Effects Of Plate Spacing Research Articles

Water Current Load on Arrays of Rectangular Plates

Abstract Water current interaction with arrays of plates is studied by use of the computational fluid dynamics focusing on hydrokinetic energy production applications. Various configurations of arrays of equidistant rectangular plates are considered. The velocity and the pressure fields around an array of plates are determined, and the forces on individual plates are computed and compared with the empirical relations. It is found that the current-induced force on the leading plate in the array is substantially different from those on the downstream plates, which may experience negative forces, due to the change of the flow field. In three parametric studies, the effect of plate spacing, the number of plates, and the relative water depth on the current-induced forces is investigated. It is shown that the relative size of the plates and the number of plates in an array play a significant role on the current-induced loads. Finally, the relative direction of the plates and the incoming flow is changed, and its effect on the hydrodynamic forces on the plates is studied in a three-dimensional computational tank. The current loads on an oriented set of plates is shown to be remarkably different, when compared with those perpendicular to the current direction. It is concluded that the current-induced loads on an array of plates cannot be estimated by empirical relations, and specific computations, similar to those shown here, or laboratory experiments are required to investigate the current loads.

Effect of plate spacing and inclination angle over the thermal performance of plate heat exchanger working with novel stabilized polar solvent-based silicon carbide nanofluid

In this work, the overall thermal performance of a commercial corrugated plate heat exchanger has been conducted for the first time by varying the three different plate corrugated angles (30°, 45°, 60°) and variable plate spacing (from 5 mm to 20 mm) working with polar solvent-based novel Silicon carbide (SiC)/DI Water nanosuspension as a coolant by focusing potential industrial application. This study aimed to identify the enhancement in thermal performance of plate heat exchanger by evaluating its overall heat transfer coefficient, pressure drop, pumping power, and exergetic efficiency by utilizing SiC/DI water nanofluid of varying volume concentration (0.20 %, 0.40 %, 0.60 %, 0.80 %, 1.00 %, 1.20 %, and 1.40 %) at ambient condition (T0 = 27 ° C), and fixed volumetric flow rate (3 L/min) for both (nanofluid and milk) sides. From the experimental results, the optimum volume concentration for the coolant was found as 0.60 %, which yields a significant enhancement in the overall heat transfer coefficient ratio by approximately 51 %, 42 %, and 38 % for 60°, 45°, and 30° corrugated plate angle respectively. The significant enhancement for 0.6 % of optimum volume concentration and 5 mm plate spacing has been reported as the best possible option at which the pumping power ratio, performance index ratio, and exergetic efficiency ratio attained the highest enhancements.

PARAMETRIC INVESTIGATION OF ORGANIC RANKINE CYCLE EVAPORATOR FOR LOW TEMPERATURE APPLICATIONS

The present work deals with the development of thermodynamic model of low temperature basic Organic Rankine Cycle (ORC) system and a chevron plate heat exchanger evaporator sub-model using Engineering Equation Solver (EES). Work output is evaluated using the ORC thermodynamic model, while the evaporator sub-model calculates the total surface area of the heat exchanger. Using these mathematical models, the effect of evaporation pressure, expander inlet temperature and pinch point temperature difference (PPTD) on the network output and evaporator cost are studied. In addition to this, the effect of plate spacing and plate width of chevron plate heat exchanger on pressure drop and evaporator cost are analyzed in detail. Finally, thermodynamic and geometric optimization is carried out using genetic algorithm to identify the optimum parameters at which the network output is maximized and pressure drop in the evaporator is minimized. Sensitivity analysis showed that optimum evaporator pressure existed at which network output is maximum. Thermodynamic optimization showed that work output was maximum (5.03 kW) at evaporator pressure of 5.77 bar. No improvement in the work output was seen with increase in PPTD and expander inlet temperature. Increase in plate width and plate spacing led to increase in evaporator cost and decrease in pressure drop.

Numerical simulation of the effect of plate spacing on heat transfer characteristics within a parallel-plate heat exchanger in a standing wave thermoacoustic system

Power can be converted with high efficiently between thermal energy and mechanical (acoustic) energy by using thermoacoustic technologies. Thus, the heat transfer characteristics are significant to the understanding of mechanisms, and improvement of efficiency for thermoacoustic devices, notably in heat exchangers. This paper introduces a two-dimensional computational fluid dynamics model of flow across a parallel-plate heat exchanger and investigates the effect of plate spacing on heat transfer characteristics. The open source CFD software OpenFOAM is applied because of the highly customizable capabilities to vary the control parameters. Firstly, the computational model including geometry, boundary conditions, equations, discretization scheme, turbulence and thermophysical properties’ models are presented, and then grid-independence validation is presented to verify the quality of mesh. The simulation results show that plate spacing influences the heat transfer between plates and adjacent area of heat exchanger, and the heat transfer coefficient goes up when the plate spacing decreases. The analysis also indicates that a possible flow transition to turbulence occurred within Re number between 247.2 and 321.4. The results in this work can help the understanding of heat transfer inside thermoacoustic system, and form a basis for future research.

Experimental Observation of the Effects of Translational and Rotational Electrode Misalignment on a Planar Linear Ion Trap Mass Spectrometer.

The performance of miniaturized ion trap mass analyzers is limited, in part, by the accuracy with which electrodes can be fabricated and positioned relative to each other. Alignment of plates in a two-plate planar LIT is ideal to characterize misalignment effects, as it represents the simplest possible case, having only six degrees of freedom (DOF) (three translational and three rotational). High-precision motorized actuators were used to vary the alignment between the two ion trap plates in five DOFs-x, y, z, pitch, and yaw. A comparison between the experiment and previous simulations shows reasonable agreement. Pitch, or the degree to which the plates are parallel along the axial direction, has the largest and sharpest impact to resolving power, with resolving power dropping noticeably with pitch misalignment of a fraction of a degree. Lateral displacement (x) and yaw (rotation of one plate, but plates remain parallel) both have a strong impact on ion ejection efficiency, but little effect on resolving power. The effects of plate spacing (y-displacement) on both resolving power and ion ejection efficiency are attributable to higher-order terms in the trapping field. Varying the DC (axial) trapping potential can elucidate the effects where more misalignments in more than one DOF affect performance. Implications of these results for miniaturized ion traps are discussed. Graphical Abstract ᅟ.

Plate-spacing effect on unsteady flows and heat transfer characteristics in a channel with inclined plates

Flow and heat transfer characteristics in a channel with inclined plates are investigated numerically. To determine the effect of plate spacing, the ratios of plate pitch to channel height L/H = 1-9; plate angles a = 60°, 90° and 120°; and plate lengths d/H = 0.2-0.6 are adopted and unsteady simulations performed. As L/H increases, unsteady flows related to the supercritical Hopf bifurcation are developed and heat transfer characteristics severely changed. Hence, the peculiar relation between plate pitch and vortex evolution is observed. When the plate pitch increases, the observed vortices between the inclined plates can be classified into three patterns, namely, recirculation bubble, standing vortex, and traveling vortex. Unsteady features depending on the plate pitch are also examined by spectral analysis. As the plate pitch increases, the steady state of recirculation bubble is changed gradually to a quasi-periodic state of the traveling vortex through the periodic state of the standing vortex. From these results, the heat transfer enhancement is discussed with vortex evolution, flow oscillation, and law of the wall.

The analytical study on heavy water enrichment in concentric circular thermal-diffusion columns with optimal plate spacing for improved performance

A two-dimensional mathematical model was developed theoretically to predict the degree of separation of heavy water in concentric circular thermal-diffusion columns with total fixed expense and with plate spacing variations. An orthogonal expansion technique for solving separation problems of heavy water enrichment to estimate optimal plate spacing for maximum separation has been developed analytically. Considerable improvements in device performance were obtained when the thermal-diffusion column with optimal plate spacing were used. The effects of plate spacing and mass flow rate and on the degree of separation have been investigated with a consideration of the fixed total expense. Further improvement can be achieved if the feed position and flow-rate fractions of top and bottom products are suitably adjusted.

Recovery of deuterium from water–isotope mixture by thermal diffusion in countercurrent-flow flat-plate Frazier scheme with optimum plate spacing

The effect of plate spacing on the degree of recovery and production rate for deuterium recovery from water–isotope mixture in flat-plate thermal diffusion columns of countercurrent-flow Frazier scheme with fixed operation expense, has been investigated. The equations for estimating optimum plate spacing for maximum recovery and maximum production rate have been derived. Considerable improvement in performance is obtainable when thermal diffusion columns with optimum plate spacing are employed for operation. The fact that countercurrent-flow operation is more effective than cocurrent-flow operation for the recovery of deuterium in a Frazier scheme, is also confirmed.

Recovery of deuterium from water-isotopes mixture in flat-plate thermal-diffusion columns of the Frazier scheme with optimum plate-spacing

The effect of plate-spacing on the degree of recovery and production rate for the recovery of deuterium from water-isotopes mixture in flat-plate thermal-diffusion columns of the Frazier scheme with fixed operation expense has been investigated. The equations for estimating optimum plate-spacing for maximum recovery and maximum production rate have been developed. Considerable improvement in performance is obtainable when thermal-diffusion columns with optimum plate-spacing are employed for operation.

Analysis of axial dispersion in an oscillatory-flow continuous reactor

Experimental results of axial mixing for single-phase flow in pulsed sieve plate column (PSPC) were presented and discussed. The study is aimed at the use of the PSPC as a new type of oscillatory-flow tubular reactor for emulsion polymerization processes. The effects of pulsation frequency and amplitude, flow rate, plate spacing and fluid viscosity were studied. Axial dispersion coefficients were determined by fitting the axial dispersion model to the measurements of residence time distribution. A total of 213 runs were carried out with water at 20 °C, covering the range of pulsation frequency from 0 to 4.5 s −1, amplitude of pulsation from 5 to 25 mm, plate spacing 25, 50 and 100 mm, and water flow rate from 3.8 to 11.8 l/h. The results show that, under absence of pulsation, axial dispersion increases with flow rate and exhibits a maximum with respect to the plate spacing. For pulsed (oscillatory) flow, axial dispersion coefficient increases with amplitude and frequency of pulsation, and the effect of plate spacing is dependent of the pulsation velocity. Additional 39 experiments for pulsed flow were performed with aqueous solution of poly(vinyl alcohol) with viscosity varying in the range 1.4–10.0 cP. The results show that the axial dispersion decreases with plate spacing, increases with the viscosity for plate spacing 25 mm and is nearly independent of viscosity for plate spacing 50 and 100 mm. A correlation proposed in the literature was tested.

Optimum Plate Spacing for the Best Performance of the Enrichment of Heavy Water in Thermal Diffusion Columns of a Countercurrent-Flow Frazier Scheme

The effect of plate spacing on the degree of separation and production rate for the enrichment of heavy water in a countercurrent-flow Frazier scheme with N flat-plate thermal diffusion columns of same size and with total expense fixed, has been investigated. The equations for estimating optimum plate spacing for maximum separation and maximum production rate have been developed. Considerable improvement in performance for the enrichment of heavy water is obtainable when the` thermal diffusion columns with optimum plate spacing are employed for operation. The fact that countercurrent-flow operation is more effective than concurrent-flow operation for the enrichment of heavy water in a Frazier scheme, is also confirmed.

Numerical investigations of flow and energy fields near a thermoacoustic couple.

The flow field and the energy transport near thermoacoustic couples are simulated using a 2D full Navier-Stokes solver. The thermoacoustic couple plate is maintained at a constant temperature; plate lengths, which are "short" and "long" compared with the particle displacement lengths of the acoustic standing waves, are tested. Also investigated are the effects of plate spacing and the amplitude of the standing wave. Results are examined in the form of energy vectors, particle paths, and overall entropy generation rates. These show that a net heat-pumping effect appears only near the edges of thermoacoustic couple plates, within about a particle displacement distance from the ends. A heat-pumping effect can be seen even on the shortest plates tested when the plate spacing exceeds the thermal penetration depth. It is observed that energy dissipation near the plate increases quadratically as the plate spacing is reduced. The results also indicate that there may be a larger scale vortical motion outside the plates which disappears as the plate spacing is reduced.

THE OPTIMUM PLATE-SPACING FOR THE BEST PERFORMANCE IN FLAT-PLATE THERMAL DIFFUSION COLUMNS OF THE FRAZIER SCHEME

The effect of plate spacing on the degree of separation and production rate in flat-plate thermal diffusion columns of the Frazier scheme with fixed operating expense, has been investigated. The equations for estimating optimum plate-spacing for maximum separation and for maximum production rate have been developed. Considerable improvement in performance is obtainable when the thermal diffusion columns with optimum plate-spacing are employed for operation.

Optimum Plate-Spacing for the Best Performance of the Enrichment of Heavy Water in Flat-Plate Thermal-Diffusion Columns of the Frazier Scheme

Abstract The effect of plate spacing on the degree of separation and production rate for the enrichment of heavy water in flat-plate thermal diffusion columns of the Frazier scheme with fixed operating expense has been investigated. The equations for estimating optimum plate-spacing for maximum separation and for maximum production rate have been developed. Considerable improvement in performance is obtainable when thermal diffusion columns with optimum plate-spacing are employed for operation.

The Effect of Plate Spacing on Free Convection Between Heated Parallel Plates

In the past, considerable attention has been given to free convection between heated vertical parallel plates. This problem is considerable interest to engineers because of its application to electronic equipment cooling and solar energy. Some attempts have been made to optimize the spacing between parallel plates in the past. Bodoia and Osterle analytically derived a criterion for an optimum plate spacing for which the heat dissipation is maximum. The objective of this paper is to predict the optimum plate spacing for single channels by using the governing equations for a continuous system model. No heat transfer coefficient known a priori will be used in these calculations, but will be calculated as part of the solution.

The Effect of Plate Spacing on the Degree of Separation in Inclined Thermal Diffusion Columns with Fixed Operating Expense

Abstract It has been found that the maximum separation obtainable in inclined thermal diffusion columns is proportional to the square root of plate spacing when the operating expense is fixed. The plate spacing is generally so small that changing it, as well as changing the angle of inclination, may not cause additional fixed charge. However, increasing the plate spacing will lead to increasing the difference of plate temperatures in order to keep the operating expense unchanged. Therefore, additional cost is needed to maintain a high value of temperature difference.

Perforated-Plate Liquid-Liquid Extraction Towers. Effect of Plate Spacing in the Methyl Isobutyl Ketone-Butyric Acid-Water System

Perforated-Plate Liquid-Liquid Extraction Towers. Effect of Plate Spacing in the Methyl Isobutyl Ketone-Butyric Acid-Water System