• Title/Summary/Keyword: Mass Flow Meter

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Heat Transfer Characteristics of Supercritical $CO_2$ in Helical Coil Gas Coolers on the Change of Coil Diameters (코일직경변화에 따른 헬리컬 코일형 가스냉각기내 초임계 이산화탄소의 냉각열전달 특성)

  • Son, Chang-Hyo
    • Journal of the Korean Institute of Gas
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    • v.11 no.3
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    • pp.44-48
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    • 2007
  • The cooling heat transfer characteristics of supercritical $CO_2$ in a helical coil gas cooler on the change of coil diameters are experimentally investigated. The main components of the refrigerant loop are a receiver, a variable speed pump, a mass flow-meter, a pre-heater and a helical coil gas cooler (test section). The test sections are made of a copper tube which the inner diameter is 4.55 mm and the helical coil diameters are done of 26.75 mm and 41.35 mm. The mass fluxes of refrigerant are varied from 200 to 800 [$kg/m^2s$] and the inlet pressures of gas cooler are 7.5 to 10.0 (MPa). A gas cooler with helical coil diameter of 26.75 mm has larger heat transfer coefficient than that of 41.35 mm. Also, when compared with experimental data and published correlations avaliable, most of correlations are under-predicted, but Pitla published correlations avaliable, most of correlations are under-predicted, but Pitla et al.'s correlation shows a relatively good coincidence with the experimental data except the region of pseudo critical temperature.

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Evaporation Heat Transfer Characteristics of $CO_2$ in a Horizontal Tube

  • Lee Dong-Geon;Son Chang-Hyo;Oh Hoo-Kyu
    • Journal of Advanced Marine Engineering and Technology
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    • v.29 no.3
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    • pp.297-305
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    • 2005
  • The evaporation heat transfer coefficient of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver. a variable-speed pump. a mass flow meter. a pre-heater and evaporator (test section). The test section consists of a smooth. horizontal stainless steel tube of 7.75 mm inner diameter. The experiments were conducted at mass flux of 200 to $500\;kg/m^{2}s$. saturation temperature of $-5^{\circ}C\;to\;5^{\circ}C$. and heat flux of 10 to $40\;kW/m^2$. The test results showed the evaporation heat transfer of $CO_2$ has greatly effect on more nucleate boiling than convective boiling. The evaporation heat transfer coefficients of $CO_2$ are highly dependent on the vapor quality. heat flux and saturation temperature. The evaporation heat transfer coefficient of $CO_2$ is very larger than that of R-22 and R-134a. In making a comparison between test results and existing correlations. the present experimental data are the best fit for the correlation of Jung et al. But it was failed to predict the evaporation heat transfer coefficient of $CO_2$ using by the existing correlation. Therefore. it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in a horizontal tube.

Evaporation Heat Transfer Characteristics of $CO_2$ in a Horizontal Tube

  • Son Chang-Hyo;Kim Dae-Hui;Choi Sun-Muk;Kim Young-Ryul;Oh Hoo-Kyu
    • International Journal of Air-Conditioning and Refrigeration
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    • v.13 no.4
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    • pp.167-174
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    • 2005
  • The evaporation heat transfer coefficient of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator (test section). The test section consists of a smooth horizontal stainless steel tube of 7.75 mm inner diameter. The experiments were conducted at mass flux of 200 to $500kg/m^2s$, saturation temperature of $-5^{\circ}C\;to\;5^{\circ}C$, and heat flux of 10 to $40kW/m^2$. The test results showed the evaporation heat transfer of $CO_2$ has greater effect on nucleate boiling than convective boiling. The evaporation heat transfer coefficient of $CO_2$ is highly dependent on the vapor quality, heat flux and saturation temperature. The evaporation heat transfer coefficient of $CO_2$ is very larger than that of R-22 and R-134a. In comparison with test results and existing correlations, the best fit of the present experimental data is obtained with the correlation of Jung et al. But the existing correlations failed to predict the evaporation heat transfer coefficient of $CO_2$. Therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in a horizontal tube.

Analysis of Heat Exchanging Performance of Heat Recovering Device Attached to Exhaust Gas Duct (열회수장치에 의한 열회수성능 분석)

  • 서원명;윤용철;강종국
    • Journal of Bio-Environment Control
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    • v.9 no.4
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    • pp.212-222
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    • 2000
  • This study was performed to investigate the performance of heat recovery device attached to exhaust gas flue connected to combustion chamber of greenhouse heating system. The experimental heat recovery system is mainly consisted of LPG combustion chamber and two heat recovery units; unit-A is attached directly to the exhaust gas flue, and unit-B is connected with unit-A. Heat recovery performance was evaluated by estimating total energy amounts by using enthalpy difference between two measurement points together with mass flow rate of gas and/or air passing through each heat recovery unit depending on 5 different flow rates controlled by voltage meter. The results of this experimental study, such as heat exchange behavior of supply air tubes and exhaust air passages crossing the tubes, pressure drop between inlet and outlet, heat recovery performance of exchange unit, etc., will be used as fundamental data for designing optimum heat recovery device to be used for fuel saving purpose by reducing heat loss amounts mostly wasted outside of greenhouse through flue.

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Improving Policy of Bunker Quality Management System in Korean Ports (우리나라 항만의 벙커 품질관리시스템 개선방안)

  • Kim, Hyung-Tae
    • Journal of Korea Port Economic Association
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    • v.38 no.2
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    • pp.11-30
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    • 2022
  • Korean ports have some problems in the aspect of quality & quantity in the bunkering process. Quality of bunker is assessed as more higher than competing ports. However, quality of bunkering procedure is assessed as lower. Especially, supply chain from loading of bunker to the bunker barge at oil terminal, transport it, and supply it to the ship has not been secured. Furthermore, aspect of quantity of bunker is more serious rather than that of quality of bunkering process. Disputes on the quantity of bunker between seller and buyer occur frequently, and residue & theft of bunker is also popularized issue and serious problem. Low bunkering fee is recognized as major reason of that problem, however, though low fee can be solved, it can not be necessary secured that problem could be solved, Therefore, this paper investigates and suggests the scheme to solve the quality problems of bunker supplying procedure, and develop solution toward advanced bunkering ports through removal of the quantity disputes. Concretely, this paper suggests introduction of quality system of bunker supply chain in the aspect of bunker supply procedure, and diversion from conventional sounding method to innovative Mass Flow Metering System in the aspect of bunker measuring. These two innovative solutions contribute to the removal and improvement of current structural problems in bunkering procedure.

The Time Responses of Spirometric Values in Response to Single Doses of Inhaled Salbutamol (기관지확장제 사용 후 시간에 따른 폐활량 측정치의 변화)

  • Park, Sun Hyo;Choi, Won-Il;Lee, Sang Won;Park, Hun Pyo;Seo, Yong Woo;Ku, Duk Hee;Lee, Mi Young;Lee, Choong Won;Jeon, Young June
    • Tuberculosis and Respiratory Diseases
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    • v.56 no.2
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    • pp.144-150
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    • 2004
  • Background : An assessment of the presence and the degree of reversibility of airflow obstruction is clinically important in patients with asthma or chronic obstructive pulmonary disease. However, the time responses of spirometric parameters in response to bronchodilator have not been well investigated. Methods: We studied 15 patients with asthma. Spirometric and mini-Wright peak expiratory flow measurements were performed at 15, 30, 45, and 60 minutes after using single dose($200{\mu}g$) of inhaled bronchodilator, salbutamol. Results : The mean values of forced expiratory volume in one second($FEV_1$) and forced vital capicaty(FVC) were significantly increased at 60 minutes after using bronchodilator in comparison to 15 minutes. And peak expiratory flow rate measured by either mass flow sensor or mini-Wright peak flow meter were significantly increased at 45 minutes after using bronchodilator in comparison to 15 minutes. Conclusions : To appropriate evaluation of the bronchodilator response in patients with reversible airflow limitation, it would be useful measuring either $FEV_1$ or PEF at the later time point 60 or 45 minutes in comparison to 15 minutes after using bronchodilator.

Evaporation Heat Transfer Characteristics of Carbon Dioxide in a Diameter Tube of 4.57mm (내경 4.57mm 관내 CO2의 증발 열전달 특성)

  • Son, Chang-Hyo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.3
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    • pp.574-579
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    • 2008
  • The evaporation heat transfer coefficient of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator (test section). The test section consists of a smooth, horizontal stainless steel tube of inner diameter of 4.57mm. The experiments were conducted at mass flux of 400 to $900kg/m^2s$, saturation temperature of 5 to $20^{\circ}C$, and heat flux of 10 to $40kW/m^2$. The test results showed the heat transfer of $CO_2$ has a greater effect on nucleate boiling more than convective boiling. Mass flux of $CO_2$ does not affect nucleate boiling too much. In comparison with test results and existing correlations, All of the existing correlations for the heat transfer coefficient underestimated the experimental data. However Jung et al.'s correlation showed a good agreement with the experimental data. Therefore, it is necessary to develope accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in horizontal tubes.

Estimation of Pollutant EMCs and Loadings in Highway Runoff (국내 고속도로 강우 유출수의 EMCs 및 유출 부하량 산정)

  • Kim, Lee-Hyung;Ko, Seok-Oh;Lee, Byung-Sik;Kim, Sunggil
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.2B
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    • pp.225-231
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    • 2006
  • The nonpoint source control is based on TPLMS (Total Pollution Load Management System) program. Recently, the Ministry of Environment in Korea has programed TPLMS for 4 major large rivers to improve the water quality in rivers by controling the total pollutant loadings from the watershed area. Usually the urbanization is the main pollutant sources, particularly for nonpoint pollutants, because of high imperviousness and high pollutant mass emissions. The stormwater runoff from urban areas is containing various pollutants such as sediments, metals and toxic chemicals due to human and vehicle activities. Of the various landuses, the highways are highly polluted landuses because of high pollutant accumulation rate by vehicle activities during dry periods. Therefore, this research is achieved to provide pollutant EMCs (Event Mean Concentrations) and mass loadings washed-off from highways during rainfall periods. Five monitoring locations were equipped with an automatic rainfall gage and an flow meter. The results show that the EMC ranges for 95% confidence intervals in highway land use are 45.52-125.76 mg/L for TSS, 52.04-95.48 mg/L for COD, 1.77-4.48 mg/L for TN, 0.29-0.54 mg/L for TP. The ranges of washed- off mass loading are $712.7-2,418.4mg/m^2$ for TSS and $684.1-1,779.6mg/m^2$ for COD.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

A study of improving filtration efficiency through SiC whisker synthesis on carbon felt by CVD VS method

  • Kim, Gwang-Ju;Choe, Du-Jin
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.150-150
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    • 2016
  • Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

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