Aero-Thermal Optimisation of a Spiral Primary Surface Recuperator: Modelling and Testing

2007 ◽  
Author(s):  
Hubert Antoine ◽  
Luc Prieels
Keyword(s):  
Pressure Drop ◽  
Heat Exchangers ◽  
Gas Flow ◽  
Central Zone ◽  
Flow Distribution ◽  
Fluid Distribution ◽  
Gas Flows ◽  
Surface Geometry ◽  
Half Angle ◽  
Flow Configurations

Recently, interest in spiral heat exchangers has grown for high temperature, high cycling applications, especially in the gas turbine industry. Air and gas flow distribution in heat exchangers is known to play a major role in their pressure drop performance and effectiveness. Modelling this distribution is needed to optimise the primary surface geometry. This optimisation has been applied to the ACTE spiral recuperator and resulted in smaller and lighter recuperators thanks to a better use of the metal. A specific CFD code was developed and used to investigate different ‘state of the art’ flow configurations and hydraulic diameters. The best of these was then adapted to ACTE’s manufacturing technology. The model has been validated by pressure drop, velocity profile and effectiveness measurements. The improved geometry consists of a primary surface cross-corrugated pattern for both air and gas flows (see fig. 4 and 5). The pattern includes a central zone with a half angle of 30° for counterflow and two lateral zones with a half angle of 45° for fluid distribution and collection. The corrugations are not strictly sinusoidal but include a flat area that allows welding the two sheets together. The sheet pair (or “doublet”) is thus made resistant to ballooning. It is also used to hoop the annular heat exchanger.

scholarly journals Two Efficient Methods for Gas Distributive Network Calculation

2018 ◽  
Author(s):  
Dejan Brkić
Keyword(s):  
Pressure Drop ◽  
Thermodynamic Properties ◽  
Gas Flow ◽  
Flow Distribution ◽  
Gas Pipeline ◽  
Gas Flow Rate ◽  
Closed Loops ◽  
Loop Method ◽  
Hardy Cross ◽  
Flow Through

Today, two very efficient methods for calculation of flow distribution per branches of a looped gas pipeline are available. Most common is improved Hardy Cross method, while the second one is so-called unified node-loop method. For gas pipeline, gas flow rate through a pipe can be determined using Colebrook equation modified by AGA (American Gas Association) for calculation of friction factor accompanied with Darcy-Weisbach equation for pressure drop and second approach is using Renouard equation adopted for gas pipeline calculation. For the development of Renouard equation for gas pipelines some additional thermodynamic properties are involved in comparisons with Colebrook and Darcy-Weisbach model. These differences will be explained. Both equations, the Colebrook’s (accompanied with Darcy-Weisbach scheme) and Renouard’s will be used for calculation of flow through the pipes of one gas pipeline with eight closed loops which are formed by pipes. Consequently four different cases will be examined because the network is calculated using improved Hardy Cross method and unified node-loop method. Some remarks on optimization in this area of engineering also will be mentioned.

scholarly journals Transformation of a mathematical model of gas flow distribution to solve the problems of gas supply system development

2020 ◽  
Vol 219 ◽  
pp. 02001
Author(s):  
Nikolay Ilkevich ◽  
Tatyana Dzyubina ◽  
Zhanna Kalinina
Keyword(s):  
Mathematical Model ◽  
Gas Flow ◽  
System Development ◽  
Flow Distribution ◽  
Supply System ◽  
Economic Environment ◽  
Gas Flows ◽  
Supply Systems ◽  
New Criteria ◽  
Gas Supply

This paper proposes taking into account new properties of gas supply systems in a mathematical model of flow distribution in comparison with the traditional formulation. The approach suggests introducing an arc coefficient, which allows for changes in the magnitude of gas flow passing along the arc, a vector of an increase in the arc throughput, and lower constraints on the gas flow along the arc. We also propose considering a new economic environment, namely, new criteria for optimizing the flow distribution and setting fictitious gas prices for consumers. These criteria enable us to take account of the priority gas supply to a definite group of consumers. As an example, the calculation of gas flows for the aggregated Unified Gas Supply System (UGSS) for 2030 is considered. This calculation takes into account the arc coefficients and the increase in the throughput of arcs.

scholarly journals Printed Circuit Heat Exchanger Flow Distribution Measurements

2017 ◽  
Author(s):  
Blake W. Lance ◽  
Matthew D. Carlson
Keyword(s):  
Pressure Drop ◽  
Coming Out ◽  
Heat Exchangers ◽  
Flow Distribution ◽  
Velocity Measurements ◽  
Flow Measurements ◽  
Compact Heat Exchangers ◽  
Printed Circuit ◽  
The Core ◽  
Flow Maldistribution

Printed circuit heat exchangers (PCHEs) have an important role in supercritical CO2 (sCO2) Brayton cycles because of their small footprint and the high level of recuperation required for this power cycle. Compact heat exchangers like PCHEs are a rapidly evolving technology, with many companies developing various designs. One technical unknown that is common to all compact heat exchangers is the flow distribution inside the headers that affects channel flow uniformity. For compact heat exchangers, the core frontal area is often large compared with the inlet pipe area, increasing the possibility of flow maldistribution. With the large area difference, there is potential for higher flow near the center and lower flow around the edges of the core. Flow maldistribution increases pressure drop and decreases effectiveness. In some header geometries, flow separation inside the header adds to the pressure drop without increasing heat transfer. This is the first known experiment to test for flow maldistribution by direct velocity measurements in the headers. A PCHE visualization prototype was constructed out of transparent acrylic for optical flow measurements with Particle Image Velocimetry (PIV). The channels were machined out of sheets to form many semi-circular cross sections typical of chemically-etched plates used in PCHE fabrication. These plates were stacked and bolted together to resemble the core geometry. Two header geometries were tested, round and square, both with a normally-oriented jet. PIV allows for velocities to be measured in an entire plane instantly without disturbing the flow. Small particles of approximately 10 micrometers in diameter were added to unheated water. The particles were illuminated by two laser flashes that were carefully timed, and two images were acquired with a specialized digital camera. The movement of particle groups was detected by a cross-correlation algorithm with a result of about 50k velocity measurements in a plane. The velocity distribution inside the header volume was mapped using this method over many planes by traversing the PCHE relative to the optical equipment. The level of flow maldistribution was measured by the spatially-changing velocity coming out of the channels. This effect was quantified by the coefficient of variation proposed by Baek et al. The relative levels of flow maldistribution in the different header geometries in this study were assessed. With highly-resolved velocity measurements, improvements to header geometry to reduce flow maldistribution can be developed.

Structure and Pressure Drop in Particle-Laden Gas Flow Through a Pipe Bend: A Numerical Analysis by the Euler/Lagrange Approach

2009 ◽  
Author(s):  
S. Lai´n ◽  
M. Sommerfeld
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Gas Flows ◽  
Wall Roughness ◽  
Mass Loading ◽  
Particle Collisions ◽  
Pipe Bend ◽  
Flow Through ◽  
Fully Coupled ◽  
Lagrange Approach

The structure of particle-laden gas flows in a horizontal-to-vertical elbow is investigated numerically for analysing the required modelling depth. The numerical computations are performed with the fully coupled Euler-Lagrange approach considering all the relevant forces: drag, gravity-buoyancy and lift forces (slip-shear and slip-rotational). Moreover, interparticle and particle-rough wall collisions are taken into account by means of stochastic approaches. The effect of the different mechanisms, i.e. wall roughness, inter-particle collisions and mass loading, on the flow structure in the bend and the resulting pressure drop are investigated.

Three-Dimensional Numerical Analysis of Gas Flow and Heat Transfer in SOFCs With Honeycomb-Like Channels

2010 ◽  
Author(s):  
Yuan Huang ◽  
Weiguo Wang ◽  
Jinliang Yuan ◽  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Diffusion Layer ◽  
Gas Flow ◽  
Stokes Equations ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Gas Diffusion ◽  
Factors Affecting

Design of advanced flow channels in bipolar plates is one of the key factors affecting SOFC stack and system performance. Various transport phenomena occurring in SOFCs with conventional interconnects with rib- or serpentine channels, etc, have been extensively studied. In this paper new designed channels are proposed and evaluated numerically by computational software. The investigated geometry consists of two computational domains: a porous anode layer and interconnect. The latter one serves as gas distribution for hydrogen or air in SOFCs. Compared with conventional designs, the configuration of interconnect having honeycomb structures is different. Such unique channels lead to gas flow in many directions, and gas flow distribution and pressure drop are significantly different from those in conventional designs. This simulation employs the Navier-Stokes equations for the gas flow in the channels, and the Darcy model in the porous layer. Combined gas and heat transfer in the channels and the porous gas diffusion layer, permeation across the interface are analyzed by a fully three-dimensional code in this paper. All the governing equations are solved utilizing the commercial code COMSOL. The velocity field, the distribution of hydrogen in the channels, the fraction of the hydrogen entering the anode diffusion layer, and the pressure drop are predicted and presented. Also, the friction factor of the unique design is compared with that of the rectangular channel. The numerical results and findings from this study are important for optimizing the flow fields, decreasing the cost of experiments and designing of the channels.

A 3-D Numerical Analysis of the Effect of Fin Pattern on the Thermo-Hydarulic Performance of Plate Heat Exchangers

2013 ◽  
Author(s):  
Kun-Hao Li ◽  
Chi-Chuan Wang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Cfd Simulation ◽  
Flow Distribution ◽  
Heat Transfer Characteristics ◽  
Effective Surface ◽  
Plate Heat ◽  
Transfer Characteristics ◽  
Transfer Capability

This study numerically examines some commercially available plate patterns of plate heat exchangers using a 3-D CFD simulation. Detailed flow distribution and heat transfer characteristics subject to three different plate patterns are examined in this study. The plate pattern include GC26 and NT10 (double chevron) and SW26. The effective surface area of the associated plate patterns are 0.8671, 0.6808, and 0.6721 m2, respectively. The corresponding chevron angle are 33°, 64° (double chevron) and 61°, repectively. The calculated results show that the heat transfer efficient for NT10 is higher than that of GC26 by approximately 6.35% and is higher than SW26 by 10.3%. The results indicate that the heat transfer characteristics for the double chevron plate outperform that of the single chevron plate. On the other hand, the pressure drop is also increased with the double chevron as well as chevron angle. However, it is found that the double chevron design provides a better heat transfer capability subject to identical pressure drop.

Effect of coal particle size distribution on packed bed pressure drop and gas flow distribution

Fuel ◽  
2006 ◽  
Vol 85 (10-11) ◽  
pp. 1439-1445 ◽  
Author(s):  
M KEYSER ◽  
M CONRADIE ◽  
M COERTZEN ◽  
J VANDYK
Keyword(s):  
Particle Size ◽  
Pressure Drop ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Coal Particle ◽  
Gas Flow ◽  
Flow Distribution ◽  
Packed Bed
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