방열관의 배치와 관내 유속이 온수난방 온실의 온도분포에 미치는 영향

신현호,김영식,남상운 (사) 한국생물환경조절학회 2019 생물환경조절학회지 Vol.28 No.4

본 연구는 난방온실의 온도분포 균일화를 위한 기초자료 제공을 목적으로 온수난방 방식의 토마토 재배 온실에서 난방실험을 통하여 난방배관의 표면온도와 실내기온 사이의 상관관계를 분석하고, 난방배관의 열전달특성분석과 난방배관 배치의 개선을 통하여 난방배관 표면온도의 편차를 줄이고 균일도를 향상시키기 위한 방안을도출하였다. 서로 다른 두 온실의 온도분포를 분석하여최대편차와 균일도를 검토한 결과, 온수의 유량이 많고난방배관의 길이가 짧게 배치된 온실의 온도편차가 작고, 균일도는 높은 것으로 나타났다. 또한 순환팬을 가동한경우에 온도편차는 작아지고 균일도가 개선되는 것을 확인할 수 있었다. 난방배관의 표면온도와 실내기온 사이의 상관관계를 분석한 결과, 두 온실 모두에서 유의적인(p<0.01) 정적 상관관계가 있는 것으로 나타났다. 온수난방 온실에서 실내기온의 분포는 난방배관 표면온도의 분포에 영향을 받는다는 것을 확인할 수 있었고, 온도편차가 최소화 되도록 난방배관을 배치함으로써 실내기온 분포의 균일도를 개선할 수 있는 것으로 판단되었다. 난방배관의 열전달 특성을 분석한 결과 배관의 길이가 길어지면 온도편차는 커지고, 관내의 유속이 빨라지면 온도편차는 작아지는 것으로 나타났다. 따라서 지선배관의길이가 짧아지도록 난방배관을 배치하고, 관내의 유속을제어함으로써 온실의 온도분포와 환경의 균일성을 개선할 수 있을 것으로 판단되었다. 국내 온실에서 가장 많이 사용하고 있는 튜브레일(40A) 방식의 온수난방시스템에서 하나의 지선배관에서의 온도편차를 3o C 이내로조절하기 위해서는 관내의 유속이 0.2, 0.4, 0.6, 0.8, 1.0m·s-1일 때 난방배관의 길이는 각각 40, 80, 120, 160, 200m 이내로 제한해야 하는 것으로 분석되었다 In order to provide basic data for uniformization of temperature distribution in heating greenhouses, heating experiments were performed in two greenhouses with a hot water heating system. By analyzing heat transfer characteristics and improving pipes layout, measures to reduce the variation of pipe surface temperature and to improve the uniformity were derived. As a result of analyzing the temperature distributions of two different greenhouses and examining the maximum deviation and uniformity, it was found that the temperature deviation of greenhouses with a large amount of hot water flow and a short heating pipe was small and the uniformity was high. And it was confirmed that the temperature deviation was reduced and the uniformity was improved when the circulating fan was operated. The correlation between the surface temperature of the heating pipe and the indoor air temperature was a positive correlation and statistically significant(p<0.01) in both greenhouses. It was confirmed that the indoor temperature distribution in a hot water heating greenhouse was influenced by the surface temperature distribution of heating pipe, and the uniformity of indoor temperature distribution could be improved by arranging the heating pipe to minimize the temperature deviation. Analysis of the heat transfer characteristics of heating pipe showed that the temperature deviation increased as the pipe length became longer and the temperature deviation became smaller as the flow rate in pipe increased. Therefore, it was considered that the temperature distribution and the uniformity of environment in a greenhouse could be improved by arranging the heating pipe to shorten the length and controlling the flow velocity in pipe. In order to control the temperature deviation of one branch pipe within 3oC in the tube rail type hot water heating system most used in domestic greenhouses, when the flow velocity in the pipe is 0.2, 0.4, 0.6, 0.8, 1.0m·s-1, the length of a heating pipe should be limited to 40, 80, 120, 160, 200m, respectively. Additional

목업 평가(Mock-up Test)를 통한 바닥 건식난방 패널의 표면온도 분포 분석 및 개선 방안

정창호(Chang-Ho Jeong),이규동(Gyu-Dong Lee),여명석(Myoung-Souk Yeo),김광우(Kwang-Woo Kim) 한국생활환경학회 2013 한국생활환경학회지 Vol.20 No.4

In this study, the surface temperature of a floor panel was measured during space heating, in a mock-up residential house in which a typical prefabricated floor heating panel was installed. Characteristics of the surface temperature distribution were analyzed, and improvement strategies for the surface temperature distribution were derived. Then, the improved effect on the surface temperature distribution for each derived alternative was compared and analyzed. The mock-up test result showed that the higher the supply water temperature, the more disadvantageous it was, in terms of the highest value, and the deviation of the surface floor temperature. Therefore, strategies to improve the surface floor distribution by increasing the vertical and horizontal heat transfer efficiency in the floor panel are needed. So, these strategies should permit the supply of relatively low temperature water. Four alternatives reflecting each improvement strategy were derived, and, through experiment, the U type panel was selected as the most effective alternative for vertical heat transfer efficiency and horizontally even heat distribution. Under the condition of the same supply water temperature(70℃, 60℃, and 50℃), compared with the typical prefabricated floor heating panel before improvement, the highest surface floor temperature was improved from 39.8℃, 28.9℃, 25.1℃, to 36.1℃, 33.6℃, 29.9℃, respectively, and the maximum deviation of surface temperature also was reduced from 8.5 K, 7.8 K, 7.0 K, to 4.6 K, 3.8 K, 2.6 K, respectively, in the U type prefabricated floor heating panel. These results showed that the vertical and horizontal heat transfer efficiency were improved in the U type prefabricated floor heating panel.

Comparative Study of Numerical Simulation and Experiment on Temperature Distribution and Central Vent Flow Velocity in Ceiling-vented Compartment Fire

Min Yeong Park,Yun Young Kim,Chi Young Lee 한국화재소방학회 2023 International Journal of Fire Science and Engineer Vol.37 No.3

In this study, we conducted numerical simulations to analyze fire phenomena in a compartment with a ceiling vent and compared these numerical simulation results with previous experimental data. Based on the previous experimental conditions, under the heat release rate of 1.5 kW, the vent areas of 1% and 10% of the floor area and the fire sources both at the center and side of the floor were tested. Overall trends of temperature distribution and central vent flow velocity in the present numerical simulations were consistent with those in the previous experiments. The temperature within the compartment was observed to be higher when the vent area was smaller. For compartment with a smaller vent area, the temperature distribution showed minor variations with the fire source location. However, with a larger vent area, temperatures were notably higher when the fire source was at the side than at the center. The present numerical simulations slightly overestimated the temperatures from the previous experimental results, resulting in a bias factor of 1.07 and a model's relative standard deviation of 0.07 for temperature. Regarding the flow velocity at the center of ceiling vent, the fluctuations over time were more pronounced when the fire source was centrally located. When the fire source was at the center, the average central vent outflow velocity was higher for compartment with a larger vent area. When the fire source was positioned to the side, the vent area appeared to have minimal impact on the average central vent outflow velocity. It was also observed that the average central vent outflow velocity was higher when the fire source was centrally placed when compared to a side location. The present numerical simulations underestimated the previous experimental results for the average central vent outflow velocity, and the bias factor and the model’s relative standard deviation for the average central vent outflow velocity were 0.63 and 0.39, respectively.

Alloy 617 의 장시간 크리프 수명 예측을 위한 다중회귀 선형 모델의 제안 및 평가

윤송남(Song-Nan Yin),김우곤(Woo-Gon Kim),정익희(Ik-Hee Jung),김용완(Yong-Wan Kim) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.4

Creep life prediction has been commonly used by a time-temperature parameter (TTP) which is correlated to an applied stress and temperature, such as Larson-Miller (LM), Orr-Sherby-Dorn (OSD), Manson-Haferd (MH) and Manson-Succop (MS) parameters. A stress-temperature linear model (STLM) based on Arrhenius, Dorn and Monkman-Grant equations was newly proposed through a mathematical procedure. For this model, the logarithm time to rupture was linearly dependent on both an applied stress and temperature. The model parameters were properly determined by using a technique of maximum likelihood estimation of a statistical method, and this model was applied to the creep data of Alloy 617. From the results, it is found that the STLM results showed better agreement than the Eno’s model and the LM parameter ones. Especially, the STLM revealed a good estimation in predicting the long-term creep life of Alloy 617.

스마트냉동컨테이너의 적재부 온도 편차 최적화에 관한 연구

박상원,김태훈,박도명,한동섭 한국산업정보학회 2023 한국산업정보학회논문지 Vol.28 No.6

냉동컨테이너는 외부 환경에 의해 냉동기가 있는 적재부의 전면과 컨테이너 문이 있는 적재부의 후면부 사이에 온도 편차가 발생한다. 특히, 신선화물 운송에서 이러한 온도 편차는 화물의 신선도에 큰 영향을 미치게 된다. 본 연구에서는 온도 편차를 줄이기 위해 T-Floor를 부분적으로 차폐하고, T-Floor 차폐율이 냉동컨테이너 적재부 온도 변화에 미치는 영향을 평가하여 온도 편차를 최소화하는 방법을 제안한다. 실험 대상은 40 feet 스마트 냉동컨테이너로 T-Floor 차폐율은 0%, 50%, 60%, 70%, 80%로 설계 변수를 설정하였다. 실험 결과, 차폐율에 따라 냉동컨테이너 적재부의 온도 편차가 다르게 발생하였으며, 차폐율 60%인 경우 온도 편차가 가장 균일한 것을 확인했다. 이러한 적재부 온도 편차 최소화를 통해 스마트 냉동컨테이너를 이용하여 신선 화물의 운송 시 화물의 부패 및 냉해를 예방할 수 있다. In a reefer container, temperature deviation occurs between the front of the loading part with the refrigerator and the rear of the loading part with the container door due to the external environment. In particular, this temperature deviation in the transport of fresh cargo has a great influence on the freshness of the cargo. In this study, we propose a method to minimize the temperature deviation by partially shielding the T-Floor to reduce the temperature deviation and evaluating the effect of the T-Floor shielding rate on the temperature change of the reefer container loading part. The subject of the experiment was a 40 feet smart reefer container, and the T-Floor shielding rates were set to 0%, 50%, 60%, 70%, and 80%. As a result of the experiment, it occurred differently in the temperature deviation of the reefer container loading part according to the shielding rate, and it was confirmed that the temperature deviation was the most uniform when the shielding rate was 60%. By minimizing the temperature deviation of the loading part, it is possible to prevent corruption and cold damage of cargo during transportation of fresh cargo by using the smart reefer container.

온도편차가 한우고기의 장기간 숙성 중 보수력, 연도, 지방산화 및 육색안전성에 미치는 영향

강선문,안달래,성필남,김진형,조수현,박범영,김윤석 한국식생활문화학회 2019 韓國食生活文化學會誌 Vol.34 No.6

This study investigated the effect of temperature deviation on the water-holding capacity, tenderness, lipid oxidation, andcolor stability of Korean Hanwoo (韓牛) beef during long-term aging. The striploins (M. longissimus lumborum) were agedfor 56 days at 2±1oC (T1), 2±2oC (T2), or 2±3oC (T3). Drip loss and cooking loss were higher (p<0.05) in T3 than in T1on day 56. The Warner-Bratzler shear force value was similar for all treatments during aging times. On day 56, the contentof 2-thiobarbituric acid reactive substances was higher (p<0.05) in T3 as compared to T1. The CIE L* and b* values weresimilar for all treatments, but the a* value was lower (p<0.05) in T3 than in T1 on the last day. These findings indicate thathigh temperature deviation adversely affects the water-holding capacity, lipid oxidation stability, and color stability ofHanwoo beef during long-term aging.

농가용 저온저장고의 제어변수에 따른 성능평가

김석우,김성만,현명택,최동호,고정삼,박영하 제주대학교 공과대학 첨단기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.2

The low temperature storage method has been used to increase the value of agricultural products by reducing quality deterioration and controlling respiration rate. The respiration rate of agricultural products depends on several factors such as temperature, moisture, gas composition and microbe inside the storage room. Among that temperature is the most important factor, which affects respiration rate and causes severe damage. The results obtained from these experiments are that electric consumption is decreased as setting temperature is decreasing and temperature deviation is increasing. In the ventilation experiment, the case ventilated four times a day(every six hours a day) with ten minutes operation each time, was inspected require as much electric consumption as non-ventilation case.

전력기기용 히트파이프 냉각장치에서 온도 편차의 통계적 평가

한창우(Chang-Woo Han),성상철(Sang-Chul Sung),정승붕(Seung-Boong Jeong) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11

The difference of the cooling performance between the heat sinks may vary depending on the operator or the time of production, even if a number of heat sinks are manufactured under the same process. And even in the same control algorithm and physical configuration, there is the difference of the electric loss between the power devices due to the current unbalance in the phase or between phases. In this paper, the deviation of the cooling performance of the heat sinks was statistically analyzed by measuring the temperature on the heat sink with heating blocks. The temperature of the heat sink with IGBT modules was then measured under various losses to assess the deviation of the cooling performance between heat sinks due to mechanical parameters such as the airflow rate and the electric parameters such as the current unbalance. As a result, the deviation of the cooling performance among a number of heat sinks was about ±5%, and the deviation of the cooling performance for the sub-system was found to be ±12%. The upper and lower specification limits on the IGBT stack compared to the heat sink component was increased due to uncontrollable factors such as the state of the power system. The heat sink with heat pipes applied the power conditioning system connected in a power system is expected to reduce the operating range by nearly 14% than ideal manufacturing and experimental conditions.

배선용차단기 단선 접속 방법에 따른 온도 상승률 및 편차율 분석

김성삼(Sung-Sam Kim) 산업기술교육훈련학회 2020 산업기술연구논문지 (JITR) Vol.25 No.4

In this study, the temperature increase and deviations were analyzed for double and single connections in solid wires. The influence of the temperature rise was flat based on the bolt-type and shutter-type clamping methods as well as single and double connection methods used, when the constant load current condition was applied. The temperature deviations of the single and double connections were measured as 4.3°C for the bolt-type and 1.1°C for the shutter-type methods over the approximately 40 min test. The front and side temperatures of the breaker were 69.4°C and 73.2°C for the bolt-type and 14.5°C and 10.2°C for the shutter-type clamping methods, respectively.

브라운관용 금형냉각의 온도편차 개선을 위한 연구

곽경민(Kyung-Min Kwak),최성종(Sung-Jong Choi),조현덕(Hyun-Deog Cho) 한국기계가공학회 2008 한국기계가공학회 춘추계학술대회 논문집 Vol.2008 No.-

This study is to propose a new model of upper mold(wind header) which can be reduced temperature deviation and increased cooling velocity in mold surface cooling The proposed mold with flow resistance partially have even pressure deviation compared to the common mold. The pressure deviation of cooling surface shows max. 40% in common mold and less than 10% in proposed mold. The heat transfer experiment verified reduction of temperature deviation in proposed mold, and the cooling velocity of proposed mold showed 15.6% higher than that of common mold.