Residential Flashover Prevention with Reduced Water Flow: Phase 2

The purpose of this study was to investigate the feasibility of a residential flashover prevention system with reduced water flow requirements relative to a residential sprinkler system designed to meet NFPA~13D requirements. The flashover prevention system would be designed for retrofit applications where water supplies are limited. In addition to examining the water spray's impact on fire growth, this study utilized thermal tenability criteria as defined in UL 199, Standard for Automatic Sprinklers for Fire-Protection Service. The strategy investigated was to use full cone spray nozzles that would discharge water low in the fire room and directly onto burning surfaces of the contents in the room. Where as current sprinkler design discharges water in a manner that cools the hot gas layer, wets the walls and wets the surface of the contents in the fire room. A series of eight full-scale, compartment fire experiments with residential furnishings were conducted with low flow nozzles. While the 23~lpm (6~gpm) of water was the same between experiments, the discharge density or water flux around the area of ignition varied between 0.3~mm/min (0.008~gpm/ft**2) and 1.8~mm/min (0.044~gpm/ft**2). Three of the experiments prevented flashover. Five of the experiments resulted in the regrowth of the fire while the water was flowing. Regrowth of the fire led to untenable conditions, per UL 199 criteria, in the fire room. At approximately the same time as the untenability criteria were reached, the second sprinkler in the hallway activated. In a completed system, the activation of the second sprinkler would reduce the water flow to the fire room, which would potentially lead to flashover. The variations in the burning behavior of the sofa resulted in shielded fires which led to the loss of effectiveness of the reduced flow solid cone water sprays. As a result of these variations, a correlation between discharge density at the area of ignition and fire suppression performance could not be determined given the limited number of experiments. An additional experiment using an NFPA~13D sprinkler system, flowing 30~lpm (8 gpm), demonstrated more effective suppression than any of the experiments with a nozzle. The success of the sprinkler compared with the unreliable suppression performance of the lower flow nozzles supports the minimum discharge density requirements of 2~mm/min (0.05~gpm/ft**2) from NFPA~13D. The low flow nozzle system tested in this study reliably delayed fire growth, but would not reliably prevent flashover.

APPROXIMATED VOLUME OF CONE AND SPHERE FROM DIFFERENT POINT OF VIEW

This paper attempts to shed light on how the volume of a cone and sphere can be perceived and derived through approximation from different perspectives. Although we all know the volume of cone and sphere, this is a small effort to get junior math readers out of their superstitions and into a new learning process. KEYWORDS: Solid, Cone, Sphere, Cylinder, Length, Area, Volume

Common Fixed Points of Two Mappings regarding a Generalized c -Distance over a Banach Algebra

In this article, applying the concept of a generalized c -distance in cone b -metric spaces over Banach algebra with a nonnormal solid cone therein, we establish several common fixed point theorems for two noncontinuous mappings satisfying the Han-Xu-type contraction. Our results are interesting, since they are not equivalent to former well-known results regarding a w t -distance in b -metric spaces while they contain recent results corresponding to a generalized c -distance in cone b -metric spaces.

Numerical simulation of atomization and combustion characteristics of high-moisture organic wastewater

The combustion method, due to its convenience and high-efficiency in harmless treatment, has been widely used in disposal of wastewater. With a wastewater burner as the study case, we performed numerical simulation by the Fluent software, analyzed the flowing and combustion process of the wastewater samples in the burner, compared the combustion effect of different atomization conditions — the spray cone model (hollow cone model, solid cone model), the spray angle, non-uniform grain size, uniform grain size. The study aims to provide suggestions for design and selection of wastewater burners.

ANALISA VARIASI DIAMETER LUBANG NOZZLE TERHADAP KARAKTERISTIK SPRAY MINYAK KELAPA DENGAN MINYAK KAPUK (B50) PADA PEMBAKARAN DIFUSI

Minyak bumi sebagai sumber utama bahan bakar mengakibatkan cadangan minyak bumi menurun. Perlu adanya upaya untuk mengganti minyak bumi dengan bahan bakar lain didapat dari tanaman atau hewan. Tanaman penghasil minyak nabati salah adalah minyak kelapa dan kapuk. Untuk mendapatkan pembakaran sempurna, perlu dilakukan penelitian menggunakan metode pembakaran spray/difusi dengan menggunakan variasi diiameter nozzle 0,2 mm, 0,4 mm dan 0,6 mm dengan bentuk spray solid cone dan tekanan yang konstan 50 bar. Bahan bakar yang digunakan campuran antara minyak kelapa dengan minyak kapuk (B50). Diameter droplet yang dihasilkan semalin besar berbanding lurus dengan diameter nozzel yang semakin besar. Bertambahnya panjang nyala api dipengaruhi oleh meningkatnya diameter nozzle. Semakin meningkatnya sudut spray seiring dengan semakin besarnya diameter nozzle. Dengan variasi penyalaan awal, flashback hanya terjadi pada jarak penyalaan awal 500 mm. Terjadi perbedaan turbulensi pada variasi nozzle, semakin besar diameter nozzle maka semakin besar turbulensi nyala api yang terjadi.

Improvement in Ignition Delay Characteristics of Diesel Engine Combustion by Varying Combustion Chamber Air Pressure

Complete and clean combustion is always desirable for better performance of engine and less emissions. An experimental work is carried in constant volume combustion chamber for getting conditions like diesel engine combustion to study the ignition delay characteristics of diesel engine combustion by varying combustion chamber air pressure. In this experimental work, air pressure of combustion chamber varied from 10 to 25 bar, hot surface temperature inside the combustion chamber varied from 350°C to 550°C and fuel injection pressures varied from 100 to 200 bar for hollow cone spray and solid cone spray . For this work a set-up is made in which the flame detection is done by digital storage oscilloscope using an optical method. The findings of the work suggests that combustion chamber air pressure and injection pressure are significantly varies the values of ignition delay at a particular hot surface temperature. It is also find that on increasing the values of combustion chamber air pressure and injection pressure, ignition delay values are decreases although the variation in ignition delay is less at higher injection pressure and combustion chamber air pressure.

Pt(II) Derivatives with Rollover-Coordinated 6-substituted 2,2′-bipyridines: Ligands with Multiple Personalities

We report here the synthesis, characterization and behavior of a series of Pt(II) cyclometalated rollover complexes with two substituted bipyridines, 6-ethyl-2,2′-bipyridine (bpy6Et) and 6-methoxy-2,2′-bipyridine (bpy6OMe), in comparison with previously studied 2,2′-bipyridine complexes. The two ligands have similar steric hindrance but different electronic properties. As a result, the reactivity of the two series of complexes follows very different routes. In particular, the new complexes behave differently towards protonation reactions, differences given by substituents and ancillary ligands, added to the presence of several nucleophilic centers. Reaction of complex [Pt(bpy6OMe-H)(PPh3)Me)] with [H3O⋅18-crown-6][BF4] results in a retro-rollover reaction whose final product is the cationic adduct [Pt(bpy6OMe)(PPh3)Me)]+. Surprisingly, only the isomer with the cis-PPh3-OMe geometry is formed; in spite of an expected instability due to steric hindrance, Density-Functional theory (DFT) calculations showed that this isomer is the most stable. This result shows that the cone angle is far from being a real “solid cone” and should lead to a different interpretation of well-known concepts concerning steric bulk of ligands, such as cone angle. Proton affinity values of ligands, neutral complexes and their protonated counterparts were analyzed by means of DFT calculations, allowing a comparison of their properties.

A Design Insight for Substitution of Metal Shims with Reverse Engineered Element in Tool Post for Alignment of Tool-Work Center

This research work propounds and analyses the comparison of solution to the issue of height adjustment of tool in four way tool post. The customary way of tool lifting in tool post to centre of work i.e. by adding/removing metal packing, is altered by introducing a design alternative for tool lifting, an upgradation in the former proposed design named solid double cone threaded pin (SDCTP). It is explicitly studied to investigate its limitation and scope for further design amendments. In the premise, a revised design is proposed including modifications named as solid cone threaded pin (SCTP) and is fabricated along with its assembly. Mathematical calculations of least count and screw thread analysis are performed on both the pins. Finite element analysis on CREO is executed to calculate stresses induced for diverse loads to analyze pin failure conditions. The results of new modified design is compared with the erstwhile concluding that SCTP design is preferable over SDCTP design entailing precise tool adjustment, saving time and higher efficiency in machining operations. The paper subsequently explores conventional tool lifting method and its shortfall, shortcomings of former design, revised design and its comparison, fabrication of revised design, conclusions and future ambit.