密閉二相熱サイフォンの熱伝達特性に関する研究

概要

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Closed two-phase thermosyphon has a high heat transfer performance and therefore is widely used forcooling of electronic devices etc. The basic conﬁguration of thermosyphon is called the single tube typethermosyphon, which is using a vertical or inclined straight tube. This conventional single tube typethennosyphon has the following two problems. One is that the non-uniform wall temperature exists because ofless ﬂuid mixing due to slight or no boiling at the bottom of the evaporator. The other one is small maximumheat transfer rate because of ﬂooding, which is caused by counter current ﬂow of steam ﬂow and return liquid.A new type of thermosyphon, which is referred to a looped parallel thermosyphon, was developed to solve theproblems. It consisted of parallel installed two conventional thermosyphons connected by two U tubes. Waterand ethanol were used as the Working ﬂuid. Experiments were carried out with three different coolingtemperatures, 25, 37.5, and 50 °C and two charge ratios, 0.5 and 0.9. The purpose of the present study is toexamine the heat transfer characteristics of the single tube thermosyphon and the looped parallel thermosyphon.The heat transfer characteristics on the evaporator and condenser of two types of thermosyphons wereclariﬁed.