Experimental and Numerical Analysis of Multi-Hole Orifice Flow Meter: Investigation of the Relationship between Pressure Drop and Mass Flow Rate.

The paper presents the results of the experimental and numerical analysis of a six-hole orifice flow meter. The experiments were performed on humid air in a 100 mm diameter duct. The aim of this research was to investigate the mass flow and pressure drop dependency in an orifice of a predetermined shape and to compare the results obtained with computational formulas recommended in the ISO 5167-2 standard for a single-hole orifice flow meter. The experiments and calculations were performed on several multi-hole orifice geometries with different contraction coefficient in a wide range of Reynolds numbers. The pressure was probed immediately upstream and downstream of the orifice. The flow coefficient determined for the six-hole orifice flow meter investigated was compared with the flow coefficient of conventional single-hole orifice with the same contraction coefficient. The results from computational formulas for single-hole orifice from ISO 5167 are also included in the paper. During some experiments, an obstacle has been introduced in the duct at variable distance upstream from the orifice. The effect of the thus generated velocity field disturbance on the measured pressure drop was then investigated. Numerical simulation of the flow with the presence of the obstacle was also performed and compared with experimental data.

Effect of the Drying Method of Pine and Beech Wood on Fracture Toughness and Shear Yield Stress.

The modern wood converting processes consists of several stages and material drying belongs to the most influencing future performances of products. The procedure of drying wood is usually realized between subsequent sawing operations, affecting significantly cutting conditions and general properties of material. An alternative methodology for determination of mechanical properties (fracture toughness and shear yield stress) based on cutting process analysis is presented here. Two wood species (pine and beech) representing soft and hard woods were investigated with respect to four diverse drying methods used in industry. Fracture toughness and shear yield stress were determined directly from the cutting power signal that was recorded while frame sawing. An original procedure for compensation of the wood density variation is proposed to generalize mechanical properties of wood and allow direct comparison between species and drying methods. Noticeable differences of fracture toughness and shear yield stress values were found among all drying techniques and for both species, but only for beech wood the differences were statistically significant. These observations provide a new highlight on the understanding of the effect of thermo-hydro modification of wood on mechanical performance of structures. It can be also highly useful to optimize woodworking machines by properly adjusting cutting power requirements.

A Critical Reanalysis of Uncontrollable Washboarding Phenomenon in Metal Band Sawing.

The article analyzes the cutting process of hard bars. Investigations conducted in industrial conditions demonstrated the presence of surface errors in the machined workpieces in the form of washboard patterns. The purpose of this study was to analyze the results of cutting on band sawing machines with different band saw blades. The cutting processes were conducted on three different horizontal band sawing machine types. Analyzed material was an alloy steel Ø40 mm rod with a hardened surface covered with a thin layer of chromium. The hardness of the outer layer was 547 HV with a core hardness of 180 HV. The surface topography measurements of the processed workpieces were carried out with the 3D Optical Profiler, which supplied information on the irregularities of the processed material texture. In each of the analyzed cases, a corrugated surface was obtained after sawing, which is the effect of the occurrence of the washboarding phenomenon, despite the fact that the teeth of each band saw had variable pitches. The washboarding phenomenon when cutting rods with hard surfaces is caused by the phenomenon of wave regeneration. Despite the use of variable pitch saw blades, the cutting process results in rippling of the sawn surface, which is caused by the high hardness of the outer layer of the workpiece, as well as by the type of tool with spring setting of teeth.

Novel Desorber for Online Drilling Mud Gas Logging.

This work presents the construction solution and experimental results of a novel desorber for online drilling mud gas logging. The traditional desorbers use mechanical mixing of the liquid to stimulate transfer of hydrocarbons to the gaseous phase that is further analyzed. The presented approach is based on transfer of hydrocarbons from the liquid to the gas bubbles flowing through it and further gas analysis. The desorber was checked for gas logging from four different drilling muds collected from Polish boreholes. The results of optimization studies are also presented in this study. The comparison of the novel desorber with a commercial one reveals strong advantages of the novel one. It is characterized by much better hydrocarbons recovery efficiency and allows reaching lower limits of detection of the whole analytical system. The presented desorber seems to be very attractive alternative over widely used mechanical desorbers.

A novel process for the fabrication of nanocomposites membranes.

The combination of electrospinning and electrospraying techniques for the deposition of inorganic nanoparticles over polymeric nanofibers to create novel multifunctional nanomaterials has been carried out. The combination of these two techniques is essential because by conventional mixing of nanoparticles with polymers and then electrospinning resulted in nanoparticles covered by the polymer and thereby nanoparticles are unavailable for the catalysis applications. This technique is also useful to exploit the application of nanofibers for various applications. Based on the materials chosen, this technology can be applied to various applications such as protective suits, biological applications, catalysis, etc. Here the challenging task is to avoid the aggregation of nanoparticles and improve the distribution of nanoparticles over nanofibers. This was achieved by optimizing various electrospraying parameters (such as feed rate, voltage) and the dispersion properties. The dispersion in solution has been achieved by using a surfactant and optimization of silane modifier concentration and sonication time. Hydrolysis of paraoxon, a nerve agent stimulant was tested for these nanocomposite membranes by UV analysis. Decrease in absorbance was observed for these membranes with time suggesting the detoxification of nerve agent. Hence these membranes can be used as filter media in protective clothing (to detoxify chemical warfare agents to replace the existing charcoal based protection suits wherein the warfare agents are not detoxified rather adsorbed) and air filter applications.

Wet electroscrubbers for state of the art gas cleaning.

Current trends observed in air pollution control technology are closely related to the development of new, more efficient hybrid systems, i.e., those, which simultaneously utilize two or more physical mechanisms for dust or gaseous contaminants removal. These systems can operate more economically than conventional devices, especially in the removal of PM2.5 particles. The electrostatic scrubber (electroscrubber), discussed in this paper, is one of such types of devices, which combines advantages of electrostatic precipitators and inertial wet scrubbers, and removes many shortcomings inherent to both of these systems operating independently. The electroscrubber is a device in which Coulomb attraction or repulsion forces between electrically charged scrubbing droplets (collector) and dust particles are utilized for the removal of particles from a gas. Unlike wet electrostatic precipitators in which particles are precipitated only on the collection electrode, in electroscrubbers, the collection of dust particles takes place in the entire precipitator chamber. Compared to inertial scrubbers, the electroscrubbers can operate at lower droplet velocities, but the collection efficiency for a single droplet can be larger than 1. The paper reviews the state-of-the-art of wet electrostatic scrubbing (electroscrubbing) technique used for gas cleaning from dust or smoke particles. Three groups of problems are discussed: (1) The fundamental problems concerning the charged dust particle deposition on a charged collector, usually a drop, with a focus on different models describing the process. (2) The experimental works of fundamental importance to our knowledge referring to the scrubbing process, which can be used for validating the theory. (3) The laboratory demonstrations and industrial tests of different constructions of electroscrubbers designed for effective gas cleaning. The electroscrubber is not designed to replace wet or dry electrostatic precipitators but can be used as a complementary device following the last stage of conventional electrostatic precipitator, which helps to remove submicron particles. It was shown in the paper that a higher collection efficiency of an electroscrubber could be obtained for higher values of Coulomb number (i.e., higher electric charges on the collector and particle), and for a Stokes number lower than5 (i.e., low particle-collector relative velocity).