| Summary: | 碩士 === 國立臺北科技大學 === 能源與冷凍空調工程系碩士班 === 96 === Pulsating heat pipe (PHP) is a new heat transfer device, which can transfer the heat from one end to the other end by the mechanism of pulsating action of the liquid-vapor system. The thesis aimed to discover area on the nano-fluid increasing heat transfer further. To discover bubble type of PHP system, changeful temperature condition by observing their actions with high speed, thermal imaging machine. Through analysis of the features, I explore the influence under different parameters of work fluid, fill ratio, angle of inclination and heating load .
The experimental results show that: (1) The input heat flux will change the flow pattern inside the PHP tube, which can be divided into three periods-oscillating, transitional and stable periods. (2) PHP fluid field type can be divided into dispersed bubble, confined bubble, slug and annular flows. Dispersed bubble only appears in periods-oscillating. After stability, the condenser exit will be confined bubble and the evaporator exit will be straight confined bubble and annular flows. (3) When the work fluid properties are different, observing the difference of confined bubble. For example, water is confined bubble, silver and titanium dioxide are dividedly elliptic mode and pipa mode. (4) The experience will make a PHP performance model. The PHP heat resistance value will be the lowest when the work fluid of nano-fluid(silver and titanium dioxide) and water under the conditions of FR 30%, angle of inclination 90°. (5) When nano-fluid is testing through the long time, its performances close to water and unuseful in long. (6) It is the two-phases circle along steady direction on spreading temperature field of stable periods. The temperature of fluid would rather be uneven spreading temperature than appear increasing along circular direction.
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