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  • Title/Summary/Keyword: Drop-in Test

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Characteristics of Hydrocarbon Refrigerants on Evaporating Heat Transfer and Pressure Drop

  • Lee Ho-Saeng;Phan Thanh Tong;Yoon Jung-In
    • International Journal of Air-Conditioning and Refrigeration
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    • v.14 no.3
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    • pp.102-109
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    • 2006
  • Experimental results for heat transfer characteristics and pressure gradients of HCs refrigerants R-290, R-600a, R-1270 and HCFC refrigerant R-22 during evaporating inside horizontal double pipe heat exchangers are presented. The test sections which has one tube diameter of 12.70 mm with 0.89 mm wall thickness, another tube diameter of 9.52 mm with 0.76 mm wall thickness are used for this investigation. The local evaporating heat transfer coefficients of hydrocarbon refrigerants were higher than that of R-22. The average evaporating heat transfer coefficient increased with the increase of the mass flux, with the higher values in hydrocarbon refrigerants than R-22. Hydrocarbon refrigerants have higher pressure drop than R-22. Those results from the investigation can be used in the design of heat exchangers using hydrocarbons as the refrigerant for the air-conditioning systems.

Experimental study on the effects of stern bulb arrangement on the slamming load

  • Park, Jongyeol;Choi, Ju Hyuck;Lee, Hyun-ho;Rhee, Shin Hyung
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.12 no.1
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    • pp.518-530
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    • 2020
  • The present study concerns the stern slamming load of container carriers, with stern bulb arrangement variation. First, a series of wedge drop tests were conducted using simple wedge models with fixed deadrise angles, and tests with the cross-section models of practical container carrier sterns were followed. The deadrise angle of the simple wedge ranged from 0° to 10°. The pressure measurement results of the simple wedge drop tests were distributed between empirical formula and analytic solution, so the experimental setup was validated. In the cases of practical hull cross-sections, the water entry of the bulb prior to that of the transom resulted in characteristic water film generation and delayed pressure peak appearance. The trapped air between the bulbs damped the pressure in the twin skeg hull case, reducing the pressure peak and causing the pressure oscillation during water entry.

Heat Transfer Characteristics of Inclined Helical Coil Type Heat Exchanger (경사진 헬리컬 코일 열교환기의 열전달 특성에 관한 연구)

  • Son, Chang-Hyo;Jeon, Min-Ju;Jang, Seong-Il;Oh, Hoo-Kyu
    • Journal of Advanced Marine Engineering and Technology
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    • v.31 no.6
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    • pp.707-714
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    • 2007
  • The heat transfer coefficient and Pressure drop during gas cooling process of CO2 (R-744) in inclined helical coil copper tubes were investigated experimentally. The main components of the refrigerant loop are a receiver. a variable-speed pump. a mass flow meter, a pre-heater and a inclined helical coil type gas cooler (test section). The test section consists of a smooth copper tube of 2.45mm inner diameter. The refrigerant mass fluxes were varied from 200 to 600[kg/m2s] and the inlet Pressures of gas cooler were 7.5 to 10.0 [MPa]. The heat transfer coefficients of CO2 in the inclined helical coil tubes increases with the increase of mass flux and gas cooling pressure of CO2. The pressure drop of CO2 in the gas cooler shows a relatively good agreement with those Predicted by Ito's correlation developed for single-phase in a helical coil tube. The local heat transfer coefficient of CO2 agrees well with the correlation by Pitla et al. However, at the region near pseudo-critical temperature. the experiments indicate higher values than the Pitla et al. correlation. Therefore. various experiments in the inclined helical coil tubes have to be conducted and it is necessary to develop the reliable and accurate prediction determining the heat transfer and pressure drop of CO2 in the inclined helical coil tubes.

Pressure Drop due to Friction in Small Rectangular Channel (미소 사각 채널에서의 마찰 압력 강하)

  • Lim, Tae-Woo;Choi, Jae-Hyuk;Kim, Jun-Hyo;Choi, Yong-Suk
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.18 no.5
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    • pp.461-467
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    • 2012
  • An experimental study was carried out to measure frictional pressure drop in flow boiling to deionized water in a microchannel having a hydraulic diameter of 500μm. Tests were performed in the ranges of heat fluxes from 100 to 400kW/m2, vapor qualities from 0 to 0.2 and mass fluxes of 200, 400 and 600kg/m2s. The frictional pressure drop during flow boiling is predicted by using two models; the homogeneous model that assumes equal phase velocity and the separate flow model that allows a slip velocity between two phases. From the experimental results, it is found that the two phase multiplier decreases with an increase in mass flux. Measured data of pressure drop are compared to a few available correlations proposed for macroscale and mini/microscale. The homogeneous model well predicted frictional pressure drop within MAE of 29.4 % for the test conditions considered in this work.

A Study on the Tolerance Band of Voltage Drop during Motor Startup for Refineries and Chemical Plants with Isolated Power Systems

  • Shin, Ho-Jeon;Cho, Man-Young;Chun, Hong-Il;Kim, Jin-Seok
    • Journal of Electrical Engineering and Technology
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    • v.12 no.1
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    • pp.486-493
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    • 2017
  • Refineries and chemical plants with isolated power systems that have a limited power supply are more susceptible to voltage changes from disturbances compared to power systems connected with a power company. Furthermore, most loads in such cases are induction motor loads, and therefore, transient voltage characteristics when starting a high-capacity motor must be examined. In general, high-capacity motors are customized appropriately to the load performance curve by the manufacturer during the construction of an industrial plant. Subsequently, when complying with the voltage drop permitted by international standards during the design process, power supply equipment such as transformers and generators is overdesigned. Therefore, a novel analysis is necessary on standards for startup and constraint voltage drops, as well as on identifying the voltage drop limitations for starting high-capacity motors in refineries and chemical plants with isolated power systems. In this study, field tests on an industrial plant were conducted, and simulations modeled under conditions identical to those of the field test system were performed using the general-purpose program ETAP in order to compare the results.

An improved 1-D thermal model of parabolic trough receivers: Consideration of pressure drop and kinetic energy loss effects

  • Yassine Demagh
    • Advances in Energy Research
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    • v.8 no.1
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    • pp.21-39
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    • 2022
  • In this study, the first law of thermodynamics was used to establish a one-dimensional (1-D) thermal model for parabolic trough receiver (PTR) taking into account the pressure drop and kinetic energy loss effects of the heat transfer fluid (HTF) flowing inside the absorber tube. The validation of the thermal model with data from the SEGS-LS2 solar collector-test showed a good agreement, which is consistent with the previously established models for the conventional straight and smooth (CSS) receiver where the effects of pressure drop and kinetic energy loss were neglected. Based on the developed model and code, a comparative study of the newly designed parabolic trough S-curved receiver versus the CSS receiver was conducted and solar unit's performances were analyzed. Without any supplementary devices, the S-curved receiver enhances the performance of the parabolic trough module, with a maximum of 0.16% compared to CSS receiver with the same sizes and mass flow rates. Thermal losses were reduced by 7% due to the decrease in the temperature of the outer surface of the receiver tube. In addition, it has been shown that from a mass flow rate of 9.5 kg/s the heat losses of the S-curved receiver remain unchanged despite the improvement in the heat transfer rate.

"Cohesiveness of Hyaluronic Acid Fillers": Evaluation Using Multiple Cohesion Tests

  • Kyun Tae Kim;Won Lee;Eun-Jung Yang
    • Archives of Plastic Surgery
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    • v.51 no.1
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    • pp.14-19
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    • 2024
  • Background Hyaluronic acid fillers can be manufactured using various processes. They have multiple properties, including their concentration, degree of modification, and rheological data. Cohesion is one such property to evaluate gel integrity; however, there is no standardized method for calculating this parameter. This study aimed to evaluate different tests for calculating hyaluronic acid cohesion and discuss the importance of hyaluronic acid cohesion as a consideration when selecting fillers. Methods The cohesion levels of five different hyaluronic acid fillers with different rheological properties were evaluated and compared using the drop weight, compression, tack, and dispersion time tests. Results The cohesion tests yielded different results in the samples. Samples 2 and 4 showed approximately two times the number of droplets when compared with Sample 5 in drop weight test. Samples 1, 2, 3, and 4 were superior to Sample 5 in tack test. Samples 1, 2, and 3 showed cohesive appearances at 95 seconds in most cases in dispersion test. Rheological test results did not reflect the measures of cohesion. Conclusion Although there are no definite standardized tests to evaluate the cohesion of hyaluronic acid fillers, our proposed tests showed similar results for different hyaluronic acid filler products. Further studies are needed to evaluate the cohesion of hyaluronic acid fillers and determine the clinical use of this distinguishing characteristic for clinicians selecting the product of choice. Level of evidence statement: These data are Level IV evidence.

Heat Transfer and Pressure Drop Characteristics of Supercritical CO2 in a Helically Coiled Tube (초임계 CO2의 헬리컬 코일관 내 열선단과 압력강하 특성)

  • Yu, Tae-Guen;Kim, Dae-Hui;Son, Chang-Hyo;Oh, Hoo-Kyu
    • Proceedings of the SAREK Conference
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    • 2005.11a
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    • pp.353-358
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    • 2005
  • The heat transfer and pressure drop of supercritical CO2 cooled in a helically coiled tube was investigated experimentally. The experiments were conducted without oil in the refrigerant loop. The experimental apparatus of the refrigerant loop consist of receiver, a variable speed pump, a mass flowmeter, a pre-heater, a gas cooler(test section) and an isothermal tank. The test section is a helically coiled tube in tube counter flow heat exchanger with CO2 flowed inside the inner tube and coolant( water) flowed along the outside annular passage, It was made of it copper tube with the inner diameter of 4.55[mm]. the outer diameter of 6.35 [mm] and length of 10000 [mm]. The refrigerant mass fluxes were 200600 [kg/m2s] and the inlet pressure of gas cooler varied from 7.5 [MPa] to 10.0 [MPa]. The main results are summarized as follows : The heat transfer coefficient of supercritical CO2 increases, as the cooling pressure of gas cooler decreases. And the heat transfer coefficient increases with the increase of the refrigerant mass flux. The pressure drop decreases in increase of the gas cooler pressure and increases with increase the refrigerant mass flux.

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Analysis of Sodium Spray Fire Using Gaussian Droplet Size Distribution (Gaussian 액적 크기 분포 함수를 이용한 분무형 화재 현상 해석)

  • Kim, B.H.;Hahn, D.H.;Suh, S.H.
    • Journal of Hydrogen and New Energy
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    • v.15 no.1
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    • pp.72-81
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    • 2004
  • Study on the analysis of sodium spray fire using Gaussian drop size distribution, which redistributes a droplet spectrum with given mean diameter if its size classes with critical diameter(D>8mm) occur, was carried out. In this case, the oversized droplets were reduced to a stable diameter. Results calculated by the code using Gaussian drop size distribution were in better agreement with AI experimental results than those of NACOM and SPRAY code. The effect of variance on pressure in the test cell appeared greatly by introducing Gaussian function, which could represent various sodium droplet size distribution. The increase of the variance with mean droplet size resulted had an important effect upon the pressure in the test cell.

COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF THE CANADIAN DEUTERIUM URANIUM MODERATOR TESTS AT THE STERN LABORATORIES INC.

  • KIM, HYOUNG TAE;CHANG, SE-MYONG
    • Nuclear Engineering and Technology
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    • v.47 no.3
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    • pp.284-292
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    • 2015
  • A numerical calculation with the commercial computational fluid dynamics code CFX-14.0 was conducted for a test facility simulating the Canadian deuterium uranium moderator thermal-hydraulic. Two kinds of moderator thermal-hydraulic tests at Stern Laboratories Inc. were performed in the full geometric configuration of the Canadian deuterium uranium moderator circulating vessel, which is called a calandria tank, housing a matrix of horizontal rod bundles simulating calandria tubes. The first of these tests is the pressure drop measurement of a cross flow in the horizontal rod bundles. The other is the local temperature measurement on the cross section of the horizontal cylinder vessel simulating the calandria system. In the present study, the full geometric details of the calandria tank are incorporated in the grid generation of the computational domain to which the boundary conditions for each experiment are applied. The numerical solutions are reviewed and compared with the available test data.