겨울철 냉기를 이용한 벼의 저온저장(I) - 벼 냉각 후 저장특성 -

이재석,한충수,함택모,연광석,Lee J. S.,Han C. S.,Ham T. M.,Yon K. S. 한국농업기계학회 2005 바이오시스템공학 Vol.30 No.3

The objective of this research was to establish a domestically available cooling storage technique by cold-air in winter, using winter cool air ventilation fur determining rough rice cooling method in the storage and dry bin. The rough rice storage characteristics of two test conditions, winter cool-air ventilation storage and ambient temperature storage, were evaluated from January to July 2001, using a storage and dry bin of 300-ton capacity. Results of this research are as follows: Grain temperature was from $-5.1\~-8.5^{\circ}C$ after winter cool-air ventilation, and grain initial temperature for ambient temperature bin storage was $0.3\~1.9^{\circ}C$. Moisture content of rough rice decreased from $0.28\;to\;0.93\%$ and from $1.53\;to\;1.92\%$ to compare with original moisture contents for winter cool-air ventilation, and for ambient temperature bin storage, respectively. Broken ratio of brown rice from winter cool-air ventilation bin increased from $0.16\;to\; 0.92\%$, and brown rice broken ratio was from $2.24\;to\;2.86\%$ for ambient temperature bin storage to compare with initial broken ratio. Hardness of stored rice increased along storage period increase in alt storage methods, and cooling bin storage increased rice hardness of 0.271kgf: this increasing was lower then the other methods from 0.059 to 2.239kgf. Germination rates were decreased approximately 9.03, 3.14 and $3.20\%$ for upper, middle, and bottom of ventilating winter air bin, respectively, and germination rates of 2.70, 3.47 and $4.14\%$ were approximately decreased for upper, middle, and bottom parts of ambient temperature bin storage, respectively.

저장 온도 및 기간이 굴참나무와 느티나무 노지묘 및 용기묘의 묘목품질에 미치는 영향

조민석 ( Min Seok Cho ),양아람 ( A-ram Yang ),노남진 ( Nam Jin Noh ) 한국산림과학회 2021 한국산림과학회지 Vol.110 No.3

연구는 굴참나무와 느티나무 노지묘 및 용기묘를 대상으로 식재 전까지 우수한 묘목품질을 유지하기 위한 최적 묘목 저장 기술을 구명하고자 수행되었다. 저온저장 온도(냉장 2℃, 냉동 -2℃)와 기간(0, 15, 30, 60, 120, 180, 240, 300, 360일)에 따른 묘목의 비구조성탄수화물 함량 및 줄기 함수율과 식재 후 묘목 생존율 및 건중량을 조사·분석하였다. 굴참나무와 느티나무 두 수종 모두 저장 기간이 길어질수록 비구조성탄수화물 함량과 줄기함수율이 감소하였으며, 180∼240일 이후 비구조성탄수화물 함량이 급격히 감소하는 것을 확인하였다. 저장 기간이 길어질수록 냉장보다는 냉동 조건이 낮은 감소율을 보였다. 줄기함수율은 두 수종 모두 노지묘보다 용기묘, 냉장보다 냉동 저장 조건에서 감소율이 낮았다. 식재 후 생존율은 두 수종 모두 냉장 저장은 60일, 냉동 저장은 180일 이후 급격히 감소하였다. 비구조성탄수화물 함량이 20 mg g^-1 이하로 감소하면, 굴참나무와 느티나무 모두 60% 이하의 식재 후 묘목 생존율을 보였다. 또한, 저장 전 줄기함수율 기준으로 굴참나무는 약 30%, 느티나무는 약 20% 감소 시 80% 이하의 생존율을 나타냈다. 본 연구 결과, 굴참나무와 느티나무 묘목의 저장 방식으로 2개월 미만의 단기저장은 냉장(1∼2℃), 2∼6개월 동안의 장기저장은 냉동(-2∼-4℃)이 적정한 것으로 판단된다. 향후 조림 전 묘목 수확 및 관리 시스템과 연계하여 적정 묘목 저장 조건의 적용은 우수한 품질의 묘목 생산과 함께 조림 성과 향상을 기대할 수 있을 것이다. This study was conducted to evaluate optimal storage techniques for bare root plants and container seedlings of Quercus variabilis and Zelkova serrata in order to maintain high quality of seedlings until planting. Refrigerated storage treatments were given at two temperatures (-2℃ [freezing] and 2℃ [cooling]) for nine different durations (0, 15, 30, 60, 120, 180, 240, 300, and 360 days after storage). We analyzed total nonstructural carbohydrate (TNC) content and measured shoot moisture content (SMC) during the storage stage and survival rate (SR) and dry weight during the planting stage of seedlings. The TNC content and SMC of the seedlings of the two species decreased with an increase in storage duration. The TNC content of seedlings rapidly decreased after 180~240 days of storage. The TNC reduction rate in the freezing treatment was lower than that in the cooling treatment. Also, with an increase in the storage duration of the two species, the SMC reduction rate in the cooling treatment increased in comparison with that in the freezing treatment. In both the species, the SR after planting decreased rapidly after 60 days of cooling storage and 180 days of freezing storage, respectively. The SR after planting was less than 60% when the TNC content for both the species dropped below 20 mg g^-1. In addition, the SR was lower than 80% when SMC measured before storage decreased by approximately 30% and 20% for Q. variabilis and Z. serrata, respectively. Our results suggest that cooling (1~2℃) storage is recommended for a short-term period (2 months or less), whereas freezing (-2∼-4℃) storage is suitable for longer periods (2∼6 months). These optimal storage techniques, allied with seedling harvesting and handling systems, will improve the quality of seedling production in nursery stages and increase seedling growth performances in plantations.

ESS(Energy Storage System) 열관리를 위한 액침 냉각 활용에 대한 수치해석 연구

함정균,조홍현,신명재,유나영 한국 지열 · 수열에너지학회 2024 한국지열에너지학회논문집 Vol.20 No.2

The introduction of the sector coupling concept has expanded the scope of ESS utilization, resulting in the importance of thermal management of ESS. To ensure the safe use of the lithium-ion batteries that are used in ESS, it is important to use the batteries at the optimal temperature. To examine the utilization of liquid cooling in ESS, numerical study was conducted on the thermal characteristics of 21700 battery modules (16S2P array) during liquid cooling using Novec-649 as insulating fluid. The NTGK model, an MSMD model in ANSYS fluent, was used to investigate thermal characteristics on the battery modules with liquid immersion cooling. The results show that the final temperature of the battery module discharged at 5 C-rate is 68.9o C using natural convection and 48.3o C using liquid cooling. However, the temperature difference among cells in the battery module was up to 0.5o C when using natural convection cooling and 5.8o C when using liquid cooling, respectively, indicating that the temperature difference among cells was significantly increased when liquid cooling was used. As the mass flow rate increased from 0.01 kg/s to 0.05 kg/s, the average temperature of the battery module decreased from 48.3o C to 38.4o C, confirming that increasing the mass flow rate of the insulating fluid improves the performance of liquid immersion cooling. Although partial liquid immersion cooling has a high cooling performance compared to natural convection cooling, the temperature difference between modules was up to 8.9o C, indicating that the thermal stress of the battery cells increased.

해수열원-계간축열 지역냉방 시스템의 기본설계

김명래,이주,윤재옥 호서대학교 공업기술연구소 2016 공업기술연구 논문집 Vol.35 No.1

우리나라의 기온은 지구온난화 영향으로 계속 상승되고 있으며 계절적으로 여름은 20세기 초보다 32일이나 길어졌다 . 이러한 추세는 냉방에너지의 급증을 초래하게 될 것이다 . 이에 대한 대응책으로 자연열원인 해수열원을 지역냉방 열원으로 활용하는 것은 바람직한 방법이다 . 이 방법을 적용하고 활용하기 위해서는 실용적으로 적용 가능한 기본적인 설계 자료가 필요하다 . 해수열원-계간축열 냉방시스템은 겨울철에 최저 수온으로 낮아진 해수열원을 취득하여 계간축열조에 저장해 두었다 여름철에 냉방열원으로 사용하는 개념이다 . 해수열원-열교환기에 대한 설계는 실용적 측면에서 지역특성에 부합되도록 발전시켜야 할 필요가 있다 . 인천 인근의 해안도서 지역에 지역냉방 단지를 조성하고 2,500nf 크기의 계간축열조를 설정하였다 . 열교환기는 주어진 조건에서 최적의 운전상태로 작동되는 해석값을 구하였다 . 계간축열조에 대한 분석은 예측식에 의한 해석과 TRNSYS 시뮬레이션을 수행한 결과를 비교하였다 . 전체 시스템의 운전 스케줄을 설정하고 요소별 특성과 냉열에너지의 흐름을 분석하는 방법체계를 수립하였다 . 이 시스템의 축열용량은 56MWh이고 히트펌프를 이용하면 가용 냉방에너지는 164MWh로 예상되었다 . 이 열량은 인천지역의 기후조건에서 1,000가구의 냉방이 가능하였다 . 부수적으로 C02 발생량을 65톤이나 감축시키는 효과를 거두었다 . 열교환기와 축열조의 설계 제원 및 시스템의 냉열에너지 분석과 운전 체계를 기본적인 설계방안 으로 제시 한다 . In Korea, temperature continues to rise due to the effect of global warming. And in terms of seasons, summer got longer by as many as 32 days than in the early years of the 20th century. These trends will come to cause an sharp increase in energy for cooling. With regard to countermeasures agamst this, it is a very desirable method to utilize seawater heat source, natural heat source, as district cooling source. Practically applicable basic design data are necessary for the application and utilization of this method. The concept of seawater heat source - seasonal thermal storage cooling system is to use seawater heat source as cooling source in summer after storing it in seasonal thermal storage following the acquisition of seawater heat source of which the temperature goes down to minimum water temperature in winter. It is necessary to develop seawater heat source - heat exchanger design so that the design conforms to regional characteristics from the practical aspect. A district cooling housing estate was built and seasonal thermal storage with a size of 2,500m3 was established in islands and coastal area around Incheon. A value calculated in an analysis was obtained, where the heat exchanger worked in optimal operating status in a given condition. Data obtained by carrying out an analysis using an equation for prediction and TRNSYS simulation were examined with regard to an analysis of seasonal thermal storage. This study established a method framework for analyzing the flow of cold energy and characteristics according to component and setting up the operating schedule of the whole system. The thermal storage capacity of this system was 56MWh. And it was estimated that available energy for cooling was 164MWh if heat pump was used. This capacity enabled 1,000 houses to be cooled down in the climate condition of Incheon area. Incidentally, this produced an effect of reducing C02 emissions by 65 tons. Heat exchanger and thermal storage design specification and system cold energy analysis and operating framework is suggested as basic design scheme.

600kJ급 SMES용 전도냉각시스템의 냉각특성 (Ⅰ)

홍용주(Yong-Ju Hong),염한길(Han-Kil Yeom),고득용(Deuk-Yong Koh),김효봉(Hyo-Bong Kim),박성제(Seong-Je Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

SMES systems need cryogenic cooling systems. Conduction cooling system has more effective, compact structure than cryogen. For the effective conduction cooling of the HTS SMES system, the temperature difference between the cryocooler and HTS coil should be minimized. In this study, an experimental study of a conduction cooling system for 600kJ HTS SMES is performed to evaluate the performance of the designed cooling system. Two GM cryocoolers are connected to HTS coil by braided wires, a heat exchanger and cooling plates. In this study, the HTS coil is not attached to the cooling system. To simulate the heat generation of HTS coil, heat load by electric heater is applied to the cooling system. The result shows the cool-down characteristics and temperature variation of the cooling system in the steady state.

히트파이프를 이용한 축열식 냉ㆍ난방 시스템에 관한 연구

김성실(Seong-Sil Kim),함성철(Seong-Chol Harm),이양호(Yang-Ho Lee),최병윤(Byoung-Youn Choi) 대한설비공학회 2006 대한설비공학회 학술발표대회논문집 Vol.2006 No.6

The heat pump system is attractive alternatives to conventional heating and cooling systems owing to their higher energy utilization efficiency. The thermal loads of commercial and institutional buildings are generally cooling-dominated. In this study have been developed ice storage type heat pump system for cooling and heating by heat pipe. This system was practiced performance test on evaluation criteria for heat storage systems. Accomplished the actual proof examination and looked into the performance of the system. In this study, measurement and analysis of ice storage type heat pump system for cooling and heating by heat pipe. The heat pump unit COP appears 3.05 for cooling and 4.20 for heating. As a result, the method to energy saving and to using a substitute energy actively that is heat pump cooling & heating system is expected by heat pipe. Thermal storage capacity appears 19.5RTH/㎥ for cooling.

온도, 습도 및 냉방부하 예측에 관한 연구

유성연(Seong-Yeon Yoo),한승호(Seung-Ho Han),이제묘(Je-Myo Lee),한규현(Kyou-Hyun Han),노관종(Kwan-Jong Noh) 대한설비공학회 2006 대한설비공학회 학술발표대회논문집 Vol.2006 No.6

The peak demand of electricity in summer season mainly comes from the day time cooling loads. Ice thermal Storage System (ITSS) uses off-peak electricity at night time to make ice for the day time cooling. In order to maximize the use of cold storage in ITSS, the estimation of day time cooling load for the building is necessary. In this study, we present a method of cooling load estimation using 5 years of normalized outdoor temperature, relative humidity, and the building construction data. We applied the hourly-based estimation to a general hospital building with relatively less sudden heat exchange and the results are compared with the measured cooling load of the building. The results show that the cooling loads estimation depends on the indoor cooling design temperature of the building.

봄배추의 전처리 및 포장방법이 저온저장 중 선도유지에 미치는 효과

박세진,김지영,Andri Jaya Laksana,김병삼 한국포장학회 2023 한국포장학회지 Vol.29 No.2

This study was examined for investigating the quality changes of spring kimchi cabbage under various treat-ments (pre-drying/pre-cooling, packaging types, and stacking and loading in container and pallete in the storage room) during cold storage. The results showed that control (upward stacking without pre-drying/pre-cooling and HDPE or PVC film cover) was increased significantly in weight loss and trimming loss, compared to other treatments such as DPDH (downard stacking + pre-drying + HDPE), DPDP (downard stacking + pre-drying + PVC), DPCH (downnard stacking + pre-cooling + HDPE), and UPCH (upward stacking + pre-cooling +HDPE) during storage for three months. In Sensory evaluation, judging from marketable properties, the desirable appearance of spring kimchi cabbage with the modified pal-let-unit MA packed, PE, and PVC film wrapping could be maintained until 9 weeks after pre-drying/pre-cooling. Mean-while, the control without any treatments after 6 weeks, the sensory score was declined, significantly. In general, the low temperature (10oC and 2oC) of pre-treatment with combination of plastic film packaging in spring kimchi cabbage storage could inhibit the physiological activity and reduce the direct exposure of environmental cold air in the storage. Therefore, these two variables were the key points for extending the shelf-life of spring kimchi cabbage.

내부발열의 확률적 성상을 고려한 슬래브축냉의 최적제어

정재훈(Jae-Hoon Jung) 대한설비공학회 2015 설비공학 논문집 Vol.27 No.6

In this paper, a method to obtain the probability distribution of room temperature and cooling load is presented, when the internal heat generation is applied to the system as a disturbance in the air conditioning system with slab cooling storage. The probability distribution of room temperature and the cooling load due to the disturbance were examined in one room of an office building. When considering only the electric power consumption as a probability component, it was found that the effect on room temperature and cooling load is small, because the probability component of the measured electric power consumption in the building is small. On the other hand, when considering the stochastic fluctuations of electric power consumption together with the heat generated by human bodies, the mean value of the cooling load was about 2,300 W and the ratio of the standard deviations was 19% (10 o’clock in second day). It was revealed that the stochastic effects of internal heat generation acting on the air conditioning system with slab cooling storage are not small.

열전소자 장치 및 플라즈마 처리에 의한 소고기 저장 중 품질특성

권기현,성정민,김지영,김병삼,김소희 한국식품저장유통학회 2017 한국식품저장유통학회지 Vol.24 No.1

This study was performed in order to examine the effect of a thermoelectric cooling system combined with plasma on beef. Beef was studied in a box with a thermoelectric cooling system and plasma generation apparatus (TCS-1), a box with thermoelectric cooling system (TCS-2) and a polystyrene box (control). A temperature inside the thermoelectric cooling system was kept below 2℃, and volatile basic nitrogen (VBN) values of TCS-1 and TCS-2 were 7.72 mg% and 9.20 mg%, respectively. The thiobarbituric acid (TBA) value (0.52 mgMA/kg) of TCS-1 was significantly lower than that (0.91 mgMA/kg) of TCS-2. For volatile basic nitrogen (VBN) value, TCS-1 maintained freshness compared to TCS-2, since the freshness of TCS-1 value (6.98-9.77 mg%) was less than that of TCS-2 (6.98-11.45 mg%) during storage. The microbial counts of TCS-1 and TCS-2 were 4.62 log CFU/g and 7.09 log CFU/g, respectively, on the 7th day, which were lower than that (8.45 log CFU/g) of control on the 3rd day. Sensory evaluation of TCS-1 showed the highest scores for appearance, color, juiciness, and overall acceptability than the others. In conclusion, TCS-1 was effective for maintaining freshness of beef during storage.