Agglomeration of particulate matter in chimneys using acoustic flow.

The emission of micrometer-sized particulate matter on an industrial scale is causing increasing environmental concern about air pollution. Numerous industries and research communities need help to reduce micrometer-sized pollutants in the atmosphere. The current research investigates the acoustic agglomeration of particulate matter through a combination of experimental and numerical methods. Acoustic agglomeration is a process that involves using acoustic waves to influence the movement of particles in the air. Acoustic agglomeration operates by facilitating particle collision and simplifying the formation of agglomerates that are later removed through filtration. This article is focused on research on acoustic pre-processing with the aim of reducing atmospheric pollution caused by toxic combustion products. The capture of fine silica particles with diameters ranging from 0.3 to 10 µm, emitted through the chimneys of industrial enterprises, can be considered a significant technological innovation. The experimental part of the current research is conducted using a newly developed experimental bench. The assembly comprises the following key components: a wind tunnel, a particle dosing device, the agglomeration camera, and a particle concentration measurement device on the edge of the bench. A loudspeaker was used to evaluate the effect of sound pressure in the frequency range of 500-3000 Hz. A comprehensive CFD study of the particles was conducted, which included analysis of the boundary layer, facilitating a better understanding of the behavior of the particles and its potential to agglomerate. An experimental study of particle agglomeration, using an acoustic field with a frequency range of 500-3000 Hz, demonstrated the effectiveness of particle agglomeration of different diameters. The efficacy of particle agglomeration is up to 80 % when the sound pressure values were 129-135 dB; the highest efficiency was found at excitation frequencies of 1500 and 3000 Hz, respectively.

Investigation of the acoustic agglomeration on ultrafine particles chamber built into the exhaust system of an internal combustion engine from renewable fuel mixture and diesel.

Reducing the pollution of internal combustion engines is a very important problem that can be solved in various ways. However, the acoustic agglomeration method is not used in diesel engines. The study used a 1.9 TDI diesel internal combustion engine supplied with a mixture of diesel (D100) and a 90% of rapeseed methyl ester - 10% propanol fuel mixture (ROMEP). The study also changed the position of the exhaust gas recirculation (EGR) valve by adjusting the 20% EGR throughput limits and maintaining a constant engine load of 90 Nm. It should be noted that the use of biofuels produces less particulate matter, which reinforces the relevance of this study. Measurements were performed using Measurement System: The Testo 380 fine particle analyzer system was used to determine the mass concentration, and a six-channel Fluke 985 particle counter with an isokinetic sampling probe was used to determine the fractional numerical concentration of the particulates. Six particle size distribution regimes in the size range of 0.3 to 10 µm were observed, controlling the transmittance of the EGR system by 20%. The direction of the sound pressure throughout the flow and the excitation frequency 21400 Hz and 33800 Hz were also investigated and compared with the results without agglomeration. The article examines the possibility of using the developed acoustic chamber in the exhaust systems of various objects that uses diesel or various alternative fuel mixtures as fuel. The acoustic field reduces the number of particles by up to 92.5% for 10 µm and up to 44.5% for 0.3 µm at an excitation frequency of 21400 Hz.

Development and Experimental Research of Different Mechanical Designs of an Optical Linear Encoder's Reading Head.

Optical linear encoders are widely used in manufacturing. They are accurate and have a relatively high resolution and good repeatability. However, there are a lot of side effects, which have an inevitable impact on the performance of an encoder. In general, the majority of these effects could be minimized by the appropriate design of an encoder's reading head. This paper discusses the working principle of and commonly occurring errors in optical linear encoders. Three different mechanical designs are developed and implemented in the experimental reading head of the linear encoder in order to evaluate how mechanical construction influences the displacement measurement accuracy and total performance of the encoder.

Modelling of silk-reinforced PDMS properties for soft tissue engineering applications.

BACKGROUND: Polydimethylsiloxane (PDMS) is widely used in biomedical research and technology, but its mechanical properties should be tuned according to the desired product specifications. Mixing ratio of base polymer to curing agent or additives enables its mechanical properties to be manipulated and fit to mechanical properties of biological tissues. OBJECTIVE: In this paper, we analysed the effect of mechanical load on silk-reinforced PDMS depending on silk concentration. METHODS: We prepared cylinder-type PDMS samples with different silk concentrations and performed cyclic uniaxial compression tests with a fixed magnitude of applied strain. Next, we analysed the mechanical charascteristics of PDMS using computational modelling. RESULTS: The stress-strain data within the large-strain region of different PDMS cylinders without silk and with 1%, 5% and 10% silk concentrations was fitted to non-linear second order Mooney-Rivlin, and third-order Ogden models. The results show the equivalence of both models for investigated strain region of PDMS. On the other hand, PDMS cylinders with 10% silk concentration allowed the successful fitting of experimental data just for the second-order Mooney-Rivlin model, while all numerical probes to find an appropriate fitting parameters for third-order Ogden models were unsuccessful. CONCLUSIONS: The second-order Mooney-Rivlin model is preferable for analysing the properties of silk-reinforced PDMS over the entire measurement range.