Influence of the Pressure Load in the Efficiency of a Longitudinal Ventilation System in Road Tunnels

2009 ◽  
Author(s):  
Mo´nica Galdo-Vega ◽  
Carlos Santolaria-Morros ◽  
Jesu´s Manuel Ferna´ndez Oro ◽  
Katia Maria Argu¨elles-Di´az
Keyword(s):  
Momentum Transfer ◽  
Ventilation System ◽  
Operating Conditions ◽  
Traffic Density ◽  
Moderate Pressure ◽  
Pressure Gradients ◽  
Operational Parameters ◽  
Satisfactory Description ◽  
Longitudinal Ventilation ◽  
Road Tunnels

The longitudinal ventilation system (LVS) efficiency in road tunnels is conditioned by geometric and operational parameters. Typical geometric parameters are the length of the tunnel, its slope and the transversal section. All these factors are generally fixed and thus not modifiable in the regular operation of the facility. On the other hand, operational parameters, like the working fans layout, the environmental conditions or the traffic density are case-sensitive and susceptible to influence the baseline performance of the ventilation system. In the present study, different pressure gradients, established between inlet and outlet location of the jet fan influence, are analyzed. This static resistance is shown to have a significant impact on the momentum transfer established between the jet expansion and the bulk flow inside the tunnel. For moderate pressure gradients, the jet discharged from fan is relativity well-mixed, allowing to reach uniform flow conditions in the streamwise direction. When the adverse pressure gradients become severe, the high-velocity flow is blocked, unable to mix out in the inter fan spacing and losing spanwise uniformity. At critical conditions, large recirculation areas can be developed within primary flow structures, generating turbulence and important energy losses, and even inducing reverse flow at the tunnel exit. The extreme operating conditions of a longitudinal ventilation system in a road tunnel have been studied using a 3D numerical simulation. Preliminary analysis for grid sensitivity and election of an accurate turbulence closure were performed to guarantee a valuable modeling. Following, systematic computations over a cluster of PC’s were executed using the well-tested Fluent code. RANS modeling with RSM scheme allowed a satisfactory description of three-dimensional vortical structure in the recirculation zones, especially for adverse pressure gradients. At this point, numerical results have provided a comprehensive overview of the mechanism associated to the momentum transfer of the jet expansion, comparing the performance for zero-pressure gradients with those observed for adverse conditions. Also, this paper gives valuable information about practical limits of the LVS, advancing operational conditions that compromise the ventilation efficiency.

Numerical Modeling and Experimental Studies of the Operational Parameters of the Earth-To-Air Heat Exchanger of the Geothermal Ventilation System

2021 ◽  
Vol 23 ◽  
pp. 42-64
Author(s):  
Boris Basok ◽  
Ihor Bozhko ◽  
Maryna Novitska ◽  
Aleksandr Nedbailo ◽  
Myroslav Tkachenko
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Ventilation System ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Operational Parameters ◽  
Cross Sectional ◽  
Distinctive Features ◽  
Sectional Shape ◽  
Experimental Bench

This article is devoted to the analysis of the heat engineering characteristics of the operation of an Earth-to-Air Heat Exchanger, EAHE, with a circular cross-sectional shape, which is a component of the geothermal ventilation system. The authors analyzed literature sources devoted to the research of heat exchangers of the soil-air type of various designs and for working conditions in various soils. Much attention is paid to the issues of modeling the operation of such heat exchangers and the distinctive features of each of these models. Also important are the results of experimental studies carried out on our own experimental bench and with the help of which the numerical model was validated. The results of these studies are the basis for the development of a method for determining the optimal diameter of an EAHE under operating conditions for soil in Kyiv, Ukraine.

Theoretical Analysis of Longitudinal Ventilation System in a Road Tunnel for Predictive Control Based on Inertia Effect

2013 ◽  
Vol 639-640 ◽  
pp. 665-669 ◽  
Author(s):  
Zhen Tan ◽  
Zhi Yi Huang ◽  
Ke Wu ◽  
Lei Ting Xu
Keyword(s):  
Theoretical Analysis ◽  
Predictive Control ◽  
Ventilation System ◽  
Settling Time ◽  
Step Response ◽  
Inertia Effect ◽  
Road Tunnel ◽  
Longitudinal Ventilation ◽  
Road Tunnels ◽  
Co Concentration

Speed control of longitudinal ventilation systems in road tunnels is being combined with typical model predictive control (MPC) strategies which may bring huge energy saving potential to the system. Theoretical analysis of the inertia effect is presented based on the energy equation of one dimensional incompressible unsteady flow, step response model is chosen to describe the dynamic behaviors of the system. The results show that the effect of jet speed change on CO concentration is nonlinear within fan’s economical working range and the settling time of CO level has similar change trend with that of the flow field but is a little longer. The system settling time is longer when jet speed decreases than it increases and is related to the change extent of jet speed. The effect of traffic intensity on CO concentration can be regarded as linear disturbance to the system output. These results may provide useful indexes to control the tunnel ventilation system more economically and lay foundation for the application of predictive control strategy in the system.

scholarly journals Numerical modelling of parameters of the operational parameters of an earth-to-air heat exchanger for geothermal ventilation

2020 ◽  
Vol 35 ◽  
pp. 41-48
Author(s):  
O. Nedbailo ◽  
I.. Bozhko ◽  
M. Tkachenko ◽  
S. Andreychuk
Keyword(s):  
Heat Exchanger ◽  
Numerical Model ◽  
Heat Exchangers ◽  
Ventilation System ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Operational Parameters ◽  
National Academy Of Sciences ◽  
Cross Sectional ◽  
Climate Conditions

The aim of this work is to develop a numerical model of the year-round operation of an earth-to-air heat exchanger (EAHE) with a circular cross-sectional shape with further its validation based on the obtained experimental data. We consider that these studies can form the basis for the development of methods for calculating and designing geothermal ventilation systems for climate conditions of Ukraine. The analysis of literature sources showed that now there are quite a lot of studies devoted to the issues of geothermal ventilation. The results of such heat exchanger modeling with various geometric data and which operate in their authentic soils under various hydraulic regimes and that are located at different depths are widely presented. However, these studies do not allow obtaining generalized patterns of heat transfer during the operation of the heat exchangers and the influence of the geometric parameters of the heat exchanger on the operation of the geothermal ventilation system as a whole. Much attention is paid to the issues of modelling the operation of such heat exchangers and the distinctive features of each of these models. Also important are the results of experimental studies carried out on our own experimental bench and with the help of which the numerical model was validated. To conduct experimental research on the operation of the geothermal ventilation system at the Institute of Engineering Thermophysics of the National Academy of Sciences of Ukraine an experimental stand was created. This stand is designed to study thermophysical processes during the operation of a geothermal ventilation system elements. The results of these studies are the basis for the development of a method for determining the optimal diameter of the earth-to-air heat exchanger under operating conditions for soil in Kyiv, Ukraine.

COMPARISON BETWEEN LONGITUDINAL VENTILATION SYSTEM AND POINT EXTRACTION SYSTEM IN ROAD TUNNEL FIRE SAFETY

2021 ◽  
Vol 77 (1) ◽  
pp. 41-59
Author(s):  
Ti-Sheng HUANG ◽  
Nobuyoshi KAWABATA ◽  
Miho SEIKE ◽  
Masato HASEGAWA ◽  
Futoshi TANAKA ◽  
...  
Keyword(s):  
Fire Safety ◽  
Ventilation System ◽  
Extraction System ◽  
Road Tunnel ◽  
Tunnel Fire ◽  
Longitudinal Ventilation

Sootblowing Optimization Improves Heat Rate and Enhances Operational Flexibility at Hawthorn Unit 5

2014 ◽  
Author(s):  
Neel J. Parikh ◽  
Peter Rogge ◽  
Kenneth Luebbert
Keyword(s):  
Control System ◽  
Closed Loop ◽  
Heat Rate ◽  
Operating Conditions ◽  
Operational Experience ◽  
Unit Operation ◽  
Gas Temperature ◽  
Dynamic Adjustment ◽  
Operational Parameters ◽  
Unit Load

Coal-fired units are increasingly expected to operate at varying loads while simultaneously dealing with various operational influences as well as fuel variations. Maintaining unit load availability while managing adverse effects of various operational issues such as, flue gas temperature excursions at the SCR inlet, high steam temperatures and the like presents significant challenges. Dynamic adjustment of sootblowing activities and different operational parameters is required to effectively control slagging, fouling and achieve reliability in unit operation. Closed-loop optimizers aim to reduce ongoing manual adjustments by control operators and provide consistency in unit operation. Such optimizers are typically computer software-based and work by interfacing an algorithmic and/or artificial intelligence based decision making system to plant control system [1]. KCP&L is in the process of implementing Siemens SPPA-P3000 combustion and sootblowing optimizers at several Units. The Sootblowing Optimizer solution determines the need for sootblowing based on dynamic plant operating conditions, equipment availability and plant operational drivers. The system then generates sootblower activation signals for propagation in a closed-loop manner to the existing sootblower control system at ‘optimal’ times. SPPA-P3000 Sootblowing Optimizer has been successfully installed at Hawthorn Unit 5, a 594-MW, wall-fired boiler, firing 100 percent Powder River Basin coal. This paper discusses implementation approach as well as operational experience with the Sootblowing Optimizer and presents longer-term operational trends showing unit load sustainability and heat rate improvement.

Studying Systems of Stabilization of Supports in Hydrostatic Machine Tool

2012 ◽  
Vol 622-623 ◽  
pp. 489-493
Author(s):  
Iskander Beisembetov ◽  
Sabyi Ussupov ◽  
Bakhyt Absadykov ◽  
Beken Arymbekov ◽  
Birzhan Bektibay
Keyword(s):  
Film Thickness ◽  
Machine Tools ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Operational Parameters ◽  
Automatic Stabilization ◽  
Design Elements ◽  
Oil Film ◽  
Hydrostatic Bearing ◽  
Automatic Control Systems

Development relevance to improve the operational parameters of the support units of machine tools in their design elements is introduced that increase the rigidity of the components, their carrying capacity, damp occurring vibrations in the process, the coefficient of performance (COP), smoothness of motion, positioning accuracy, reducing the wear of their working surfaces and maintain the original accuracy. A number of engineering development [1], [2], aimed at improving the above characteristics of the machine by changing and improving design of reference nodes used in these rails rolling bearings, aerostatic and hydrostatic guides, as well as the use of automatic control systems of its basic parameters, determine its quality. However, in some operating conditions in which errors occur, mainly due to the instability of oil-film thickness (gap) between the mobile and immobile elements of the hydrostatic bearing. For high accuracy requirements it will negatively affect the quality of machined parts and equipment performance. On this basis, it becomes apparent urgency of the problem of automatic stabilization of oil-film thickness (gap) in the IR. To ensure high precision equipment to improve power system hydrostatic bearing units of machine tools. This, in turn, creates the prerequisite for the development of stabilization systems of the gap in the hydrostatic bearing, with the help of which the thickness of oil layer in them would be kept constant even with significant dynamic load on the support.

Data Analytics into Hydraulic Modelling for Better Understanding of Well/Surface Network Limits, Proactively Identify Challenges and, Provide Solutions for Improved System Performance in the Greater Burgan Field

2021 ◽  
Author(s):  
Qasem Dashti ◽  
Saad Matar ◽  
Hanan Abdulrazzaq ◽  
Nouf Al-Shammari ◽  
Francy Franco ◽  
...  
Keyword(s):  
Production Management ◽  
Planning Process ◽  
System Optimization ◽  
Development Planning ◽  
Operating Conditions ◽  
Flow Assurance ◽  
Operational Parameters ◽  
Field Development ◽  
Hydraulic Models ◽  
Surface Network

Abstract A network modeling campaign for 15 surface gathering centers involving more than 1800 completion strings has helped to lay out different risks on the existing surface pipeline network facility and improved the screening of different business and action plans for the South East Kuwait (SEK) asset of Kuwait Oil Company. Well and network hydraulic models were created and calibrated to support engineers from field development, planning, and operations teams in evaluating the hydraulics of the production system for the identification of flow assurance problems and system optimization opportunities. Steady-state hydraulic models allowed the analysis of the integrated wells and surface network under multiple operational scenarios, providing an important input to improve the planning and decision-making process. The focus of this study was not only in obtaining an accurate representation of the physical dimension of well and surface network elements, but also in creating a tool that includes standard analytical workflows able to evaluate wells and surface network behavior, thus useful to provide insightful predictive capability and answering the business needs on maintaining oil production and controlling unwanted fluids such as water and gas. For this reason, the model needs to be flexible enough in covering different network operating conditions. With the hydraulic models, the evaluation and diagnosis of the asset for operational problems at well and network level will be faster and more effective, providing reliable solutions in the short- and long-terms. The hydraulic models enable engineers to investigate multiple scenarios to identify constraints and improve the operations performance and the planning process in SEK, with a focus on optimal operational parameters to establish effective wells drawdown, evaluation of artificial lifting requirements, optimal well segregation on gathering centers headers, identification of flow assurance problems and supporting production forecasts to ensure effective production management.

Influence of Operational Parameters on Photocatalytic Degradation of Linuron in Aqueous TiO2 Pillared Montmorillonite Suspension

2021 ◽  
Vol 16 (3) ◽  
pp. 673-685
Author(s):  
D. Hadj Bachir ◽  
Hocine Boutoumi ◽  
H. Khalaf ◽  
Pierre Eloy ◽  
J. Schnee ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Physicochemical Characterization ◽  
Operating Conditions ◽  
Cod Removal ◽  
Pollutant Concentration ◽  
Catalyst Loading ◽  
Operational Parameters ◽  
X Ray ◽  
Pillared Montmorillonite ◽  
Initial Ph

TiO2 pillared clay was prepared by intercalation of titan polyoxocation into interlamelar space of an Algerian montmorillonite and used for the photocatalytic degradation of the linuron herbicide as a target pollutant in aqueous solution. The TiO2 pillared montmorillonite (Mont-TiO2) was characterized by X-ray photoelectron spectroscopy (XPS), X-Ray diffraction (XRD), X-Ray fluorescence (XRF), scanning electronic microscopy (SEM), thermogravimetry and differential thermal analysis (TG-DTA), Fourier transformed infra-red (FT-IR), specific area and porosity determinations. This physicochemical characterization pointed to successful TiO2 pillaring of the clay. The prepared material has porous structure and exhibit a good thermal stability as indicated by its surface area after calcination by microwave. The effects of operating parameters such as catalyst loading, initial pH of the solution and the pollutant concentration on the photocatalytic efficiency and COD removal  were evaluated. Under initial pH of the solution around seven, pollutant concentration of 10 mg/L and 2.5 g/L of catalyst at room temperature, the degradation efficiency and COD removal of linuron was best then the other operating conditions. It was observed that operational parameters play a major role in the photocatalytic degradation process. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

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