scholarly journals Calculation of Critical Water Flow Rates for Wildfire Suppression

Fire ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 3 ◽  
Author(s):  
Greg Penney ◽  
Daryoush Habibi ◽  
Marcus Cattani ◽  
Murray Carter
Keyword(s):  
Water Flow ◽  
Fire Suppression ◽  
Water Suppression ◽  
Flow Rates ◽  
Forest Fuels ◽  
Fire Engineering ◽  
Active Fire ◽  
Direct Head ◽  
Wide Range ◽  
Wildfire Suppression

Predicting water suppression requirements and its impacts on firefighting strategies and logistics within the urban environment has been the subject of many previous studies, however the same level of research has yet to be applied in the realm of wildfire suppression. To work towards addressing this knowledge gap, this paper provides guidance for Incident Controllers in relation to critical water flow rates required to extinguish large wildfire across a wide range of forest fuel loads, fire weather and active fire front depths. This is achieved through mathematical empirical analysis of water flow rates required for head fire suppression during 540 simulated wildfires in forest vegetation. This research applies a fire engineering approach to wildfire suppression logistics and deterministically assess the suitability of appliance and aircraft based head fire suppression. The results highlight the limitations of offensive wildfire suppression involving direct head fire attacks by appliances once wildfires attain a quasi-steady state in forest fuels.

An Assessment of the Importance of Secondary Spray on a Water Sprinkler Scenario

2009 ◽  
Author(s):  
Alexander L. Brown ◽  
Sam S. Yoon
Keyword(s):  
Fire Suppression ◽  
Solid Surfaces ◽  
Water Suppression ◽  
Single Drop ◽  
Reasonable Approximation ◽  
Wide Range ◽  
Industrial Fire ◽  
Simplifying Assumptions ◽  
Impact Events ◽  
Suppression System

Recent development efforts have resulted in new models that are capable of predicting water spray interactions with solid surfaces for a wide range of drop sizes and velocities. These models provide a reasonable approximation to single drop impact events, and significantly improve the expected accuracy of the splash. The models are implemented in the Vulcan software, a CFD code for fire modeling. We wanted to understand how important the splash is to a suppression scenario and the implications of common simplifying assumptions. A scenario with several rectangular objects located beneath a water suppression system is examined. This scenario was designed to be representative of an industrial fire and suppression situation. We compare the deposition masses on the surfaces for three cases, one with the recently developed model, another assuming no splash, and another assuming all splashing drops eject an excessive fraction of their mass. The results of the higher fidelity predictions compared with the more commonly employed and simpler assumptions suggest the importance of splashing to the outcome of an industrial water sprinkler fire suppression event.

scholarly journals Experimental Study on Hydroelectric Energy Harvester Based on a Hybrid Qiqi and Turbine Structure

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7601
Author(s):  
Bin Bao ◽  
Quan Wang ◽  
Yufei Wu ◽  
Pengda Li
Keyword(s):  
Energy Harvesting ◽  
Flow Velocity ◽  
Water Flow ◽  
Energy Harvester ◽  
Hybrid Structure ◽  
High Flow ◽  
Low Flow ◽  
Flow Rates ◽  
Hydroelectric Energy ◽  
Wide Range

The Qiqi structure design can automatically upset and spill its content once it arrives at limit capacity under vertical water flow excitation. Considering this function, the Qiqi structure has been utilized for small hydroelectric energy harvesting lately. To investigate the tradeoff between the Qiqi structure and the turbine structure for small hydroelectric energy harvesting, an energy harvester based on a hybrid Qiqi and turbine structure is proposed for vertical water flow hydroelectric applications. The hybrid structure is composed of a rectangular Qiqi structure, with two blades inserted on both sides. Self-tipping function of the hybrid Qiqi structure and working principle of the structure is investigated in detail. The proposed structure has both the advantages of low flow velocity energy harvesting of the Qiqi structure and high flow velocity energy harvesting of the turbine structure. A hydroelectric energy harvesting application using the hybrid structure is given to demonstrate that the hybrid structure had a higher rotational speed than the Qiqi structure under vertical low water flow excitation and was able to work at relatively high flow rates. Thus, the investigated hybrid structure can help small rotational hydropower achieve better energy harvesting performance and work at wide-range flow rates under vertical ultra-low water flow applications. At 600 mL/min, 902 μJ of electrical energy was charged by the investigated structure, which is six times higher than that using the Qiqi structure alone.

Characteristics of the Hydrodynamic Coefficient for Flow of a Steam-Water Mixture in a Pebble Bed

2006 ◽  
Vol 129 (9) ◽  
pp. 1291-1294 ◽  
Author(s):  
Alexandr A. Avdeev ◽  
Boris F. Balunov ◽  
Rostislav A. Rybin ◽  
Ruslan I. Soviev ◽  
Yuri B. Zudin
Keyword(s):  
Water Flow ◽  
Mass Flow ◽  
Pressure Loss ◽  
Single Phase ◽  
Water Mixture ◽  
Pebble Bed ◽  
Hydrodynamic Coefficient ◽  
Flow Rates ◽  
Wide Range ◽  
Mass Flow Rates

Pressure loss for flow of a steam-water mixture in a pebble bed is experimentally investigated (the first stage of the study was described in Avdeev, et al., 2003 [High Temp., 41, pp. 371–383]). The measurements of the care performed within the wide range of regime parameters: pressures of 0.9-15.6MPa, mass-flow rates of 107-770kg∕(m2s) and steam quality of 0–0.49. The experimental data for the pressure loss of single-phase air and water flows were used as reference data. The final results are represented in the form of the ratio of the pressure loss for the steam-water flow to that for the single-phase water flow at identical mass-flow rates.

Evidence for the effect of homes on wildfire suppression costs

2013 ◽  
Vol 22 (4) ◽  
pp. 537 ◽  
Author(s):  
Patricia H. Gude ◽  
Kingsford Jones ◽  
Ray Rasker ◽  
Mark C. Greenwood
Keyword(s):  
Sierra Nevada ◽  
Fire Suppression ◽  
Empirical Studies ◽  
Active Fire ◽  
Confounding Variables ◽  
Unit Increase ◽  
Wildfire Suppression ◽  
In Fire ◽  
The Relationship ◽  
Expected Increase

This paper uses wildfires in the Sierra Nevada area of California to estimate the relationship between housing and fire suppression costs. We investigated whether the presence of homes was associated with increased costs of firefighting after controlling for the effects of potential confounding variables including fire size, weather, terrain and human factors such as road access. This paper investigates wildfires in a way that other published studies have not; we analysed costs at the daily level, retaining information that would have been lost had we aggregated the data. We used linear mixed models to estimate the effects of homes on daily costs while incorporating within-fire variation. We conclude that the expected increase in the log daily cost with each unit increase in the log count of homes within 6 miles (~9.7 km) of an active fire is 0.07 (P = 0.005). The findings of this study are in agreement with most other previous empirical studies that have investigated the relationship between fire suppression costs and housing using cumulative fire costs and more generalised data on home locations. The study adds to mounting evidence that increases in housing lead to increases in fire suppression costs.

Automation of Process Control in Chemical Plant

2015 ◽  
Vol 2 (1) ◽  
pp. 6-12
Author(s):  
Agus Sugiarta ◽  
Houtman P. Siregar ◽  
Dedy Loebis
Keyword(s):  
Process Control ◽  
Pid Control ◽  
Control Algorithm ◽  
Chemical Engineering ◽  
Chemical Plant ◽  
Raw Material ◽  
Flow Rates ◽  
Material Supply ◽  
Wide Range ◽  
Inherent Problem

Automation of process control in chemical plant is an inspiring application field of mechatronicengineering. In order to understand the complexity of the automation and its application requireknowledges of chemical engineering, mechatronic and other numerous interconnected studies.The background of this paper is an inherent problem of overheating due to lack of level controlsystem. The objective of this research is to control the dynamic process of desired level more tightlywhich is able to stabilize raw material supply into the chemical plant system.The chemical plant is operated within a wide range of feed compositions and flow rates whichmake the process control become difficult. This research uses modelling for efficiency reason andanalyzes the model by PID control algorithm along with its simulations by using Matlab.

Nitrogen Removal from Anaerobically-Treated Leachate

1984 ◽  
Vol 19 (1) ◽  
pp. 87-100
Author(s):  
D. Prasad ◽  
J.G. Henry ◽  
P. Elefsiniotis
Keyword(s):  
Nitrogen Removal ◽  
Air Flow ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Flow Rates ◽  
Anaerobic Filter ◽  
Ph Values ◽  
Wide Range ◽  
Ammonia Desorption ◽  
Effects Of Ph

Abstract Laboratory studies were conducted to demonstrate the effectiveness of diffused aeration for the removal of ammonia from the effluent of an anaerobic filter treating leachate. The effects of pH, temperature and air flow on the process were studied. The coefficient of desorption of ammonia, KD for the anaerobic filter effluent (TKN 75 mg/L with NH3-N 88%) was determined at pH values of 9, 10 and 11, temperatures of 10, 15, 20, 30 and 35°C, and air flow rates of 50, 120, and 190 cm3/sec/L. Results indicated that nitrogen removal from the effluent of anaerobic filters by ammonia desorption was feasible. Removals exceeding 90% were obtained with 8 hours aeration at pH of 10, a temperature of 20°C, and an air flow rate of 190 cm3/sec/L. Ammonia desorption coefficients, KD, determined at other temperatures and air flow rates can be used to predict ammonia removals under a wide range of operating conditions.

scholarly journals Geometrical Optimization of a Venturi-Type Microbubble Generator Using CFD Simulation and Experimental Measurements

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 4
Author(s):  
Dillon Alexander Wilson ◽  
Kul Pun ◽  
Poo Balan Ganesan ◽  
Faik Hamad
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Air Flow ◽  
Bubble Diameter ◽  
Diameter Ratio ◽  
Experimental Measurements ◽  
Cfd Model ◽  
Flow Rates ◽  
Throat Diameter

Microbubble generators are of considerable importance to a range of scientific fields from use in aquaculture and engineering to medical applications. This is due to the fact the amount of sea life in the water is proportional to the amount of oxygen in it. In this paper, experimental measurements and computational Fluid Dynamics (CFD) simulation are performed for three water flow rates and three with three different air flow rates. The experimental data presented in the paper are used to validate the CFD model. Then, the CFD model is used to study the effect of diverging angle and throat length/throat diameter ratio on the size of the microbubble produced by the Venturi-type microbubble generator. The experimental results showed that increasing water flow rate and reducing the air flow rate produces smaller microbubbles. The prediction from the CFD results indicated that throat length/throat diameter ratio and diffuser divergent angle have a small effect on bubble diameter distribution and average bubble diameter for the range of the throat water velocities used in this study.

scholarly journals Comparison of Optimization-Regulation Algorithms for Secondary Cooling in Continuous Steel Casting

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 237
Author(s):  
Michal Brezina ◽  
Tomas Mauder ◽  
Lubomir Klimes ◽  
Josef Stetina
Keyword(s):  
Convergence Rate ◽  
Water Flow ◽  
Steel Casting ◽  
Casting Process ◽  
Continuous Steel Casting ◽  
Continuous Steel ◽  
Cooling Zone ◽  
Secondary Cooling ◽  
Flow Rates ◽  
Secondary Cooling Zone

The paper presents the comparison of optimization-regulation algorithms applied to the secondary cooling zone in continuous steel casting where the semi-product withdraws most of its thermal energy. In steel production, requirements towards obtaining defect-free semi-products are increasing day-by-day and the products, which would satisfy requirements of the consumers a few decades ago, are now far below the minimum required quality. To fulfill the quality demands towards minimum occurrence of defects in secondary cooling as possible, some regulation in the casting process is needed. The main concept of this paper is to analyze and compare the most known metaheuristic optimization approaches applied to the continuous steel casting process. Heat transfer and solidification phenomena are solved by using a fast 2.5D slice numerical model. The objective function is set to minimize the surface temperature differences in secondary cooling zones between calculated and targeted surface temperatures by suitable water flow rates through cooling nozzles. Obtained optimization results are discussed and the most suitable algorithm for this type of optimization problem is identified. Temperature deviations and cooling water flow rates in the secondary cooling zone, together with convergence rate and operation times needed to reach the stop criterium for each optimization approach, are analyzed and compared to target casting conditions based on a required temperature distribution of the strand. The paper also contains a brief description of applied heuristic algorithms. Some of the algorithms exhibited faster convergence rate than others, but the optimal solution was reached in every optimization run by only one algorithm.

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