Carrier Fluid Research Articles

Evaluation of the effect of cold normal saline as a carrier fluid in reducing propofol induced pain

Evaluation of the effect of cold normal saline as a carrier fluid in reducing propofol induced pain

Front-Tracking and Gelation in Sessile Droplet Suspensions: What Can They Tell Us about Human Blood?

Recently developed imaging techniques have been used to examine the redistribution of human red blood cells and comparator particles dispersed in carrier fluids within evaporating droplets. We demonstrate that progressive gelation initiates along an annular front, isolating a central pool that briefly remains open to particulate advection before gelation completes across the droplet center. Transition to an elastic solid is evidenced by cracking initiating proximal to front locations. The arrested flow of cellular components, termed a "halted front", has been investigated using a time-lapse analysis "signature". The presence of a deformable biocellular component is seen to be essential for front-halting. We show a dependence of front-halt radius on cell volume-fraction, potentially offering a low-cost means of measuring hematocrit. A simple model yields an estimate of the gel zero-shear yield-stress. This approach to understanding the drying dynamics of blood droplets may lead to a new generation of point-of-care diagnostics.

On the electrohydrodynamic jet printing of two-dimensional material-based inks for printed electronics

Electrohydrodynamic (EHD) jet printing is a well-known advanced manufacturing technique that uses electric fields to generate and control fine jets of fluid for high-precision deposition of materials. This method enables the printing of extremely fine features, making it ideal for applications such as printed electronics. However, little is known about the optimal conditions for achieving consistent jet stability and droplet formation, especially when dealing with complex and volatile fluids laden with two-dimensional (2D) nanoparticles. In this work, we study the electrohydrodynamic printing process of 2D material-based inks using toluene as the main carrier fluid. Adding ethyl cellulose to toluene allows us to increase the stability of the suspensions and establish the steady cone-jet mode of electrospray. A small amount of ethanol increases the fluid conductivity, stabilizing the steady cone-jet mode and reducing the jet diameter. The inks behave as leaky-dielectric, weakly viscoelastic liquids. For this reason, the jet diameter and minimum flow rate obey the scaling laws for electrospray of Newtonian liquids. We determine the optimal parameter conditions for the EHD printing of our inks directly onto a non-conductive substrate. The influence of the substrate's velocity on the width of the printed lines is analyzed. These findings enlarge the knowledge about how to increase the throughput in the EHD jet printing process while controlling the resolution of the printed lines when using volatile solvents, 2D nanomaterials, and non-conductive substrates.

CO2 thermal network prototype: Identifying control parameters for optimal operation in transcritical mode

An innovative concept has been developed and patented recently called CO2 Thermal Network (CO2TN) to improve the performance of heating and cooling systems in buildings. It is a decentralized system circulating two-phase CO2 at 20 ± 5 °C inside a building, instead of water, as a heat carrier fluid (HCF) in a single pipe. Heat pumps connected to this pipe provide heating and cooling inside a building using CO2 at their source side. Thus, the heat pumps operate with enhanced and consistent performance. The pipe also facilitates heat recovery between the connected units. Additionally, leveraging the latent heat of two-phase CO2, the CO2TN operates with a reduced mass flow rate in the loop, requiring a lower circulation energy consumption than conventional hydronic systems.This study introduces the concept and the first prototype of a CO2TN system. Then, the paper experimentally investigates the influential parameters that control the system’s operation and optimize its performance in transcritical mode. The results showcase that a CO2TN’s performance depends on its gas cooler (GC) temperature and pressure, the number of working heat pumps, and their mode of operation. An optimal GC outlet temperature exists for each GC pressure, which can improve system performance by up to 30%. Moreover, the GC pressure depends on the temperature range of the thermal energy sources used to balance the CO2TN. Additionally, the system shows significant performance improvement—up to 63%—when multiple heat pumps operate simultaneously in different modes.

Heat Transfer Performance Factors in a Vertical Ground Heat Exchanger for a Geothermal Heat Pump System

Ground heat pump systems (GHPSs) are esteemed for their high efficiency within renewable energy technologies, providing effective solutions for heating and cooling requirements. These GHPSs operate by utilizing the relatively constant temperature of the Earth’s subsurface as a thermal source or sink. This feature allows them to perform greater energy transfer than traditional heating and cooling systems (i.e., heating, ventilation, and air conditioning (HVAC)). The GHPSs represent a sustainable and cost-effective temperature-regulating solution in diverse applications. The ground heat exchanger (GHE) technology is well known, with extensive research and development conducted in recent decades significantly advancing its applications. Improving GHE performance factors is vital for enhancing heat transfer efficiency and overall GHPS performance. Therefore, this paper provides a comprehensive review of research on various factors affecting GHE performance, such as soil thermal properties, backfill material properties, borehole depth, spacing, U-tube pipe properties, and heat carrier fluid type and velocity. It also discusses their impact on heat transfer efficiency and proposes optimal solutions for improving GHE performance.

Novel lattice Boltzmann method for simulation of strongly shear thinning viscoelastic fluids

AbstractThe simulation of viscoelastic liquids using the Lattice–Boltzmann method (LBM) in full three dimensions remains a formidable numerical challenge. In particular the simulation of strongly shear‐thinning fluids, where the ratio between the high‐shear and low‐shear viscosities is large, is often prevented by stability problems. Here we present a novel approach to overcome this issue. The central idea is to artificially increase the solvent viscosity which allows the method to benefit from the very good stability properties of the LBM. To compensate for this additional viscous stress, the polymer stress is reduced by the same amount. We apply this novel method to simulate two realistic cell carrier fluids, methyl cellulose and alginate solutions, of which the latter exhibits a viscosity ratio exceeding 10,000.

A numerical investigation of the polyethylene glycol‐based tetra hybrid nanofluid flow over a stretched porous rotatory disk

AbstractPolyethylene glycol (PEG) is a great heat and mass transmissive fluid that has promising applications in medical, pharmaceutical, and electronic industries. Tetra‐hybrid nanofluids (HNFs) are the most upgraded version of heat and mass transmissive nanofluids that are synthesized by dispersing four distinct nanoparticles in the carrier fluid. The study of the flow of nanofluids and their advanced classes across rotatory disks is receiving remarkable interest in research and innovation due to their considerable applications like gas turbine rotors, aeronautical, medical equipment, rotating machinery, thermal power developing systems, and so forth. Therefore, the present paper aims to inspect the magnetohydrodynamic, steady, three‐dimensional, and incompressible flow of a non‐Newtonian tetra‐HNF over a stretched porous rotating disk. The chosen tetra‐HNF consists of four distinct nanoparticles namely, molybdenum disulfide, copper oxide, magnesium oxide, and zirconium oxide with PEG as the carrier fluid. The flow model is modified with innovative impacts of variable thermal conductivity, thermal radiation, chemical reaction, variable mass diffusivity, and suction/injection to make this research more convenient. The mathematical computation is conducted via the bvp4c numerical method, and the outputs are determined via tables and graphs. Mounting values of the Deborah number amplify the axial velocity while augmentation is noticed in the fluid's radial and azimuthal velocities for rising values of the rotation parameter. Besides, the rotation parameter aids in enhancing both the heat and mass transportation rates while the chemical reaction parameter significantly aids the mass transportation rate. One of the significant results of this inspection is that tetra‐HNF exhibits better heat and mass transportation rates than the ternary‐HNF, and the HNF whereas it has lesser skin friction than the ternary‐HNF, and the HNF.

One-dimensional model for vertical hydraulic transport of high-concentration mineral particles

A novel model is proposed for analyzing high-concentration granular flow systems comprising equally sized spherical particles within vertical, long straight pipelines. This model is specifically tailored for simulating the vertical hydraulic transport of ore particles in marine mining projects. The proposed model treats the granular system akin to a pseudo-fluid and operates through three mechanisms. First, fluid characteristics of the granular system are derived from particle–particle collisions. Second, the resistance exerted by the pipe wall on the granular system is calculated based on the momentum loss of particles during particle–wall collisions. Third, the interaction between individual particles and the surrounding fluid is transformed into an interaction between the carrier fluid and the pseudo-fluid. Additionally, the present work develops a dedicated numerical format and iterative method for solving the one-dimensional two-fluid governing equations. The one-dimensional (1D) model notably enhances computational efficiency and facilitates accurate tracking of high-concentration particles over extended distances within straight pipelines. Notably, the proposed 1D model demonstrates a high degree of predictive accuracy when compared against experimental data as well as results from computational fluid dynamics and discrete element method simulations.

Sustainable reuse of oil and gas wells for geothermal energy production: Numerical analysis of deep closed loop solutions in Italy

This study assesses the feasibility of repurposing abandoned oil and gas wells in Italy for geothermal energy production employing a geothermal closed-loop system. A systematic methodology was developed, beginning with raw data collection and progressing to numerical simulations using COMSOL Multiphysics to model a U-shaped deep closed-loop geothermal heat exchanger. The analysis relied on a public database of wells drilled in Italy since the mid-20th century. The Horner plot correction method was applied to measured temperature data to obtain accurate geothermal gradients across Italy, which were then used as input parameters for a numerical sensitivity analysis. The results highlight the critical role of the geothermal gradient and heat carrier fluid flow rate in determining system performance. Regions in Italy with geothermal gradients exceeding 40 °C/km, particularly in the Tyrrhenian area, were identified as having high potential for this technology. A preliminary analysis of a virtual Organic Rankine Cycle (ORC) system estimated power production of 73 kW, with an efficiency of 11.66 % after 25 years of operation under optimal conditions (5 l/s flow rate, 60 °C/km geothermal gradient, and 70 °C evaporation temperature).

Implementation of An Optical Gauss Meter Based on Ferrite and Hematite Ferrofluids

Three compositions Ni0.5Fe2.5O4, Ni0.7Fe2.3O4, and Fe2O3 were prepared by the co-precipitation method and checked by XDR, SEM, and VSM. The nanoparticles show a good match with the XRD standards. The particle sizes were 25, 32, and 18nm for the above compositions, respectively. The first composition showed the highest magnetization saturation. Suspensions containing the mentioned nanoparticles were prepared with two carrier fluids, distilled water, and dimethylsulphoxide (DMSO). A transmission to ultraviolet-visible light was tested and showed good transparency of more than 60 % in the red light region. The transparency to 623nm laser light under different magnetic fields of the six suspensions was tested. A simple device was fabricated to perform this test. The water suspension in water Ni0.5Fe2.5O4 has a larger variation in the transmitted power. The suspension of hematite shows no sensible change in the transmitted power. The magnetic properties of the nanoparticles and the dispersion property of the carrier fluid were behind the explanation of the suspension behaviors under the influence of the magnetic field.

Particle Dynamics Study on Influencing Factors of Ice Slurry Flow Characteristics in District Cooling Systems

In district cooling systems, substituting the conventional cooling medium with ice slurry represents an ideal approach to achieve economical operation. During pipeline transportation, ice slurry exhibits heterogeneous flow characteristics distinct from those of pure fluids. Consequently, investigating the flow field characteristics of non-homogeneous ice slurry, quantitatively analyzing the rheological variations and flow resistance laws due to the uneven distribution of ice particles, and standardizing the comprehension and depiction of flow patterns within ice slurry pipes hold significant theoretical importance and practical value. This study analyzes the heterogeneous isothermal flow characteristics of ice slurry in a straight pipe by employing particle dynamics and the Euler–Euler dual-fluid model. Taking into account the impact of ice particles’ non-uniform distribution on the rheological properties of ice slurry, a particle concentration diffusion equation is incorporated to develop an isothermal flow resistance model for ice slurry. The flow behavior of ice slurry with initial average ice particle fractions (IPFs) ranging from 0% to 20% in DN20 horizontal straight and elbow pipes is examined. The findings reveal that the degree of heterogeneous flow in ice slurry is inversely proportional to the initial velocity and directly proportional to the initial concentration of ice particles. When the flow velocity is close to 0.5 m/s, the flow resistance of ice particles exhibits a linear positive correlation with changes in flow velocity, whereas the flow resistance of the fluid-carrying phase displays a linear negative correlation. As the flow rate increases to 1 m/s, the contribution of each phase to the total flow resistance becomes independent of the initial velocity parameter. Additionally, the drag fraction of the ice particle phase is positively associated with the initial concentration of ice particles. Furthermore, the phenomenon of “secondary flow” arises when ice slurry flows through an elbow, enhancing the mixing of ice particles with the carrier fluid. The extent of this mixing intensifies with a decrease in the turning radius and an increase in the initial velocity.

Polygenic scores stratify neurodevelopmental copy number variant carrier cognitive outcomes in the UK Biobank

Rare copy-number variants associated with neurodevelopmental conditions (ND-CNVs) exhibit variable expressivity of clinical, physical, behavioural outcomes. Findings from clinically ascertained cohorts suggest this variability may be partly due to additional genetic variation. Here, we assessed the impact of polygenic scores (PGS) and rare variants on ND-CNV carrier fluid intelligence (FI) scores in the UK Biobank. Greater PGS for cognition (PSCog) and educational attainment (PSEA) is associated with increased FI scores in all ND-CNVs (n = 1317), 15q11.2 del. (n = 543), and 16p13.11 dup. carriers (n = 275). No association of rare variants associated with intellectual disability, autism, or putatively loss-of-function, brain-expressed genes was found. Positive predictive values in the first deciles of PScog and PSEA showed a two- to five-fold increase in the rate of low FI scores compared to baseline rates. These findings demonstrate that PGS can stratify ND-CNV carrier cognitive outcomes in a population-based cohort.

Augmentation of heat transfer in a DPHE with bowl cut twisted tape inserts and TiO2/CuO hybrid nanofluids

Double pipe heat exchangers, or DPHEs, are employed in the power, oil, and process sectors. They cannot handle demanding applications. They have restrictions if they have to be utilized for heavy-duty applications. To get beyond these restrictions and use them for heavy-duty applications, heat transmission must be improved. In this work, a DPHE fitted with bowl-cut twisted tapes at different scale ratios (25, 50, and 75%) width (D) of bowl-cut from the center and circulated with TiO2/CuO hybrid nanofluids (NFs) is studied to assess its friction factor, thermal performance factor and Nusselt number. The working fluid was TiO2/CuO hybrid nanofluids (NFs) at varying concentrations (0.01, 0.03, and 0.05%) with Reynolds numbers from 2000 to 12,000. The bowl-cut twisted tape’s twisted ratio (H/D = 3) was kept constant. The hybrid NFs’ Nusselt number improvement was 66.09% more than that of the conventional tube. For varying scale ratios, the improvement in heat transfer was found to be 83.35, 115.31, and 172% with the bowl-cut twisted tapes and hybrid NFs. It was discovered that the friction factor penalty was 8.28, 0.83, and 1.075 times greater than that of the carrier fluid. Additionally, it was noticed that the thermal performance factor (TPF) was 1.65 times higher than the original fluid.

Mathematical Formulations for Predicting Pressure Drop in Solid–Liquid Slurry Flow through a Straight Pipe Using Computational Modeling

The study establishes two mathematical formulations to predict the pressure drop in a solid–liquid slurry flowing through a straight pipe. Employing the Eulerian–Eulerian RNG k-ε model, the computational investigation uses water as the carrier fluid and glass beads as solid particles. The analysis spans various particle sizes (d50 = 75–175 μm), volumetric concentrations (Cvf = 10–50%), and velocities (Vm = 1–5 m/s). The first model, developed using the MATLAB curve-fitting tool, is complemented by a second empirical equation derived through non-polynomial mathematical formulation. Results from both models are validated against existing experimental and computational data, demonstrating accurate predictions for d50 = 75–175 µm particles within a Reynolds number range of 20,000 ≤ Re ≤ 320,000.

Non-linear filtration model with splitting front

We consider filtration of a suspension in a homogeneous porous medium which is described by a macroscopic 1-D model including the mass exchange equation and the kinetic equation for deposit growth. The standard model assumes that suspended particles move at the same speed as the carrier fluid. However, in some experiments, a lag between the front boundary of suspended particles and the front of the carrier fluid was observed. This article proposes a modification of the standard model that provides a description of the separation between the fluid front and the particle front. For this purpose, a non-smooth non-linear function depending on the concentration of the suspension is introduced into the deposit growth equation. In case of a non-smooth suspension function, the concentration of suspended particles at the front decreases to zero in a finite time. At this moment the united front splits into the front of pure injected water and the front of suspended and retained particles. The particle front moves slower than the pure water front. In case of a linear filtration function (Langmuir coefficient), an exact solution is constructed in a closed form. For the filtration problem with a suspension function in the form of a square root, explicit analytical formulae are obtained. In case of a non-smooth filtration function, the filtration time is finite. The curvilinear boundary separates the filtration domain, where concentrations increase with time, from the stabilization domain, where the concentrations of suspended and retained particles have reached their limits. The limit speeds of the stabilization border and of the particle front coincide.

Influence of convection on the thermal storage performance of energy tunnels

The decarbonization of the built environment requires rapid growth in energy storage solutions due to the intermittent nature of most renewable energy sources. This paper focuses on the efficacy of so-called energy tunnels (i.e., tunnels equipped with pipe heat exchangers) used for underground thermal energy storage. By harnessing a 3-D thermo-hydraulic finite element model validated against full-scale experimental data, this work specifically explores seasonal, medium-temperature, thermal energy storage operations of energy tunnels. Numerical simulations are performed to unravel the influence of convection resulting from groundwater flows and airflows on the thermal energy storage performance of energy tunnels. The analyses address the impact of different groundwater flow velocities, air temperatures, and airflow velocities on the thermal losses and storage efficiency of energy tunnels used as thermal batteries. The study discourages underground thermal energy storage in the presence of convection due to significant heat losses. It shows that thermal energy storage operations via energy tunnels are feasible in site conditions characterized by no groundwater flow, limited temperature differentials between the heat carrier fluid circulating in the pipe heat exchangers and the surroundings, and thermal insulation on the tunnel intrados.

Controlling phase separations and reactions in trapped microfluidic droplets

Microfluidics and droplet-based assays are the basis for numerous high-throughput experiments, including bio-inspired microreactors and selection platforms for directed evolution. While elaborate techniques are available for the production of picoliter-sized droplets, there is an increasing demand for subsequent manipulation and control of the droplet interior. Here, we report on a straightforward method to rapidly adjust the size of single to several hundred double-emulsion droplets in a microfluidic sieve by varying the carrier fluid’s salt concentration. We show that the concomitant concentration changes in the droplet interior can drive a reversible demixing transition in a biomimetic binary fluid. As another application, we show that growing and shrinking of trapped droplets can be utilized to achieve a reversible dissociation of double-stranded DNA into single strands, i.e. cycles of reversible DNA hybridization, similar to PCR cycles, can be achieved by reversibly changing the droplet size at constant temperature. Altogether, our approach shows how a simple and temporally tunable manipulation of the size and the chemistry in prefabricated droplets can be achieved by an external control parameter.

On particle-modified velocity fields of particulate Taylor–Couette flow

Particulate Taylor–Couette flow of a particle-laden viscous fluid between two coaxial rotating cylinders is studied using a novel hydrodynamic model. With the volume fraction of particles as the dimensionless small parameter, explicit leading-order solutions are derived for the general case of dispersed particles heavier or lighter than the carrier fluid. It is shown that, unlike the classical azimuthal velocity field of a clear fluid without particles, dispersed particles generally have a radial velocity toward the outer or inner cylinder depending on the angular velocities and radii of the two cylinders and whether the particles are heavier or lighter than the carrier fluid, in qualitative agreement with some known results reported in literature on heavier or lighter particles, respectively. In some cases, such as the flow driven by rotating inner cylinder with a wider gap between the two cylinders and a moderate value of Stokes number of particles, our results predict the existence of a circular ring between two cylinders, which attracts or repels heavier or lighter particles that could have relevant physical implications. Beyond existing literature on the Taylor–Couette flow with neutrally buoyant particles, these results could offer new insight and useful explicit solutions to the Taylor–Couette flow with particles heavier or lighter than the carrier fluid.

Microstructural analysis on the compatibility of various dilution oils on magnetorheological grease performance

This research explores the effects of dilution oils on the storage stability of magnetorheological grease (MRG) by studying the effect of dilution oil viscosity on the microstructure of carrier fluids medium for MRG, which can help address practical challenges encountered in the development and deployment of MRG. Three samples of MRG with 70 wt% CIP are prepared; a control, and 2 samples diluted until 10 wt% hydraulic fluid and kerosene respectively. The resulting samples were analysed using a modular compact rheometer (MCR) for oscillatory strain sweep and rotational current sweep. Rheological analyses were repeated after one year in storage. Fourier-Transform Infrared (FTIR) spectroscopy and Atomic Force Microscopy (AFM) results show significant microstructural and performance deterioration of grease thickener in the sample with kerosene, which concludes that kerosene had a very significant effect on the degradation of the grease thickener. From this study, it was revealed that low viscosity oils disrupt the reconstruction of the thickener of lithium grease, which in turn causes deteriorating shear rheological performance of MRG at off-state conditions. This comprehensive analysis explains the relationships between MRG composition, microstructural characteristics, and performance parameters, offering a foundational framework for further exploration and advancement in this scientific field.

Preparation of a novel MR fluid for squeeze-shear mode by compositing micron-scale and nano-scale particles

The magnetorheological (MR) fluid under the squeeze-shear mode has an enhanced structure by reducing the distance between particles, significantly increasing the yield stress compared to the single shear mode. The existing research on preparing MR fluid is all based on single shear mode. This work mixes micron-scale carbonyl iron powders and micron-scale soft magnetic particles to prepare the specialized MR fluid for the devices working under squeeze-shear mode. Several kinds of micron-scale carbonyl iron powders and micron-scale soft magnetic particles are selected, of which the magnetic properties are tested to obtain the suitable soft magnetic particles for MR fluid. Then, the optimal combination of micron-scale carbonyl iron powders and micron-scale soft magnetic particles is obtained when the orthogonal test is used to compare the yield stress of different combinations. At the same time, the appropriate surfactants and base carrier fluid were selected, according to the previous work. On this basis, the novel MR fluid is prepared by the base fluid displacement method, and its performances are tested. The results show that the sedimentation rate is 0.8 % after standing for 20 days, which can keep the MR device in a stable state. The viscosity of the novel MR fluid is 8.0 Pa·s at room temperature, exhibiting good liquidity, which allows it to be injected into MR devices. The shear yield stress of the novel MR fluid is 60.28 kPa at the squeeze pressure of 600 kPa, which is 1.5 times higher than that under single shear mode, significantly enhancing the mechanical performance of MR fluid. The novel MR fluid with good sedimentation stability, appropriate viscosity, and better mechanical performance can be applied to more MR devices, especially the MR devices under squeeze-shear mode.