation after a startup (see figure 2). Thus, the LHP showed at least two stable states and transitioned between them on its own, seemingly in dependence from the vapor-liquid distribution within CC and evaporator (see the differing charges of the LHP).…”

Section: Lhp Problems In Transientsmentioning

confidence: 99%

Review of “cold shock” cases in operation of loop heat pipes and related thermal instabilities

Ivanovskis,

Mishkinis

2024

J. Phys.: Conf. Ser.

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Loop Heat Pipes (LHP) are passive two-phase heat transfer devices, driven by capillary pumps that source energy for circulation of working fluid solely from the heat source. They have a proven track record in spacecraft thermal control as well as terrestrial applications. However, LHP may experience partial or complete wick dryout and thermal instabilities at rapid power-up steps or (and) rapid condenser cooling conditions change due to a rapid inflow of subcooled liquid from the condenser into the evaporator. Such cases do not have very wide coverage in literature and are usually presented as a little nuisance in testing of a particular LHP, for which some design workaround was found. Oftentimes suggested solutions trade performance or other design merits for robustness of operation. This article aims to review such case studies where phenomena similar to the described “cold shock” affected LHP performance. The aforementioned instabilities become even more pronounced in grid-like multievaporator LHP having multiple parallel connections between capillary pumps and compensation chambers, as heat and mass transfer between those elements becomes less definite and can eventually increase the heat leak into compensation chambers. Vulnerability of LHP with distributed network of evaporators to seemingly “safe” transient regimes fosters deeper analysis of the “cold shock” phenomenon. With comprehensive definition to the problem and a list of research questions, technical measures for getting rid of it in perspective LHP designs can be foreseen.

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Section: Lhp Problems In Transientsmentioning

confidence: 99%