scholarly journals Heat transfer and evaporation of salt solution on a horizontal heating wall

2020 ◽  
Vol 24 (3 Part B) ◽  
pp. 2171-2179
Author(s):  
Sergey Misyura
Keyword(s):  
Heat Transfer ◽  
Salt Concentration ◽  
Salt Solution ◽  
Water Solution ◽  
Thin Layers ◽  
Heated Wall ◽  
Salt Solutions ◽  
Heating Wall ◽  
Air Atmosphere ◽  
Over Time

An experimental study of non-isothermal heat transfer and evaporation of thin layers of aqueous solutions of salts has been carried out. Evaporation was realized on a horizontal heated wall in the air atmosphere at a pressure of 1 bar. In the evaporation of water and salt solution, the heat transfer coefficient is constant for a long time period and increases in the final stage due to the multiple reduction of the layer thickness. Evaporation curves for different types of salt solutions have a different character. Due to the increase in salt concentration, the evaporation rate of LiBr-water, CaCl2-water, LiCl-water, and MgCl2-water decreases over time. Salt solutions decreases with time. Evaporation rates for solutions of NaCl-water, CsCl-water, and BaCl2-water slightly change over time. To analyze the effect of free convection on heat transfer, experimental curves for the ratio of Nusselt numbers (A = Nu(salt)/Nu(water)) for the salt and water solution have been built. Parameter A is greater than one and increases with time. The effect of convection on heat transfer varies with time and depends on the current salt concentration and solution layer height, which should be considered in the simulation.

scholarly journals Production of Magnesium Oxides from Raw Salt Solution Using Electrochemical Precipitation Method as a Heterogeneous Catalyst for Transesterification of Coconut Oil

2020 ◽  
Vol 71 (8) ◽  
pp. 148-158
Author(s):  
Kamisah D. Pandiangan ◽  
Wasinton Simanjuntak ◽  
R. Supriyanto ◽  
Ilim Ilim ◽  
Ponco Prasetyo ◽  
...  
Keyword(s):  
Salt Concentration ◽  
Salt Solution ◽  
Coconut Oil ◽  
Precipitation Method ◽  
Electrolysis Time ◽  
Salt Solutions ◽  
X Ray ◽  
Electrochemical Conversion ◽  
Concentration Potential ◽  
Main Component

This study was conducted to explore the production of magnesium oxide from raw salt solution using electrochemical precipitation, followed by calcination. Electrochemical precipitation was conducted by electrolysis of the salt solution using nickel rods as cathodes and graphite as anodes. Two sets of salt solutions were prepared: one set without pretreatment and another with BaCl2 pretreatment. The solutions were used to study the effect of salt concentration, potential, and electrolysis time. The representatives of the MgO produced were tested as catalysts for transesterification of coconut oil. The results indicate that optimum mass of precipitate was produced from 400 mg/L salt solution electrolyzed using 8 V for 60 min. Elemental analysis using X-Ray Fluorescence (XRF) revealed the presence of Mg as the main component of the precipitate, confirming the electrochemical conversion of Mg2+ into solid Mg(OH)2. The MgO with the purity of 74.23% and 88.87% was produced from non-pretreated and pretreated salt solution, respectively. The transesterification experiments indicate that the yield of 90% and 98% was achieved using the MgO produced from non-pretreated and pretreated salt solution, respectively.

Synthesis and conformation of sequential basic polypeptides with branched and linear side chains

1985 ◽  
Vol 50 (12) ◽  
pp. 2925-2936 ◽  
Author(s):  
Štěpánka Štokrová ◽  
Jan Pospíšek ◽  
Jaroslav Šponar ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Salt Concentration ◽  
Salt Solution ◽  
Theoretical Work ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Cd Spectra ◽  
Low Salt ◽  
Conformational Freedom ◽  
Basic Polypeptides

Polypeptides (Lys-X-Ala)n and (Lys-X-Gly)n in which X represents residues of isoleucine and norleucine, respectively, and polypeptide (Tle-Lys-Ala)n, were synthesized via polymerization of 1-hydroxysuccinimidyl esters of the appropriate tripeptides to complete previously studied series. Circular dichroism (CD) spectra of the respective polymers were measured as a function of pH and salt concentration of the medium. The results were correlated with those obtained previously with the same series containing different amino acid residues at the X-position. The helix forming ability of the polypeptides (Lys-X-Ala)n with linear X side chain was found to be independent of the length. In the series (Lys-X-Gly)n the unordered conformation was the most probable one except (Lys-Ile-Gly)n. This polymer assumed the β conformation even in low salt solution at neutral pH. An agreement with some theoretical work concerned with the restriction of conformational freedom of amino acid residue branching at Cβ atom with our experimental results is evident.

scholarly journals Uncertainties Analysis on the Prediction of Flow and Heat Transfer of Liquid Sodium with CFD Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhanwei Liu ◽  
Xinyu Li ◽  
Tenglong Cong ◽  
Rui Zhang ◽  
Lingyun Zheng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Coefficient ◽  
Liquid Sodium ◽  
Heat Transfer Characteristics ◽  
Backward Facing Step ◽  
Heating Wall ◽  
Transfer Characteristics ◽  
Cfd Models ◽  
Flow And Heat Transfer

The prediction of flow and heat transfer characteristics of liquid sodium with CFD technology is of significant importance for the design and safety analysis of sodium-cooled fast reactor. The accuracies and uncertainties of the CFD models should be evaluated to improve the confidence of the numerical results. In this work, the uncertainties from the turbulent model, boundary conditions, and physical properties for the flow and heat transfer of liquid sodium were evaluated against the experimental data. The results of uncertainty quantization show that the maximum uncertainties of the Nusselt number and friction coefficient occurred in the transition zone from the inlet to the fully developed region in the circular tube, while they occurred near the reattachment point in the backward-facing step. Furthermore, in backward-facing step flow, the maximum uncertainty of temperature migrated from the heating wall to the geometric center of the channel, while the maximum uncertainty of velocity occurred near the vortex zone. The results of sensitivity analysis illustrate that the Nusselt number was negatively correlated with the thermal conductivity and turbulent Prandtl number, while the friction coefficient was positively correlated with the density and Von Karman constant. This work can be a reference to evaluate the accuracy of the standard k-ε model in predicting the flow and heat transfer characteristics of liquid sodium.

scholarly journals Numerical Analysis on Enhancing Spray Performance of SCR Mixer Device and Heat Transfer Performance Based on Field Synergy Principle

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 786
Author(s):  
Jiedong Ye ◽  
Junshuai Lv ◽  
Dongli Tan ◽  
Zhiqiang Ai ◽  
Zhiqiang Feng
Keyword(s):  
Heat Transfer ◽  
Conversion Rate ◽  
Water Solution ◽  
Three Dimensional ◽  
Field Synergy ◽  
Field Synergy Principle ◽  
Spray System ◽  
Injection Methods ◽  
Wall Injection ◽  
Dimensional Simulation

The NH3 uniformity and conversion rate produced by the urea–water solution spray system is an essential factor affecting de-NOx efficiency. In this work, a three-dimensional simulation model was developed with the CFD software and was employed to investigate the effects of two typical injection methods (wall injection and center injection) and three distribution strategies (pre-mixer, post-mixer, pre-mixer, and post-mixer) of two typical mixers on the urea conversion rate and uniformity. The field synergy principle was employed to analyze the heat transfer of different mixer flow fields. The results show that the single mixer has instability in optimizing different injection positions due to different injection methods and injection positions. The dual-mixer is stable in the optimization of the flow field under different conditions. The conclusion of the field synergy theory of the single mixer accords with the simulation result. The Fc of the dual-mixer cases is low, but the NH3 conversion and uniformity index rate are also improved due to the increase in the residence time of UWS.

scholarly journals Nanofluid Flow on a Shrinking Cylinder with Al2O3 Nanoparticles

Mathematics ◽  
2021 ◽  
Vol 9 (14) ◽  
pp. 1612
Author(s):  
Iskandar Waini ◽  
Anuar Ishak ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Friction Factor ◽  
Surface Heat Flux ◽  
Transfer Rate ◽  
Surface Heat ◽  
Al2o3 Nanoparticles ◽  
Nanofluid Flow ◽  
Curvature Parameter ◽  
Over Time

This study investigates the nanofluid flow towards a shrinking cylinder consisting of Al2O3 nanoparticles. Here, the flow is subjected to prescribed surface heat flux. The similarity variables are employed to gain the similarity equations. These equations are solved via the bvp4c solver. From the findings, a unique solution is found for the shrinking strength λ≥−1. Meanwhile, the dual solutions are observed when λc<λ<−1. Furthermore, the friction factor Rex1/2Cf and the heat transfer rate Rex−1/2Nux increase with the rise of Al2O3 nanoparticles φ and the curvature parameter γ. Quantitatively, the rates of heat transfer Rex−1/2Nux increase up to 3.87% when φ increases from 0 to 0.04, and 6.69% when γ increases from 0.05 to 0.2. Besides, the profiles of the temperature θ(η) and the velocity f’(η) on the first solution incline for larger γ, but their second solutions decline. Moreover, it is noticed that the streamlines are separated into two regions. Finally, it is found that the first solution is stable over time.

scholarly journals Effects of Temperature on the Flow and Heat Transfer in Gel Fuels: A Numerical Study

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 821
Author(s):  
Qin-Liu Cao ◽  
Wei-Tao Wu ◽  
Wen-He Liao ◽  
Feng Feng ◽  
Mehrdad Massoudi
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Transport System ◽  
Apparent Viscosity ◽  
Thermal Design ◽  
Straight Pipe ◽  
Heating Wall ◽  
Supply Pressure ◽  
Flow And Heat Transfer ◽  
The Mean

In general, rheological properties of gelled fuels change dramatically when temperature changes. In this work, we investigate flow and heat transfer of water-gel in a straight pipe and a tapered injector for non-isothermal conditions, which mimic the situations when gelled fuels are used in propulsion systems. The gel-fluid is modeled as a non-Newtonian fluid, where the viscosity depends on the shear rate and the temperature; a correlation fitted with experimental data is used. For the fully developed flow in a straight pipe with heating, the mean apparent viscosity at the cross section when the temperature is high is only 44% of the case with low temperature; this indicates that it is feasible to control the viscosity of gel fuel by proper thermal design of pipes. For the flow in the typical tapered injector, larger temperature gradients along the radial direction results in a more obvious plug flow; that is, when the fuel is heated the viscosity near the wall is significantly reduced, but the effect is not obvious in the area far away from the wall. Therefore, for the case of the tapered injector, as the temperature of the heating wall increases, the mean apparent viscosity at the outlet decreases first and increases then due to the high viscosity plug formed near the channel center, which encourages further proper design of the injector in future. Furthermore, the layer of low viscosity near the walls plays a role similar to lubrication, thus the supply pressure of the transport system is significantly reduced; the pressure drop for high temperature is only 62% of that of low temperature. It should be noticed that for a propellent system the heating source is almost free; therefore, by introducing a proper thermal design of the transport system, the viscosity of the gelled fuel can be greatly reduced, thus reducing the power input to the supply pressure at a lower cost.

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