Chevron Plate Heat Exchanger Research Articles

Study of a multi-phase hybrid heat exchanger-reactor (HEX reactor): Part I – Experimental characterization

This study focuses on gaining fundamental insights into the sparsely explored area of reacting multiphase flows in a compact heat exchanger. Chevron plate heat exchangers have been demonstrated to possess superior thermal performance, scalability, and mixing capability compared to more traditional shell-in-tube heat exchangers or stirred tank batch reactors. This study explores the hydrodynamic behavior of gas-evolving reacting flows in chevron plate heat exchangers. Experimental characterization of a plate heat exchanger/chemical reactor (in multi-phase flow configuration) utilizing high-speed video and axial pressure measurements was conducted. Existing correlations that were developed using air–water flow in PHEs predicted with acceptable accuracy the total pressure drop in the HEX reactor.

Study of a multi-phase hybrid heat exchanger-reactor (HEX reactor): Part II – Numerical prediction of thermal performance

Numerical models were developed to assess the thermal performance of a HEX reactor with solid-to-gas reacting flow. Based on the experimental results obtained in part I of this study, numerical models were developed to predict the thermal performance of a plate heat exchanger-based HEX reactor involving multi-phase flow with chemical reactions. A reduced-order numerical model of a chevron plate heat exchanger was developed with thermal and momentum transfer analogies. Empirical correlations for momentum transfer and void fraction (validated in part I of this study) were implemented in the numerical model. The numerical model, coded in Maple 13™, was used to size a compact reactor with a thermal load rating of 2kW for the desired operating temperature; the modeling framework developed can also be used to study different candidate gas-generating reacting species, working fluids, and PHE configurations.

Chevron plate heat exchanger optimization using efficient approximation-assisted multi-objective optimization techniques

This article presents a comparison between different multi-objective optimization approaches that can be used to efficiently optimize the design of different thermal systems and components. Plate heat exchanger optimization is taken as case study to compare the different optimization techniques. The plate heat exchanger flow channel geometry is optimized to maximize the thermal-hydraulic performance of the heat exchanger. The thermal-hydrodynamic characteristics of single phase turbulent flow in chevron-type plate heat exchangers with sinusoidal-shaped corrugations have been analyzed using a commercially available computational fluid dynamics tool. The computational domain consists of a corrugation channel, and the simulations adopted the shear-stress transport κ-ω model as the turbulence model. The analysis of even a single design is computationally expensive, and hence, approximation techniques are used to speed up the optimization process. Exhaustive search, offline approximation-assisted optimization, and online approximation-assisted optimization are compared to optimize plate heat exchanger design. For both approximation techniques (offline and online), design optimization is performed using the multi-objective genetic algorithm based on metamodels that are built to represent the entire design space. In offline approximation, globally accurate metamodels are built, which requires adding samples in the entire design space. However in online approximation-assisted optimization, samples are added just to improve metamodel performance in the expected optimum region. Approximated optimum designs are verified using computationally expensive actual computational fluid dynamics simulations. Finally, a comparison between exhaustive search and offline/online approximation-assisted optimization is presented with guidelines to apply both approaches in the area of heat exchanger design optimization. The methods presented in this article are generic and can be applied to optimize different types of heat exchangers, electronic cooling devices, and other thermal system components.

Application of Equipartition of Entransy Loss Principle in Heat Exchangers

The entransy loss minimization approach for the heat exchanger optimization design was established by Guo Z Y; the study based Guo Z Y’s works, found relationship between the entransy loss uniformity and the heat exchanger performance and the expression of the local entransy loss rate for heat convection was derived, numerical results of the heat transfer in a chevron plate heat exchanger and helix baffle heat exchanger show that the larger entransy loss uniformity factor appear in about Re=2000 and the entransy loss uniformity factor of chevron plate heat exchanges higher than helix baffle one.

Experimental study and analysis of a novel multi-media plate heat exchanger

The experimental study and analysis of a novel multi-media plate heat exchanger were performed in this paper. This novel multi-media plate heat exchanger was self-developed during the process of the investigation and design of the alpha magnetic spectrometer (AMS) thermal system. The plate of this kind of novel plate heat exchanger is formed by discontinuous structure wave consisting of convex sphere and concave sphere, its heat transfer performance is better than that of the BR1 chevron plate heat exchanger, and its resistance characteristics are superior to those of the normally used 60-degree plate heat exchanger. Furthermore, the mechanism analysis of heat transfer enhancement shows that the spherical wave structure can reduce the local field synergy angle, so as to improve the field synergy degree of velocity vector and temperature gradient vector.

Experimental investigation of evaporation heat transfer and pressure drop of ammonia in a 30° chevron plate heat exchanger

Ammonia, an environment friendly natural refrigerant with attractive thermo-physical properties is a potential replacement of the synthetic refrigerants with high ozone depletion and global warming potentials. Experimental heat transfer and pressure drop data are obtained for two phase evaporation of ammonia in a commercial plate heat exchanger for symmetric 30°/30° chevron plates. The plate heat exchanger was configured in a single pass U-type counter flow arrangement with liquid ammonia evaporating in upward flow direction and glycol/water solution simulating the heat load in counter flow. Experiments were carried out for saturation temperatures ranging from −25 °C to −2 °C. The heat flux was varied between 21 kW m−2 and 44 kW m−2. Experimental results show significant effect of saturation temperature, heat and exit vapor quality on heat transfer coefficient and pressure drop. Two phase Nusselt number and friction factor correlations are proposed.

Experimental investigation of evaporation heat transfer and pressure drop of ammonia in a 60° chevron plate heat exchanger

Ammonia is an environment friendly natural refrigerant with attractive thermo-physical properties. Experimental heat transfer and pressure drop data are obtained for evaporation of liquid ammonia in a commercial plate heat exchanger for symmetric 60°/60° (hard) chevron angle plates. Experiments were carried out for mass flux ranging from 8.5 to 27 kg m−2 s−1 at saturation temperatures ranging from −25 °C to −2 °C. The heat flux was varied between 21 kW m−2 and 44 kW m−2. The heat transfer coefficient increased with an increase in saturation temperature and mass flux. Furthermore, heat transfer coefficient was observed to increase with exit vapor quality. The friction factor decreased with exit vapor quality and equivalent Reynolds number, while it increased with the fluid temperature. The work reveals that ammonia has far better heat transfer and pressure drop characteristics compared to HFCs. Two phase Nusselt number and friction factor correlations are also proposed.

Generalized correlations for predicting heat transfer and pressure drop in plate heat exchanger channels of arbitrary geometry

Characteristics of the flow in chevron plate heat exchangers are investigated through visualization tests of channels with β=28° and β=61°. Mathematical model is then developed with the aim of deriving correlations for prediction of f and Nu for flow in channels of arbitrary geometry (β and b/l). Thermal and hydraulic characteristics are evaluated using analytical solutions for the entrance and fully developed regions of a sinusoidal duct adapted to the basic single cell. The derived correlations are finally adjusted so as to agree with experimental results from tests on channels with β=28° and β=65°. f and Nu calculated by the presented correlations are shown to be consistent with experimental data from the literature at Re=2–10,000, β=(15–67)° and b/l=0.26–0.4.

Better Thermal Calculations Using Modified Generalized Leveque Equations for Chevron Plate Heat Exchangers

Plate heat exchangers are becoming vital process energy exchange equipment in chemical industries. The present work looks into the applicability of the Generalized Leveque Equation (GLE), which is used to generate thermal performance calculations for chevron-type plates utilized in plate and frame heat exchangers. New Modified Generalized Leveque Equations are proposed to improve calculation accuracy, which will enhance energy utilization and cost reduction in the design stage. A case study was selected to examine the GLE applicability when implemented to pure and mixed chevron plates. The GLE and other modified equations are compared with known classical correlations for different corrugation angles of 30°, 45°, 50°, 60° and 65° as pure chevron plates, and 45°/90°, 23°/90°, 45°/45°, 23°/45°, and 23°/23° as mixed chevron plates. Both the GLE and single Modified Generalized Leveque Equation (MGLE) gave good results only for 30° and 50° pure chevron angles and failed to give acceptable results in 45°, 60° and 65° chevron angles; both, however, gave acceptable results with all tested mixed angles. Also, the GLE has the tendency to be more applicable in the laminar region where Re < 2100, but the inaccuracy increases when applied in the turbulent region, while MGLE gave slightly lower relative error at high Re. Based on the classification of soft and hard chevron plates, two new Modified Generalized Leveque Equations, MGLE(1) and MGLE(2), were developed from the set of Kumar's data for pure chevron plates. The proposed system of equations are capable of providing excellent results for both pure and mixed chevron angles when compared with a large set of classical correlations available in the literature.

Two-Phase Flow Visualization in Chevron and Bumpy Style Flat Plate Heat Exchangers

Adiabatic flow visualization in a chevron plate, a 1:1 aspect ratio bumpy plate, and a 2:1 aspect ratio bumpy plate heat exchangers were investigated for vertical upward flow with R134a. Qualities ranging from 5% to 90% and mass fluxes of 60, 90, and 125 kg/m2-s were investigated. The flow visualization experiments were conducted at a 10°C inlet temperature. Four flow regimes were observed for the flat plate geometries investigated: bubbly flow, rough annular flow, smooth annular flow, and mist flow. The four flow regimes are mapped out on a mass flux versus quality basis for each geometry. The chevron geometry was seen to undergo flow transitions at lower qualities and mass fluxes than the bumpy plate geometries, and the 2:1 aspect ratio bumpy plate geometry was seen to undergo flow transitions at lower qualities and mass fluxes than the 1:1 aspect ratio bumpy plate geometry.

Enhanced Heat Transfer Characteristics of Viscous Liquid Flows in a Chevron Plate Heat Exchanger

Steady-state heat transfer and pressure drop data for single-phase viscous fluid flows (2 ≤ Re ≤ 400) in a single-pass U-type counterflow plate heat exchanger (PHE) with chevron plates are presented. With vegetable oil as test fluid (130 &lt; Pr &lt; 290), three different plate arrangements are employed: two symmetric (β = 30 deg/30 deg and 60 deg/60 deg) and one mixed (β = 30 deg/60 deg). The effects of chevron angle β, corrugation aspect ratio γ, and flow conditions (Re, Pr, μ/μw on Nu and f characteristics of the PHE are delineated. The results show a rather complex influence of plate surface corrugations on the enhanced thermal-hydraulic behavior. Relative to the performance of equivalent flat-plate packs, chevron plates sustain up to 2.9 times higher heat transfer rates on a fixed geometry and constant pumping power basis, and require up to 48 percent less surface area for the fixed heat load and pressure drop constraint.