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열전달 향상 장치를 삽입한 평판형 태양열 집열기의 열전달 특성과 압력강하에 관한 수치해석
허주녕(Joonyoung Heo),김지훈(Jihoon Kim),신지영(Jeeyoung Shin),손영석(Young-Seok Son) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
Heat transfer and pressure drop characteristics of a flat-plate solar collector have long been investigated since they were widely used. The use of artificial roughness in different forms, shapes and sizes is the most common and effective way to improve the performance of a solar collector. In the present study, numerical analysis was performed on heat transfer and pressure drop in a rectangular channel with rib arrays. The uniform heat flux is applied to the channel from the upper side. The forms of ribs considered in this study were rectangular rib, rib with groove, and baffle. The ribs were deployed transverse or aligned 60° to the main direction of the flow. Air is the working fluid with the flow rate in terms of Reynolds numbers ranging from 3200 to 17800. Nusselt number and friction factor were investigated to predict the performance of the system with various type of roughness geometry. The average Nusselt number and pressure drop were increased with the increase of velocity. The highest heat transfer occurred for the rib with groove which was aligned 60° to the main flow direction.
한국인 성인남자의 개별 이도내 음향응답에 대한 경계요소 해석
이두호(Lee, Dooho),안태수(Ahn, Tae-Soo),손영석(Son, Young-Seok),신지영(Shin, Jeeyoung) 한국소음진동공학회 2013 한국소음진동공학회 논문집 Vol.23 No.3
Individual differences in head-related transfer functions(HRTFs) were calculated using boundary element(BE) models for three Korean adults. The BE models for the individuals were developed from the computerized tomography(CT) images of the individuals. The BE models were composed of the head, pinna, and ear canal. The frequency-dependent impedance boundary conditions were imposed on the skin, hair, and tympanic membrane. The HRTFs calculated from the individual BE models showed large difference above 2 kHz in magnitude and in the locations of peaks and valleys of the frequency spectrums, which should be considered in virtual auditory sound field. The identified individual differences in the HRTFs demonstrate that the developed BE models can be utilized successfully in order to obtain the HRTFs information of individuals.
립이 설치된 수평채널의 압력강하 및 열전달 특성에 관한 수치해석
김지훈(Jihoon Kim),허주녕(Joonyoung Heo),손영석(Young-Seok Son),신지영(Jeeyoung Shin) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
In this study, simulations of turbulent flow and heat transfer in a channel with a detached rib array have been conducted. Air is the working fluid with the flow rate in term of Reynolds numbers ranging from 8,900 to 35,000. The forms of ribs considered in this study were ribs with rectangular cross section, ribs with groove, broken ribs, and V-shaped ribs. The ribs were deployed transverse or aligned 60?to the main direction of the flow. Local heat transfer coefficients were obtained at various Reynolds numbers within the turbulent flow regime. Area-averaged data were calculated in order to compare the overall performance of the tested ribbed surfaces and to evaluate the degree of heat transfer enhancement induced by the ribs with respect to the smooth channel. The highest heat transfer occurred for the rib with groove was aligned 60?to the main flow direction.
고온 수전해 고체 산화물 시스템의 온도 분포에 대한 수치해석
이지원(Jiwon Lee),이상일(Sang-il Lee),계덕훈(Deok Hoon Kye),박현재(Hyun Jae Park),박경태(Kyungtae Park),신지영(Jeeyoung Shin),박우성(Woosung Park) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Solid oxide electrolysis is a potential candidate for hydrogen production, and a key challenge for its commercialization is to achieve both efficient and reliable fuel generation.While the temperature nonuniformity of solid oxide cell significantly affects associated electrochemical reactions, the relation between the electrochemical reaction and the temperature distribution is elusively understood. In this work, we model a 3D solid oxide electrolysis cell and investigate the local temperature distribution of the cell using numerical simulation. The multi-physics model includes electrochemistry, ion/charge transport, and heat transfer. As a validation purpose, we compare our model with existing experimental data and further quantify the temperature nonuniformity due to associated electrochemical reactions. We find that the average temperature across the channel is predominantly dicated by electrochemical reaction, and the minimal temperature rise is expected at thermalneutral voltage.