• Title/Summary/Keyword: freezing air temperature

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Temporal Variation of Air Temperature in Ice-Valley at Milyang in Association with Ice Formation

  • Lee, Soon-Hwan;Hwang, Soo-Jin
    • Journal of the Korean earth science society
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    • v.28 no.5
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    • pp.598-602
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    • 2007
  • A long-term in situ observation was carried out in the Ice-valley at Milyang in order to explain the factors and processes associated with the summertime ice formation. The variation of temperature inside Ice-valley in relation with ice formation in summer time was found to depend on precipitation rate in spring and cold air sinking in autumn and winter. The rate of temperature rising tends to correspond to sensible heat release depending on the precipitation amount at the freezing location. The reason of the cold air accumulation in a talus in the Ice-valley is the cold air sinking over the surface of talus due to the occurrence of outside clod air mass and the accumulated cold air from autumn to spring flow outside at the bottom of talus. The out-flowing cold air can result in the ice formation in the hot summer.

Adhesion of Ice Slurry in an Aqueous Solution Cooling with Stirring (수용액의 교반/냉각을 동반한 슬러리 얼음의 빙부착)

  • Kang, Chae-Dong;Son, Kwon;Baek, Jong-Hyun;Hong, Hee-Ki
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.12
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    • pp.1071-1077
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    • 2002
  • Ice adhesion on cooling wall is very important in continuous ice formation. The purpose of the present study is to investigate the possibilities of a three-component aqueous solution as a thermal storage material for the continuous ice formation. By freezing under stirring the solution of 300 mL in a stainless steel vessel which was immersed and cooled in a temperature controlled bath, an ice slurry was formed experimentally with measuring the temperature and stirring load variation. From the experiment, the ice adhesion was suppressed when the supercooling degree decreased and the concentration of aqueous solution increased.

Adhesion of Ice Slurry in a Multi-component Aqueous Solution with Stirring and Cooling (다성분계 수용액의 교반/냉각에 의한 빙부착)

  • 강채동;강용태;홍희기
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.12
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    • pp.1063-1070
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    • 2002
  • To resist ice adhesion on cooling wall is concerned to continuous ice formation in thermal storage system. In this study, ice slurries were formed with two ecological aqueous solution, one is ethanol+silanol and the other is propylene glycol+silanol. By freezing under stirring the solution of $300m\ell$ in a stainless steel vessel which was immersed and cooled in a temperature controlled bath, the shape of ice slurry and the strength of ice adhesion on wall was observed with measuring the temperature and stirring load variation. As the concentration is smaller and the supercooling degree is larger, the ice adhesion is easy to occur. When the stirring load is larger than$ 2.1\times10^{-5}W$, the ice adhesion occurred.

The Construction and Investigation of The 1/4 Wavelength Thermoacoustic Refrigerator (1/4파장 열음향 냉동기의 제작 및 성능시험)

  • Song, Kyu-Joe;Park, Jong-Ho;Lee, Sung-Ro;Lee, Jae-Ho
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.223-228
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    • 2001
  • The thermoacoustic refrigerator has not only considerable possibility but also commercial usability, because it has high reliability, lower vibration, no moving part, and can easily be constructed. In this study, The thermoacoustic refrigerator were constructed. The apparatus is capable of driving closed systems containing He or air at mean pressures ranging from 1-9.3 bar, at frequencies ranging from 100-1000Hz. The resonance characteristics of the thermoacoustic refrigerator were investigated for better performance, The resonance tube is 340.5mm in length. In case of using air as a coolant. Freezing frequency is 174Hz, In case of using He as a coolant Freezing frequency is 625Hz. Using He, The cold-part temperature of the heat exchanger fell to $-23.7^{\circ}C$ after 120 minutes in 70W.

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An Experimental Study of Frost Formation on the Horizontal Cylinder (수평 실린더 표면의 착상에 대한 실험적 연구)

  • Paik, Sang-Jin;Lee, Yoon-Been;Ro, Sung-Tack
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.240-245
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    • 2000
  • In this study, thickness, density and effective thermal conductivity of frost forming on the horizontal cylinder were measured with various air temperature and humidity. Reynolds number and temperature of cooling surface are controlled 17300 and $-l5^{\circ}C$ respectively. In each case of air temperature $5^{\circ}C,\;10^{\circ}C,\;15^{\circ}C,$ varying absolute humidity, experiments were executed. In measuring frost surface temperature and thickness of frost layer, infrared thermocouples and CCD camera were used. Frost was gathered from cylinder to measure mass of frost layer. Experimental data showed that the thickness and effective thermal conductivity of the frost layer increase with respect to time. Thickness of frost layer increase with humidity increasing, and density of frost layer increase with air temperature rising. Frost growth with air temperature and density of frost layer with humidity are affected by whether dew point is below or above freezing point.

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A study on the solar assisted heating system with refrigerant as working fluid (냉매를 작동유체로 사용하는 태양열 난방시스템에 관한 연구)

  • Kim, Ji-Young;Ko, Gawng-Soo;Park, Youn-Cheol
    • Journal of the Korean Solar Energy Society
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    • v.25 no.4
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    • pp.37-44
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    • 2005
  • An experimental study was conducted to analyze performance of a heating system with variation of control logic of the system. The system uses a solar as heat source and composed with heat pump that uses R-22 as working fluid. The difference between the developed system and the commercially available heating system is working fluid. The solar assisted heating system which was widely distributed in the market uses water as a working fluid. It could be freezing in case of the temperature drops down under freezing point. The anti-freezing fluids such as methyl-alcohol or ethylene-glycol are mixed with the water to protect the freezing phenomena. However, the system developed in this study uses a refrigerant as a working fluid. It makes the system to run under zero degree temperature conditions. Another difference of the developed system compare with commercial available one is auxiliary heating method. The developed system has removed an auxiliary electric heater that has been used in conventional solar assisted heating system. Instead of the auxiliary electric heater, an air source heat exchanger which generally used as an evaporator of a heat pump was adapted as a backup heating device of the developed system. As results, an efficiency of the developed system is higher than a solar assisted heat pump with auxiliary electric heater. The merit of the developed system is on the performance increment when the system operates at a lower solar energy climate conditions. In case of the developed system operates at a normal condition, COP of the solar collector driven heat pump is higher than the air source heat exchanger driven heat pump's.

Evaluation of Floor Heating Performance and Design Criteria for Operating an Outdoor Swimming Pool During Winter : A Case Study (동절기 옥외 수영장 시설의 운영을 위한 바닥난방 성능평가 및 설계기준에 관한 사례연구)

  • Cho, Jinkyun;Woo, Kyunghun;Kim, Jin-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.289-296
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    • 2017
  • This study aimed to analyze the deck floor heating system of an outdoor swimming pool in terms of the thermal capacity/output and the surface temperature distribution based on the outdoor temperature, to design for anti-freezing during winter. Through the transient heat transfer simulation with PHYSIBEL and theoretical equations, the surface temperature distribution of the floor heating system at two outdoor conditions in Jeju, were calculated and evaluated. The results indicate that the specific thermal output required for maintaining $4^{\circ}C$ surface temperature at the design outdoor temperature of $0.1^{\circ}C$, was about $90W/m^2$. This performance analysis can be applied for future design criteria, including optimizations of system capacity and size.

Effects of Storage Temperature and Packaging Methods on the Physicochemicl Quality of Boiled-Dried Anchovies (저장온도 및 포장조건이 건멸치의 이화학적 품질에 미치는 영향)

  • 권중호;정형욱;변명우;김정숙
    • Journal of Food Hygiene and Safety
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    • v.10 no.2
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    • pp.97-102
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    • 1995
  • For improved preservation of boiled-dried anchovies, the current preservation method of corrugated-cardboard box packaging and freezing below -18$^{\circ}C$ was compared to the nylon/polyethylene(NY/PE) packaging along with cooling temperature ranging from 5$^{\circ}C$ to 1$0^{\circ}C$ as well as ambient condition for eight months by determining physicochemical quality of stored samples. Lipid oxidation of stored anchovies and their browning increased with storage time. The phenomenon was delayed under the conditions of lower temperature and air-tight packaging. As quality-indicative criteria of stored anchovies, carbonyl value(r=-0.989), browning (r=-0.949) and color a value(r=-0.989), browning(r=-0.965), Hunter's color b value(r=-0.949) and color a value(r=-0.940) showed a highly-negative correlations with organoleptic qualities of the samples. Based on the above results, air-tight packaging in a laminated film and subsequent storage at cooling temperature was found to be a possible alternative to the current freezing-storage of boiled-dried anchovies from the physicochemical point of view.

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Processing Conditions and Quality Stability during Storage of Frozen-dried Filefish (말쥐치 동건품의 가공조건 및 저장중의 품질변화)

  • LEE Eung-Ho;KIM Hee-Yun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.15 no.2
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    • pp.111-116
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    • 1982
  • For the effective utilization of the fish resources in coastal regions, investigations on processing conditions of frozen-dried product, quality stability of the Product during storage, and utilization as a food material were carried out with the filefish, Navoden modestus. The processing condition was determined with the moisture content and texture of the product. The duality of the product was evaluated on chemical composition, rehydration capacity, TBA value, browning, omission test and sensory score. The conditions for the processing of frozen-dried filefish under the conditions of freezing temperature at $-10^{\circ}C$ and forced air thawing at $56{\pm}2^{\circ}C$ with a velocity of 1 m/sec were as follows : freezing temperature, $-10^{\circ}C$ : freezing time, 10 hours; thawing time, 2 hours ; and repeated number of freezing and thawing, 5 times. The yield, the condition of moisture and protein were $10.2\%,\;23.6\%\;and\;70.6\%$, respectively. The frozen-dried product packed with air and stored at room temperature showed no remarkable changes in TBA value, rehydration capacity, browning during the storage period of 90days. The frozen-dried filefish showed no remarkable differences in the taste, odor and texture, comparing with frozen-dried Alaska pollack on the market.

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Temperature Changes during Freezing and Effect of Physicochemical Properties after Thawing on Meat by Air Blast and Magnetic Resonance Quick Freezing (식육의 송풍식 냉동과 전기자장 냉동 중 온도 변화 및 이화학적 품질에 미치는 영향)

  • Kim, Young Boong;Woo, Sung Min;Jeong, Ji Yun;Ku, Su Kyung;Jeong, Jin Woong;Kum, Jun Seok;Kim, Eun Mi
    • Food Science of Animal Resources
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    • v.33 no.6
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    • pp.763-771
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    • 2013
  • This study was carried out to investigate the effects of various temperatures of electro-magnetic resonance and air blast freezing methods on the physicochemical quality of meat. Beef (loin and round), pork (belly and ham) and chicken (breast and leg) were purchased at a commercial market, and the meat was frozen using three methods: air blast freezing ($-20^{\circ}C$ and $-45^{\circ}C$) and electro-magnetic resonance quick freezing. Changes in the physicochemical properties of meat were analyzed by drip loss, cooking loss, water holding capacity (WHC) and proximate compositions. In comparison, regardless of the animal species and cuts of meat, electro-magnetic resonance quick freezing (2 h) resulted in a completely frozen product in a much shorter time than $-20^{\circ}C$ and $-45^{\circ}C$ air blast freezing (24 h and 8 h, respectively). Drip loss of loin which had underwent electro-magnetic resonance quick freezing were significantly (p<0.05) lower than those of the other two treatments, but cooking loss and water holding capacity were the highest at 43.7% and 60.7%, respectively (p<0.05). Characteristics such as crude protein, crude fat and moisture compositions showed significant differences, depending on the cuts and freezing methods (p<0.05). The fat composition of electro-magnetic resonance quick frozen loin and round were significantly low (p<0.05). However, moisture content was the highest compared to other freezing methods, as 67.1% and 71.9%, respectively (p<0.05). Electro-magnetic resonance quick freezing was an appropriate way to reduce the deterioration of meat quality due to freezing, and the drip loss was least for the part with low moisture, low protein, and high fat.