Performance of Sprinkler in Atria

1996 ◽  
Vol 14 (6) ◽  
pp. 466-488 ◽  
Author(s):  
W.K. Chow
Keyword(s):  
Response Time ◽  
Thermal Response ◽  
Sprinkler System ◽  
Water Requirement ◽  
Zone Model ◽  
Activation Time ◽  
Fire Plume ◽  
Coeffi Cients ◽  
Different Response ◽  
Sprinkler Head

The performance of a sprinkler installed in an atrium roof was evaluated in this paper by considering three points: possibility of activating the sprinkler head, thermal response, and water requirement. Crude analysis us ing the empirical expressions of the fire plume and the zone model CFAST 2.0 were used to study the possibility of activating the sprinkler head. Smoke spreading out from a fire shop to the atrium was discussed. The software DETACT was used to calculate the activation time for the sprinkler heads of different response time indices installed at different ceiling heights under unsteady t-squared fires. Correlation expressions of the activation time with ceiling height, response time indices of the sprinkler head, fire growth coeffi cients, and ambient temperature were derived. The water requirement at the atrium floor was discussed by calculating the trajectories of water droplets. Higher flow rate and pressure are required for discharging the same water den sity at the floor level. Results indicated that installing an ordinary sprinkler system in a high headroom atrium would not be effective in controlling a fire.

Thermal Response Time of LV Fuse Gear in Secondary Substations and Cable Distribution Cabinets

2021 ◽  
Author(s):  
E. Fjeld ◽  
O. D. Sjaastad ◽  
W. Rondeel ◽  
T. R. Eriksen ◽  
F. W. Bekken
Keyword(s):  
Response Time ◽  
Thermal Response ◽  
Thermal Response Time

scholarly journals 3D Mapping of the Sprinkler Activation Time

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1450
Author(s):  
Wojciech Węgrzyński ◽  
Grzegorz Krajewski ◽  
Piotr Tofiło ◽  
Wolfram Jahn ◽  
Aleksander Król ◽  
...  
Keyword(s):  
Fire Safety ◽  
Natural Ventilation ◽  
Sprinkler System ◽  
Activation Time ◽  
Ansys Fluent ◽  
Design Fire ◽  
Novel Approach ◽  
Rti Model ◽  
Safety Features

Sprinkler activation is one of the key events defining the course of a compartment fire. The time when activation occurs is commonly used in the determination of the design fire scenario, which is the cornerstone of the design of building fire safety features. A well-known model of sprinkler activation (response time index (RTI) model) was introduced into the numerical scheme of the ANSYS Fluent computational fluid dynamics (CFD) package. The novel way in which the model is used is the calculation of the time for sprinkler activation within each discrete cell of the domain. The proposed novel approach was used in a case-study to assess the effects of comfort mode natural ventilation on a sprinkler’s activation pattern. It was found that hinged vents in the comfort mode had a significant effect on sprinkler activation, both in terms of delaying it as well as limiting the total number of cells in which the sprinkler would have activated. In some scenarios with a hinged vent, no activation was observed in the central point of the vent, possibly indicating problems with the autonomous triggering of the fire mode of such a device. It was also found that the RTI and C (related to the conductive transport of sprinkler fitting) parameter values had a moderate influence on sprinkler activation time—only for high-temperature sprinklers (≥ 141 °C). This study shows the applicability of the 3D activation time mapping for research focused on the fire safety of sprinkler-protected compartments and for the performance-based approach to sprinkler system design. Even though the RTI model is the industry standard for the determination of sprinkler response, the model implementation in ANSYS Fluent was not validated. This means that sources of uncertainty, mainly connected with the determination of flow velocity and temperature are not known, and the model should be used with caution. An in-depth validation is planned for subsequent studies.

Machine learning-based thermal response time ahead energy demand prediction for building heating systems

2018 ◽  
Vol 221 ◽  
pp. 16-27 ◽  
Author(s):  
Yabin Guo ◽  
Jiangyu Wang ◽  
Huanxin Chen ◽  
Guannan Li ◽  
Jiangyan Liu ◽  
...  
Keyword(s):  
Machine Learning ◽  
Response Time ◽  
Energy Demand ◽  
Thermal Response ◽  
Heating Systems ◽  
Demand Prediction ◽  
Thermal Response Time ◽  
Energy Demand Prediction

Fluid-Structure Simulations for a 2D Fire Applications

2005 ◽  
Author(s):  
Wei Xie ◽  
Changsong Luo ◽  
Paul E. DesJardin
Keyword(s):  
Mass Transfer ◽  
Level Set ◽  
Stokes Equations ◽  
Numerical Algorithms ◽  
Thermal Response ◽  
Navier Stokes ◽  
Fire Plume ◽  
Fluid Structure ◽  
Local Boundary ◽  
Level Set Function

This study is on the development of numerical algorithms and models for simulation of a structure response in a fire. The flow field from the fire plume is modeled using the 2D Navier-Stokes equations supplemented with a transport equation for thermal energy and solved using a vorticity-streamfunction approach. Coupling of the fluid to the FEM based structure model is based on the use of a level set method describing the structure geometry in the fluid domain. The level set function allows for computation of normal gradients at the fluid-solid interface to enforce local boundary conditions of heat and mass transfer at prescribed fluid-structure coupling time increments. Numerical simulations of a two-dimensional composite cantilever beam subject to convection heat loading from a fire plume are presented requiring coupling of both the thermal and mass transfer processes at the fluid-structure interface. Results are presented showing the thermal response of a composite beam to a fire plume and the sensitivity of the heating to fire location.

scholarly journals DB Construction of Activation Temperature and Response Time Index for Domestic Fixed-temperature Heat Detectors in Ceiling Jet Flow

2020 ◽  
Vol 34 (3) ◽  
pp. 35-42 ◽  
Author(s):  
Ga-Yeong Yoon ◽  
Ho-Sik Han ◽  
Sun-Yeo Mun ◽  
Chung-Hwa Park ◽  
Cheol-Hong Hwang
Keyword(s):  
Response Time ◽  
Activation Time ◽  
Fixed Temperature ◽  
Activation Temperature ◽  
Time Index ◽  
Heat Detector ◽  
Experimental Apparatus ◽  
Temperature Heat ◽  
Fire Detector ◽  
Heat Detectors

The accurate prediction of fire detector activation time is required to ensure the reliability of fire modeling during the safety assessment of performance-based fire safety design. The main objective of this study is to determine the activation temperature and the response time index (RTI) of a fixed heat detector, which are the main input factors of a fixed-temperature heat detector applied to the fire dynamics simulator (FDS), a typical fire model. Therefore, a fire detector evaluator, which is a fire detector experimental apparatus, was applied, and 10 types of domestic fixed-temperature heat detectors were selected through a product recognition survey. It was found that there were significant differences in the activation temperature and RTI among the detectors. Additionally, the detector activation time of the FDS with the measured DB can be predicted more accurately. Finally, the DB of the activation temperature and RTI of the fixed-temperature heat detectors with reliability was provided.

scholarly journals Comparison of Different Response Time Outlier Exclusion Methods: A Simulation Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Alexander Berger ◽  
Markus Kiefer
Keyword(s):  
Response Time ◽  
Simulation Study ◽  
Signal To Noise Ratio ◽  
High Rate ◽  
Type I ◽  
Population Difference ◽  
Type I Errors ◽  
Absolute Bias ◽  
Z Scores ◽  
Different Response

In response time (RT) research, RT outliers are typically excluded from statistical analysis to improve the signal-to-noise ratio. Nevertheless, there exist several methods for outlier exclusion. This poses the question, how these methods differ with respect to recovering the uncontaminated RT distribution. In the present simulation study, two RT distributions with a given population difference were simulated in each iteration. RTs were replaced by outliers following two different approaches. The first approach generated outliers at the tails of the distribution, the second one inserted outliers overlapping with the genuine RT distribution. We applied ten different outlier exclusion methods and tested, how many pairs of distributions significantly differed. Outlier exclusion methods were compared in terms of bias. Bias was defined as the deviation of the proportion of significant differences after outlier exclusion from the proportion of significant differences in the uncontaminated samples (before introducing outliers). Our results showed large differences in bias between the exclusion methods. Some methods showed a high rate of Type-I errors and should therefore clearly not be used. Overall, our results showed that applying an exclusion method based on z-scores / standard deviations introduced only small biases, while the absence of outlier exclusion showed the largest absolute bias.

scholarly journals Developing an Intelligent Quiz System based on Genetic Algorithm

2019 ◽  
Vol 8 (10) ◽  
pp. 70-76
Keyword(s):  
Genetic Algorithm ◽  
Response Time ◽  
Experimental Result ◽  
Difficulty Level ◽  
Accuracy Rate ◽  
Different Response

In the normal quiz system, all questions are the same. However, the questions of an intelligent quiz system have different difficulty level, different response time, etc. This paper proposed a novel solution based on genetic algorithm (GA) to build an intelligent quiz system. This solution is experimented with website system via PHP and MySQL. The question bank for experiment is input into the system by lecturers. The experimental result obtains very good with the accuracy rate of 95%.

Numerical simulations of concealed residential sprinkler head activation time in a standard thermal response room test

2020 ◽  
Vol 42 (1) ◽  
pp. 98-111
Author(s):  
Charlie Hopkin ◽  
Michael Spearpoint
Keyword(s):  
Response Time ◽  
Residential Buildings ◽  
Thermal Sensitivity ◽  
Computational Modelling ◽  
Thermal Response ◽  
Fire Dynamics ◽  
Effective Response ◽  
Fire Dynamics Simulator ◽  
Time Index ◽  
Factor C

It is common for sprinkler heads in residential buildings to be of the concealed type. Key parameters for the thermal sensitivity of sprinkler heads are the response time index (m½s½) and conductivity factor (C factor, m½s−½). BS 9252:2011 and BS EN 12259-14:2020 outline test methods to determine whether sprinkler heads achieve adequate thermal sensitivity, stipulating that a room test be undertaken for concealed heads. In carrying out this test, neither the response time index nor C factor is defined. This paper uses computational modelling tools Fire Dynamics Simulator and B-RISK to simulate the room test. In running these simulations, maximum values for the ‘effective’ response time index and C factor needed to pass the room test can be estimated, assuming concealed heads can be represented as equivalent pendent heads. Initial deterministic simulations are used to calibrate results between Fire Dynamics Simulator and B-RISK. Monte Carlo modelling is then utilised within B-RISK, with variable parameters for the response time index and C factor (C), to estimate the relationship between the two parameters necessary to pass the room test. As a result, it is proposed that this relationship can be represented using a simple, empirical power law equation of response time index = 100 (5.4–C)2/3, where C < 5.4. Practical application: The results indicate that the minimum RTI and C factor values needed to pass the room test are greater than those needed to pass wind tunnel testing methods. In observing that equivalency is not demonstrated by the room test, and by defining the RTI/C factor relationship needed to pass the test, this paper provides fire safety engineers with amended values for concealed heads to be adopted in future assessments. In the absence of any detailed specification for sprinkler heads, it is recommended that an RTI of 290 m½s½ and a C factor of 0.5 m½s−½ may be applied.

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