Suppression System Research Articles

Hydrogen explosion mitigation in DEMO vacuum vessel pressure suppression system using passive recombiners

An important issue for the Fusion Reactors is the hydrogen explosion hazard assessment. For this reason, in the Work Package of Safety Analyses and Environment (WPSAE) of the EUROFusion consortium, a task was established to identify the potential for hydrogen production in DEMO vessel in accident situations and to investigate the possible solutions which can prevent the risk of hydrogen and dust explosion. The hydrogen in the Vacuum Vessel (VV) can lead to combustion progressing in deflagration and detonation. Besides, the tungsten dust could enhance the effects of H2 reaction as demonstrated by experiments, however, in this first set of accidents, only the H2 generated by the chemical reaction is accounted for.For these reasons, the solutions to avoid or limit the H2 production and/or to control safely the risk of H2 accumulation and explosion need to be screened starting from the solutions adopted in the fission technology, and later on, adapted and assessed in the Pressure Suppression System (PSS) foreseen in DEMO. One promising idea seems to install passive catalytic recombiners in the PSS.The aim of this paper is firstly to set a range of operating parameters for the PAR functioning and intervention suitable in DEMO PSS configuration. Secondly to verify if the present criteria and parameters work efficiently in mitigating the H2 accumulation a PSS in accidental conditions. To test the theoretical effectiveness of the PAR intervention, two reference accidents have been analyzed: an in-VV Loss Of Coolant Accident (LOCA) in the frame of the Design Basis Accident (DBA) and a Loss Of Flow Accident (LOFA) without active plasma shutdown in the context of the Beyond Design Basis Accidents (BDBA).The results seem promising if the performances of the PAR will be confirmed in sub atmospheric and saturated conditions.

Fungal Lung.

Foot and nail care specialists spend a great portion of their day using nail drills to reduce nail thickness and smooth foot calluses. This process generates a large amount of dust, some of which is small enough to breathe in and deposit into the deepest regions of the respiratory tract, potentially causing health problems. Foot and nail dust often contains fungi, from both fungus-infected and healthy-appearing nails. Although the majority of healthy individuals can tolerate inhaled fungi, the immune systems of older, immunocompromised, and allergy-prone individuals often react using the inflammatory T helper cell type 2 pathway, leading to mucus overproduction, bronchoconstriction, and, in severe cases, lung tissue damage. To protect vulnerable podiatry professionals, wearing a surgical mask, using a water spray suppression system on nail drills, installing air filtration systems, and considering drilling technique can help reduce exposure to nail dust.

Hail characteristics in Serbia based on data obtained from the network of hail suppression system stations

AbstractSerbia is located in the mid‐latitudes of the Northern Hemisphere and is exposed to frequent hailfall. Consequently, a hail suppression system was gradually developed during the last 54 years. In this study, data from densely distributed hail suppression stations were used to better understand the hail characteristics. Two data subsets are differentiated: the first from the territory of Serbia, excluding the northern province of Vojvodina, during 1981–2015 (P1) and the second from the entire territory of Serbia during 2002–2015 (P2). The distribution of hail size shifted to smaller diameters in P2 compared to P1. The hailfall lasted less than 5 min in about 75% of events while the duration was greater than or equal to 10 min in only 8%. The influence of Serbia's complex orography on hailfall is reflected in the greater average annual number of days with hailfall in mountainous areas, with a maximum mean value of 1.2 in the southwestern part of Serbia, while the maximum number was 2.7. Hail and small hail occurred mainly in the afternoon and evening, with 92.24% of cases being observed from 12:00 to 21:00 local time (UTC + 1). A positive monotonic trend in the annual number of days with hailfall was observed. In both subsets, there was no statistically significant trend in hail frequency. The average seasonal duration of hail and small hail falls showed a decreasing trend in P1. Results showed that the first occurrence of hail falls did not appear earlier in the season.

Full scale test facility for operability verification of tokamak pressure suppression system at sub-atmospheric conditions

The reliable and safe operation of tokamak fusion reactors is mainly based on radioactive contaminants confinement, achieved preserving the integrity of robust barriers, among which the Vacuum Vessel (VV) performs an essential role. The VV protection against postulated over pressurization events is guaranteed by the safety functions implemented in the Pressure Suppression System (PSS), in which steam from VV is discharged and Direct Contact Condensation (DCC) occurs at sub-atmospheric conditions. Aiming to verify the VVPSS performance of ITER machine (i.e. steam condensation efficiency at different DCC regimes with/without non-condensable), in steady state and transient conditions relevant for fusion reactor postulated events, and contribute to fill the knowledge gap regarding sub-atmospheric condensation, an extensive experimental research activity is ongoing with the Large and Full Scale Test Facility (LSTF and FSTF): designed, assembled, instrumented and commissioned at Laboratory B. Guerrini at DICI University of Pisa. This facility is mainly composed of a Steam Generator (up to 500 g/s, about 1.8 MW), three different steam lines for wide mass flowrate regulation, two air lines for mixed condensation characterization, Experimental Test Tank (92 m3, where steam condensation is investigated adopting two different spargers, scaled and full scale with 100 and 1000 holes, respectively), Auxiliary Tank (10 m3 for plant conditioning), Vacuum Pump, Chiller and Water Storage Tank (15 m3). Two Steam Storage Tanks (15 m3 each) allow to accumulate and provide the foreseen steam peak flowrate value (of 5 kg/s) in the postulated accident. FSTF is highly instrumented (81 thermo-resistances, 28 thermocouples, 35 pressure transmitters, 18 strain gauges and 4 vortex flow meters) and fully remotely controlled (64 on-off and control valves) by a dedicated Data Acquisition and Control System (DACS). Six video cameras and 4 led lights assure steam injection video-recording, for detailed characterization of condensation regimes. Preliminary results are shown for 50 g/s of steam injected through the scaled sparger into water pool at 30 °C with cover gas at 0.1 bar absolute, providing a condensation efficiency of about 100% and verifying instable chugging condensation regime.

Silylation of Deoxynucleotide Analog Yields an Orally Available Drug with Antileukemia Effects.

DNA methyltransferase inhibitors have improved the prognosis of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). However, because these agents are easily degraded by cytidine deaminase (CDA), they must be administered intravenously or subcutaneously. Recently, two orally bioavailable DNA methyltransferase inhibitors, CC-486 and ASTX727, were approved. In previous work, we developed 5-O-trialkylsilylated decitabines that resist degradation by CDA. However, the effects of silylation of a deoxynucleotide analog and enzymatic cleavage of silylation have not been fully elucidated. Enteric administration of OR21 in a cynomolgus monkey model led to high plasma concentrations and hypomethylation, and in a mouse model, oral administration of enteric-coated OR21 led to high plasma concentrations. The drug became biologically active after release of decitabine (DAC) from OR21 following removal of the 5'-O-trisilylate substituent. Toxicities were tolerable and lower than those of DAC. Transcriptome and methylome analysis of MDS and AML cell lines revealed that OR21 increased expression of genes associated with tumor suppression, cell differentiation, and immune system processes by altering regional promoter methylation, indicating that these pathways play pivotal roles in the action of hypomethylating agents. OR21 induced cell differentiation via upregulation of the late cell differentiation drivers CEBPE and GATA-1 Thus, silylation of a deoxynucleotide analog can confer oral bioavailability without new toxicities. Both in vivo and in vitro, OR21 exerted antileukemia effects, and had a better safety profile than DAC. Together, our findings indicate that OR21 is a promising candidate drug for phase I study as an alternative to azacitidine or decitabine.

Synthesis of an active flutter suppression system in the transonic domain using a computational model

ABSTRACTControl laws for implementing active flutter suppression are generally derived from linear aeroelastic models. In this paper, families of control laws for implementing an active flutter suppression system were initially designed using linearised aeroelastic models based on the doublet lattice method after ignoring the aerodynamic loads associated with relatively faster time scales. Using these preliminary sets of control laws and the nonlinear transonic small disturbance theory, near-optimum control laws were chosen in the transonic domain to maximally increase the flutter speed of a typical aircraft wing by at least 16% or more. Thus it is shown that it is feasible to systematically design near-optimal control laws for active flutter suppression using computational models in transonic flow. The doublet lattice method coupled with the zeroth-order matrix Padé approximant provided the fastest method for synthesising a large number of preliminary control laws. The methodology was successfully demonstrated by applying it to two benchmarking examples.

Adaptation of an artificial bait to an automated aerial delivery system for landscape-scale brown treesnake suppression

Dead neonatal mice are currently used as bait for delivery of toxin to invasive brown treesnakes (Boiga irregularis) on Guam; once deployed in the field the mice are highly attractive to the snakes but only for about four days. An artificial bait containing a mixture of fats mimicking those in skin of the mice is also highly attractive to the snakes and remains attractive 2–3 times longer. The artificial bait, however, costs more than the mice, and is more difficult to attach to the capsules of a novel aerial bait delivery system. This paper describes a reformulation of the bait which reduced the ingredient cost to 11% of its former value, without compromising its attractiveness to free-ranging snakes. Three lipid formulations using different source materials to produce the same fatty acid profile target were tested along with two levels of pork fat to yield six test formulations. No differences in bait disappearance were noted in field testing of the baits, indicating that decisions regarding bait formulation could be made on the basis of cost without sacrificing efficacy. Separately, testing of 17 commercially available adhesives identified five for field testing. Among these, two demonstrated strong, weather-resistant bonds between the oily surface of the artificial baits and the bait capsules as evidenced by only 13.4% and 4.5% of baits falling off suspended capsules. Importantly, neither of these adhesives impacted bait removal by snakes in field trials in comparison to baits with no adhesive.. The results represent an advance in technology development for landscape-scale suppression of brown treesnake populations.

Analysis of nodalization strategies to model a suppression tank for fusion plants with TRACE code

The Ingress of Coolant Event (ICE) in the plasma chamber is one of the main safety issues in nuclear fusion plants. The ICE is caused by the rupture of the coolant tubes installed in the plasma facing components; the coolant ingress causes a pressure rise in the plasma chamber and vacuum vessel, normally under high-vacuum conditions. To mitigate the system pressurization leading to mechanical structure failure, a pressure suppression system is installed. Safety analyses of the hypothetical challenging accidental scenarios can be conducted by deterministic models that need to be validated against experimental data characterizing the target phenomena. The paper presents a study of different nodalization strategies for modeling a suppression tank for fusion plants, using the best estimate thermal-hydraulic system code TRACE (TRAC/RELAP Advanced Computational Engine). The TRACE code is developed by USNRC to perform safety analyses for light water fission reactors. Both mono-dimensional and three-dimensional approaches were adopted to model the suppression tank. The experimental data from the JAERI Integrated ICE facility (scaling factor of 1/1600 with respect to the ITER-FEAT design) was used to benchmark different nodalization options. In addition to the qualitative accuracy evaluation, the Fast Fourier Transform Based Method (FFTBM) was applied to quantify the accuracy of the code results for different nodalizations.

Design and experimental verification of self-powered electromagnetic vibration suppression and absorption system for in-wheel motor electric vehicles

A self-powered electromagnetic vibration suppression and absorption system integrated with a magnetorheological damper and a linear motor is designed to attenuate the negative effect of vertical vibration caused by the increased unsprung mass for in-wheel motor electric vehicles in this article. The magnetorheological damper is used as a suspension damper to suppress body vibration, and linear motor is used as a dynamic vibration absorber, namely, linear electromagnetic dynamic vibration absorber, to absorb tire vibration, and regenerates the vibration power to drive the magnetorheological damper, realizing self-power. Based on power flow theory, the power transfer mechanism of the vertical vibration for in-wheel motor electric vehicles and the regeneration potential are analyzed. The negative effect on the dynamic performance of in-wheel motor electric vehicles is analyzed through the root mean square of dynamic responses. Moreover, the specific structure scheme of the self-powered electromagnetic vibration suppression and absorption system is provided. The influence of system mass, stiffness, and damping of the linear electromagnetic dynamic vibration absorber on the dynamic performance is analyzed, and these parameters are optimized by particle swarm optimization. Simulation results show that in comparison with a passive damper, the self-powered electromagnetic vibration suppression and absorption system can reduce the body acceleration by 17.05%, which is better than the magnetorheological damper (10.08%). The self-powered electromagnetic vibration suppression and absorption system increases the tire dynamic load by 5.62%, but it is 8.68% less than the magnetorheological damper. Additionally, the regenerated power can offset the consumed power adequately to realize self-power. Finally, a bench test is conducted to verify the effectiveness and feasibility of the self-powered electromagnetic vibration suppression and absorption system.

Active system for reduction of noise parameters of car muffler with the use of pressure sensors based on silicon microcrystals

Purpose: The article contains the results of research and development of a system for active noise damping of an automobile engine. The proposed system of active noise suppression can significantly reduce the sound pressure level in the frequency band up to 500 Hz. The robotic principle of the developed system is based on the addition of an additional buffer tank with a variable volume in the silencer system. The use of high-temperature sensors with strain gauges based on silicon microcrystals to obtain information on the parameters of sound vibrations arising during the exhaust gas outflow made it possible to create a control system for changing the volume of the buffer tank. The results of testing the proposed system of active noise suppression of an internal combustion engine are presented. Design/methodology/approach: The active noise suppression system based on the Helmholtz resonator used tools to control general noise levels, experimental tests, complex mathematical modelling of acoustic processes in Solidworks, taking into account the conditions of propagation and attenuation of sound energy by intermediate closed volumes. Findings: The use of an additional resonator chamber with variable volume in the exhaust muffler of the internal combustion engine allowed to reduce the resonant phenomena in the zone of low-frequency pulsations of exhaust gas pressure from 57 Hz to 43 Hz at frequency drift in the range of 310… 350 Hz, which significantly improved its noise characteristics. Research limitations/implications: For further research, to improve the characteristics of the active noise suppression system, it is advisable to consider the use of several inadditional cameras of the Helmholtz resonator and to clarify the algorithm of the controller in transient modes of engine operation. Practical implications: The developed design of active noise reduction is simpler in comparison with analogs and allows reducing the noise of exhaust gases in a low-frequency range. Originality/value: To reduce the noise, a variable-volume Helmholtz resonator was used, the efficiency of which is provided by high-temperature sensors of the original design.

Economic impacts of storm surge events: examining state and national ripple effects

Understanding socioeconomic consequences of natural disasters both locally and nationally is critical in assessing and informing mitigation strategies to combat future catastrophic threats. We develop a state-level computable general equilibrium model and assess the vulnerability of state and US national economies to surge events affecting coastal communities and strategic industrial assets including petroleum and chemical manufacturing in the south-eastern region of Texas. In addition to enumerating these impacts, our model also assesses loss avoidance associated with one kind of adaptation strategy, a storm surge suppression system, that has been proposed for the region to address growing concerns over storm surge inundation. Our results indicate persistent and adverse long-term impacts of storm surge events on the economies of Texas and the USA without the surge suppression system. Importantly, while neighboring states may temporarily benefit from substitution effects and reallocation of resources, the majority of states will suffer welfare losses as a result of surge-induced impacts in Texas. Adjusting impacts by storms’ return probabilities, the average annualized decline in Texas Gross State Product is approximately 0.05% in 2066, corresponding to $5 billion, while welfare and personal income will decline by 0.05% and 0.04%, respectively. Model simulations with the storm suppression system indicate moderation in negative impacts. Our research provides a modeling framework for assessing economic impacts of disasters and further contributes to estimating ripple effects on national and regional economies.

Hangar fire detection alarm with algorithm for extinguisher

A fire alarm is a high-performance system that detects smoke, heat or flames and actuates fire suppression system, for the protection of lives and property. It is employed in aircraft hangars for the protection of aircraft, personnel as well as the hangar structure. The need for a fire alarm in a hangar with algorithm for extinguishers cannot be overemphasized. The structure of the hangar building, type of aircraft housed in the hangar and activities carried out at the hangar such as inspections, overhauls and modifications of aircraft, determine the type of fire alarm to be used, whether it should be automatic or manual [2]. The detection employed, be it smoke detection, heat sensing or both and the process of extinguishing in the face of a fire threat or hazard is equally important. The effectiveness of the alarm is dependent on genuine alerts and not false alarm triggers, hence in this research paper, the employment of intelligent detection using comparators in programmed IC, the Micro-controller, was interfaced with a 555 Timer, a multi-vibrator for generating aural sound for alarm, LCD Display for indicated readings as well as algorithm for extinguishing using water or foam via sprinklers. The basic work started with a block diagram representation, thereafter, individual subsystems, which form the building blocks were analyzed and the components parts identified. A circuit diagram for the project was analyzed and built using Proteus. This was simulated and found to be achievable, hence a program was written in C++ for the micro-controller using Arduino Language known as the source code. The results show hangar fire detection alarm with algorithm for extinguishing and was investigated as an effective means of suppressing fire threat in the hangar [4].

Development of a direct penetrating signal compensator in a distributed reception channel of a surveillance radar

General structure of a compensator of a direct penetrating signal in the diversed reception channel was developed. It is advisable to use the antenna and the receiver of the auxiliary diverted reception channel as an auxiliary antenna and an auxiliary channel. To be able to suppress the penetrating signal in the band of the receiving device of the surveillance radar, distance between the antennas should be up to 6 m. In general, the compensator of the penetrating signals should contain an adder in which the signals received by the main channel are added with the signals received by the auxiliary channel and sent through the amplifier with a corresponding complex transmission coefficient. The direct penetration signal compensator features the obligatory condition of adjusting the value of the complex transmission coefficient of the auxiliary channel signal amplifier. The direct penetration signal compensator is digital and uses the direct method of forming weighting coefficients without the use of feedback. To reduce the time of formation of weighting coefficients when using direct methods of calculation of the correlation matrix, the technology of parallel computational processes was used. The quality of operation of the direct penetrating signal suppression system in the diverted reception channel was evaluated. It was established that without the use of suppression of direct penetrating signals, their powerful response at the output of the matched filter mask weak echo signals. When using a direct penetrating signal in the main channel of the compensator, its response at the output of the matched filter is significantly reduced. This makes it possible to observe weak echoes against the background of a strong penetrating signal. The use of the developed direct penetrating signal compensator provides suppression of the direct penetrating signal from 57 dB to 70 dB

Numerical assessment for aircraft cargo compartment fire suppression system safety

Fire on board an aircraft cargo compartment can lead to catastrophic consequences. Therefore, fire safety is one of the most important considerations during aircraft design and certification. Conventionally, Halon-based agents were used for fire suppression in such cases. However, an international agreement under the Montreal Protocol of 1994 banned further production of Halon and several other halocarbons considered harmful to the environment. There is therefore a requirement for new suppression agents, along with suitable system design and certification. This article aims to describe the creation of a mechanism to validate a preliminary design for fire suppression systems using Computational Fluid Dynamics and provide further guidance for fire suppression experiments in aircraft cargo compartments. Investigations were performed for the surface burning fire, one of the fire testing scenarios specified in the Minimum Performance Standard, using the numerical code Fire Dynamics Simulator. This study investigated the use and performance of nitrogen, a potential replacement for Halon 1301, as an environmentally friendly agent for cargo fire suppression. Benchmark fires using the pyrolysis model and fire design model were built for the surface-burning fire scenario. Compared with experiment results, the two Computational Fluid Dynamics models captured the suppression process with high accuracy and displayed similar temperature and gas concentration profiles. Fire consequences in response to system uncertainties were studied using fire curves with various fire growth rates. The results suggested that using nitrogen as a fire suppression agent could achieve a lower post-suppression temperature compared to a Halon 1301-based system. It can therefore be considered as a potential candidate for aircraft cargo fire suppression. Such work will feed directly into system safety assessments during the early design stages, where analyses must precede testing. Future work proposed for the application of this model can be extended to other fire scenarios such as buildings, shipping, and surface transport vehicles.

Influence of hail suppression systems over silver content in the environment in Aragón (Spain). I: Rainfall and soils

In several countries, hail is considered as the most harmful climatic phenomenon from an agricultural perspective. The surroundings of the Gallocanta Lake (North-East Spain), is one of the areas where the storms affecting the Ebro Valley are formed. For this reason, silver iodide from hail suppression systems has been emitted to the atmosphere for half a century.Nowadays, there is an increasing social concern about the potential environmental consequences of this activity, which has promoted the analysis of the influence of hail suppression systems regarding the amount of silver concentration in the ecosystem. This study focuses on silver atmospheric deposition and its accumulation in soils.To this end, silver concentrations in rainfall (5 gauges, 16 samples per site, from April 2017 to March 2019) and soils (72 samples) distributed across the hail suppression network managed by the Anti-hail Consortium of Aragón, were analysed.The results show that the amount of silver is much higher in rainfall gauges and soils close to ground-based silver iodide generators (85 μg/m2·day and 10 mg/kg soil, respectively), but concentrations considerably decrease when samples are collected far from them (downing to 0.3 μg/m2·day and 0.1 mg/kg soil).Apart from the samples obtained nearby silver iodide generators, most of the other soil samples display silver concentrations below the legal threshold established for the most vulnerable activities (1 mg/kg soil in agricultural and forestry land uses). Nevertheless, silver content, both in precipitation and in soils, is higher in regions where hail suppression has been developed for decades when compared to nearby areas in which silver iodide emissions did not occur.Silver content observed in soils is not high, but their cumulative effect in sediments and biota should be analysed, which is the aim of the second part of the present study.

End-to-end design of a robust attitude control and vibration suppression system for large space smart structures

The standard approach of controlling in-orbit large flexible structures only by adopting actuators and sensors located at platform level is currently being challenged by new missions’ stringent requirements in terms of demanding guidance profiles and instrument performance. In this perspective, smart materials offer a different solution to improve the performance of space systems by controlling the vibrations of such lightweight structures. In this paper, the problem of designing an end-to-end architecture for active control of large in-orbit structures is addressed. First, a FE model of a large space antenna is derived by using commercial software. The instrument is designed to be supported by an active deployable frame hosting an optimal minimum set of collocated smart actuators and sensors. To this purpose, a comparison among different placement techniques, as Gramian and Modal Strain Energy (MSE) based methods, is proposed to find the final configuration for both actuators and sensors. Attention is paid to create a GNC strategy combining collocated control on flexible appendages with platform control, while minimizing the relative displacements among the most critical points of the antenna. To achieve high performance, Linear Fractional Transformation (LFT) modelling and advanced multivariable techniques are implemented. Finally, to validate the proposed controller, the control system is tested by simulating typical spacecraft manoeuvre profiles.

Large scale experimental facility for performance assessment of the vacuum vessel pressure suppression system of ITER

The nuclear fusion reactor ITER (International Thermonuclear Experimental Reactor) foresees a Pressure Suppression System (PSS) in order to manage a Loss of Coolant Accident (LOCA) in the Vacuum Vessel (VV). A LOCA scenario is postulated to occur in the cooling systems of plasma facing components. The Vacuum Vessel Pressure Suppression System (VVPSS) has a key safety function because a large internal pressure in the VV could lead to a breach of the primary confinement barrier.Steam condensation would occur in ITER at sub-atmospheric pressure, differently than the applications in nuclear fission reactors. Steam direct contact condensation (DCC) in sub-atmospheric conditions have never been implemented before, therefore an experimental assessment of the VVPSS is necessary to simulate this phenomenon in ITER's thermal-hydraulic conditions.Under the financial support of ITER Organization, an experimental program was performed at the Department of Civil and Industrial Engineering (DICI) of the University of Pisa in the past 3 years, using a small-scale experimental rig (1/22 scale factor).In order to assess the scale laws elaborated by means of the experimental results obtained in this small scale facility, a Large Scale facility was built at University of Pisa. This facility is almost a full scale mock-up of ITER's VVPSS from the geometric point of view (1/1.09 scale factor) and it is 1/10 scale factor from the steam mass flow rate point of view.This paper illustrates the results of the first test campaign. A 1/10 scale sparger system SPS-A (having a diameter equal to DN125 and 100 holes) was used with a maximum steam mass flow rate of 0.5 kg/s. This experimental configuration represents real operating conditions on the basis of the results of elaborated similitude analysis. The preliminary analysis of the experimental results confirms the agreement in terms of condensation regimes between the two reduced scale (1/22 and 1/10 scale) as foreseen by the elaborated scale laws.

Direct steam condensation at sub-atmospheric pressure: experimental tests and similitude analysis

This paper deals with experimental and theoretical analyses of the steam direct condensation at sub-atmospheric pressure. These operation conditions occur in the Vacuum Vessel Pressure Suppression System (VVPSS) of ITER Nuclear Fusion Reactor. This safety system permits to manage the Ingress of Coolant Event (ICE cat. IV) accident condition, postulated to occur in the ITER Vacuum Vessel (VV) as a consequence of the rupture of the shielding blanket cooling piping or the rupture of the divertor cassette piping.Experimental tests of steam direct condensation at sub-atmospheric pressures in a 1:22 scale facility were performed at the laboratory Guerrini of DICI-University of Pisa. Presently a full-scale facility is being building at DICI. This paper illustrates the similitude analysis elaborated to scale up the experimental results obtained in the reduced scale facility. The main variables which influence the steam direct condensation were analyzed and the relative scale laws determined. CFD numerical simulations of direct steam condensation in the actual geometry and in a vessel of equal volume permitted to verify some of the assumptions on which the scale laws are based. Scaling studies were first performed in order to calculate the transient of steam mass flow rate occurring during the ICE IV event in the scale apparatus, starting from the thermal hydraulic studies performed at ITER and successfully compared with the experimental results carried out in scaled apparatus. This confirmed the suitability of scale laws and in the same time the capability of the VVPSS to condense the injected steam at sub-atmospheric pressure, matching the safety goal to reduce the system pressurization.

Implementation of Low Pressure Water Mist System for Fire Suppression inside a Model of Road Tunnel

Previous studies have proven the performance of certain water mist system in general or in suppressing certain tunnel fires. The southern tunnel under the Suez Canal in the province of Ismailia length of 4 kilometers and 800 meters is serving the movement from Ismailia to Sinai through the Suez Canal old and new, while serving the northern tunnel movement from Sinai to Ismailia through the two channels. This tunnel in Ismailia is the largest in the world, with outer diameter of 12.6 meters, the internal 11,40 meters, the length of the tunnel is 4830 meters and reaches 6830 meters with the entrances and exits, the distance between the north and south tunnels 12 meters, and the maximum depth of the tunnel 45 meters down both Suez Canals. Since completing this project in the begin of 2019, this Tunnel did not experimentally test. This paper describes an experimental study of a low-pressure water-mist system (LPWMS) used in a scaled fire test conducted in a section of a scaled down road tunnel. The length, width, and height of the tunnel were 6 m, 2.4 m, and 2 m, respectively, which are in a ratio of 1:4 to the dimensions of an actual tunnel. The LPWMS used a pump pressure of 5.5 bar, and the system configuration was designed according to the pressure generated by the pump. Without a ventilation fan, the fire suppression time was 275 s, and amount of water required to fully suppress the fire was 696.67 L. When a ventilation fan was used, the maximum temperature location was moved from the center of the 6 m long tunnel toward the air inlet end of the tunnel (upstream). While this study will find the performance of the LPWMS in suppressing a fire in a small section of the Ismailia tunnel, determining the times spent and the amount of water consumed in the various stages of fire suppression, and in addition to studying the effect of the ventilation fan on These results and the location of the maximum temperature in the tunnel.

The Evolution of Gasses in Fire Suppression Systems to Promote Changes in Industrial Towards Global Sustainability

The historical development of fire suppression technology evolved in the 1930s since the application of Halons as a fire extinguishing agent. The fire may cause tremendous losses to organizations. It affects the chain of businesses and the stability of the economic growth of a country. The key issues of greenhouse effects and safety and health as well contributes to the sudden change of the technology of fire extinguishing systems. The establishment of the Montreal Protocol and Kyoto Protocols controls the producers to develop, supply and use of environmentally hazardous gasses worldwide. Hence, promote global sustainable for upcoming generations. This paper is highlighting the reasons gas type fire extinguishing agents extensively used substituting conventional methods against fire. The fundamental equations of Ozone Depleting Potential and Global Warming Potential were properly discussed to show how severe these gasses exposed to the environment. The effectiveness of these gases as a clean agent in extinguishing the fire may convince prospect users to carry out the decision of changes. Potential extinguishing agents will be deliberated to investigate their needs as new fire suppression agents. It will be then to be suggested and recommended for further studies.