• Title/Summary/Keyword: vacuum cooling

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A Study on the Rapid Cooling Vacuum System for the Storage and Transportation of the Cold Agriculture and Livestock Products (농축산물의 저장 및 유통을 위한 감압증발 급냉각 시스템에 관한 연구)

  • 김성규;김원녕;김경석;최순열;전현필
    • Journal of Advanced Marine Engineering and Technology
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    • v.21 no.1
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    • pp.26-36
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    • 1997
  • Recently, the new refrigerating system, using non - fluorinated hydrocarbon refrigerants has to be developed for the agricultural fields. One of that kinds of systems is the cooling system using the water vapor and vacuum, in which the water evaporate at the low temperature under vacuum and absorb the large amount of the latent heat. If vapor with large amount of latent heat is removed from the system, the system is cooled accordingly. The characteristics of cooling under the vacuum was observed and measured using experimental apparatus, which is consisted of vacuum chamber, the ejectors, the pumps and the measurement apparatus. As the results of experiments, we know that the evaporation in the vacuum occurs vigorously when the materials to be cooled has more amounts of heat before cooling, and by which effects the materials can be cooled. The cooling vacuum system is more efficient than other methods when the agricultural products is chilled or dried.

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A Study on the Combined Equipment for the Pre-cooling and the Thawing using the Low Temperature Vacuum System (저온진공기술을 이용한 예냉 및 해동 겸용장치에 관한 연구)

  • 김성규;박영승;최현규;이정혜;김경근
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.2
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    • pp.280-288
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    • 2003
  • We need refrigeration system which can maintain the freshness of agricultural products, because of being distance from a tiller to a consumer. Vacuum Pre-cooling system has an advantage in quality maintenance through vapid cooling down by using latent heat of evaporation of stored products. A number or thawing methods in current use have also several disadvantages in thawing time. discoloration mass loss caused by drying, capital costs and running cost. These damages are, it is claimed, either eliminated or improved by the vacuum thawing system. An experimental study on the pre-cooling for the bean sprouts and cabbage, and thawing for hairtail and croaker by the low temperature vacuum system were carried out. The cabbage cooling time with this Pre-cooling vacuum system took about 60 minutes to reach from $23.2^{circ}C to 4.5^{\circ}C$ at 5 mmHg abs. ($6.66\times10^{-4}$ MPa). The croaker thawing time with this low temperature vacuum thawing system took about 170 minutes to reach from $-10.3^{circ}C to -0.8^{\circ}C$ at 20 mmHg abs ($2.67\tiems10^{-3}$MPa). The vacuum Pre-cooling and thawing system have merits compared with present systems in their short intervals to cool down and to thaw without any quality losses.

Characteristics of Cooling Down in the Enclosed Vacuum Tank by Water Driving Ejector (수 이젝터를 이용한 밀폐형 진공탱크내의 온도저감 특성)

  • Kim, Se-Hyun;Shin, You-Sik;Bae, Kang-Youl;Lee, Youn-Whan;Jeong, Hyo-Min;Chung, Han-Shik
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.700-705
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    • 2003
  • The general cooling tower is a device for making a cooling water in refrigerant condensers or industrial process heat exchangers. The present cooling tower have defects with noises, complicated structure and environmental problems. In this paper, we constituted a new water cooling system by using a evaporating latent heat in an enclosed tank, and this system is consisted of an enclosed vacuum tank and water driving ejector system. Several experimental cases were carried out for improvement methods of high vacuum pressure and water cooling characteristics. The ejector performance was tested in case of water temperature variations that flows in the ejector. Based on the vacuum pressure by water driving ejector, the water cooling characteristics were investigated for the vaporized air condensing effects.

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Vacuum Cooling System and Their Use (진공냉각장치와 그 이용)

  • 김명환;김경근;박형진
    • Journal of Advanced Marine Engineering and Technology
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    • v.19 no.4
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    • pp.7-16
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    • 1995
  • This article describes the working prnciple, structure and main characteristics of vacuum coolers for vegetables, and gives concrete examples of vacuum coolers that srebeing put to practical use. In particular, newly-developed cavuum coolers with cold storage, utilizing night-time electricity, are focused upon. Processing plants for vegetables, cold-storage rooms and vacuum cooling devices were investigated as possible application of vacuum cooling technology.

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Effects of Vacuum Cooling Followed by Water Spraying on the Quality of Precooked Skipjack Katsuwonus pelamis (진공분무 냉각에 의한 자숙 가다랑어(Katsuwonus pelamis)의 냉각 및 품질 특성에 관한 연구)

  • Lee, Tae-Hun;Koo, Jae-Geun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.47 no.1
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    • pp.12-17
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    • 2014
  • The cooling of precooked skipjack Katsuwonus pelamis is a critical thermal process in tuna canning because it affects the quality and yield of the canned tuna, as well as productivity. The combined method of vacuum cooling followed by water spraying (VC-WS) was investigated to increase cooling rates, and prevent loss of yield of the precooked tuna during vacuum cooling. For VC-WS, the precooked skipjack was cooled to $30^{\circ}C$ by vacuum at 31 mmHg and then wetted by spraying water for 2 min. The effects of VC-WS on cooling times, cooling loss, color, texture and lipid oxidation of the precooked tuna were compared with conventional spray cooling (SC).The cooling times for precooked skipjack from $75^{\circ}C-30^{\circ}C$ were 11 min for VC-WS and 145 min for SC. The cooling losses were 1.7 % for VC-WS and 1.6 % for SC. Peroxide and thiobarbituric acid (TBA) values of VC-WS were lower than those of SC. The loin of the VC-WS-treated skipjack was brighter and harder than the SC loin, as indicated by higher lightness and hardness values. Based on these results, we believe that the VC-WS process could compensate for the cooling loss of vacuum cooling and minimize changes in quality that occur during cooling of precooked skipjack tuna.

Improvments in Cost Reduction for Vacuum Sintering and Vacuum and Overpressure Sintering for Tungsten Carbides

  • Ermel, Dieter
    • Journal of Powder Materials
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    • v.5 no.4
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    • pp.293-298
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    • 1998
  • In all larger hardmetal workshops furnaces for dewaxing, vacuum sintering or vacuum and overpressure sintering are today's standard. The furnace technology is well established. Equipment specifications such as operating overpressure, determine sintering cost, product quality, safety and reliability of the furnace and ultimately influence the competitiveness of the hard metal procucer in the global market. Essential furnace requirements are an efficient utilization of the furnace, an environmental friendly dewaxing system, high temperature uniformity, metallurgical treatment with process gases, as well as reduced cooling time by means of rapid cooling. Examples of reduced sintering costs are described achieved using a new design of vacuum sintering furnace with an improved rapid cooling device, cooling times are reduced by up to 45%. Additionally, a cost comparison of two different designs of vacuum overpressure sintering furnaces are included.

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Vacuum Cooling System by the Various Ejectors (각종 이젝터를 이용한 진공냉각장치)

  • 윤석훈;김원녕;전현필
    • Journal of Advanced Marine Engineering and Technology
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    • v.19 no.4
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    • pp.1-6
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    • 1995
  • Recently, outstanding progresses have been made in food industry, in all the processes involved in the conversion of raw materials into food products. This article describes two kinds of coolers for processing uncooded foor, namely vacuum coolers capable of rapidly cooling decomposing bacteria down to their critical temperature, and also cooling equipment for fresh vegetables based on the same principle as the vacuum cooler.

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A Study on Cooling of Piezoelectric Element of Multifunction Equipment for Vacuum Exhaust and Ultrasonic Joining (진공 배기 및 초음파 접합 복합기 진동자 냉각에 관한 연구)

  • Park, Sang-Jun;Lee, Young-Lim
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.4
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    • pp.1511-1517
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    • 2012
  • Vacuum chamber or vacuum tube for the exhaust process of vacuum glazing is presently used, where excessive time and expenses are required to make the whole vacuum chamber or tube vacuum. To solve this problem, multifunction equipment for vacuum exhaust and ultrasonic joining at atmospheric pressure has been developed, in which a piezoelectric vibrator experiences excessive temperature rise resulting in optimizing the cooling of the equipment. Therefore, in this study, cooling effects of natural convection and forced convection methods were identified by numerical analysis and experiments, and cooling performance of the multifunction equipment was optimized.

Fabrication and Testing of Injection Mold for Cosmetic Container with Conformal Cooling Channels Using Vacuum Diffusion Bonding (진공확산접합을 이용한 형상적응형 냉각채널을 가진 화장품 용기용 사출금형의 제작 및 시험사출)

  • Yu, Man-Jun;Park, Jong-Cheon
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.3
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    • pp.92-98
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    • 2020
  • In this study, an injection mold with conformal cooling channels was designed and manufactured for use in the production of a thick plastic cosmetic container that required high gloss surfaces. A cooling analysis verified the design of the conformal cooling channel for the cosmetic container, and also showed that the cooling efficiency was superior to that of the straight cooling channel. Slide cores designed with the conformal cooling channel were manufactured using the Layers Parting method and vacuum diffusion bonding. Subsequent test injection and quality inspection showed no problem in the appearance and dimensional accuracy of the produced product. The cycle time for product production was about 110 seconds, sufficient for mass production.

A study on the characteristic of vegetables temperature in the pre-cooling vacuum unit (진공 예냉장치 내에서의 야채류의 온도 변화 특성에 관한 연구)

  • Won, Jong-Ho;Park, Sang-Gyun;Yoon, Seok-Hoon;Oh, Cheol
    • Journal of Navigation and Port Research
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    • v.31 no.10
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    • pp.879-884
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    • 2007
  • This study is to observe the change of temperature and relative humidity for various vegetables in vacuum precooling system. The materials for experiments were the lettuce, chinese cabbage, pak choi and cabbage. The experimental apparatus was constructed of vacuum chamber, vapor/water separator, water tank, pumps ejecting and cooling water circulation, refrigerator unit, cooling coil for water cooling, Hygrometer and Data logger measuring of the temperature change. The experiments were operated in 20torr and recorded every 3 minutes. It was found that the cooling temperature and speed of vegetables are depending on the percentage of its water content. The more water contains, the faster cooling speed and the lower cooling temperature.