다공성 단열재를 포함한 열방어구조의 열 특성 분석

황경민,김용하,이정진,박정선 항공우주시스템공학회 2016 항공우주시스템공학회지 Vol.10 No.4

In a number of industries, porous insulations have been frequently used, reducing thermal insulation space through excellent performance of the thermal insulation’s characteristics. This paper suggests an effective thermal conductivity prediction model. Firstly, we perform a literature review of traditional effective thermal conductivity prediction models and compare each model with experimental heat transfer results. Furthermore, this research defines the effectiveness of thermal conductivity prediction models using experimental heat transfer results and the Zehner-Schlunder model. The newly defined effective thermal conductivity prediction model has been verified to better predict performance than other models. Finally, this research performs a transient heat transfer analysis of a thermal protection system with a porous insulation in a high speed vehicle using the finite element method and confirms the validity of the effective thermal conductivity prediction model. 본 논문에서는 다공성 단열재의 정확도가 높은 유효 열전도율 예측 모델을 새롭게 제안하고, 기존 예측 모델 및 시험 결과와 비교 검증하였다. 이를 위해 기존 유효 예측 모델들을 다공성 단열재의 고체 부피율에 따른 열전도율 시험 결과 값과 비교하였다. 그리고 고체의 부피율에 따른 유효 열전도율 시험 결과와 비교하여 가장 높은 정확도를 가진 Zehner-Schlunder 모델 및 시험 결과 데이터를 기반으로 고체-유체의 부피율과 열전도율 비로 구성된 다항식을 추가하여, 새로운 유효 열전도율 예측 모델을 정의하였다. 예측 모델을 시험 결과와 비교하여 검증하였다. 또한, 예측 모델을 적용하여 열방어구조의 과도 열전달 해석을 수행하였으며, 열전달 시험 결과와의 비교를 통해 유효 열전도율 예측 모델의 유효성을 확인하였다.

내장형 모터와 리니어 모터를 적용한 초고속 수평형 머시닝센터의 열 특성 해석

김석일,조재완 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-

This paper presents the thermal characteristic analysis of a high-speed horizontal machining center with spindle speed of 50,000rpm and feedrate of 120m/min. The spindle system is designed based on the built-in motor, angular contact ceramic ball bearings, oil-air lubrication and oil-jacket cooling method. The X-axis and Y-axis feeding systems are composed of the linear motors and linear motion guides, and the Z-axis feeding system is composed of the servo-motor, ball screw and linear motion guides. The thermal characteristics such as the temperature distribution, temperature rise, thermal deformation and step response, are estimated based on the finite element model of machining center and the heat generation rates of heat sources related to the machine operation conditions. Especially, the thermal time constant assessed from the step response function is introduced as an index of thermal response characteristics.

내장형 모터와 리니어 모터를 적용한 초고속 수평형 머시닝센터의 열 특성 해석

김석일,조재완 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.5

This paper presents the thermal characteristic analysis of a high-speed horizontal machining center with spindle speed of 50,000rpm and feedrate of 120m/min. The spindle system is designed based on the built-in motor, angular contact ceramic ball bearings, oil-air lubrication and oil jacket cooling method. The X-axis and Y-axis feeding systems are composed of the linear motors and linear motion guides, and the Z-axis feeding system is composed of the servo-motor, ball screw and linear motion guides. The thermal characteristics such as the temperature distribution, temperature rise, thermal deformation and step response, are estimated based on the finite element model of machining center and the heat generation rates of heat sources related to the machine operation conditions. Especially, the thermal time constant assessed from the step response function is introduced as an index of thermal response characteristics.

선형 열선전달기를 이용한 발포폴리스티렌 폼 판재 절단시 절단경사각이 제품특성에 미치는 영향에 관한 연구

안동규,양동열 朝鮮大學校 機械技術硏究所 2003 機械技術硏究 Vol.6 No.1

선형 열선, 절단기에 의한 발포 폴리스티렌 폼 절단시 절단 제품의 특성을 발포 폴리스티렌 폼 내부의 열분포에 의존적이다. 이 열분포는 열선 절단기의 절단 공정 변수인 열입력, 절단 속력 및 절단 경사각의 크기 등에 의하여 결정된다. 본 논문에서는 선형 열선 절단기에 의한 발포 폴리스티렌 폼 절단시 절단 경사각이 절단 폭과 제품 특성에 미치는 영향에 대하여 실험과 수치해석을 통하여 고찰하였다. 선형 열선 절단시 발포 폴리스티렌 폼에 발생하는 온도 분포를 예측하기 위하여 이동좌표계와 선형 체적 열원 가정을 이용한 3차원 비선형 열전달 해석을 수행하였다. 실험 및 수치해석 결과 x축 절단 경사각의 경우 선형 열선 절단기의 운영 범위내에서는 발포 폴리스티렌 폼의 절단 폭과 모서리 용융 면적에 각각 0.1㎜ 와 0.11㎟ 미만으로 영향을 미침을 알 수 있었다. During the linear hotwire cutting of expendable polystyrene foam sheet, characteristics of the cut part are highly dependent upon the thermal field in the expendable polystyrene foam sheet. The thermal field is determined by operating parameters such as heat input, cutting speed and cutting angle. The objective of this study is to investigate into effect of cutting angle on the kerfwidth, characteristics of the cut part in linear hotwire cutting of expendable polystyrene foam sheet using the experiments and the numerical analysis for the case of a single-sloped cutting. In order to predict an accurate temperature distribution, the transient thermal analysis using a moving coordinate system and the volumetric sloped heat flux model is carried out. From the results of the experiments and the analysis, it has been shown that the influence of the cutting angle about the x-axis on kerfwidth and the melted area in the edge are 0.1 mm and 0.11 mm².

공동주택의 세대위치별 열부하 특성 분석

윤성환(Yoon Seong-Hwan),장희경(Jang Hee-Kyung),김영탁(Kim Young-Tag) 대한건축학회 2009 대한건축학회논문집 Vol.25 No.10

This study is focused on analysis of the characteristics of thermal load using dynamic heat load simulation according to building exterior thermal performance and direction classified by each household in apartment house. The conclusion of the study is as follows. 1) The characteristics of thermal load classified by each household in a view of the story showed that the mean heating and cooling load at the top floor was the highest(371MJ/㎡yr), the second highest at the ground floor(339MJ/㎡yr) and the lowest at the center floor(281MJ/㎡yr). The heating load of each household in the same story was increased by 10%(side wall of center floor)∼52%(side wall of ground floor) than the center household of center floor which has the lowest in heating load. In the case of cooling load small change occurred except the ground floor. 2) As a result of investigating the characteristics of thermal load according to the change of direction, apartment block which has 25th floor and one hundred of household showed that the south(232MJ/㎡yr) was the most advantageous direction for heating load and the northeast(290MJ/㎡yr) was the most disadvantageous. In the case of cooling load, the south and north(51MJ/㎡yr) was the most advantageous direction and the east(63MJ/㎡yr) was the most disadvantageous. 3) As improving building exterior thermal performance by 10% against the legal standards of building, the mean heating load of one hundred household showed a increased by 22∼23MJ/㎡yr as the mean thermal disadvantage factor was increased by 0.1W/㎡K. Mean heating load and the mean thermal disadvantage factor showed liner correlations. As improving building exterior thermal performance, the mean cooling load of one hundred household showed a constant pattern.

인도네시아산 자원 내에 포함된 역청성 오일의 경질화를 위한 열분해 특성에 관한 연구

장정희(Jung Hee Jang),한기보(Gi Bo Han),박천규(Cheon-kyu Park),전철환(Cheol-Hwan Jeon),김재곤(Jae-Kon Kim),곽현(Hyun Kwak) 한국청정기술학회 2016 청정기술 Vol.22 No.4

본 연구에서는 인도네시아 현지로부터 수급된 지층 자원에 포함된 역청성 오일의 경질화를 위하여 열분해 공정이 적용되었다. 이러한 자원 내에 포함된 역청성 오일에 대한 조성 및 기초성상을 조사하기 위하여 공업분석, 원소분석 등이 수행되었으며, 열중량분석을 통해 역청성 오일의 전환에 대한 열분해반응 기초특성이 조사되었다. 이러한 결과를 바탕으로 원료 내에 포함된 역청성 오일을 경질화하기 위하여 필요한 열분해 온도 등의 운전조건 범위가 선정되었으며, 실험실 규모의 고정층 반응기를 이용하여 반응온도에 따른 역청성 오일의 전환율 및 열분해 오일의 회수율을 확인하였다. 550 ℃에서 수행된 열분해 공정에서 원료 내 포함된 역청성 오일의 전환율은 약 21%였으며, 경질화된 열분해 오일의 회수율은 약 80%였다. In this study, the pyrolysis process was carried out in order to upgrade of heavy oil contained in the resources from Indonesia. In order to investigate the composition and basic properties of the heavy oil contained in the resources, the various analytical methods was used and then the TGA (thermogravimetric) method was especially used for the thermal degradation characteristics of heavy oil in the pyrolysis. From the results obtained from the various analytical methods, the reaction conditions such as the reaction temperature was collected for the pyrolysis process and the pyrolysis using the resources containing the heavy oil was conducted using the fixed-bed reactor under the various reaction conditions. Consequently, We found that the content of heavy oil contained in the resources was about 35% and the conversion of heavy oil and the recovery efficiency of thermal degradation oil were about 21 and 80%, respectively.

유한요소법을 이용한 다기능 고능률 광폭 센터리스 연삭기의 열적 특성 해석

황인범(I. B. Hwang),김석일(S. I. Kim),박한식(H. S. Park) 한국정밀공학회 2013 한국정밀공학회 학술발표대회 논문집 Vol.2013 No.5월

태양열과 가스 연소열을 복합 적용한 흡수기의 열특성 연구

강명철(Kang, Myeong-Cheol),김진수(Kim, Jin-Soo),강용혁(Kang, Yong-Heack),윤환기(Yoon, Hwan-Ki),유창균(Yu, Chang-Kyun),이상남(Lee, Sang-Nam) 한국신재생에너지학회 2006 한국신재생에너지학회 학술대회논문집 Vol.2006 No.11

The Dish/Stirling system with the Stirling engine is currently used to convert solar energy directly to electrical energy successful operation of dish/Stirling system is supported by hybrid system, which will allow continuous operation driven by solar and combustion heat ins. The hybrid Receiver has to be provided with an additional combustion system. The heat pipe receiver and conbustion system were manufactured and tested for thermal characteristics of receiver. Maximum temperature difference along the heat pipe surface is 200?C. Emission measurements showed low NOx values of 28 to 46 ppm and very high CO values of 18 to 201 ppm.

유동분배판에 의한 원통-다관형 열교환기의 성능 특성에 관한 수치해석적 연구(Ⅱ)

박영민(Y.M. Park),정희택(H.T. Chung),김형범(H.B. Kim) 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.11

The flow pattern inside the inlet chamber of the tube side is one of the key parameters influencing on the performances of the shell-and-tube type of heat exchangers(STHE). In order to improve the flow distribution, the baffle shaped as the porous plate is installed in the inlet chambers. In the present study, numerical simulation has been performed to investigate the flow features of the tube side of the STHE in sense of the thermal performances. The flow fields have been analysed by the three-dimensional Navier-Stokes solvers with the proper turbulent models. Computational domain is ranged in the whole of the STHE. The numerical results showed that the presence of the baffles improves the redistribution of the heat transfer to the tube bundles though the overall performance drop slightly on the present flow conditions

CA안경테 가공장비 주축의 열특성 해석

최현진(Hyun-Jin Choi),최성대(Seong-Dae Choi) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.5

For the domestic glasses industry to procure competitiveness in the world CA(Cellulose Acetate) frame of spectacles market, CNC machining system for CA frame including high-value added CA cutting technologies should be developed with new materials for the rim based on Cellulose and sheet manufacturing base. The spindle system of glasses frame equipment that is the core to the quality of CA frame is the key technologies to realize high-speed, high-precision so its importance is remarkably emerging. In the study, at the structural design of the high spindle system of the private equipment for CA glasses frame embedded a motor of 40,000rpm, the stability of design was analyzed and investigated through selecting lubrication structure and thermal characteristics of the spindle system.