Analysis Exploring the Uniformity of Flow Distribution in Multi-Channels for the Application of Printed Circuit Heat Exchangers

The maldistribution of fluid flow through multi-channels is a critical issue encountered in many areas, such as multi-channel heat exchangers, electronic device cooling, refrigeration and cryogenic devices, air separation and the petrochemical industry. In this paper, the uniformity of flow distribution in a printed circuit heat exchanger (PCHE) is investigated. The flow distribution and resistance characteristics of a PCHE plate are studied with numerical models under different flow distribution cases. The results show that the sudden change in the angle of the fluid at the inlet of the channel can be greatly reduced by using a spreader plate with an equal inner and outer radius. The flow separation of the fluid at the inlet of the channel can also be weakened and the imbalance of flow distribution in the channel can be reduced. Therefore, the flow uniformity can be improved and the pressure loss between the inlet and outlet of PCHEs can be reduced. The flow maldistribution in each PCHE channel can be reduced to ± 0.2%, and the average flow maldistribution in all PCHE channels can be reduced to less than 5% when the number of manifolds reaches nine. The numerical simulation of fluid flow distribution can provide guidance for the subsequent research and the design and development of multi-channel heat exchangers. In summary, the symmetry of the fluid flow in multi-channels for PCHE was analyzed in this work. This work presents the frequently encountered problem of maldistribution of fluid flow in engineering, and the performance promotion leads to symmetrical aspects in both the structure and the physical process.

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Experimental and Theoretical Analysis of Transient Response of Plate Heat Exchangers in Presence of Nonuniform Flow Distribution

Journal of Heat Transfer ◽

10.1115/1.2885153 ◽

2008 ◽

Vol 130 (5) ◽

Cited By ~ 4

Author(s):

N. Srihari ◽

Sarit K. Das

Keyword(s):

Steady State ◽

Heat Exchangers ◽

Sudden Change ◽

Temperature Response ◽

Flow Distribution ◽

Transient Temperature ◽

Nonuniform Flow ◽

Flow Rates ◽

Plate Heat ◽

Flow Maldistribution

Transient analysis helps us to predict the behavior of heat exchangers subjected to various operational disturbances due to sudden change in temperature or flow rates of the working fluids. The present experimental analysis deals with the effect of flow distribution on the transient temperature response for U-type and Z-type plate heat exchangers. The experiments have been carried out with uniform and nonuniform flow distributions for various flow rates. The temperature responses are analyzed for various transient characteristics, such as initial delay and time constant. It is also possible to observe the steady state characteristics after the responses reach asymptotic values. The experimental observations indicate that the Z-type flow configuration is more strongly affected by flow maldistribution compared to the U-type in both transient and steady state regimes. The comparison of the experimental results with numerical solution indicates that it is necessary to treat the flow maldistribution separately from axial thermal dispersion during modeling of plate heat exchanger dynamics.

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Numerical simulation of flow distribution in the header of plate-fin heat exchanger

International Journal of Modern Physics B ◽

10.1142/s0217979220401116 ◽

2020 ◽

Vol 34 (14n16) ◽

pp. 2040111

Author(s):

Shu-Ling Tian ◽

Ying-Ying Shen ◽

Yao Li ◽

Hai-Bo Wang ◽

Sheryar Muhammad ◽

...

Keyword(s):

Numerical Simulation ◽

Fluid Flow ◽

Heat Exchanger ◽

Heat Exchangers ◽

Optimization Design ◽

High Efficiency ◽

Flow Distribution ◽

Optimal Number ◽

Compact Structure ◽

Flow Maldistribution

Plate-fin heat exchangers are widely used in industry at present due to their compact structure and high efficiency. However, there is a problem of flow maldistribution, resulting in poor performance of heat exchangers. The influence of the header configuration on fluid flow distribution is studied by using CFD software FLUENT. The numerical results show that the fluid flow inside the header is seriously uneven. The reliability of the numerical simulation is validated against the published results. They are found to be basically consistent within considerable error. The optimal number of the punch baffle is investigated. Various header configuration with different opening ratios have been studied under the same boundary conditions. The gross flow maldistribution parameter (S) is used to evaluate flow nonuniformity, and the flow maldistribution parameters of different schemes under different Reynolds numbers are listed and compared. The optimal header with minimum flow maldistribution parameter is obtained through the performance analysis of headers. It is found that the flow maldistribution of the improved header is significantly smaller compared with the conventional header. Hence, the efficiency of the heat exchanger is effectively enhanced. The conclusion provides a reference for the optimization design of plate-fin heat exchanger.

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Printed Circuit Heat Exchanger Flow Distribution Measurements

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2017-64560 ◽

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.

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Steam Condensation in Parallel Channels of Plate Heat Exchangers

Volume 7: Fluid Flow, Heat Transfer and Thermal Systems, Parts A and B ◽

10.1115/imece2010-39974 ◽

2010 ◽

Cited By ~ 1

Author(s):

Prabhakara Rao Bobbili ◽

Bengt Sunden

Keyword(s):

Heat Exchanger ◽

Heat Exchangers ◽

Flow Distribution ◽

Small Degree ◽

Flow Conditions ◽

Steam Condensation ◽

Cooling Fluid ◽

Plate Heat ◽

Parallel Channels ◽

Flow Maldistribution

An experimental investigation has been carried out to find the nature of temperature profiles of the process and cooling fluids during steam condensation across the port to channel in plate heat exchangers (PHEs). In the present study, low corrugation angle (30°) plates have been used for different plate package of PHEs with 41 and 81 plates. The process steam entered at 1 bar with a small degree of superheat. Water has been used as the cold fluid. A traverse temperature probe is inserted into both inlet and outlet ports of the plate heat exchanger. The temperature of the process steam and cooling fluid have been measured and recorded at the location of first, middle and last channels for different inlet and exit flow conditions for each plate package of the heat exchanger. Also, the overall pressure drop has been measured at different conditions at the outlet of the process steam, i.e., full and partial condensation. The traverse temperature measurements have indicated that there is a considerable variation in temperature along inlets and outlets of process steam and cooling fluid, due to flow maldistribution. The experimental data has been analyzed to show how the flow distribution on the cooling side affects the condensation of steam in plate heat exchangers. The present results will help to study further the nature of steam condensation in parallel channels of heat exchangers.

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Experimental Investigation on Fluid Flow Maldistribution in Plate-Fin Heat Exchangers

Heat Transfer Engineering ◽

10.1080/01457630304028 ◽

2003 ◽

Vol 24 (4) ◽

pp. 25-31 ◽

Cited By ~ 25

Author(s):

Jiao Anjun ◽

Li Yanzhong ◽

Chen ChunZheng ◽

Zhang Rui

Keyword(s):

Experimental Investigation ◽

Fluid Flow ◽

Heat Exchangers ◽

Flow Maldistribution

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CFD Simulation on Flow Distribution in Plate-Fin Heat Exchangers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.655-657.445 ◽

2013 ◽

Vol 655-657 ◽

pp. 445-448

Author(s):

Zhe Zhang ◽

Jin Jin Tian ◽

Yong Gang Guo

Keyword(s):

Fluid Flow ◽

Heat Exchanger ◽

Cfd Simulation ◽

Perforated Plate ◽

Flow Distribution ◽

Numerical Results ◽

Flow Maldistribution ◽

The Mathematical Model ◽

First Time ◽

Flow Nonuniformity

The influences of the conventional header configuration used in industry at present on the fluid flow distribution in plate-fin heat exchanger were numerically investigated. The numerical results showed that the fluid flow maldistribution is very serious in the heat exchanger. The header configuration with perforated plate was brought forward for the first time. The computational results indicated that the improved header configuration can effectively improve the performance of fluid flow distribution in the heat exchanger. The fluid flow distribution for the header configuration with curving perforated plate is more uniform than for the header configuration with plane perforated plate. The absolute degree of fluid flow nonuniformity in plate-fin heat exchanger has reduced from 3.47 to 0.32 by changing the header configuration. The numerical results are compared with the experimental results. They are basically consistent which indicates that the mathematical model and the calculating method are reliable.

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The combined effects of wall longitudinal heat conduction and inlet fluid flow maldistribution in crossflow plate-fin heat exchangers

Heat and Mass Transfer ◽

10.1007/s002310050392 ◽

2000 ◽

Vol 36 (3) ◽

pp. 247-256 ◽

Cited By ~ 21

Author(s):

Ch. Ranganayakulu ◽

K. N. Seetharamu

Keyword(s):

Fluid Flow ◽

Heat Conduction ◽

Heat Exchangers ◽

Combined Effects ◽

Flow Maldistribution

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Experimentally Verified Flow Distribution Model for a Composite Modelling System

Energies ◽

10.3390/en14061778 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1778

Author(s):

Dominika Babička Fialová ◽

Zdeněk Jegla

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Numerical Models ◽

Flow Distribution ◽

Parallel Flow ◽

Heat Fluxes ◽

Distribution Model ◽

Flow Systems ◽

Using Data ◽

Modelling System

Requirements of modern process and power technologies for compact and highly efficient equipment for transferring large heat fluxes lead to designing these apparatuses as dense parallel flow systems, ranging from conventional to minichannel dimensions according to the specific industrial application. To avoid operating issues in such complex equipment, it is vital to identify not only the local distribution of heat flux in individual parts of the heat transfer surface but also the uniformity of fluid flow distribution inside individual parallel channels of the flow system. A composite modelling system is currently being developed for accurate design of such complex heat transfer equipment. The modeling approach requires a flow distribution model enabling to yield accurate-enough predictions in reasonable time frames. The paper presents the results of complex experimental and modeling investigation of fluid flow distribution in dividing headers of tubular-type equipment. Different modeling approaches were examined on a set of header geometries. Predictions obtained via analytical and numerical models were validated using data from the experiments conducted on additively manufactured header samples. Two case studies employing parallel flow systems (mini-scale systems and a conventional-size heat exchanger) demonstrated the applicability of the distribution model and the accuracy of the composite modelling system.

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