• 제목/요약/키워드: Water transfer characteristic

검색결과 94건 처리시간 0.03초

아이스슬러리형 빙축열 시스템을 이용한 냉각 시스템의 성능에 관한 실험적 연구 (Characteristic Analysis of the Cooling System Using Ice Slurry Type Heat Storage System)

  • 이동원;김정배
    • 에너지공학
    • /
    • 제20권1호
    • /
    • pp.30-35
    • /
    • 2011
  • 2중관형과 판형 열교환기에 에틸렌 클리콜-물 수용액으로 만들어진 아이스슬러리를 적용하는 경우의 유동 및 열적 특성을 규명하기 위하여 실험을 수행하였다. 아이스슬러리의 질량유속과 얼음 분율은 각각 800에서 3500 kg/$m^2s$과 0에서 25%이었다. 실험을 통해, 압력강하와 열전달율은 질량유속과 얼음 분율에 따라 증가하였다. 그러나 얼음 분율의 효과는 높은 질량유속 영역에서는 크지 않은 것으로 나타났다. 낮은 질량유속에서는 압력강하와 열전달율의 급속한 증가가 질량 유속에 관계되는 것으로 나타났다.

정밀금형 알루미늄 합금주조공정시 주물/금형 접촉면에서의 Inverse 열전달해석에 관한 연구 (Inverse Heat Transfer Analysis at the Mold/Casting Interface in the Aluminum Alloy Casting Process with Precision Metal Mold)

  • 문수동;강신일
    • 한국주조공학회지
    • /
    • 제18권3호
    • /
    • pp.246-253
    • /
    • 1998
  • Precision metal mold casting process is a casting method manufacturing mechanical elements with high precision, having heavy/light alloys as casting materials and using permanent mold. To improve dimensional accuracy and the final mechanical properties of the castings, the solidification speed and the cooling rate of the casting should be controlled with the optimum mold cooling system, and moreover, to obtain more accurate control of the whole process interfacial heat transfer characteristic at the mold/casting interface must be studied in advance. In the present study, aluminum alloy casting system with metal mold equipped with electrical heating elements and water cooling system was designed and the temperature histories at points inside the metal mold were measured during the casting process. The heat transfer phenomena at the mold/casting interface was characterized by the heat flux between solidifying casting metal and metal mold, and the heat flux history was obtained using inverse heat conduction method. The effect of mold cooling condition upon the heat flux profile was examined, and the analysis shows that the heat flux value has its maximum at the beginning of the process.

  • PDF

VCHP에서 불응축 가스량이 열전달 성능에 미치는 영향에 관한 실험적 연구 (An Experimental Study on the affect of Non-condensable Gas Quantity on the Heat Transfer Performances in a Variable Conductance Heat Pipe)

  • 박기호;이기우;이욱현;이계중;서정세
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2003년도 추계학술대회
    • /
    • pp.19-24
    • /
    • 2003
  • This paper is to research the heat transfer characteristic in copper-water variable conductance heat pipes(VCHP) with a non-condensable gas and gas reservoir. The heat transfer characteristics in the VCHP have not yet been studied much researches. VCHP are used in many applications. These applications range from thermal control of components and systems on satellites, to precise temperature calibration duties, conventional electronics temperature control and thermal diodes. The practical use of VCHP is a simple way to control the temperature of satellites. As the quantity of NCG was increased, there was an increase in the saturation vapor temperatures. As the input heat has loaded from 90 W to 110 W, the difference of the evaporator surface is lower than $10^{\circ}C$.

  • PDF

수중 원통형 쉘 구조물의 고주파 진동 전달특성에 대한 실험적 연구 (Experimental Study on High Frequency Vibration Transfer Characteristic of Underwater Cylindrical Shell)

  • 정현기;민천홍;박한일
    • 한국해양공학회지
    • /
    • 제25권5호
    • /
    • pp.58-63
    • /
    • 2011
  • Underwater vehicles such as UUVs (Unmanned Underwater Vehicles) and ROVs (Remotely Operated Vehicles) use sonar to detect their underwater environment or other underwater vehicles. The underwater vehicles designed recently have an electrical power system with high rotational speed. This system can generate high frequency vibrations above 10 kHz, and these vibrations can cause bad (negative) effects on the performance of the sonar. In many previous investigations, numerical analyses have been used for high frequency vibration problems. In this study, an experimental analysis was carried out, and a circular cylindrical shell was considered as the hull structure of an underwater vehicle. Frequency transfer functions for the circular cylindrical shell were identified using an experimental vibration analysis in the air and in a fully-submerged condition. We compare the frequency transfer functions in the air and water to obtain hydro-elastic effects. It is found that the dynamic characteristics of the circular cylindrical shell are changed by varying the response position.

A Study on the Calculation Model for the Emissivities of Carbon Dioxide and Water Vapor

  • Kim, Chong-Bo;Hur, Byung-Ki;Kim, Nam-Jin;Seo, Tae-Beom
    • Journal of Mechanical Science and Technology
    • /
    • 제15권2호
    • /
    • pp.248-258
    • /
    • 2001
  • The main mode of heat transfer of combustion gases at high temperature is thermal radiation of the participating gases, which are mainly carbon dioxide and water vapor. Therefore, the information of the emissivities of carbon dioxide and water vapor would be very important in the thermal performance analysis of a furnace. In this study, an exponential model for the emissivities of carbon dioxide and water vapor is derived as a function of the product of the partial pressure and characteristic length and a polynomial of reciprocal of temperature. Error analysis of the calculated values from the present model is performed for the temperature ranges of 555.6∼2777.8K and the partial-pressure-length product ranges of 0.09144∼609.6 cm-atm. For carbon dioxide, the difference between the values from the present model and the Hottels chart is less than 2.5% using a polynomial in 1/T of degree of 4. For water vapor, the model can predict the emissivity within 2.5% difference using a polynomial in 1/T of degree of 3.

  • PDF

시화조력발전소 수차발전기 제어시스템의 동적 특성 해석 (Dynamic Characteristic Analysis of Water-Turbine Generator Control System of Sihwa Tidal Power Plant)

  • 안상지;반우현;박철원
    • 전기학회논문지P
    • /
    • 제61권4호
    • /
    • pp.180-185
    • /
    • 2012
  • Tidal power is one of new and renewable energy sources. The seawater is stored inside a tidal embankment built at the mouth of a river or bay, where tides ebb and flow. The water turbine-generators produce power by exploiting the gap in the water level between the water outside and inside the embankment. Tidal power plant is a large plant that is installed on the sea. And then, the facility's operations and a separate control system for monitoring and maintenance is required. However, this plant predictive control of building systems and technologies have been avoided the transfer of technology from advanced global companies. Accordingly, the control system for core technology development and localization is urgently needed. This paper presents modeling and simulation using by PSS/E about generator, governor, exciter, and power system stabilizer for control system in Sihwa tidal power plant to improve the efficiency and develope of core technology. And the dynamic characteristics of governor and exciter were analyzed.

수중 빙 제조방식을 적용한 빙축열시스템의 축방냉 특성 실험 (Experiment of Characteristic on the Charge and Discharge of Cold in Ice Storage System Applied Ice Making Method In-Water)

  • 최인수;김재돌;윤정인
    • 설비공학논문집
    • /
    • 제14권1호
    • /
    • pp.31-37
    • /
    • 2002
  • This paper is concerned with the development of a new method for making and separating ice and saving floated ice by installing an evaporation plate at in-water within a storage tank. In a conventional harvest-type ice storage system, a tank saves ice by separating a formed ice from an installed evaporation plate, which is located above an ice storage tank as an ice storage system. A new harvest-type method shows very good heat transfer efficiency than a convectional method. It is because the evaporation panel is directly contacted with water in a storage tank. Also, at a conventional system a circulating pump, a circulating water distributor and a piping are installed, but these components are not necessary in a new method. In this study two kinds of ice storage systems are experimentally investigated to study the thermal characteristics of ice storage tanks. The results showed discharge of cold capacity of new type indicated the high values about 30~40% based on five time of drive, the temperature difference of inlet/outlet occurred the big range about $1.3^{\circ}C$. So, the new type which makes ice in water showed superiorly.

Measurement of Proton Beam Dose-Averaged Linear Energy Transfer Using a Radiochromic Film

  • Seohyeon An;Sang-il Pak;Seonghoon Jeong;Soonki Min;Tae Jeong Kim;Dongho Shin;Youngkyung Lim;Jong Hwi Jeong;Haksoo Kim;Se Byeong Lee
    • 한국의학물리학회지:의학물리
    • /
    • 제33권4호
    • /
    • pp.80-87
    • /
    • 2022
  • Purpose: Proton therapy has different relative biological effectiveness (RBE) compared with X-ray treatment, which is the standard in radiation therapy, and the fixed RBE value of 1.1 is widely used. However, RBE depends on a charged particle's linear energy transfer (LET); therefore, measuring LET is important. We have developed a LET measurement method using the inefficiency characteristic of an EBT3 film on a proton beam's Bragg peak (BP) region. Methods: A Gafchromic EBT3 film was used to measure the proton beam LET. It measured the dose at a 10-cm pristine BP proton beam in water to determine the quenching factor of the EBT3 film as a reference beam condition. Monte Carlo (MC) calculations of dose-averaged LET (LETd) were used to determine the quenching factor and validation. The dose-averaged LETs at the 12-, 16-, and 20-cm pristine BP proton beam in water were calculated with the quenching factor. Results: Using the passive scattering proton beam nozzle of the National Cancer Center in Korea, the LETd was measured for each beam range. The quenching factor was determined to be 26.15 with 0.3% uncertainty under the reference beam condition. The dose-averaged LETs were measured for each test beam condition. Conclusions: We developed a method for measuring the proton beam LET using an EBT3 film. This study showed that the magnitude of the quenching effect can be estimated using only one beam range, and the quenching factor determined under the reference condition can be applied to any therapeutic proton beam range.

살바도르 달리(Salvador Dali)의 회화에 나타난 편집광적 비판방법(Paranoiac Critical Method)을 활용한 네일아트에 관한 연구 (A Study on Nail Art Applying the Paranoiac Critical Method of Salvador Dali)

  • 정승은;김정미
    • 한국의상디자인학회지
    • /
    • 제16권2호
    • /
    • pp.151-161
    • /
    • 2014
  • This study suggests method of expression of nail art utilizing Salvador Dali's Paranoiac Critical Method and produced the actual works based on discussions on Salvador Dali's painting, Paranoiac Critical Method, Nail Art's artistry and technique of expression. The result of the study is as follows: 1) Characteristic of Dali's painting is a Paranoiac Critical Method. If suggesting this characteristic in a method of expression of nail art, a good work which can be expressed on a small space, a nail, representing Dali is selected and 5 tips which are very similar to the rate of the painting are used in order to obtain an aesthetic effect just like a painting. And after composing on tips using the whole paining or part of painting, actual techniques of expression such as Hand Painting, Protranse or Water Decal are used. 2) the result of nail art produced utilizing Dali's Paranoiac Critical Method is as follows. Most of all, for nail art I with the topic of "The Persistence of Memory" (1931), after giving changes to 5 tips for the watch which is a part of the painting, Hand Painting technique is used using Acrylic Painting with colors which are similar colors to the painting. Then for nail art II which adopted "Slave Market with Invisible Bust of Voltaire" (1940), the whole painting is divided into 5 tips and Protranse technique which attaches printed paper onto nails was used. Lastly, for nail art III with the subject of "The Enigma of Desire My Mother, My Mother, My Mother" (1929), Water Decal which is emphasizing the parts of the painting and composing on 5 tips and copying printed picture onto Water Transfer Paper in order to attach on the nails is used. These nail arts show aesthetic characteristics such as fantasy, unconsciousness, grotesque, infinity, non-realism and horror just like paintings.

  • PDF

강변여과수 시설에서의 지열에너지 활용 가능성 평가 (Assessment for geothermal energy utilization in the riverbank filtration facility)

  • 신지연;김경호;배광옥;이강근;정우성;석희준;김형수
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 한국신재생에너지학회 2007년도 추계학술대회 논문집
    • /
    • pp.485-488
    • /
    • 2007
  • Riverbank filtration is a kind of artificial aquifer recharge for the fresh water supply. By construction of several production wells penetrating the riverbank, surface water withdrawn from the river would pass riverbed. This extracted water is well known to be cooler than surface water in summer and warmer than surface water in winter, showing more constant water temperature. This characteristic of extracted water is applied to geothermal energy utilization. Prediction of the annual temperature variation of filtrated water is the major concern in this study. In Daesan-myeon, Changwon-si, Gyeongsangnam-do, South Korea, riverbank filtration facility has been on its operation for municipal water supply and thermal energy utilization since 2006. Appropriate hydraulic and thermal properties were estimated for flow and heat transfer modeling with given pumping rate and location. With the calibrated material properties and boundary conditions, we numerically reproduced measured head and temperature variation with acceptable error range. In the numerical simulation, the change of saturation ratio and river stage caused by rainfall was calculated and the resulting variation of thermal capacity and thermal conductivity was considered. Simulated temperature profiles can be used to assess the possible efficiency of geothermal energy utilization using riverbank filtration facility. Influence of pumping rate, pumping location on the extracted water temperature will be studied.

  • PDF