Range Of Volume Flow Rates Research Articles

Analysis of circulating tumour cells separation in a curved microchannel under a high gravitational field

Cancer cells can detach from their original place and travel through tiny blood vessels or lymphatic capillaries in nearby tissues, forming a new tumour in other places of the body. While these circulating tumour cells (CTCs) are usually few in relation to the native blood cells, they provide crucial information about the characteristics of the primary tumour. Therefore, detecting and separating such cells from the bloodstream is an essential step in terms of diagnosis, treatment and prognosis of cancer patients. Perhaps, one of the well-known methods of separating CTCs is inertial focusing using a curved microchannel. This approach leaves CTCs separation strongly dependant on the channel design and Reynolds number for a given sample’s properties. Thus, the design suitable for a certain sample does not necessarily suit others. Here, a novel micro-analytical device is proposed and analysed. The device is based on using a spiral microchannel spinning around its axis at low rotation speed. The rotation generates Corilois secondary motions, focusing the separation of CTCs. The strength and structure of these Corilois motions can be adjusted easily by changing the rotation rate, which is under external control. This opens up the possibility of handling samples with different properties, achieving both higher throughput and complete separation of CTCs. The present work demonstrates the separation of human breast cancer cells using this approach over a wide range of volume flow rates (100–1000 ml/h) at different rotation rates (0–200 rpm), operating at relatively moderate Reynolds number. A model is developed, giving a quantitative prediction of flow and cells separation. It is shown that, for a single design, the cancer cells can be sorted completely with 100 % purity over a wide range of flow rates (400–700 ml/h) with a small adjustment of the rotation rate.

Noninvasive Method to Measure Thermal Energy Flow Rate in a Pipe

Abstract A noninvasive, thermal energy flowrate sensor based on a combination of heat flux and temperature measurements is developed for measuring the volume flowrate and the fluid temperature in a pipe. The sensor is covered by a thin-film heater and clamped onto the outer surface of the pipe. Two types of thin-film thermocouple elements are compared to minimize the thermal contact resistance R″ between the thermocouple and the surface of the pipe. A thin, flexible thermopile heat flux sensor (PHFS) is mounted over the thermocouples. A one-dimensional transient thermal model is applied before and during activation of the external heater to provide estimates of the fluid heat transfer coefficient h. The results are correlated with the volume flowrate Q and the fluid temperature Twc. Several different parameter estimation codes are used to estimate the optimal parameters by using the minimum root-mean-square (rms) error between the analytical and experimental sensor temperature values. The experiments are completed over a range of volume flowrates—1.3 gallons/min to 14.5 gallons/min. Encouraging measurement results give good correlation, repeatability, and sensitivity between the heat transfer coefficient h and the volume flowrate Q with an accurate estimation of the fluid temperature Twc. The resulting noninvasive thermal energy flowrate sensor can be used to estimate the volume flowrate and the fluid temperature in a variety of applications.

Mixing Performance of a Cross-Channel Split-and-Recombine Micro-Mixer Combined with Mixing Cell.

A new cross-channel split-and-recombine (CC-SAR) micro-mixer was proposed, and its performance was demonstrated numerically. A numerical study was carried out over a wide range of volume flow rates from 3.1 μL/min to 826.8 μL/min. The corresponding Reynolds number ranges from 0.3 to 80. The present micro-mixer consists of four mixing units. Each mixing unit is constructed by combining one split-and-recombine (SAR) unit with a mixing cell. The mixing performance was analyzed in terms of the degree of mixing and relative mixing cost. All numerical results show that the present micro-mixer performs better than other micro-mixers based on SARs over a wide range of volume flow rate. The mixing enhancement is realized by a particular motion of vortex flow: the Dean vortex in the circular sub-channel and another vortex inside the mixing cell. The two vortex flows are generated on the different planes perpendicular to each other. They cause the two fluids to change their relative position as the fluids flow into the circular sub-channel of the SAR, eventually promoting violent mixing. High vorticity in the mixing cell elongates the flow interface between two fluids, and promotes mixing in the flow regime of molecular diffusion dominance.

Optimization of Converging and Diverging Microchannel Heat Sink for Electronic Chip Cooling

This article presents a steady-state 3-D conjugate heat transfer and single-phase liquid flow simulation in the microchannel heat sink (MCHs). The 3-D governing equations with boundary conditions are solved for a constant heat flux of 200 W/cm2, applied at the bottom surface of MCHs. An array of microchannels with three different cross-sections—uniform, converging, and diverging—are investigated for a fixed chip dimension of 20-mm length, 4-mm width, and 0.15-mm substrate thickness. This article aims to present a comparative analysis of the hydraulic and thermal performance of MCHs with three different cross-sections. Simulations are performed for volume flow rate and microchannel depth range of 20–140 mL/min and 0.25–1.25 mm, respectively, with silicon microchannel using water as the working fluid. Numerical simulations are performed using COMSOL Multiphysics 5.3. Comparative analysis shows that for a wide range of volume flow rate, diverging channels MCHs shows superior thermohydraulic performance. Furthermore, it is observed that with an increase in depth or aspect ratio of the channel, there is a significant reduction in pumping power requirement with some marginal reduction in thermal performance. Furthermore, to calculate the optimized channel dimensions for minimum thermal resistance and pressure drop, a MATLAB code was written. Based on the results, the optimized channel dimensions are identified. The work presented and discussed in this article is relevant and beneficial for designing compact MCHs for electronic cooling applications.

Numerical Investigation of Pressure Recovery for an Induced Draught Fan Arrangement

This study investigates the potential gain in operating volume flow rate and static efficiency for an induced draught fan arrangement by reducing the outlet kinetic energy loss. The reduction is achieved through pressure recovery, which is the conversion of dynamic pressure into static pressure. Downstream diffusers, stator blade rows, or a combination of these can recover pressure. Six different discharge configurations are tested for a fan. An annular diffuser with equiangular walls at an angle of 22° from the axial direction and a length equal to the fan diameter recovers the most pressure over a range of volume flow rates. The diffuser causes the operating volume flow rate and static efficiency to increase by 6.3 % (relative) and 20 % (absolute), respectively, compared to the initial design point of the particular fan.

Experimental Studies of Ethyl Acetate Saponification Using Different Reactor Systems: The Effect of Volume Flow Rate on Reactor Performance and Pressure Drop

Microreactors intensify chemical processes due to improved flow regimes, mass and heat transfer. In the present study, the effect of the volume flow rate on reactor performance in different reactors (the T-shaped reactor, the interdigital microreactor and the chicane microreactor) was investigated. For this purpose, the saponification reaction in these reactor systems was considered. Experimental results were verified using the obtained kinetic model. The reactor system with a T-shaped reactor shows good performance only at high flow rates, while the experimental setups with the interdigital and the chicane microreactors yield good performance throughout the whole range of volume flow rates. However, microreactors exhibit a higher pressure drop, indicating higher mechanical flow energy consumption than seen using a T-shaped reactor.

Experimental investigation of cooling photovoltaic (PV) panels using (TiO2) nanofluid in water -polyethylene glycol mixture and (Al2O3) nanofluid in water- cetyltrimethylammonium bromide mixture

Cooling of photovoltaic (PV) panels was investigated experimentally outdoors using two nanofluids and water as a cooling medium for volume flow rate ranging from 500 to 5000 mL/min at concentrations (0.01 wt.%, 0.05 wt.%, and 0.1 wt.%) under different radiation intensity. Two types of nanofluids were used, namely Al2O3 in water -polyethylene glycol mixture at pH 5.7, and TiO2 in water- cetyltrimethylammonium bromide mixture at pH 9.7, respectively. The cooling of PV panel required incorporating a heat exchanger of aluminium rectangular cross section at its back surface to accommodate different volume flow rate of the cooling medium aforementioned. The system was tested under climate conditions of Jerash-Jordan. Determination of flow characteristics; friction factor, f and product of friction factor Reynolds number, of TiO2, Al2O3 nanofluids and water as a cooling medium were investigated. Also, a fRe comparison of the temperature between the cooled PV cell and without cooling for volume flow rate ranging from 500 to 5000 mL/min was presented. Results showed that the nanofluid cooled PV cell in both types caused higher decrease in the average PV cell temperature compared with the cooled cell with water and without cooling. In addition, Al2O3 nanofluid showed better performance than TiO2 nanofluid. Furthermore, experimental results showed that higher concentration of nanofluid produces a better cooling effect of the PV cell for all the studied range of volume flow rate. Also, electrical analysis of power and efficiency showed that TiO2 nanofluid gives better performance for the studied range of volume flow rate and concentrations compared with water cooling and without cooling.

Air entrainment onset in skimming flows on steep stepped spillways: an analysis

ABSTRACTWe discuss, apply and validate several physics-based criteria for air entrainment into flows on steep stepped spillways, using laboratory observations and numerical results published elsewhere. To the best of our knowledge, this is the first time a validation of these criteria is undertaken for any chute flow in general, and for the skimming flow in steep stepped spillways in particular. To undertake the validation, we employed experimental and numerical data covering a considerable range of volume flow rates and step heights. We observed an overall good performance of most of the criteria, especially taking into account the intrinsic difficulties in defining the time-averaged location and depth of the inception point of air entrainment experimentally. Finally, we present two novel non-dimensional numbers designed to facilitate the physical interpretation of the location of the inception point of air entrainment.

Single walled carbon nanotube channel flow electrode: Hydrodynamic voltammetry at the nanomolar level

The use of single walled carbon nanotube (SWNT) band electrodes in a channel flow cell, for low concentration detection, with hydrodynamic voltammetry is reported. A two dimensional SWNT network electrode is combined with a one piece channel flow cell unit, fabricated by microstereolithography. This configuration provides well defined hydrodynamics over a wide range of volume flow rates (0.05–25mL min−1). Limiting current measurements, from linear sweep voltammograms, are in good agreement with the channel electrode Levich equation, for the one electron oxidation of ferrocenylmethyl trimethylammonium (FcTMA+), over a wide concentration range, 1×10−8M to 2.1×10−5M, with a detection limit of 5nM. At the highest flow rates, some influence of the slightly recessed electrode geometry arising from the SWNT electrode fabrication is noted. However, this can be accounted for by a full simulation of the hydrodynamics and solution of the resulting convection–diffusion equation. Application of this hydrodynamic configuration to the voltammetric detection of dopamine is also demonstrated.

Collection of Xylem Sap at Flow Rate Similar to in vivo Transpiration Flux

We have explored a method to collect xylem sap using a Scholander pressure chamber for potted plants. Intact root system in pots which fitted the pressure chamber was pressurised at a pneumatic pressure numerically equal to the absolute value of shoot water potential. The rate of xylem flow obtained from the stem stump under such pressure was found similar to the rate of transpiration before detopping. The rate of pressurised flow from detopped roots was linearly related to the pressure applied in both well-watered and soil-dried plants. The osmotic concentration of the xylem sap was negatively related to the rate of volume flow, suggesting the necessity to collect xylem sap at in vivo flow rate if original solute concentration is to be evaluated. The concentration of ABA in the xylem sap, however, did not show such a relationship with water flux. Both well-watered and soil-dried plants showed the concentration of ABA in xylem sap largely stable with a range of volume flow rate, indicating a linear relationship between the rate of ABA delivery through xylem and that of volume flow. We also compared the concentrations of ABA in xylem sap sequentially collected from pressurised roots with that from detached shoots of the same plants. The concentration of ABA in the initial saps from shoots showed to be similar to that from roots. However, a decrease in the concentration of ABA in the xylem sap collected from detached leaf or twig was observed when more volume of sap was collected, which might also be dependent on the plant species and the volume of xylem vessels concerned.

A Simple Model For Predicting Foam Spread Over Liquids

An approximate theoretical model of foam spreading on a liquid surface has been formulated. The model is analogous to the spreading of oil slicks on water surfaces. Viscous friction is assumed to be the dominating mechanism in opposing the foam spread. The friction is described by a lumped friction constant. The spreading process is decoupled from the mass transport due to evaporation and drainage of water contained in the foam. This work constitutes the first step in an attempt to formulate a model describing foam spread on a burning surface. Preliminary experiments have been carried out with foam spreading in a circular water basin without external heating. The friction coefficient is determined from experimental data. The model fits reasonably well with the experimental results for a wide range of volume flow rates and foam expansion numbers. Thus it can be concluded that the model correctly describes the basic phenomena of the foam spread.

Digital sampling of low fluid flow: application to coronary flow measurements

A novel, simplified and inexpensive solution to the on-line monitoring of low fluid flow is reported. The method can utilise a variety of common liquid flow sampling devices (i.e. fraction collector volumeters) as a front-end, constant-volume dispenser coupled to a described sample-and-hold circuit. The latter, on triggering, samples a variably set ramp voltage which is directly proportional to liquid volume flow rate. The system is easily calibrated, has a wide dynamic range of volume flow rates, and can be configured accurately for high signal resolution of very low flow phenomena. An application to coronary flow measurement is provided as well as circuit descriptions and typical performance parameters which can be measured and adjusted for optimisation.