충격기류식 여과집진장치의 운전조건 변화에 따른 적정 탈진주기 및 탈진압력 설정

이덕기 ( Deok-gi Lee ),임우택 ( Woo-taik Lim ),조재환 ( Jae-hwan Cho ),최금찬 ( Kum-chan Choi ),신현무 ( Hyun-moo Shin ),장성호 ( Seong-ho Jang ),서정민 ( Jeong-min Suh ) 한국환경과학회 2018 한국환경과학회지 Vol.27 No.6

In this study, using coke dust from ironwork, the pulse pressure on a pulse air jet bag filter was investigated considering the influence of the pressure loss due to filtration velocity and pressure intervals. The research on the optimal pulse pressure prediction of a pulse air jet type bag filter using coke dust showed the following results. Pressure loss volatility produced by the pulse pressure under low dust concentration(0.5, 1 g/m³) and low face velocity(1.25 m/min) was less than 10 mmH₂O. This suggests that the pulse pressure has a low impact on the pressure loss. In contrast, pressure loss volatility under high dust concentration(3g/m³) and high face velocity(1.75 m/min) was 25 mmH₂O. Therefore, pulse pressure with high dust concentration and high face velocity has a strong influence on the pressure loss volatility, compared to the condition of low dust concentration and low face velocity. The optimal pulse pressure of inlet dust concentration(0.5 g/m³) was 6 kg/cm² under the same face velocity(1.75 m/min). As concentration increased from 1 to 2 g/m³, the pulse pressure gradually reached 5 kg/cm² thus indicating that the pulse pressure(5 kg/cm²) is pertinent at a high concentration(3 g/m³) The pulse intervals: 20, 25 and 30 sec, which are relatively longer than 10 and 15 sec, corresponded to high pressure loss volatility produced by the pulse pressure. Furthermore, low pressure loss volatility was noted at 5 kg/cm² of the overall pulse pressure.

소방호스 전개 상태에 따른 압력손실 실험연구

이형은(Hyung Eun Lee) 국립소방연구원 2020 소방안전연구 Vol.1 No.1

본 연구에서는 평지에서 소방호스 전개 상태에 따른 압력손실을 피에조미터로 측정하였다. 측정 결과 소방호스가 많이 꺾일수록 압력손실은 커지는 것으로 측정되었다. 소방호스 3개가 180도 꺾인 상태에서의 압력손실이 71.9%로 최대치였다. 이처럼 소방호스 전개 상태에 따라, 방수압력과 유량이 충분하지 않아 화재진압능력이 저하될 가능성이 있다. 현장대응을 보다 효율적으로 하기 위해 소방호스의 상태별 압력손실값은 유용한 정보가 될 것이며, 현장에서는 이를 참고하여 소방호스의 압력손실을 고려한 소방호스 전개가 이루어지기를 기대한다. This study reviews water pressure loss in fire hoses under various deployment situations. Pressure loss was measured using a piezo-meter connected next to the nozzle. Water pressure loss was measured by varying the number of fire hoses and the folding angle. According to the measurement, the pressure loss rate was the highest at 71.9 percent when three fire hoses were folded at 180 degrees. The other words, pressure loss in fire hose may also occur due to various deployment situations of the fire hose. Pressure loss may reduce firefighting capacity by reducing the water pressure and water flow below the level required for putting out the fire. Therefore, this study measures pressure loss under various deployment situations and propose ways to minimize pressure loss.

DFSS를 이용한 Air induction system의 pressure loss 개선을 위한 inlet duct 최적화 연구

박원준(Wonjun Park),김선우(Sunwoo Kim),조은희(Eunhee Cho) 한국자동차공학회 2016 한국자동차공학회 학술대회 및 전시회 Vol.2016 No.11

Main function of Air induction system (AIS) is to allow clean air to read to power train (PT). In order to transfer enough clean air to PT, it is important to minimize loss which is been occurred when airflow is transferred from AIS to PT. this loss is a pressure loss. This paper is an inlet duct optimization study of Air induction system in order to minimize pressure loss with DFSS. Inlet duct is said snorkel, this is first inlet section in which air is introduced and has free design variable than other parts, air box and clean side duct. On the other hands, it should be considered of a design to be able to allow enough clean air from inlet snorkel to PT for securing airflow. In addition, snorkel has various design constrain condition due to clearance issue between AIS and PT and has long design distance so, it is easy to occur high-pressure loss. Control factor for DFSS are inlet shape, airflow corner and bell mouth, which is, supported well flow. Then I make various analysis matrix and then, find good design to be able improve pressure loss. Through this, I would like to present guideline for improvement of pressure loss.

Simple Pressure Sensor for a Vehicle Seat Using a Woven Polymer Optical-fiber Sheet

이태호,김응수,김태훈,정명영 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.12

We developed a textile pressure sensor sheet for a vehicle seat by weaving polymer optical fibers (POFs). The vehicle-seat pressure sensor was fabricated in the form of a sheet by weaving POFs and fiber yarns. The weaving was performed in the form of a mesh structure so that intersections occurred between the woven POFs. When incident light from a light source passes through the inner POF sections of the textile pressure sensor, it suffers optical losses owing to bending at the intersection regions, and these losses linearly increase with increasing applied pressure. The curvature and the deformation occurring in the intersection regions were analyzed by using a multiphysics tool, and the results were optically analyzed by using a 2D Beam propagation method. The analysis results indicated that a curvature of approximately 135 mm occurred, assuming that a pressure of 4 kPa occurred when a maximum load of 100 kg was applied to the vehicle seat. The areas for analyzing were selected on the basis of the results from the curvature analysis. The results from analyzing the curvatures, which ranged from 200 to 1000 mm, indicated that a maximum loss of approximately 1.2 dB occurred. A linear increase in the optical losses with increasing pressure was experimentally confirmed for the woven textile pressure sensor, and a vehicle textile sensor with a low-cost Photodiode (PD) was developed by considering the soft characteristics of the vehicle seat and analyzing the multiple POF intersection regions.

CFD ANALYSIS OF HEAVY LIQUID METAL FLOW IN THE CORE OF THE HELIOS LOOP

Batta, A.,Cho, Jae-Hyun,Class, A.G.,Hwang, Il-Soon Korean Nuclear Society 2010 Nuclear Engineering and Technology Vol.42 No.6

Lead-alloys are very attractive nuclear coolants due to their thermo-hydraulic, chemical, and neutronic properties. By utilizing the HELIOS (Heavy Eutectic liquid metal Loop for Integral test of Operability and Safety of PEACER$^2$) facility, a thermal hydraulic benchmarking study has been conducted for the prediction of pressure loss in lead-alloy cooled advanced nuclear energy systems (LACANES). The loop has several complex components that cannot be readily characterized with available pressure loss correlations. Among these components is the core, composed of a vessel, a barrel, heaters separated by complex spacers, and the plenum. Due to the complex shape of the core, its pressure loss is comparable to that of the rest of the loop. Detailed CFD simulations employing different CFD codes are used to determine the pressure loss, and it is found that the spacers contribute to nearly 90 percent of the total pressure loss. In the system codes, spacers are usually accounted for; however, due to the lack of correlations for the exact spacer geometry, the accuracy of models relies strongly on assumptions used for modeling spacers. CFD can be used to determine an appropriate correlation. However, application of CFD also requires careful choice of turbulence models and numerical meshes, which are selected based on extensive experience with liquid metal flow simulations for the KALLA lab. In this paper consistent results of CFX and Star-CD are obtained and compared to measured data. Measured data of the pressure loss of the core are obtained with a differential pressure transducer located between the core inlet and outlet at a flow rate of 13.57kg/s.

CFD ANALYSIS OF HEAVY LIQUID METAL FLOW IN THE CORE OF THE HELIOS LOOP

A. BATTA,JAE HYUN CHO,A.G. CLASS,IL SOON HWANG 한국원자력학회 2010 Nuclear Engineering and Technology Vol.42 No.6

Lead-alloys are very attractive nuclear coolants due to their thermo-hydraulic, chemical, and neutronic properties. Byutilizing the HELIOS (Heavy Eutectic liquid metal Loop for Integral test of Operability and Safety of PEACER2) facility, athermal hydraulic benchmarking study has been conducted for the prediction of pressure loss in lead-alloy cooled advancednuclear energy systems (LACANES). The loop has several complex components that cannot be readily characterized withavailable pressure loss correlations. Among these components is the core, composed of a vessel, a barrel, heaters separatedby complex spacers, and the plenum. Due to the complex shape of the core, its pressure loss is comparable to that of the restof the loop. Detailed CFD simulations employing different CFD codes are used to determine the pressure loss, and it is foundthat the spacers contribute to nearly 90 percent of the total pressure loss. In the system codes, spacers are usually accountedfor; however, due to the lack of correlations for the exact spacer geometry, the accuracy of models relies strongly on assumptionsused for modeling spacers. CFD can be used to determine an appropriate correlation. However, application of CFD alsorequires careful choice of turbulence models and numerical meshes, which are selected based on extensive experience withliquid metal flow simulations for the KALLA lab. In this paper consistent results of CFX and Star-CD are obtained andcompared to measured data. Measured data of the pressure loss of the core are obtained with a differential pressure transducerlocated between the core inlet and outlet at a flow rate of 13.57kg/s

코어유동모델과 익형이론을 이용한 사이클론 동압회복 기구의 설계

허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.9

Pressure loss of cyclone consists of cyclone body friction loss and dynamic pressure loss of vortex finder which hold most of cyclone pressure loss. The pressure recovery vane or rectifier is generally used mechanism to convert rotational flow in vortex finder into axial flow. Conventional circular arc rectifier has no theoretical design guide line and depends on trial error. In this paper, we propose a theoretical design method of pressure recovery vane to reduce pressure loss in cyclone vortex finder. Core flow model is used to decide the angle of attack and width of vane. Theory shows that there exists an effective width of vane. The shape of pressure recovery vane is borrowed from the static blade of axial blower using NACA airfoil data. The design method of axial blower static blade provides theoretical guide line that can decide number of vane and stagger angle.

Numerical Investigation of the Pressure-Time Method, Head loss in Developed and Developing Flows

Mehrdad Kalantar Neyestanaki,Georgiana Dunca,Pontus Jonsson,Michel J. Cervantes 한국유체기계학회 2023 International journal of fluid machinery and syste Vol.16 No.4

Hydraulic efficiency is a crucial parameter in estimating the performance of hydraulic turbines. However, the flow rate makes such estimation challenging. Several methods have been developed over the years to measure the flow rate. The pressure-time method is an accurate and inexpensive alternative for flow rate estimation, based on transforming momentum into pressure during the deceleration of a liquid mass. The flow rate is obtained by integrating the differential pressure and the pressure loss history between two cross-sections. In the present work, three-dimensional (3D) computational fluid dynamics (CFD) analyses are performed to investigate in detail the influence of the head loss due to friction over the method accuracy when applied in developing flows. One important novelty of the CFD analyses is the use of the immersed solid method for the valve movement modeling for studying the pressure-time method, which is less expensive and more stable than the dynamic mesh method applied in previous CFD studies. The losses are investigated with the assumptions of constant, quasi-steady and unsteady friction factors and compared with detailed data obtained from CFD simulation. The calculated flow rate is not found to be precisely related to the initial pressure drop based on quasi-steady and unsteady friction factors in developing flows. Therefore, a friction factor correction coefficient is proposed and implemented, decreasing the error. The numerical results are validated with experimental data and compared with the dynamic mesh method.

The loss coefficient for fluctuating flow through a dominant opening in a building

Haiwei Xu,Shice Yu,Wenjuan Lou 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.24 No.1

Wind-induced fluctuating internal pressures in a building with a dominant opening can be described by a second-order non-linear differential equation. However, the accuracy and efficiency of the governing equation in predicting internal pressure fluctuations depend upon two ill-defined parameters: inertial coefficient CI and loss coefficient CL, since CI determines the un-damped oscillation frequency of an air slug at the opening, while CL controls the decay ratio of the fluctuating internal pressure. This study particularly focused on the value of loss coefficient and its influence factors including: opening configuration and location, internal volumes, as well as wind speed and approaching flow turbulence. A simplified formula was presented to predict loss coefficient, therefore an approximate relationship between the standard deviation of internal and external pressures can be estimated using Vickery\'s approach. The study shows that the loss coefficient governs the peak response of the internal pressure spectrum which, in turn, will directly influence the standard deviation of the fluctuating internal pressure. The approaching flow characteristic and opening location have a remarkable effect on the parameter CL.

The loss coefficient for fluctuating flow through a dominant opening in a building

Xu, Haiwei,Yu, Shice,Lou, Wenjuan Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.24 No.1

Wind-induced fluctuating internal pressures in a building with a dominant opening can be described by a second-order non-linear differential equation. However, the accuracy and efficiency of the governing equation in predicting internal pressure fluctuations depend upon two ill-defined parameters: inertial coefficient $C_I$ and loss coefficient $C_L$, since $C_I$ determines the un-damped oscillation frequency of an air slug at the opening, while $C_L$ controls the decay ratio of the fluctuating internal pressure. This study particularly focused on the value of loss coefficient and its influence factors including: opening configuration and location, internal volumes, as well as wind speed and approaching flow turbulence. A simplified formula was presented to predict loss coefficient, therefore an approximate relationship between the standard deviation of internal and external pressures can be estimated using Vickery's approach. The study shows that the loss coefficient governs the peak response of the internal pressure spectrum which, in turn, will directly influence the standard deviation of the fluctuating internal pressure. The approaching flow characteristic and opening location have a remarkable effect on the parameter $C_L$.