Dual Fluid Research Articles

A preliminary study on the feasible design of bionic blanket concept

A bionic concept originating from the mechanism of gastric mucosa protecting a gastric wall from corrosion by gastric acid is creatively proposed, with the intention of finding a new way to reduce the corrosion of insulation coatings in liquid metal blankets. A compatible fluid barrier that mimics the function of gastric mucosa is used to prevent the flowing liquid metal from contacting the inner wall of a loop pipeline. The design of the bionic structure and the control of the barrier fluid are the most critical and difficult. A single-channel simulation is performed using Computational Fluid Dynamics (CFD) analysis to evaluate the effect of a compatible fluid barrier on separating the liquid lithium and insulation coating. The results show that the compatible fluid barrier can completely cover the inner wall of the pipeline within which the liquid metal is flowing, indicating that the bionic design can eliminate the corrosion of insulation coatings with flowing liquid lithium. Based on this, a compatible fluid barrier is investigated with multiple conditions, including the coverage area and film thickness, by changing the velocity ratio of the lithium to the barrier fluid, the shape of the inlet port, and the curvature radius of the bend pipes. In addition, an S-shaped pipe is confirmed to be completely corrosion free. This bionic concept is aimed at all corrosive liquid metals, and this work only starts with the extreme case of pure lithium. This work is expected to provide a preliminary feasibility basis for anti-corrosion design for a pipeline with dual fluids.

Exergy based sustainability analysis of a dual fluid hybrid photovoltaic/thermal (PV/T) solar collector

This paper aims to investigate the exergetic sustainability index (SI) of a dual-fluid PV/T type solar collector that integrates both air and water into the same solar collector. The contribution of the exergy efficiency of each of the dual fluid PV/T collector's components to the overall sustainability of the whole system was analysed. A theoretical approach based on an experimentally validated numerical model was employed. The results show that the SI of the PV component of the dual fluid PV/T system is in general higher than the solar thermal component by approximately 9% since it is higher in quality. When evaluated under three different climatic conditions, the contribution of the thermal component as a cooling medium to the PV is only prominent in hot climates with SI higher by 4% compared to the stand-alone PV system. For the cool and cold temperate climates, the difference is less than 0.1%.

Exergy-based sustainability analysis of a dual fluid hybrid photovoltaic and thermal solar collector

This paper aims to investigate the exergetic sustainability index (SI) of a dual-fluid PV/T type solar collector that integrates both air and water into the same solar collector. The contribution of the exergy efficiency of each of the dual fluid PV/T collector's components to the overall sustainability of the whole system was analysed. A theoretical approach based on an experimentally validated numerical model was employed. The results show that the SI of the PV component of the dual fluid PV/T system is in general higher than the solar thermal component by approximately 9% since it is higher in quality. When evaluated under three different climatic conditions, the contribution of the thermal component as a cooling medium to the PV is only prominent in hot climates with SI higher by 4% compared to the stand-alone PV system. For the cool and cold temperate climates, the difference is less than 0.1%.

MHD Mixed Convection Flow and Heat Transfer of a Dual Stratified Micropolar Fluid Over a Vertical Stretching/ Shrinking Sheet With Suction, Chemical Reaction and Heat Source

The purpose of this study was to investigate the magnetohydrodynamic (MHD) mixed convection flow and heat transfer of a dual stratified micropolar fluid over a vertical permeable stretching/ shrinking sheet with chemical reaction and heat source. The governing nonlinear partial differential equations are reduced into a system of nonlinear ordinary differential equations using an appropriate similarity transformation. Then, the obtained ordinary differential equations are solved numerically using the boundary value problem solver (bvp4c) in MATLAB software. The numerical results are tabulated and plotted for the heat transfer characteristics, namely, the skin friction coefficient, the local Nusselt number, the local Sherwood number as well as the velocity, temperature and concentration profiles for some values of the governing parameters. The present numerical results also have been compared with the previous reported results for a particular case and the comparisons are found to be in an excellent agreement. The results indicate that the skin friction coefficient and the local Nusselt number increase with chemical reaction and heat source. The magnitude of the local Sherwood number increases with the increasing of chemical reaction parameter. However, the magnitude of the local Sherwood number decreases with heat source effect.

Multi-objective optimization of a geothermal-based multigeneration system for heating, power and purified water production purpose using evolutionary algorithm

This study aims to develop a new multigeneration system based on geothermal energy and liquefied natural gas cold energy. The developed system includes dual fluid organic Rankine cycle and stirling engine to produce power, a desalination unit to produce purified water and a water heater to produce heating. Exergy and exergoeconomic analyses are carried out to determine the irreversibilities and the inefficient costs of each component of the developed process. The results show that the used heat exchanger (number 4), in liquefied natural gas regasification plant (26.72 $/h) and the used pump (number 3), in the desalination system (0.001 $/h), obtain the maximum and the minimum amount of exergy destruction cost. Moreover, multi-objective optimization is performed based on genetic algorithms. Achieved outcomes demonstrate that at the optimal point where exergy efficiency of the whole system as well as product cost rate are optimized, the corresponding values are 52.65% and 4.35 $/GJ, respectively. A sensitivity analysis is provided to assess the effects of design parameters on objective functions. Finally, advanced exergy analysis is performed on the most inefficient system components. Based on the avoidable endogenous part of irreversibility, heat exchangers (number 4) (843 kW), (number 3) (664 kW) and (number 1) (599 kW) should be modified first, respectively.

Gravity dual of Navier-Stokes equation in a rotating frame through parallel transport

The fluid-gravity correspondence documents a precise mathematical map between a class of dynamical spacetime solutions of the Einstein field equations of gravity and the dynamics of its corresponding dual fluid flows governed by the Navier-Stokes (NS) equations of hydrodynamics. This striking connection has been explored in several dynamics-based approaches and has surfaced in various forms over the past four decades. In a recent construction, it has been shown that the manifold properties of geometric duals are in fact intimately connected to the dynamics of incompressible fluids, thus bypassing the conventional on-shell standpoints. Following such a prescription, we construct the geometrical description that effectively captures the dynamics of an incompressible NS fluid with respect to a uniformly rotating frame. We propose the gravitational dual(s) described by bulk metric(s) in $(p+2)$-dimensions such that the equations of parallel transport of an appropriately defined bulk velocity vector field when projected onto an induced timelike hypersurface require that the incompressible NS equation of a fluid relative to a uniformly rotating frame be satisfied at the relevant perturbative order in $(p+1)$-dimensions. We argue that free fluid flows on manifold(s) described by the proposed metric(s) can be effectively considered as an equivalent theory of non-relativistic viscous fluid dynamics with respect to (w.r.t) a uniform rotating frame. We also present suggestive insights as to how space-time rotation parameters encode information pertaining to the inertial effects in the corresponding fluid dual.

Thermal Hydraulics Analysis of the Distribution Zone in Small Modular Dual Fluid Reactor

The Small Modular Dual Fluid Reactor (SMDFR) is a novel molten salt reactor based on the dual fluid reactor concept, which employs molten salt as fuel and liquid lead/lead-bismuth eutectic (LBE) as coolant. A unique design of this reactor is the distribution zone, which locates under the core and joins the core region with the inlet pipes of molten salt and coolant. Since the distribution zone has a major influence on the heat removal capacity in the core region, the thermal hydraulics characteristics of the distribution zone have to be investigated. This paper focuses on the thermal hydraulics analysis of the distribution zone, which is conducted by the numerical simulation using COMSOL Multiphysics with the CFD (Computational Fluid Dynamics) module and the Heat Transfer module. The energy loss and heat exchange in the distribution zone are also quantitatively analyzed. The velocity and temperature distributions of both molten salt and coolant at the outlet of the distribution zone, as inlet of the core region, are produced. It can be observed that the outlet velocity profiles are proportional in magnitude to the inlet velocity ones with a similar shape. In addition, the results show that the heat transfer in the center region is enhanced due to the velocity distribution, which could compensate the power peak and flatten the temperature distribution for a higher power density.

Low-Temperature Triggered Shape Transformation of Liquid Metal Microdroplets.

Shape transformable materials that can respond to external environments have attracted widespread interest over the fields of soft robotics, flexible electronics, and tissue engineering. Among stimuli-responsive materials, liquid metals exhibit rather unique characteristics of versatile morphological changes upon diverse stimuli, including chemicals, electrical field, and mechanical force, etc. Herein, a superfast (few milliseconds), large-scaled (13.8% deformation increase), and fierce (cracks formation) transformation of liquid metal microdroplets (LMMs) with strong impulse expanded force due to liquid-solid phase transition in a dual fluid system composed of LMMs and aqueous solution is reported. When subject to low-temperature stimulus, LMM would transform from ellipsoidal shape to amorphous shape induced by thermal stress, driving the shape morphing. Furthermore, the phase changes of LMMs as well as the formation of surrounding ice crystals are proven to be responsible for this phenomenal behavior. The densification of ice crystals is demonstrated to play a significant role in the transformable behavior. In particular, these nonconductive LMMs in aqueous solutions are discovered to turn into conducive materials with an impedance change of about 105 times. The present discovery is of fundamental and practical significance, and would open new venues in fields such as fluid mechanics, thermal science, flexible electronics, biomedicine, and so forth.

Performance of Dual Phase non-Newtonian Fluid in an Eccentric Annuli with Rotation of Inner Cylinder

The eccentric annular flow is a flow with special considerations; it forms a vital part of practical industrial flow analysis. In this work eccentric, dual phase flow through horizontal wells are simulated with the help of CFD. In horizontal annuli, flow occurs in an adverse pressure gradient condition, that makes the particle inside it susceptible to reversed flow. Thus the flow has to be analyzed in a three dimensional manner. Moreover, the non-Newtonian behavior of the fluid makes the problem really challenging in numerical and physical aspects. The results of this work clarify the relationship between different flow characteristics with the speed of inner wall rotation. The flow characteristics include swirl of flow, wall shear stress, and axial velocity.

Dual Fluid Reactor as a long‐term burner of actinides in spent nuclear fuel

Dual Fluid Reactor as a long‐term burner of actinides in spent nuclear fuel

Estimation of rheological characteristics of dual phase fluid at high temperature utilizing transfer learning

Steel, when first refined and put into widescale use changed construction and engineering. Skyscrapers, mega bridges and other massive structures reinforced with this miracle material changed skylines all over the world and opened the door for vast improvements in infrastructure. Steel is still a major component of building projects today and the steel beam is often considered as one of the impressive feats of human engineering. Steel is what chemists and engineers refer to as an alloy, meaning it is a composite material of several different elements. This alloy is mostly made with iron and carbon but can contain other elements as well. The blending of these elements with iron, the base metal of steel, gives it a high tensile strength at a low cost of production, making it the transformative material we know today. However, this metal is not without drawbacks as the process of refining steel generates several difficult to deal with by-products. Professor Noritaka Saito, who is based in the Department of Materials Science & Engineering, at Kyushu University in Japan, is looking at developing accurate ways to measure the properties of these mixtures so that industry can more efficiently produce precise composite materials.

New Methods for Nuclear Waste Treatment of the Dual Fluid Reactor Concept

New Methods for Nuclear Waste Treatment of the Dual Fluid Reactor Concept

Design of an accelerator-driven subcritical dual fluid reactor for transmutation of actinides

An accelerator-driven subcritical dual fluid reactor (AD-DFR), which is a hybrid core operated by a high power accelerator, is designed for the transmutation of minor actinides. The subcritical core is dual in the sense that a lead-bismuth-eutectic-cooled fast reactor (LFR) is combined with a molten salt reactor (MSR). Thus, the core has two loops: one for the liquid metal coolant and the other for the molten salt fuel. The combination of LFR and MSR can take advantages of both reactor types. A subcritical core allows for loading a high fraction of minor actinides in fuels. An 800MW_t AD-DFR can transmute minor actinides approximately 120kg/year with only the maximum beam power of 13MW.

Mixed Convective Flow and Heat Transfer of a Dual Stratified Micropolar Fluid Induced by a Permeable Stretching/Shrinking Sheet

The present study accentuates the magnetohydrodynamics (MHD) flow and heat transfer characteristics of a dual stratified micropolar fluid over a permeable stretching/shrinking sheet. Thermal and solutal buoyancy forces are also included to incorporate with the stratification effect. Similarity, transformation is applied to reduce the governing model (partial differential equations) into a set of nonlinear ordinary differential equations (ODEs) due to its complexity. Using bvp4c solver in the MATLAB software, numerical results for some limiting cases are in favorable agreement with the earlier published results. Both assisting and opposing buoyancy flows have dual similarity solutions within specific range of suction and stretching/shrinking parameters, whereas only a distinctive solution is observed for pure forced convective flow. The micropolar fluid shows a disparate pattern of flow, heat and mass transfer characteristics between stretching and shrinking cases. Unlike the shrinking flow, the surface velocity gradient, local Nusselt and Sherwood numbers for stretching flow intensify with the increment of the material parameter. The result from stability analysis reveals that the first solution is the real solution, whereas the second solution is virtual.

Comparative study of combined organic Rankine cycle and vapor compression cycle for refrigeration: Single fluid or dual fluid?

Combined organic Rankine cycle and vapor compression cycle (ORC-VCC) systems for heat activated cooling are widely concerned because of their simple structures and convenient maintenance. According to the number of the working fluids, there are two different ORC-VCC systems, which are single-fluid and dual-fluid ORC-VCC systems. However, it lacks a deep understanding of their applicability. In this paper, using the geothermal water of 140 °C as heat source, the flash tank vapor injection cycle is coupled with ORC (ORC-FTVIC) in order to improve the efficiency. Meanwhile, four different systems of ORC-VCC and ORC-FTVIC based on single-fluid and dual-fluid are compared. Six kinds of working fluids are selected to analyze the effects of system parameters on the system performance. Taking the second law efficiency of thermodynamic as the objective function, the key parameters and working fluids of four heat activated cooling systems are optimized simultaneously and compared. When the heat source temperature is 140 °C, the cooling capacity of dual-fluid ORC-FTVIC system is maximum (2282.0 kW), followed by single-fluid ORC-FTVIC system (2177.5 kW), dual-fluid ORC-VCC system (2132.8 kW), single-fluid ORC-VCC system (1918.8 kW). The corresponding optimum working fluids are R1234yf-R152a, R1234yf, R1234yf-R152a and R1234yf, respectively.

RANCANG BANGUN SISTEM REM MOBIL LISTRIK FUSENA

The brake system is a device to slow down or stop the movement of the wheel automatically so that the vehicle will move slowly. This completeness in the vehicle is very important and vital because it functions as a safety for life in driving. In the process of making the Electric Car Fusena brake system has steps in the process, consists of size planning, materials used, designs realized, manufacturing brake system supporting components, assembly, installation and testing of brake systems. The Fusena Electric Car brake system use a disc-type hydraulic brake system with one brake master that can work simultaneous with dual circuit fluids (front and rear braking). The comparison of the brake pedal is changed to 3: 1, designing and recreating the caliper stand to make it more precise so that it gets maximum brake performance and is better than the system used before. Static testing of the Fusena Electric Car hydraulic brake system is done by positioning the vehicle on an inclined plane at a slope of 15 and 20 with a variable driver load of 40 kg, 50 kg, 60 kg and 70 kg. The test results are that the vehicle does not experience displacement or movement. And the results of the average dynamic test of the Brake System at a speed of 27.3 km/h with an average braking distance of 171 cm = 1.71 meters and the average deceleration time is 0.26 seconds.

Methanol synthesis from renewable H2 and captured CO2 from S-Graz cycle – Energy, exergy, exergoeconomic and exergoenvironmental (4E) analysis

Thermodynamic, economic and environmental analyses of a combined CO2 capturing system, including, geothermal driven dual fluid organic Rankine cycle (ORC), proton exchange membrane electrolyzer (PEME), S-Graz cycle and methanol synthesis unit (MSU) were carried out. The presented zero emission system was designed based on the oxy-fuel combustion carbon capturing to produce power, hydrogen and methanol, while released CO2 can be captured. Generated renewable power by the ORC was utilized by the PEME to produce renewable hydrogen. Part of the produced hydrogen is fed to the MSU, while the rest was stored in hydrogen tanks. In fact, CO2 hydrogenation to produce methanol suggested via direct methanol synthesis in order to utilize the captured CO2 from the S-Graz cycle. Exergy efficiency of the system defined to analyze the system thermodynamically, while SPECO method utilized to evaluate system economically. Results revealed that the most important part of the system is the S-Graz cycle, from the viewpoint of capital investment. Also, the average product unit cost of 24.88 $/GJ obtained for the whole system.

Optimal Design and Flow-field Simulation of a Dual Fluid Atomizer

Two-dimensional turbulent flow-field properties of two types dual fluid atomizers which are currently popular in the market were numerically simulated and studied by using the commercial fluid dynamics software FLUENT. The present paper summarized their atomization characteristics respectively after studying the distribution rules of internal pressure, streamline and turbulent kinetic energy of the two kinds of dual fluid atomizers at different air flow rates. Finally, the conclusion was reached that the water absorption of the Type B atomizer is better than that of the Type A atomizer, but the secondary atomization effect of the Type B atomizer is not as good as the Type A’s.

Experimental investigation on the performance of a novel dual synthetic jet actuator-based atomization device

A synthetic jet actuator is a zero net mass flux device. In order to improve the compactness of spray cooling system, a novel dual synthetic jet actuator-based atomization device (DSJAA) is proposed and designed. In this atomization system, water is atomized by the oscillating dual synthetic jets instead of high-pressure air source. Moreover, no extra power for supplying water is needed. The effects of driving voltage, driving frequency, fluid volumetric flow rate and spray height are investigated on atomization rate, water droplet size, surface temperature and heat flux. The maximum atomization rate is 3.4 L/h at driving frequency of 700 Hz and driving voltage of 210 V. The dimensionless correlations between the physical properties of dual synthetic jet and the size of water droplet are presented, which provides guideline for the design of a dual synthetic jet actuator-based fluid atomizer. The experimental results show that when the resonance frequency of piezoelectric diaphragm is equal to half the Helmholtz frequency of DSJAA, the atomization performance is the best by setting driving frequency to resonance frequency. The best spray height is equal to the fluid stroke length of DSJAA. The cooling capability is mainly influenced by the Reynolds number of dual synthetic jet and volumetric flow rate of water. A correlation for DSJAA cooling is established. A maximum heat flux of the novel spray cooling method reaches as high as 59 W/cm2 in the experiments.

Effect of Process Parameters on Microencapsulation of Active Compounds by Co-flow Air Assisted Microfluidic Extrusion

A co-flow microfluidic system consists of two concentric channels inside which flow the inner dispersed phase (sodium alginate) and the outer continuous phase. The size and shape of microbeads depend on the physical-chemical properties and flow rate of fluids and on the process conditions such as diameter, material type of dripping tip and collecting distance. In order to reduce the microbeads size, external forces are used to break up the droplets. These forces could be generated by pressurized air, electrostatic charges and vibration. The technologies presented in literature for matrix encapsulation are based on a liquid-liquid dual immiscible fluid configuration, introducing a series of problems in industrial production, like gelation, oil separation and cleaning which would not arise using air as continuous phase. However, the use of air introduces a more complex fluid dynamics in possibly turbulent flow regime. The aims of this study include: firstly the developing an integrated system pump-microfluidic device; secondly the analysis of the size of Ca-alginate beads at different air flow rates setting the dispersed phase flow rate at 1 ml min-1; and finally the study of the influence of alginate sodium flow rate on beads size distribution and the capsules payload . For these purposes, a 3% (w/v) solution of sodium alginate was used. The air focused the dispersed phase at dripping tip, applying a shear force generating micro-droplets. A 0.2 M solution of calcium chloride dehydrate allowed the extruded drops gelation. Then, the size distribution was investigated using laser diffraction. The results showed that the size of microbeads decreased with increasing air flow rate (from 0.7 to 2.4 ln min-1).