Heat Transfer To Fiber Suspensions - Studies Of Particle Characterization And Fouling And Corrosion Mitigation / Ghulamullah Khan

Fibre suspension heat transfer and frictional pressure drop aspects were usually done in order to characterize fibres while flowing through a pipe lines. Fibre flow behaviour in pipe lines strongly depends on the fiber charateteristics like concentration, properties and suspension flow velocity. Moreover, fibre suspension flow is most significant scientific aspect paerticularly in the pulp and paper industry in such equipment as pipes, pumps, screens, washers etc. Many of them are well known, but still there is some lack of scientific research data regardign to the heat transfer and fricitonal losses to fibre suspensions and this is the major thrust of the current research reported in this thesis. A special conventional flow loop system with externally mounted heaters clamped on the outside of the pipe test section was constructed in order to measure the primarily heat transfer and frictional pressure drop to wood pulp. Fibre characterisation studies were examined employing various types of chemical and mechanical pulp fibre with the emphasis on three types of the one species of accasia mangium and accasia mangium hybrid. Heat trasfer coefficient hc values under the turbulent flow conditiosn, and all data were taken at different velocities and concentrations and at constant heat flux, similarly frictional pressure drops ΔP/L were aslo obtained simultaneously. The results show that most fibre dimensions and paper property data could be correlated with both hc and ΔP/L. The magnitude of hc and ΔP/L were found to depend on flow velocity, fibre concentration, flocculation, fibre population, fibre length, flexibility, coarseness, fibre surface topography, and the amount of fibrillar fines. Due to adhesive and hydrophilic nature of natural fibre, particularly at a lower flow rates, the accumulation of fibre at inner metallic wall surface cause stains and lead to metallic corrosion at particular fibre concnetration and may lead the fouling corosion as well. Alloys of iron epically mild steel and carbon steel are reactive materials and susceptible to corrosion process. The appliation of organic or environmental friendly inhibitor is one of the most widely used and effective industrial technique for the protection of metals against corrosion and in different aggressive mediums due to the advantages of their environmentally friendly, biodegradable in nature and can be synthesized by simple procedure with low cost. This study investigated the effect of environmental friendly additives as Schiff Bases and Gelatin for the mitigation of both fouling and corrosion. These additives comprises electronegative heteroatoms as Nitrogen, Oxygen and Sulfur atoms, different functional groups like -OCH3, -OH, -NO2 and Glutamic acid are responsible to make these additivves as excellent corrosion and fouling inhibitors. The objective of the present research work was to investigate heat trasfer coefficent hc and fricitonal pressure losses for different fibre sepicies as well as corrosion and fouling mechanim to the aggressive and fouling solutions and their mitigation by the application of environmental friendly additives

Kinetic Study of Cotton Stalk and Rice Husk Samples under an Inert and Oxy Combustion Atmospheres

International audienceBiomass materials such as CS (Cotton Stalks) and RH (Rice Husk) are a renewable source of energy. As biomass resources have potential to offer a uninterpted supply of biofuels through thermal decomposition processes. Nevertheless, an appropriate understanding of reaction kinetics and thermal properties of biomasses play a vital role in designing of the commercial plants using biomass as a raw material for energy generation. The kinetic characteristics of the CS and RH samples under pure nitrogen 99.9% and pure oxygen 99.9% was performed. The temperature was raised from ambient to 900 o C maintaining the heating rate of 10 o C/min. CS and RH decomposition was noticed in three dissimilar regions. The kinetic characteristics such as (pre-exponential factor, the order of reaction and activation energy) were calculated for both selected materials. The activation energies calculated under nitrogen environment for CS and RH was 68.77 and 72.31 kJ/mole, whereas the regression coefficient (R 2) was 0.9877 and 0.9731 respectively. The activation energies under oxygen environment were higher, it was 106 and 118 kJ/mole. The regression coefficient (R 2) under oxygen environment was 0.9987 and 0.99883 for above sample sequence

Corrosion Inhibition Performance and Adsorption Mechanism of Novel Quinazoline Schiff Base on Low Alloy Steel in HCl Media

The inhibition performance of synthesized Quinazoline Schiff Bases 2-(3,3-Dimethyl-2,3-dihydro-indol-2-ylidene)-3-[(2-hydroxyphenyl) imino] propylidene (DHIP1) and 2-(3,3-Dimethyl-2,3-dihydro-indol-2-ylidene)-3-[(2-hydroxyphenly) imino] propanal (DHIP2) on low carbon steel (LAS) in 1 M HCl has been examined using weight loss, electrochemical measurements and scanning electron microscopy (SEM). The obtained experimental results indicated that both DHIP1 and DHIP2 have fairly enhanced the corrosion resistance of LAS and extremely exhibited better inhibitive efficiencies at a concentration of 5 mM. The results of potentiodynamic polarization results clarified that investigated Schiff Bases acts as mixed-type inhibitors and follow Langmuir adsorption isotherm is fitted well for adsorption. It was found that the inhibition efficiency increases with increase in inhibitor concentration as confirmed by all the measurements

Effect of various refining processes for Kenaf Bast non-wood pulp fibers suspensions on heat transfer coefficient in circular pipe heat exchanger

Heat transfer coefficients were obtained for a range of non-wood kenaf bast pulp fiber suspensions flowing through a circular pipe heat exchanger test loop. The data were produced over a selected temperature and range of flow rates from the flow loop. It was found that the magnitude of the heat transfer coefficient of a fiber suspension is dependent on characteristics, concentration and pulping method of fiber. It was observed that at low concentration and high flow rates, the heat transfer coefficient values of suspensions were observed higher than that of the heat transfer coefficient values of water, on the other hand the heat transfer coefficient values of suspensions decreases at low flow rates and with the increase of their concentration. The heat transfer were affected by varying fiber characteristics, such as fiber length, fiber flexibility, fiber chemical and mechanical treatment as well as different pulping methods used to liberate the fibers. Heat transfer coefficient was decreased with the increase of fiber flexibility which was also observed by previous researchers. In the present work, the characteristics of fibers are correlated with the heat transfer coefficient of suspensions of the fibers. Deviations in fiber properties can be monitored from the flowing fiber suspensions by measuring heat transfer coefficient to adjust the degree of fiber refining treatment so that papers made from those fibers will be more uniform, consistent, within the product specification and retard the paper production loss

Toward improved heat dissipation of the turbulent regime over backward-facing step for the AL2O3-water nanofluids: An experimental approach

Experimental study of nanofluid flow and heat transfer to fully developed turbulent forced convection flow in a uniformly heated tubular horizontal backward-facing step has reported in the present study. To study the forced convective heat transfer coefficient in the turbulent regime, an experimental study is performed at a different weight concentration of Al2O3 nanoparticles. The experiment had conducted for water and Alumina-water nanofluid for the concentration range of 0 to 0.1 wt.% and Reynolds number of 4000 to 16000. The average heat transfer coefficient ratio increases significantly as Reynolds number increasing, increased from 9.6% at Re of 4000 to 26.3% at Re of 16,000 at the constant weight concentration of 0.1%. Alumina-water nanofluid exhibited excellent thermal performance in the tube with a backward-facing step in comparison to distilled water. However, the pressure losses increased with the increase of the Reynolds number and/or the weight concentrations, but the enhancement rates were insignificant

Decomposition-adsorption-deposition: An effective and novel technique for synthesis of hexagonal boron nitride microsheets

Magnesium diboride as a precursor with dual role of Nitrogen introduces a simple “decomposition-adsorption-deposition (DAD)” technique for the synthesis of Hexagonal Boron nitride microsheets (BNMSs) on silicon (Si) substrate at 1100 °C. The synthesized BNMSs has the apparent morphology like the white dispersed feathers on a plate surface with diameter in the range of 3–15 µm and lengt greater than 30 µm. All the BNMSs has the characteristics of h-BN lattice with an interlayer spacing of 0.34 nm. Boron and Nitrogen elemental compositions and h-BN phase of the synthesized BNMSs are verified from its characterization by X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FTIR) spectroscopy and Raman

Magnesium diboride (MgB2): An effective and novel precursor for the synthesis of vertically aligned BNNTs

Vertically aligned Boron nitride nanotubes (BNNTs) have exceptional electrical, mechanical and thermal properties suitable for its potential applications without any further purification. However, the synthesis of aligned BNNTs via previously reported techniques is not only complicated, lengthy and misleading but also result in useless impurities in the final product. Here, we report Magnesium diboride (MgB2) as an effective and novel precursor for the synthesis of vertically aligned BNNTs directly on SiO2 substrate at 1000 °C. Magnesium (Mg) from MgB2 in partially melted form diffuses on SiO2 substrate whereas the adsorbed Boron with Mg reacts with Nitrogen from decomposed ammonia and synthesized vertically aligned BNNTs. The morphology, alignment, structure and compositions of the as-synthesized BNNTs are studied via field emission scanning electron microscope, high resolution transmission electron microscope, energy dispersive x-ray spectroscopy, x-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy

Plastic Waste Recycling, Applications, and Future Prospects for a Sustainable Environment

Plastic waste accumulation has been recognized as one of the most critical challenges of modern societies worldwide. Traditional waste management practices include open burning, landfilling, and incineration, resulting in greenhouse gas emissions and economic loss. In contrast, emerging techniques for plastic waste management include microwave-assisted conversion, plasma-assisted conversion, supercritical water conversion, and photo reforming to obtain high-value products. Problems with poorly managed plastic waste are particularly serious in developing countries. This review article examines the emerging strategies and production of various high-value-added products from plastic waste. Additionally, the uses of plastic waste in different sectors, such as construction, fuel production, wastewater treatment, electrode materials, carbonaceous nanomaterials, and other high-value-added products are reviewed. It has been observed that there is a pressing need to utilize plastic waste for a circular economy and recycling for different value-added products. More specifically, there is limited knowledge on emerging plastic waste conversion mechanisms and efficiency. Therefore, this review will help to highlight the negative environmental impacts of plastic waste accumulation and the importance of modern techniques for waste management