Plate-fin Heat Exchanger Research Articles

Numerical and experimental study on intermittent spray cooling for plate-fin heat exchanger

This study develops numerical models to analyze evaporative cooling and air cooling in an intermittent spray cooling system. The impact of heat load and film thickness on evaporation time and heat transfer enhancement is investigated. Results indicate that a thinner initial liquid film improves cooling performance due to quicker heat transfer and evaporation. The average cooling performance ratio between evaporative cooling and air cooling is evaluated for different spray intervals. Experimental findings demonstrate a 20 % to 40 % enhancement in cooling performance across varying intervals, with a spraying surface ratio of 0.45. Comparison between numerical and experimental results shows that with a fixed spray period of 5 s and intervals ranging from 25 s to 45 s, the numerical inaccuracy remains within 15%. The calculation of heat transfer performance considers the effective water utilization percentage. Shorter intervals lead to increased water loss as subsequent spray droplets wash out the liquid water on the fins. For instance, with a spraying interval of 5 s, water loss reaches 32.2%, whereas it is 20% with a 25 s interval. These findings underscore the reliability of the numerical model in capturing system behavior and validating heat transfer enhancements under different operational conditions.

The Heat Transfer in Plate Fin Heat Exchanger for Adsorption Energy Storage: Theoretical Estimation and Experimental Verification of the Methodology for Heat Accumulation Process

Adsorption energy storage is a promising resource-saving technology that allows the rational use of alternative heat sources. One of the most important parts of the adsorption heat accumulator is the adsorber heat exchanger. The parameters of heat transfer in this unit determine how fast heat from an alternative energy source, such as the Sun, will be stored. For the design of adsorption heat accumulators, plate fin heat exchangers are mainly used. In this paper, the procedure for the estimation of the global heat transfer coefficient for the adsorber heat exchanger depending on its geometry is considered. The heat transfer coefficient for a LiCl/SiO2 sorbent flat layer under conditions of heat storage stage was measured. Based on these data, the global heat transfer coefficients for a number of industrial heat exchangers were theoretically estimated and experimentally measured for the adsorption cycle of daily heat storage. It was shown that theoretically obtained values are in good agreement with the values of the global heat transfer coefficients measured experimentally. Thus, the considered technique makes it possible to determine the most promising geometry of the plate fin heat exchanger for a given adsorption heat storage cycle without complicated experiments.

Structural improvement of catalyst filled channel of continuous ortho-para hydrogen conversion technology

The continuous ortho-para hydrogen conversion (OPHC) technology is a novel and effective method for solving the OPHC challenge in hydrogen liquefaction, whose key application is the catalyst filled plate-fin heat exchanger (CFPFHE). However, the incoordination of the OPHC and heat transfer greatly limits the overall performances of the CFPFHE. To solve it, this paper attempts various catalyst filled channels to improve the overall performances of the CFPFHE by numerical simulation. Firstly, for the perforated fin channel, the special perforated structure makes its overall performances slightly better than the plain fin channel. Secondly, considering the excellent heat transfer of the catalyst filled channel and the demand increasing the catalyst filled amount, the plate channel is proposed by removing the fins between the plates. The results indicate that the surface heat transfer coefficient αh of the plate channel matches well with the serrated fin channel of the cold side. Compared with the plain fin channel, the pressure drop Δp of the plate channel is decreased by 25.12% ∼ 27.89%, and the OPHC index YYpH2 is increased by 2.62% ∼ 4.50%. From the perspective of YYpH2 ≥ 95%, the allowable working condition of the plate channel is more than 3 times that of the plain fin channel. Meanwhile, the plate channel with a large plate spacing dh sacrifices a part of αh, but it greatly improves the flow performance and OPHC performance. Further, the performance correlations of the plate channel are obtained to facilitate the design of the plate channel in the CFPFHE.

Investigation on strength and fracture mechanism of aluminum plate-fin structures at cryogenic temperature

In order to improve the service life of aluminum plate-fin heat exchangers and prevent them from thermal stress damage at cryogenic temperature, the strength and fracture mechanism of their plate-fin structures is studied at cryogenic temperature based on axial tensile test and scanning electron microscope (SEM) observation. Through axial tensile test, the mechanical properties and stress-strain curve can be obtained for plate-fin structures. Compared to the performance of plate-fin structures at room temperature, the yield limit, tensile strength and strain interval length (from yield limit to tensile strength) increased by 42.9 %, 49.5 % and 23.6 % for plate-fin structures at cryogenic temperature, respectively. This shows that plate-fin structures at cryogenic temperature have greater toughness and plasticity. Through SEM observation, the differences and commonality of fracture mechanism are compared and analyzed for the typical zones of plate-fin specimens. The results can be concluded that the fracture mode of plate-fin specimens belongs to quasi-cleavage fracture, and mainly shows the morphological characteristics of small cleavage sections, tearing ridges and dimples. Meanwhile, the fracture process and specific morphological characteristics of plate-fin specimens at cryogenic temperature are different from those at room temperature. Under the influence of thermal stress at cryogenic temperature and stress concentration, the fracture area of plate-fin specimens at cryogenic temperature is only located in the brazing zone. There is a significant displacement in the horizontal direction for specimens at cryogenic temperature when their temperature returns to room temperature after fracture. Therefore, the fracture in the brazing zone can be prevented for plate-fin structures at cryogenic temperature by adding brazing filler metal and improving the brazing process under process permission. The slow heating/cooling mode can be adopted for aluminum plate-fin heat exchangers to prevent them from thermal stress damage in the start-stop and operation stages.

A multi-strategy boosted prairie dog optimization algorithm for global optimization of heat exchangers

Abstract In this article, a new prairie dog optimization algorithm (PDOA) is analyzed to realize the optimum economic design of three well-known heat exchangers. These heat exchangers found numerous applications in industries and are an imperative part of entire thermal systems. Optimization of these heat exchangers includes knowledge of thermo-hydraulic designs, design parameters and critical constraints. Moreover, the cost factor is always a challenging task to optimize. Accordingly, total cost optimization, including initial and maintenance, has been achieved using multi strategy enhanced PDOA combining PDOA with Gaussian mutation and chaotic local search (MSPDOA). Shell and tube, fin-tube and plate-fin heat exchangers are a special class of heat exchangers that are utilized in many thermal heat recovery applications. Furthermore, numerical evidences are accomplished to confirm the prominence of the MSPDOA in terms of the statistical results. The obtained results were also compared with the algorithms in the literature. The comparison revealed the best performance of the MSPDOA compared to the rest of the algorithm. The article further suggests the adaptability of MSPDOA for various real-world engineering optimization cases.

Cheetah optimization algorithm for optimum design of heat exchangers

Abstract Thermal system optimization is always a challenging task due to several constraints and critical concepts of thermo-hydraulic aspects. Heat exchangers are one of those devices that are widely adopted in thermal industries for various applications such as cryogenics, heat recovery, and heat transfer applications. According to the flow configurations and enhancement of fins, the heat exchangers are classified as plate-fin heat exchangers, shell and tube heat exchangers, and tube-fin heat exchangers. This article addresses the economic optimization challenge of plate-fin heat exchangers using cheetah optimization (CO) algorithm. The design variables were optimized using the CO algorithm, and statistical results were compared with eight well-established algorithms. The study revealed that the cheetah algorithm is prominent in terms of realizing minimizing the overall cost of the plate-fin heat exchanger with a 100 % of success rate. Furthermore, the study suggests adopting the cheetah optimizer for solving optimization challenges in different fields.

An intelligent plate fin-and-tube heat exchanger design system through integration of CFD, NSGA-II, ANN and TOPSIS

This paper attempts to develop an intelligent plate fin-and-tube heat exchanger (PFTHE) design system, which is entirely self-programming, to achieve quickly design. The proposed design system consists of four modules: (1) formulation, (2) optimization, (3) post-processing, and (4) decision-making. The proposed design system is implemented and validated with the application of shape optimization of ellipse tubes of plate-fin heat exchanger. In the formulation module, the physical problem to be studied is mathematized and the main design variables will be determined. In the optimization module, a famous algorithm, non-dominated sorting genetic algorithm of type II (NSGA-II), is embedded in an in-house Multi-concept Heat Transfer (MHT) code to achieve call CFD simulation during optimization process. To reduce computation time, Open multi-processing (OpenMP) is employed. The optimal solutions (Pareto solutions) obtained by the optimization module will be stored in the database and also taken as the input for the post-processing module and the decision-making module. In the post-processing module, Artificial neural network (ANN) is utilized to establish the correlation between design variables and heat transfer performance indicators assisting engineers to quickly design. As a short cut for heat exchanger design, both forward and backward designs have been implemented. Finally, in the decision-making module, technique for order preference by similarity to an ideal solution (TOPSIS) is applied to determine the best compromise solution from Pareto solutions according to the actual requirements provided by users. Results show that the proposed design system could determine a best compromise solution by reducing the pressure drop (80%) of the tube bundle without sacrificing too much heat transfer performance (5%) and also save much time for designers. For the forward design, the ANNs taken six decision variables as inputs are modelled to forecast two objectives has reached acceptable precisions. This research provides a promising tool for PFTHE optimization to improve heat transfer and comprehensive performance, also for quickly design based on historical simulation or experimental results.

Enhancement of Plate-Fin Heat Exchanger Performance with Aid of (RWP) Vortex Generator

Enhancement of Plate-Fin Heat Exchanger Performance with Aid of (RWP) Vortex Generator

Enhanced Performance of Structurally Optimized Plate-Fin Heat Exchangers Through Numerical Modeling of Heat Transfer and Pressure Drop

This study aims to optimize the structure of compact Plate-Fin Heat Exchangers (PFHE) by incorporating corrugated fins and validating their improved performance through numerical modeling and simulation. The results provide valuable insights for refining application-specific design guidelines and enhancing the performance of PFHEs. Using Computational Fluid Dynamics (CFD), the PFHE geometry was created in SolidWorks and Ansys Fluent, with fins modeled in three layers inside the heat exchanger both with and without a cover. To investigate the fins' performance, flow field, and heat transfer, fin thickness, entry velocities, and locations of water and air were varied across three wavelengths (10, 20, and 30) during the numerical investigation. The analysis focused on the variations in pressure, temperature, and fluid velocity within the heat exchanger. Key findings include the observation that temperature distribution is influenced by the velocities of both water and air, with the upper layer experiencing a temperature increase due to the warm fluid stream, while the opposite effect is observed near the bottom layer. Furthermore, fluid temperature variation in the depth direction is attributed to conductive heat transfer through side plates and convective heat transfer to the surroundings. The outcomes of this study have the potential to reduce the pressure difference generated during heat exchange and increase the thermal efficiency of PFHEs.

An investigation of multistream plate-fin heat exchanger modelling and design: a review

Abstract In line with population expansion and industrial development, the world’s energy consumption has been rising gradually over the past three decades. As a result, methods for energy conservation have been sought. One of the most common strategies is heat recovery, which is efficient and cost-effective to the extent possible. Heat recovery is not just about saving energy for primary consumption; it is also about lowering emissions and protecting the environment. In this respect, one of the most important strategies for heat recovery is to develop heat exchangers and exploit the energy associated with many of the processes’ output products in order to use it in new processes. Many researchers working in the field of heat engineering are now looking into novel heat transfer techniques. Use of the heat exchanger as a compact is one of these ways that might be considered. The current review therefore concentrates on the design of plate-fin heat exchangers (PFHE) and multi-stream plate-fin heat exchangers (MSPFHE) based on various models. The current review offers some suggestions for upcoming studies on improving heat transfer and minimizing power use.

Improvement of Plate-Fin Heat Exchanger Performance with Assistance of Various Types of Vortex Generator

A 3-dimensional incompressible laminar flow and heat-transfer in a plate-fin heat exchanger (PFHE) where investigated numerically in this article. The influence of mounting a longitudinal vortex generator (LVG) on the offset rectangular-triangular fin (ORT) in the PFHE, on thermal and hydro-dynamic fields are presented. The novelty of this study is by attaching a LVG to an offset strip fin (OSF) surface. The cases of study for the PFHE are established, by using a built-in rectangular winglet pair type RWP longitudinal vortex generator carried out and fitted on this fin to improve the convective heat transfer of the (ORT) fin while minimizing pressure loss. The upper and lower plates are exposed to constant heat flux and the working fluid is air where chosen under a laminar range of RE (600 to 1400). The laminar flow and heat-transfer are governed by continuity, momentum and energy equations. ANSYS FLUENT (2021 R1) is used to get the numerical results, based on the finite volume method. The performance of the VG is assessed for an optimum winglet attack angle (45°), as well as by modifying the geometrical size parameters, namely the height and placement (L) of the RWP LVG. The result shows that the Nusselt number reaches its optimum enhancement values by using a common flow up CFU built-in rectangular winglet pair type RWP VG with a height and entrance length of (h=1.25mm, L=0.5mm), by 22.23% as compared with base case configuration (ORT). Finally, a two more LVG are tested with the optimum conditions of the RWP, which they are a delta winglet pair (DWP) and trapezoidal winglet pair (TWP). In addition, the temperature fields for the primary and secondary flows were shown in contour and streamline diagrams

Study on multi-stream plate fin heat exchanger coupled with ortho-para hydrogen conversion based on distributed parameter model

The distributed parameter model is used to simulate full domain of multi-stream CFPFHE (catalyst filled plate fin heat exchanger). The heat transfer due to the extended catalyst surface area, the ortho-para hydrogen conversion heat and the flow resistance in porous catalyst are integrated in the model. The results show that increasing the mass flow of fluid channel filled with catalyst not only decreases HEPUP (heat exchange amount per unit pump power), but also weakens efficiency of o-p conversion. For example, when the mass flow of fluid A (in which catalyst is filled) increases from 0.06 kg/s to 0.084 kg/s, the pump power increases by 34.6%, and the HEPUP and the average outlet para-hydrogen decreases by 30.9% and 7.0% respectively. In addition, A deviation parameter ϕ is defined to qualitatively describe the degree of inlet maldistribution. Although no catalyst filled in fluid C channel, the effect of ϕC on the outlet para-hydrogen mass fraction is obvious. With ϕC increasing from 0 to 1.5, the outlet para-hydrogen mass fraction in the layer numbered by 42 (middle layer of fluid A) increases by 6.8%, decreases by 11.9% and 11.9% respectively, in the layer numbered by 6 (upmost layer of fluid A) and 76 (downmost layer of fluid A). The increase of inlet maldistribution of fluid C prevents the potential of catalyst filled in up and down layers of fluid A from being fully utilized.

Experimental Characterization of an Additively Manufactured Inconel 718 Heat Exchanger for High-Temperature Applications

This work presents the experimental results of a novel, air-to-air, additively manufactured manifold-microchannel heat exchanger with straight fins on both sides. The heat exchanger was made of Inconel 718 using a direct metal laser sintering technique. The overall core size of the heat exchanger was 94 mm × 87.6 mm × 94.4 mm, with a fin thickness of 0.220 mm on both the hot and cold sides. The heat exchanger was tested with pressurized nitrogen gas at 300 °C and 340 kPa for the hot side, while air at an ambient condition was used for the cold side. An overall heat transfer of 276 W/m2K was obtained for Reynolds number values of 132 and 79 for the cold and hot sides, respectively. A gravimetric heat transfer density (Q/m∆T) of 4.7–6.7 W/kgK and a volumetric heat transfer density (Q/V∆T) of 6.9–9.8 kW/m3K were recorded for this heat exchanger with a coefficient of performance value that varied from 42 to 52 over the operating conditions studied here. The experimental pressure drop results were within 10% of the numerical values, while the corresponding heat transfer results were within 17% of the numerical results, mainly due to imperfections in the fabrication process. Despite this penalty, the performance of the tested heat exchanger was superior to the conventional plate-fin heat exchangers: more than 60% of improvements in both gravimetric and volumetric heat transfer densities were recorded for the entire range of experimental data.

Numerical model improvement of a plate-fin heat exchanger filled with catalyst for hydrogen liquefaction

The continuous ortho-para hydrogen conversion technology represented by the plate-fin heat exchanger filled with catalyst (PFHEFC) is one of the key technologies for the breakthrough of large-scale hydrogen liquefaction system. An appropriate numerical model of the PFHEFC can provide reference and guidance for its design. The thermal-hydraulic behaviors of the catalyst filled layer (CFL) are essential for the model development of the PFHEFC. In this paper, the thermal-hydraulic correlations of the high-pressure and low-temperature hydrogen in the CFL are investigated by the numerical simulation and then used to improve the existing numerical models of the PFHEFC. The results show that the simulation results of the face centered cubic (FCC) packing structure are close to the results of some classical correlations of the CFL with most relative deviations within ±10% and can be used to approximate the actual CFL. And taking 40 K as the dividing point, the new thermal-hydraulic correlations of the high-pressure and low-temperature hydrogen in the CFL are obtained with the relative deviations within ±10%. Further, the New model of the PFHEFC is developed with the new thermal-hydraulic correlations. The New model has some margin in the heat transfer performance, considers the special thermal-hydraulic performances of the high-pressure and low-temperature hydrogen in the CFL, and is consistent with the existing numerical models in the ortho-para hydrogen conversion performance. It shows the New model is more suitable for the PFHEFC and can provide more accurate results for the design of the PFHEFC than the existing numerical models.

Numerical investigation on the effect of cylindrical turbulator on performance of corrugated plate-fin heat exchanger

The corrugated fin is one of the common fin types in plate-fin heat exchangers. The corrugated fins can promote fluid turbulence and separate or destroy the boundary layer. To further increase the turbulence of the fluid in the channel, the cylindrical turbulator is innovatively added to the corrugated finned channel, and its effects on heat transfer and flow resistance is investigated by numerical simulation. Moreover, the field synergy theory is used to analyze why the heat transfer effect of the channel is improved after adding the cylindrical turbulator. Considering the heat transfer effect and flow resistance synthetically, the comprehensive performance of the heat transfer channel can be improved by adding the cylindrical turbulator at low Reynolds numbers. Correspondingly, at high Reynolds numbers, adding the cylindrical turbulator will reduce the comprehensive performance. On this basis, the influence of corrugated channel geometric sizes on the heat transfer and flow properties is investigated. The correlations of Reynolds number, Prandtl number and geometric dimension on heat transfer and friction factor is established for different geometrical dimensions. The correctness of the correlation is verified by choosing four models with random geometric dimensions, and the average absolute error of heat transfer and friction factor is 6.45% and 5.53%.

Experimental study on heat transfer characteristics of spray cooling system with plate-fin heat exchanger

ABSTRACT An intermittent spray cooling system is applied to fuel cell vehicle heat dissipation using a plate-fin heat exchanger. The effects of various system parameters on cooling performances are evaluated. Experimental results indicate that the cooling performance can be increased by 20% to 80% at various operating conditions and fixed spray area percentage of 45%. An empirical correlation is constructed to characterize heat transfer enhancement percentage. For the 124 data points examined, 92.73% of the data are within 20% of the error range, and 81.8% are within 15% of the error range. The average absolute deviation is 9.30%.

Optimization Analysis of Thermodynamic Characteristics of Serrated Plate-Fin Heat Exchanger.

This study explores the use of Multi-Objective Genetic Algorithm (MOGA) for thermodynamic characteristics of serrated plate-fin heat exchanger (PFHE) under numerical simulation method. Numerical investigations on the important structural parameters of the serrated fin and the j factor and the f factor of PFHE are conducted, and the experimental correlations about the j factor and the f factor are determined by comparing the simulation results with the experimental data. Meanwhile, based on the principle of minimum entropy generation, the thermodynamic analysis of the heat exchanger is investigated, and the optimization calculation is carried out by MOGA. The comparison results between optimized structure and original show that the j factor increases by 3.7%, the f factor decreases by 7.8%, and the entropy generation number decreases by 31%. From the data point of view, the optimized structure has the most obvious effect on the entropy generation number, which shows that the entropy generation number can be more sensitive to the irreversible changes caused by the structural parameters, and at the same time, the j factor is appropriately increased.

Experimental and Numerical Optimization Study on an Airfoil-Shaped Heat Exchanger

Heat exchanger design is a laborious and time-consuming task that often relies on a trial-and-error process. In light of this, our study proposes a design method for optimizing airfoil-shaped heat exchangers using the improved stochastic ranking evolutionary strategy (ISRES) algorithm. The ISRES algorithm provides significant advantages in identifying the global optimum, surpassing genetic algorithms (GAs). In the present study, the thermal model of the heat exchanger protype was validated using experimental techniques. Additionally, the ISRES algorithm was employed for the optimization of a plate-fin heat exchanger with airfoil-shaped fins by minimizing the total heat transfer area and pressure drops, while considering the main geometrical parameters of the exchanger as the design variables. The corresponding computer code was developed, and two case studies were conducted. In case study 1, the total heat transfer area was saved up to 25.7%, while in case study 2, the objective function value reached its minimum value of 0.0738. The numerical results demonstrate that the ISRES algorithm can be successfully applied in optimizing heat exchangers. Finally, a parametric analysis was conducted to evaluate the sensitivity of the proposed method to the heat transfer area.

Numerical investigation of turbulent nanofluid flow behavior in a multi-stream plate-fin heat exchanger with a novel design of fractal fins

Plate heat exchangers are widely used in various industries. This study considers using a novel design of fractal shape fins with a new structure on the performance of multi-stream plate-fin heat exchangers for the first time, which has not been studied by researchers before. The numerical study is done with a 3D finite volume method. The effect of using Oil/MWCNT nanofluid and using various configurations of fractal fins with different attack angles ranging from 30 degrees to 100 degrees with the range of Reynolds number of 10,000–40,000, have been studied in the current research. These changing parameters have a significant impact on the flow field and heat transfer in the heat exchanger. The results of this study show that increasing the angle of attack of fractal fins creates more flow deflection and higher fluid mixing. The rise of the Reynolds number creates stronger vortexes as the flow passes over the fins, thereby it can augment the fluid mixing in the areas which are close to the finned. As the Reynolds number rises, the growth of the thermal boundary layer diminished. It can also be seen that as the fluid impacts the fractal fins at higher angles of attack, the temperature distribution becomes more uniform in the heat exchanger. Increasing the Reynolds number from 10,000 to 40,000 increases the heat transfers up to 63 %. At the constant Reynolds numbers, increasing the fraction of solid nanoparticle volume up to 4 % in the cooling fluid augment the heat transfer rate by 48 % compared to the base fluid. Increasing the fluid velocity results the amplification of longitudinal vortex formation. Therefore, the pressure loss is higher at the increased Reynolds numbers. At the lower Reynolds numbers, the pumping power has a weaker dependency on the nanofluids concentration. Increasing the angle of attack of fractal fins increases the pumping power by 50 % compared with the angle of attack of 30 degrees. Increasing the fractal fin angle of attack compared with 30 degrees increases friction by 45–85 %. Changes in the Colburn factor show that considering all parameters that increase heat transfer, the Colburn factor increases by 23–42 % compared with the base scenario with Re = 10,000 and angle of attack = 30 degrees.

Design of Plate-Fin Heat Exchanger for CO2 Separation by Cryogenic Distillation

Carbon capture, utilization, and storage (CCUS) is a technique to curb carbon dioxide (CO2) emissions from significant point sources. CO2 separation is the first stage in the CCUS. Cryogenic CO2 separation is the emerging method of separating CO2 from different sources. Plate-fin heat exchanger (PFHE) is one of the compact heat exchangers generally used in cryogenic applications. Due to its advantages, it is also used in the cryogenic CO2 separation process. In this analysis, a PFHE is designed and analyzed by using an analytical method and Aspen software, and the results are compared. In the analytical design, the Maiti and Sarangi correlations are considered. The effect of the change in the thermos-physical properties on the volume and cost of the heat exchanger (HX) is analyzed. The energy penalty to separate CO2 from a CO2/N2 gas mixture with a 30% CO2 concentration is observed to be 1.063 MJ/kg of CO2. The volumes of HXs “A” and “B” determined by the analytical approach are found to be around 0.323 m3 and 0.978 m3, respectively. The volumes of HXs “A” and “B” by the Aspen EDR approach are found to be around 0.239 m3 and 0.839 m3, respectively.