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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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A Novel Thermal Module with 3-D Configuration Pulsating Heat Pipe for High-Flux Applications
(2018-12-01)
Tseng, Chih-Yung
;
Wu, Ho-Meng
;
Wong, Shwin-Chung
;
Yang, Kai-Shing
;
Wang, Chi-Chuan
A pulsating heat pipe (PHP) contains a wickless design with aligned serpentine tube configuration whose simple structure offers a comparatively easy manufacturing capability. The bends with large curvature are often used for serpentine PHPs. This eventually results in a decline in effective contact surface area between evaporator/condenser and PHP circuitry, thereby impairing the benefit of the wickless design of a PHP. A novel thermal module featuring a 3-D configuration pulsating heat pipe, an evaporator, and a fin-and-tube condenser is proposed to tackle the high-flux application. Methanol is used as the working fluid with a filling ratio of around 60%. Test results indicate the thermal resistance of the proposed module varies from 0.148 K/W to 0.0595 K/W when the supplied power changes from 100 to 1000 W. The proposed thermal module can handle a supplied power up to 1 kW and the corresponding power or heat flux is much higher than any existing literatures.
Effect of partial bypass on the heat transfer performance of dehumidifying coils
(2014-11-01)
Wang, Chi-Chuan
;
Cheng, Yu-Cheng
;
Liaw, Jane-Sunn
;
Tseng, Chih-Yung
;
機械工程學系
This study extends a so called "partial bypass" concept to dehumidifying fin-and-tube heat exchangers. Tests are performed for a 2-row and 4-row fin-and-tube heat exchangers having plain fin configuration. The inlet dry bulb temperature is fixed at 25 degrees C while the inlet relative humidities are 50% and 80%, respectively. Test results showed that for a 2-row coil under RH = 50%, the corresponding heat transfer augmentation ratio (Q(R)) and pressure penalty ratio (P-R) decrease with the rise of bypass ratio (BR). At a smaller frontal velocity, the regime of appropriate bypass ratio where Q(R) > 1 and P-R < 1 is more apparent. The effect of partial bypass decreases as the velocity increases. As the velocity gets close to 2 m s(-1), it shows that the performance at high bypass ratio becomes more efficient. At the same time, when bypass ratio becomes lager, the tendency of the decreasing of Delta P is more drastic than the decreasing of Q. Nevertheless, not for all the cases that the performances get better as the bypass ratio increases. For V-fr = 4 m s(-1), the experiment results show that the overall effect is less efficient\' than at V-fr = 2 m s(-1). The major reason is caused by the flow pattern. The rise of bypass airflow is quite large which may act as an air curtain to distort the main airflow, and result in higher pressure drop. This implies that the design of the bypass design is quite imperative in the practice of real applications. For a 4-row heat exchanger, the experiment data of QR and PR for the 4-row coil performs better than a 2-row coil. (C) 2014 Elsevier Ltd. All rights reserved.
A new correlation and the review of two-phase flow pressure change across sudden expansion in small channels
(2010-09-01)
Wang, Chi-Chuan
;
Tseng, Chih-Yung
;
Chen, Ing Youn
;
機械工程學系
;
Department of Mechanical Engineering
In this study, the authors first present a short overview on the single-phase flow across sudden expansion, followed by a thorough review of the relevant literature for two-phase flow across sudden expansion, and examination of the applicability of the existing correlations. Also, 282 data available from five publications are collected. It is found that none of the existing correlations can accurately predict the entire database. Most of the correlations highly over predict the data with a mini test section which has a Bond number being less than 0.1 in which the effect of surface tension dominates. Also, some of the correlations significantly under predict the data for very large test sections. Among the models/correlations being examined, the homogeneous model shows a poor predictive ability than the others, but it is handy for the engineering aspect. Hence by taking account the influences of Bond number, Weber number, Froude number, liquid Reynolds number, gas quality and area ratio into the original homogeneous model, a modified homogeneous model is proposed that considerably improves the predictive ability over existing correlations with a mean deviation of 23% and a standard deviation of 29% to all the data with wider ranges of operating parameters for application. (C) 2010 Elsevier Ltd. All rights reserved.
Performance and two-phase flow pattern for micro flat heat pipes
(2014-10-01)
Yang, Kai-Shing
;
Lin, Chen-Chuan
;
Shyu, Jin-Cherng
;
Tseng, Chih-Yung
;
Wang, Chi-Chuan
In this study, thermal performance and flow visualization of a double layer flat micro vapor chamber are reported. Two micro vapor chambers having pin fin and pin fin array support structure are fabricated and tested. The micro vapor chambers are composed of silicon and glass wafers having an overall size of 35 x 40 x 1.525 mm. Test results show that both the pin fin and pin fin array vapor chambers show an appreciably lower thermal resistance as compared to the solid silicon counterpart, the thermal resistance of the pin fin vapor chamber is about 52-60% of the solid silicon whereas the corresponding thermal resistance of pin fin array is only 17-20% of the solid silicon. The thermal resistance of the pin fin vapor chamber is moderately increased subject to the increase of supplied power whereas opposite trend is encountered for the pin fin array. The phenomenon is associated with the influence of dry-out phenomenon. It is found that the pin fin array vapor chamber is still in function even for an upside-down arrangement. The thermal resistance, however, is reduced with the rise of tilt angle, and the vertical arrangement gives the lowest thermal resistance. However, the thermal resistance is considerably increased if the heat source is placed upwards, and the corresponding thermal resistance for an upside-down heat source can be threefold higher than that of the vertical arrangement. (C) 2014 Elsevier Ltd. All rights reserved.
Investigation of the performance of pulsating heat pipe subject to uniform/alternating tube diameters
(2014-04-01)
Tseng, Chih-Yung
;
Yang, Kai-Shing
;
Chien, Kuo-Hsiang
;
Jeng, Ming-Shan
;
Wang, Chi-Chuan
The present study examines the performance of closed-loop pulsating heat pipes (CLPHPs) with an ID of 2.4 mm. The effect of uniform and alternating tube diameter on the performance is investigated. The working fluids include distilled water, methanol and HFE-7100. Tests are performed with both horizontal and vertical arrangement. For the horizontal arrangement, when compared to uniform design, the alternating channel design can be started at a rather low heat input with a much smaller thermal resistance. Normally the thermal resistance is decreased with the rise of heat input, and reveals a minimum value at a certain heat input followed by shows a marginal rise when the heat input is increased further. Both uniform and alternating design reveals the similar trend. For the vertical arrangement, the thermal resistance is much lower than that in horizontal arrangement. Different from that in horizontal arrangement, the thermal resistance shows a continuous decline against heat input for all the working fluids. For a low input power, CLPHP with HFE-7100 shows the least thermal resistance. By contrast, CLPHP with distilled water shows the smallest thermal resistance when the input power is increased over 60 W. (C) 2014 Elsevier Inc. All rights reserved.

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