Fast-Response Sprinkler Technology: Hsiang-Cheng Kung, Gunnar Heskestad, Robert Bill, Roger Allard: The 2019 Phillip J. DiNenno Prize

Croce, Paul Jerome; Beyler, Craig L.; Dubay, Chris; Johnson, Paige; McNamee, Margaret

doi:10.1007/s10694-020-00961-7

Cited by 3 publications

(1 citation statement)

References 24 publications

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“…Therefore two well recognized analytical models were applied. The thermal properties of a sprinkler head are summarized in a single value called the response time index (RTI) [20]. Due to the relatively small dimensions of the link and its high conductivity, the Biot number (a ratio of the heat transfer resistances inside of a body and at the surface of a body) is much less than the unity (about 0.1 to 0.2), and lumped heating of the link by the hot combustion gases can be assumed [21].…”

Section: Foundations Of Numerical Modeling Of Heat Sensorsmentioning

confidence: 99%

A Study on the Reliability of Modeling of Thermocouple Response and Sprinkler Activation during Compartment Fires

et al. 2022

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Real and numerical fire experiments involve temperature measurements with thermocouples, and thus some considerations on numerical modeling of this process are presented and a new approach to thermocouple modeling is introduced. Using ANSYS Fluent software a well-recognized analytical thermocouple model was implemented in each cell of the computational domain, which allows for determination of thermocouple responses as a continuous field. Similarly, sprinklers are key elements of fire-protection systems. Sprinklers activation is one of the breakthrough moments during the course of a compartment fire. Therefore, assumptions on sprinkler activation time are of crucial importance when designing a fire safety system. Just as for thermocouple modeling, virtual sprinklers based on a commonly admitted response time index (RTI) model were placed in all cells. The proposed approach provides data on sprinklers activation or thermocouple response for the whole domain instead of retrieving data point by point only for predefined locations. In this study, experimental data available in the literature were used for the validation of the proposed approach. In addition, the results were compared with those obtained with the commonly used Fire Dynamic Simulator (FDS) software. The outcomes might be of a significant importance for practitioners, who deal with fire experiments and fire protection. Furthermore, some issues on accurate modeling of fire gases flow are discussed extensively. It was found that commonly applied k-ε and k-ω turbulence models might fail in the case of modeling of fire plumes in confined spaces.

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Section: Foundations Of Numerical Modeling Of Heat Sensorsmentioning

confidence: 99%

A Study on the Reliability of Modeling of Thermocouple Response and Sprinkler Activation during Compartment Fires

et al. 2022

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3D Mapping of the Sprinkler Activation Time

et al. 2020

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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.

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Analysis on the Effect of Obstruction on Sprinkler Skipping in Air Conditioner Room Fire

et al. 2022

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Sprinkler skipping is an important issue in fire spread. In general, two sprinklers are installed in air conditioner rooms at the ceiling and 30 cm below to avoid spray failure by energy recovery ventilator in the ceiling. However, there is a problem in that sprinkler skipping occurs in the air conditioner room. In this study, the sprinkler skipping phenomenon was analyzed through numerical analysis and the applicability of the open type of sprinkler operation method was reviewed. As a result, when the upper sprinkler works, sprinkler skipping occurred in all cases. The lower sprinkler shall not rise above the operating temperature of 68.3 °C with a maximum temperature of 65 °C. In particular, the spray failure caused by the energy recovery ventilator reduces the sprinkler head temperature by more than 8 °C by concentrating the spray droplets. As an open type, simultaneous operation of two sprinklers is capable of obtaining an appropriate fire extinguishing effect by covering the fire source with the spray of the lower sprinkler. The research results are expected to help in fire protection in buildings such as modern apartments with air-conditioned rooms.

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Fast-Response Sprinkler Technology: Hsiang-Cheng Kung, Gunnar Heskestad, Robert Bill, Roger Allard: The 2019 Phillip J. DiNenno Prize

Cited by 3 publications

References 24 publications

A Study on the Reliability of Modeling of Thermocouple Response and Sprinkler Activation during Compartment Fires

A Study on the Reliability of Modeling of Thermocouple Response and Sprinkler Activation during Compartment Fires

3D Mapping of the Sprinkler Activation Time

Analysis on the Effect of Obstruction on Sprinkler Skipping in Air Conditioner Room Fire

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