자동차 응축기용 다채널관의 압력강하 특성에 관한 연구

전창덕,정재원,이진호,강신형,Jeon, Chang Duk,Chung, Jae Won,Lee, Jinho,Kang, Shin Hyung 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.7

Experiment was performed to study the characteristics of pressure drop of multi-channel tubes for automotive condenser using HFC-134a. Single phase liquid and two phase flow pressure drop were measured in one rectangular plain and three micro-fin tubes with 10 channels. Data are presented for the following range of variables: mass flux(200 to $600kg/m^2s$), and inlet saturation pressure of the refrigerant(1.0 and 1.6MPa). For subcooled flow, pressure drops are 10% and 12% higher than that predicted by the Petukhov equation with hydraulic diameter respectively. Two-phase flow pressure drop are compared with the previously proposed correlations, and well predicted by modified correlation that was derived from Traviss correlation. and correlated within -30~+20%. Also experimental data are correlated within -56%~+18% by Webb's prediction method based on the equivalent mass velocity concept originally proposed by Akers et al.

다채널 편평관의 응축 열전달 및 압력강하특성에 관한 실험

전창덕,정재원,이진호,Jeon, C.D.,Chung, J.W.,Lee, J.H. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.3

In this study, an experiment was performed to investigate the characteristics of pressure drop and heat transfer of multi-channel tubes for automotive condenser using HFC-134a as an alternative refrigerant. The mass flux and inlet saturation pressure of the refrigerant were controlled, respectively, in the range of 200 to $500kg/m^2s$ and 1.0 to 1.6MPa. Pressure drop and heat transfer coefficient were compared with the previously proposed correlations and new correlations based on Traviss' correlation were suggested. Prediction of pressure drop and heat transfer coefficient based on the new correlations agrees with experimental results within ${\pm}9%$ and -18~+11%, respectively.

실외기 기능 교번을 통한 착상 방지 및 지연에 대한 실증 연구

전창덕,Jeon, Chang Duk 한국교통대학교 융복합기술연구소 2011 융ㆍ복합기술연구소 논문집 Vol.1 No.1

The object of this experimental study is to investigate the effect on frost prevention and delay by the method of alternating the function of outdoor coil rows under the frost conditions ($2^{\circ}C/1^{\circ}C$). The heat pump system with the new method can make frost delay time longer and eliminate frost effectively. It is withstand over 280 minutes without a conventional defrosting method. Maximum COP in case of adopting new method is 13% higher than that in case of reverse cycle defrosting method. Also in case of moving air injection duct faster, the frost delay time is lengthened and its COP is enhanced more.

MEH-PPV의 농도에 따른 황색 고분자 유기발광다이오드의 제작과 특성평가

전창덕(Jeon, Chang-Duk),신상배(Shin, Sang-Baie),공수철(Gong Su-cheol),박형호(Park, Hyung-Ho),전형탁(Jeon, Hyeong-Tag),장호정(Chang Ho Jung) 한국산학기술학회 2008 한국산학기술학회 학술대회 Vol.- No.-

본 연구에서는 ITO/PEDOT:PSS//PFO:MEH-PPV/LiF/Al 구조를 갖는 고분자 유기발광다이오드를 제작하여 발광 도펀트인 MEH-PPV의 농도에 따른 황색 PLED 소자의 전기·광학적 특성에 대하여 조사하였다. MEH-PPV의 농도를 각각 6, 7, 8, 9, 10 wt% 로 변화시켜 소자를 평가한 결과 9 wt%의 농도에서 가장 우수한 전기 및 광학적 특성을 보였으며, 16 V의 인가전압에서 약 630 cd/m2의 휘도 특성과 256 mA/cm2의 전류밀도 특성이 관찰되었다. 또한 10 wt%의 소자에서는 오히려 낮은 광학적 특성이 관찰되어 9 wt%에서 도펀트의 농도가 포화됨이 관찰되었고, 제작된 소자의 색좌표 (CIE coordiante)는 모든 소자에서 (x ,y = 0,49, 0.49)로 거의 동일하게 나타났다.

광센서를 이용한 제상제어 방법에 대한 연구

전창덕(ChangDuk Jeon) 대한설비공학회 2017 설비공학 논문집 Vol.29 No.4

This study attempted to investigate the value of photoelectric sensors in terms of a defrost-control method. Tests were conducted in a calorimeter room under the heating with the defrost-performance test conditions described in KS C 9306. Accordingly, the photoelectric technology is a competitive defrost-control method that can precisely control the operational defrost cycle using the output voltages that are proportional to the frost height. The heating period is gradually reduced because the complex defrost-control method, for which the sensors initiate the defrosting process and the defrosting process is terminated by the time parameter, could not adjust the net defrosting time by itself. Therefore, a complex defrost-control method, for which the photoelectric sensors start the defrosting process and it is terminated by the temperature parameter, is preferred because of the adjustment of the net defrosting time. Regardless of the defrost-control method, the first defrosting cycle is activated earlier than the times that are determined in the second and third cycles and so on, because the first operation cycle can decide the characteristics of the subsequent cycle.

착상조건에서 연속난방이 가능한 히트펌프 성능 향상 기술

전창덕(Jeon, Chang-Duk) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.2

히트펌프는 에너지 효율이 높고, 지열, 폐열, 공기열 등 다양한 열원 사용이 가능하기 때문에 보급이 빠르게 확대되고 있다. 공기를 열원으로 이용하는 공랭식 히트펌프의 경우는 실외기 표면에 형성되는 서리를 제거하기 위해 제상운전이 요구된다. 일반적으로 사용하는 역사이클(reverse cycle) 제상운전 방법은 연속난방이 불가능하며 이로 인 해 성능계수가 감소하는 원인이 된다. 본 연구에서는 실외기 코일용 휜-관 열교환기를 3열로 구성하고 난방과 제상이 동시에 가능하도록 일정시간 간격으로 열교환기의 한 개의 열을 응축기로, 나머지 열은 증발기로 교번 운전을 수행하 여 KS C 9306에 규정된 제상-난방 시험조건(건구온도 2℃, 습구온도 1℃)에서 최소 180분 이상 연속난방이 가능함을 실증하였으며 역사이클 제상방법을 사용하는 일반적인 히트펌프 대비 COP가 약 20% 향상됨을 알 수 있었다. Heat pumps come into wide use because high energy efficiency can be obtained and diverse heat sources like geothermal heat, waste heat and air are available. It is necessary for an air source heat pump to defrost in order to remove frost on the surfaces of an outdoor heat exchanger. It is impossible for continuous heating if reverse cycle operation is used as defrosting method, furthermore it causes the degradation of COP. In this study an fin-tube heat exchanger with three rows was used as an outdoor coil. One row among three rows of the heat exchanger was used like a condenser in order to remove frost on it, the others were used as evaporator to accomplish continuous heating. Each row was switched in order from a condenser to an evaporator in specified time interval. Tests were carried out during minimum 180 minutes at the defrost-heating test condition(dry bulb temperature 2℃, wet bulb temperature 1℃) described in KS C 9306. Time-averaged COP was about 20% higher than that of conventional defrosting method.

온도차 감지 제상법과의 비교를 통한 광센서 제상법의 타당성 검증을 위한 연구

전창덕(Chang-Duk Jeon),김동선(Dong-Seon Kim) 대한설비공학회 2014 설비공학 논문집 Vol.26 No.9

Experiments were performed to verify if performance and characteristic curves obtained from the temperature differential defrosting method, where surface temperature is measured to judge defrosting condition, can be reproduced by the photoelectric technology where defrosting condition is judged by photoelectric sensors. The output voltage of a phototransistor and heating capacity, power consumption, and surface temperature of the outdoor heat exchanger are compared. The results showed that the photoelectric sensors can be used as a defrost control device. On-off control timings in temperature differential defrosting method are in good agreement with those predicted by the high and low threshold output voltages of the photoelectric sensor.

광센서를 이용한 제상제어 방법에 대한 타당성 검토

전창덕(Jeon, Chang-Duk),김동선(Kim, Dong-Sun),이승준(Yi, Seung-Jun) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.6

제상제어 수단으로 사용하고 있는 일정 시간 제어방식, 온도차 제어방식 등은 종종 제상 오작동과 에너지 낭비를 가져오므로 좀 더 정확하게 제상을 제어할 수 있는 방법이 요구되고 있다. 수광부와 발광부로 구성된 광센서를 실외 열교환 기 전방에 설치하여 서리의 유무에 따른 출력전압의 변화를 관찰함으로서 정확하게 제상제어를 할 수 있다. 본 연구에서는 기존의 일정시간 제상 방법을 사용하는 경우 나타나는 시스템 성능 및 특성 곡선을 광센서를 사용하여 재현가능한지 판단하 기 위해 KS C 9306에 따른 난방 제상능력 시험조건(건구온도 2℃/습구온도 1℃)에서 실험을 수행하였다. 실험을 통해 측정한 난방능력, 소비전력, 열교환기 표면온도와 광센서 수광부 출력전압을 비교, 분석한 결과 제상 제어수단으로 광센서의 사용 가능성을 확인하였다. 일정시간 제상방법을 통해 구한 제상 제어 단속 주기는 광센서를 통해 측정한 출력 전압의 단속 주기 와 잘 일치하였다. Conventional methods, such as the clock time control method and temperature difference control method, for defrost control often encounter mal-defrost and a waste of energy. Therefore, a more efficient method is needed to control defrosting precisely. A photoelectric sensor unit consisting of an emitter and a collector was installed in the front of outdoor heat exchanger. Accurate defrost control was performed by monitoring and using the change in output voltage according to the presence of frost. In this study, experiments were performed to determine if the performance and characteristic curves obtained using the clock time control method can be reproduced using a photoelectric sensor under the heating and defrosting capacity test condition described at KS C 9306. The output voltage of the phototransistor (receiver) and heating capacity, power consumption, and surface temperature of the outdoor heat exchanger, were compared. The results showed that photoelectric sensors can be used as a defrost control method. On-off control timing of the clock time defrosting method was in good agreement with those predicted by the output voltage of the photoelectric sensor.

광센서를 이용한 서리높이 예측 상관식 개발

전창덕(Jeon, Chang-Duk) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.10

본 연구에서는 KS C 9306에 따른 난방 제상능력 시험조건(건구온도 2℃/습구온도 1℃)에서 확대모형이 아닌 실제 열교환기의 전방에 디지탈 현미경과 광센서의 발광부와 수광부를 나란히 설치하여 광센서 출력전압과 서리 높이간의 연관성 을 규명하기 위한 실험을 수행하였다. 150개의 실험 데이터로부터 서리높이를 예측할 수 있는 선형 상관식을 개발하여 계산 한 결과, 측정값의 54%가 상관식으로 예측한 값의 ±10% 이내에서 일치하였으며 서리 높이가 0.3mm 이상의 실험데이터에서 는 데이터의 90% 이상이 ±10% 이내에서 일치하였다. Xiao 등의 상관식과 비교하였을 때 출력전압 변화에 따른 서리 높이의 변화를 나타내는 기울기는 2.3% 오차 범위에서 일치하였으나 Xiao 등의 상관식은 실제 열교환기가 아닌 모사 열교환기를 사용한 이상적인 조건에서 개발되었기 때문에 절편 값에서는 큰 차이를 보였다. In this study, experiments were conducted to investigate the correspondence between the output voltage of the photoelectric sensor and the frost height under heating and defrosting capacity test condition (dry bulb temperature 2℃, wet bulb temperature 1℃) described at KS C 9306, where a real heat exchanger was used as a test rig instead of a large-scale model. A digital microscope and a photoelectric sensor unit consisting of an emitter and a transistor (receiver) were installed in the front of it. A linear correlation is proposed to predict the frost height based on 150 experimental data, approximately 54% of the measured data are consistent with the predicted frost heights within a relative deviation of ±10%, it yields good agreement with 90% of the measured data when the frost height larger than 0.3mm with in a relative deviation of ±10%. Compared with Xiao's correlation, the slope namely, the change of frost height in accordance with the change of output voltage is consistent within the error of 2.3%. But vertical intercept shows big difference with Xiao's correlation, because it was developed with a large scale model instead of a real heat exchanger.

루우버휜형 열교환기의 열전달 특성에 관한 실험적 연구

전창덕(C. D. Jeon),홍주태(J. T. Hong),이진호(J. Lee) 대한설비공학회 1995 대한설비공학회 학술발표대회논문집 Vol.1995 No.6