Effect of evaporator preheating on the startup characteristics of capillary pumped loop. (25th January 2023)

• Record Type: Journal Article
• Authors: Hirata, Masaru; Odagiri, Kimihide; Ogawa, Hiroyuki
• Is Part Of: Applied thermal engineering. Volume 219(2022)Part C
• Publication Date: 2023-01-25
• Subjects: Capillary pumped loop -- Startup reliability -- Startup behavior -- Evaporator preheating; CPL Capillary pumped loop -- LHP Loop heat pipe; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2022.119573
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Startup of Capillary Pumped Loop becomes easier when the evaporator is preheated. The vapor–liquid distribution in the evaporator is changed by evaporator preheating. The changes of vapor–liquid distribution is important for the successful startup. Superheat at startup is reduced by evaporator preheating before reservoir control. Abstract: A capillary pumped loop (CPL) is a capillary force-driven heat transport device that uses the phase change of a working fluid. A CPL has excellent properties in terms of heat transport capability, heat transport distance, and flexibility in heat transport path arrangement. However, its startup reliability is low, and its startup characteristics have yet to be determined. This study aims to investigate the startup characteristics of a CPL and improve its startup reliability. The startup procedures are newly proposed and experimentally verified in this paper. In the proposed method, the evaporator was preheated in addition to the reservoir preheating before startup. Verification was done by switching the order of the reservoir preheating and evaporator preheating. The experimental results showed that the proposed methods enable the CPL to start up even in conditions where the CPL was unable to start up by a conventional method (reservoir temperatures ranging from 40 °C to 80 °C). It was also confirmed that the order of the evaporator preheating and reservoir preheating affects the degree of overshoot of the evaporator temperature. The maximum temperature of the evaporator at the startup was reduced by up to 91.5 °C in case the evaporator was preheated before the reservoir preheating.