Design Of Plate-fin Heat Exchangers Research Articles

Irreversibility analysis for optimization design of plate fin heat exchangers using a multi-objective cuckoo search algorithm

This paper introduces and applies an improved multi-objective cuckoo search (IMOCS) algorithm, a novel met-heuristic optimization algorithm based on cuckoo breeding behavior, for the multi-objective optimization design of plate-fin heat exchangers (PFHEs). A modified irreversibility degree of the PFHE is separated into heat transfer and fluid friction irreversibility degrees which are adopted as two initial objective functions to be minimized simultaneously for narrowing the search scope of the design. The maximization efficiency, minimization of pumping power, and total annual cost are considered final objective functions. Results obtained from a two dimensional normalized Pareto-optimal frontier clearly demonstrate the trade-off between heat transfer and fluid friction irreversibility. Moreover, a three dimensional Pareto-optimal frontier reveals a relationship between efficiency, total annual cost, and pumping power in the PFHE design. Three examples presented here further demonstrate that the presented method is able to obtain optimum solutions with higher accuracy, lower irreversibility, and fewer iterations as compared to the previous methods and single-objective design approaches.

A robust approach for optimal design of plate fin heat exchangers using biogeography based optimization (BBO) algorithm

Abstract Design of plate-fin heat exchangers is a very complex task generally based on trial and error process. Traditional designing methods are very time consuming and do not guarantee the archive of an optimal solution; therefore heuristic based computation methods are used, usually. So, in present paper a new design method proposed for optimization of plate fin heat exchangers using biogeography-based optimization (BBO) algorithm. The BBO algorithm has some advantages in detecting the global minimum compared with other heuristic algorithms. In present research the BBO scheme has been employed for optimal design of the plate fin heat exchanger by minimization of the total annual cost, heat transfer area and total pressure drops of the equipment considering main structural and geometrical parameters of the exchanger as design variables. Based on proposed approach, a full computer code was developed and three various case studies are investigated by it to illustrate the effectiveness and accuracy of the proposed method. Comparison of the results with those obtained by previous methods reveals that the BBO algorithm can be successfully employed for optimization of plate fin heat exchangers. Finally, parametric analysis carried out to evaluate the sensitivity of the proposed method to the cost and structural parameters.

General prediction of the thermal hydraulic performance for plate-fin heat exchanger with offset strip fins

Abstract The heat transfer and flow friction coefficients for offset strip fins (OSF) used in plate-fin heat exchangers are numerically investigated with well validated 3D models. The effect of the geometrical three-dimensionality is analyzed in a distinctive way to understand the general behavior of the thermal hydraulic performance. Based on the analysis of a large amount of numerical data by CFD techniques for OSF fins, a couple of new correlations for general prediction of the j and f factors are developed, which excellently correlate a variety of geometrical parameters with blockage ratio ranging from 10% to 60%. Moreover, 252 experimental data-points for j and 290 experimental data-points for f covering 24 OSF fins are collected from literatures to examine the predicting abilities of the proposed correlations. The comparisons show that the proposed correlations can present the basic behavior of experimental data with nice accuracy. Further comparisons with the previous correlations from literatures have been done with regards to the same experimental data, which reflect that the proposed ones provide well-adapted predictions for OSF fins with different fin thickness covering a broad range of blockage ratio, while the previous correlations express growing prediction deviations as the blockage ratio increases. On the whole, the proposed correlation predicts 92.5% of the j data and 90.3% of the f data within 20%, with the RMS errors of less than 15%. The present work might be very helpful to guide the optimum design of plate-fin heat exchangers and also evaluate the performance of heat transfer enhancement in the OSF fin channels.

Optimization of a plate-fin heat exchanger design through an improved multi-objective teaching-learning based optimization (MO-ITLBO) algorithm

Teaching-learning-based optimization (TLBO) is a recently developed heuristic algorithm based on the natural phenomenon of teaching-learning process. In the present work, multi-objective improved teaching-learning-based optimization (MO-ITLBO) algorithm is introduced and applied for the multi-objective optimization of plate-fin heat exchangers. The basic TLBO algorithm is improved to enhance its exploration and exploitation capacities by introducing the concept of number of teachers, adaptive teaching factor, tutorial training and self-motivated learning. The MO-ITLBO algorithm uses a grid-based approach to adaptively assess the non-dominated solutions maintained in an external archive. Minimizing total annual cost and the total weight of heat exchanger as well as minimization of total pressure drop and maximization of heat exchanger effectiveness for specific heat duty requirement are considered as objective functions. Two application examples are presented to demonstrate the effectiveness and accuracy of the proposed algorithm.

Optimal design of plate-fin heat exchangers by a Bees Algorithm

In this study, the application of Bees Algorithm (BA) in the optimum design of a cross flow plate-fin heat exchanger with offset strip fin is investigated. First, heat exchanger is optimized and designed according to the effectiveness optimization. Then, an analysis based on the second law of thermodynamics and minimizations of entropy generation units is performed. Specific heat duty, space restriction and permitted pressure drop are considered as the constraints for maximizing the effectiveness and minimizing the entropy generation units. Hot and cold flow length of the heat exchangers, number of fin layers, fin frequency, fin height, fin strip length and fin thickness are introduced as optimization variables. The effectiveness and accuracy of the suggested algorithm are compared with literature. The results have shown that BA can find optimum configuration with higher accuracy in comparison with Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Imperialist Competitive Algorithm (ICA) and preliminary design.

Development of structural design procedure of plate-fin heat exchanger for HTGR

Highly efficient plate-fin heat exchanger for application to HTGR has been focused on recently. Since this heat exchanger is fabricated by brazing a lot of plates and fins, a new procedure for structural design of brazed structures in the HTGR temperature region up to 950°C is required. Firstly in this paper influences on material strength due to both thermal aging during brazing process and helium gas environment were experimentally examined, and failure mode and failure limit of brazed side-bar structures were experimentally clarified. Secondly allowable stresses for aging materials and brazed structures were newly determined on the basis of the experimental results. For the purpose of validating the structural design procedure including homogenization FEM modeling, a pressure burst test and a thermal fatigue test of partial model for plate-fin heat exchanger were carried out. Finally, results of reference design of plate-fin heat exchangers of recuperator and intermediate heat exchanger for HTGR plant were evaluated by the proposed design criteria.

An imperialist competitive algorithm for optimal design of plate-fin heat exchangers

This paper presents the application of imperialist competitive algorithm (ICA) for optimization of a cross-flow plate fin heat exchanger. Minimization of total weight and total annual cost are considered as objectives. Seven design parameters, namely, heat exchanger length at hot and cold sides, fin height, fin frequency, fin thickness, fin-strip length and number of hot side layers are selected as optimization variables. A case study from literature is presented to show the effectiveness of the proposed algorithm. The numerical results reveal that ICA can find optimum configuration with higher accuracy in less computational time when compared to conventional genetic algorithm (GA).

Optimal design of plate-fin heat exchangers by a hybrid evolutionary algorithm

This study explores the first application of a Genetic Algorithm hybrid with Particle Swarm Optimization (GAHPSO) for design optimization of a plate-fin heat exchanger. A total number of seven design parameters are considered as the optimization variables and the constraints are handled by penalty function method. The effectiveness and accuracy of the proposed algorithm is demonstrated through an illustrative example. Comparing the results with the corresponding results using GA and PSO reveals that the GAHPSO can converge to optimum solution with higher accuracy.

The Numerical Simulation of Air-Cooled Plate-Fin Heat Exchanger

According to the periodic structure of the plate-fin heat exchanger, 3D model of the heat exchanger is established which simplifies the computation amount of the numerical simulation on flow field and temperature field. The relationship of fluid velocity, temperature, pressure drop and heat transfer coefficient is analyzed. The flow and heat transfer characteristics can be well predicted. Based on the simulation results, the conclusion makes reference to the design of plate-fin heat exchanger.

Incorporating Moldability Considerations During the Design of Polymer Heat Exchangers

Recently, available formulations of thermally enhanced polymer composites are attractive in heat exchanger applications due to their low cost and improved corrosion resistance compared to the conventional metal options. This paper presents a systematic approach to the design of plate-fin heat exchangers made out of thermally enhanced polymer composites. We have formulated the design problem as the life cycle cost minimization problem. The integrated design model introduced here accounts for heat transfer performance, molding cost, and assembly costs. We have adopted well-known models to develop individual parametric models that describe how heat transfer performance, molding cost, and assembly cost varies as a function of the geometric parameters of the heat exchanger. Thermally enhanced polymer composites behave differently from the conventional polymers during the molding process. The desired thin walled large structures are expected to pose challenges during the filling phase of the molding process. Hence, we have utilized experimentally validated simulations to develop a metamodel to identify difficult and impossible to mold design configurations. This metamodel has been integrated within the overall formulation to address the manufacturability considerations. This paper also presents several case studies that show how the material and labor cost strongly influence the final design.

An Improved Particle Swarm Algorithm for Optimal Design of Plate-Fin Heat Exchangers

In this paper, an improved particle swarm optimization (PSO) was used to optimize the structure dimensions of the plate-fin heat exchangers (PFHEs). The major objectives are to minimize the total weight and total annual cost of the PFHEs for given constrained conditions. The total weight target ensures an exchanger of the smallest size with minimum capital cost, whereas the annual cost target yields the optimum pressure drops accounting for the trade-off between power consumption and heat exchanger weight. The total length and width of the PFHE core, number of hot side layers, fin height, and pitch on each side of the PFHE are considered as optimization variables. The logarithmic mean temperature difference method is used for the design of the PFHE. Also compared with the results obtained by PSO and the traditional genetic algorithm, the PSO algorithm presents a shorter computational time and better results under the same design parameters and the same optimization variables.

The Entropy Generation Minimisation based on the Revised Entropy Generation Number

In the present work, an improved Entropy Generation Minimisation (EGM) approach aiming at minimising the revised entropy generation number which is the non-dimensionalised entropy by the ratio of heat flow to the input temperature of the cold fluid is developed for a plate-fin heat exchanger design with multiple design variables with the help of genetic algorithm. It is found that the approach can decrease the total fan power dramatically and improve the exchanger effectiveness simultaneously. Finally, this approach is applied to a heat recovery system where the heat exchanger works as a component of the system.

Experimental investigation of header configuration on two-phase flow distribution in plate-fin heat exchanger

The two-phase flow distribution in a plate-fin heat exchanger has been experimentally studied under different operation conditions. The results indicate that two-phase flow distribution is more complex and nonuniform than that of single-phase flow. The distribution uniformity of liquid-phase deteriorates with the decrease of Re gas and Re liq . The distribution uniformity of gas-phase deteriorates with Re liq , but improves with Re gas . The improved header with perforated baffle can effectively improve the uniformity of two-phase flow distribution and dryness distribution. The values of S liq , S gas and S dry decrease by 5.4–44.0%, 4.7–35.0% and 11.7–30.0%, respectively. The conclusion is of great significance in the optimum design of plate-fin heat exchanger.

Second law based optimisation of crossflow plate-fin heat exchanger design using genetic algorithm

A genetic algorithm based optimisation technique has been developed for crossflow plate-fin heat exchangers using offset-strip fins. The algorithm takes care of large number of continuous as well as discrete variables in the presence of given constraints. The optimisation program aims at minimising the number of entropy generation units for a specified heat duty under given space restrictions. The results have also been obtained and validated through graphical contours of the objective function in the feasible design space. The effect of variation of heat exchanger dimensions on the optimum solution has also been presented.

Optimal design approach for the plate-fin heat exchangers using neural networks cooperated with genetic algorithms

The paper demonstrates the successful application of genetic algorithm (GA) combined with back propagation neural networks (BP) for the optimal design of plate-fin heat exchangers (PFHE). The major objectives in the PFHE design are the minimum total weight and total annual cost for a given constrained conditions. The total weight target ensures an exchanger of the smallest size with minimum capital cost, whereas the annual cost target yields the optimum pressure drops accounting for the tradeoff between power consumption and heat exchanger weight. Total length and width of PFHE core, number of hot side layers, fin height and pitch on each side of PFHE are considered as variables to be optimized by means of GA combined with BP method. This optimization method of PFHE is universal and can be used for various PFHEs.

PIV Investigations of Flow Patterns in the Entrance Configuration of Plate-fin Heat Exchanger

Abstract Flow characteristics in the entrance of plate-fin heat exchanger have been investigated by means of particle image velocimetry (PIV). The flow field was measured using the two-frame cross-correlation technique. Streamline and velocity contour graphs at different cross-sections were obtained in the experiment. The experimental results indicate that flow maldistribution in the conventional header is very serious, while the improved header configuration with punched baffle can effectively improve the uniformity. The flow maldistribution parameter in plate-fin heat exchanger has been reduced from 1.21 to 0.21, and the ratio of the maximum velocity to the minimum is reduced from 23.2 to 1.8 by installing the punched baffle. The results suggest room for the optimum design of plate-fin heat exchanger.

An experimental and numerical investigation of flow patterns in the entrance of plate-fin heat exchanger

The turbulent flow structure inside the entrance of plate-fin heat exchanger was characterized by CFD simulation and PIV experiment under the similar conditions. A series of velocity vectors and streamline graphs of different cross-sections are achieved for three distinct header configurations, involving conventional and improved configurations. The numerical and experimental results indicate that the performance of fluid maldistribution in conventional entrance is deteriorated, while the improved configuration with punched baffle can effectively improve the performance in both radial and axial direction. And the baffle on which the small holes are distributed in staggered arrangement is the first choice for the improvement. CFD results and PIV data are in good agreement with each other. The results validate that PIV and CFD are well suitable to investigate complex flow patterns and the conclusion of this paper is of great significance in the optimum design of plate-fin heat exchanger.

PIV experimental investigation of entrance configuration on flow maldistribution in plate-fin heat exchanger

Flow characteristics of flow field in the entrance of plate-fin heat exchanger have been investigated by means of particle image velocimetry (PIV). The velocity fields were measured using the two-frame cross-correlation technique. A series of velocity vector and streamline graphs of different cross-sections are achieved in the experiment. The experimental results indicate that performance of fluid maldistribution in conventional entrance configuration is very serious, while the improved entrance configuration with punched baffle can effectively improve the performance of fluid flow distribution in the entrance. Based on the analysis of the fluid flow maldistribution, a baffle with small holes is recommended to install in the entrance configuration in order to improve the performance of flow distribution. When the punched baffle is proper in length, the small holes is distributed in staggered arrangement, and the punched ratio gradually increases from central axis to the boundary along with the baffle length, the performance of flow distribution in plate-fin heat exchanger is effectively improved by the optimum design of the entrance configuration. The flow maldistribution parameter S in plate-fin heat exchanger has been reduced from 1.21 to 0.209 and the ratio of the maximum velocity to the minimum θ is reduced from 23.2 to 1.76 by installing the punched baffle. The results validate that PIV is well suitable to investigate complex flow pattern and the conclusion of this paper is of great significance in the optimum design of plate-fin heat exchanger.

Dephlegmator Design in Low Temperature Gas Separation

Dephlegmators can be used to reduce power consumption in low temperature gas separation processes. Most existing models have focused on separation process simulation, while the heat exchange characteristics and the refrigeration design were either ignored or based on highly simplified assumptions. This paper presents a new framework for the design of dephlegmators that addresses simulation of multicomponent partial condensation, design of plate-fin heat exchangers (PFHEs) and design of the refrigeration processes that service the dephlegmator. For simulation, a film model is applied to estimate local mass and heat transfer and integration across the separation area. In the design of PFHEs, the key issue is to determine the controlling stream according to the flow pattern in the separation passages. Design of refrigeration focuses on the optimization of the composition when mixed refrigerants are used, and on partition temperature when cascade cycles are used. A systematic methodology is proposed to include all these aspects. Various cases are studied to provide guidelines in the design of dephlegmators used for multicomponent gas mixtures with different refrigeration systems.

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

The plate-fin heat exchanger is normally designed with the assumption that the fluid is uniformly divided among all the parallel passages. In practice, however, the design of the exchanger, the heat transfer process, the operation of the external system, etc., may create high flow maldistribution. The performance deterioration of plate-fin heat exchangers due to flow maldistribution may be serious. In this review, the flow distribution performance in a plate-fin heat exchanger has been experimentally studied and the distribution performance of different distributors' inlet angles has been measured. The combined effects of the inlet angle and mass flow rate on flow maldistribution have been studied. The study is useful in the optimum design of plate-fin heat exchangers.