Browsing by Author "Huang, Jeng-Min"

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A numerical investigation of the geometric effects on the performance of plate finned-tube heat exchanger
(2011-03-01)
Lu, Chi-Wen
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Huang, Jeng-Min
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Nien, W. C.
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Wang, Chi-Chuan
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機械工程學系
This study numerically examines the geometric parameters on the performance of a two-row fin-and-tube heat exchanger. Effects of fin pitch, tube pitch, fin thickness, and tube diameter are termed with. The simulation indicates that the performance, in terms of Q/Delta P and COP, increases with longitudinal tube pitch or with transverse tube pitch, and it decreases with larger tube diameter or fin thickness. An optimum value for Q/Delta P occurs at a 6-8 fpi at a fixed flow rate condition. There is not much difference in choosing the index of Q/Delta P or COP under fixed flow rate condition. However, when the simulation are performed with the actual axial fan whose P-Q curve being implemented. It is found that Q/Delta P peaks at 12 fpi while COP peaks at 16 fpi. (C) 2010 Elsevier Ltd. All rights reserved.
Development of a High Efficiency In-Line Tube Fan Using CFD
(2015-04-01)
Yen, Hung-Cheng
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Hsu, Wen-Syang
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Huang, Jeng-Min
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Lu, Chi-Wen
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Hsu, Chin-Nan
An in-line tube fan with design flow rate 1 m(3)/s, static pressure 1030 Pa, rotation speed 3450 rpm, and specific speed 2.1 was investigated. Inverse design method was used to design deswirl vane while CFD to analyze its flow field. Results showed that although the efficiency of the axial straight flat plate is poor, it remained better than that of the vaneless type. The efficiency of deswirl vane was much higher than the previous two. However, when the casing-impeller ratio was lower than 1.25, completely recovering tangential velocity would result in large recirculation flow near outlet of deswirl vane. When the casing-impeller ratio increased to 1.33, the recirculation flow and pressure loss were obviously reduced. When the casing-impeller ratio increased to 1.46, the deswirl vane almost completely recovered tangential velocity, and pressure loss was further reduced. Static pressure and efficiency at operating point were 10% and 6% higher than the casing-impeller ratio 1.33.
The Flow Analysis and Performance Improvement of the Flow Return System in High Pressure Fans
(2012-12-01)
Yen, Hung-Cheng
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Cheng, Yung Jen
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Huang, Jeng-Min
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Lu, Chi-Wen
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Tsai, Yeah-Hann
This study numerically investigated the flow return system performances of two-stage high pressure fans. The parameters include inflow angle, length, exit width of vaneless diffuser and the blade number of deswirl vane. This study used the tested impeller to verify the accuracy of numerical calculations, with good consistency. The analytic results showed that the overall pressure loss of impeller and flow return system is effectively reduced when the inflow angle of vaneless diffuser is 15 degrees and tangential to wheel velocity ratio is 0.46. A vaneless diffuser was required and its length referred to the maximum outer diameter of the volute casing. The performance of a contracted-wall vaneless diffuser was not improved over that of a parallel-wall one. The suggested number of blades in a deswirl vane was 12. The downstream affects the upstream in several areas inside the flow return system, thus, the flow return system must be calculated integrally.