Design optimization of shell-and-tube heat exchanger using particle swarm optimization technique

Shell-and-tube heat exchangers (STHEs) are the most common type of heat exchangers that find widespread use in numerous industrial applications. Cost minimization of these heat exchangers is a key objective for both designer and users. Heat exchanger design involves complex processes, including selection of geometrical parameters and operating parameters. The traditional design approach for shell-and-tube heat exchangers involves rating a large number of different exchanger geometries to identify those that satisfy a given heat duty and a set of geometric and operational constraints. However, this approach is time-consuming and does not assure an optimal solution. Hence the present study explores the use of a non-traditional optimization technique; called particle swarm optimization (PSO), for design optimization of shell-and-tube heat exchangers from economic view point. Minimization of total annual cost is considered as an objective function. Three design variables such as shell internal diameter, outer tube diameter and baffle spacing are considered for optimization. Two tube layouts viz. triangle and square are also considered for optimization. Four different case studies are presented to demonstrate the effectiveness and accuracy of the proposed algorithm. The results of optimization using PSO technique are compared with those obtained by using genetic algorithm (GA).     

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.     

Inverse radiation analysis using repulsive particle swarm optimization algorithm

In this study, an inverse radiation analysis is presented for the estimation of the radiation properties for an absorbing, emitting, and scattering media with diffusely emitting and reflecting opaque boundaries. The repulsive particle swarm optimization (RPSO) algorithm, which is a relatively recent heuristic search method, is proposed as an effective method for improving the search efficiency for unknown radiative parameters. To verify the performance of the RPSO algorithm, it is compared with a basic particle swarm optimization (PSO) algorithm and a hybrid genetic algorithm (HGA) for the inverse radiation problem in estimating the various radiation properties in a two-dimensional irregular medium, when the temperatures are given at only four measurement positions. A finite-volume method is applied to solve the radiative transfer equation of a direct problem to obtain measured temperatures. RPSO is proven to be quite a robust tool for simultaneous estimation of multi-parameters even in a strongly-coupled environment.     

A design optimization tool of earth-to-air heat exchanger using a genetic algorithm

Advancement in genetic algorithm (GA) optimization tools for design applications, coupled with techniques of soft computing, have led to new possibilities in the way computers interact with the optimization process. In this paper, the concept of goal-oriented GA has been used to design a tool for evaluating and optimizing various aspects of earth-to-air heat exchanger behavior. A new optimization method based on GA is applied as a generative and search procedure to optimize the design of earth-to-air heat exchanger. The GA is used to generate possible design solutions, which are evaluated in terms of passive heating and cooling of building, using a detailed thermal analysis of non air-condition building environment The results from the simulations are subsequently used to further guide the GA search to find the high-energy solutions for optimized design parameters. The specific problem addressed in this study is the sizing of earth-to-air heat exchanger in a non air-conditioned residential building. The developed algorithm is suitable for the calculation of the outlet air temperature and therefore of the heating and cooling potential of the earth-to-air heat exchanger system. This methodology is applicable to a wide range of design optimization problems like choice of building such as green house, solar house, or heating and cooling of buildings by mechanical system.     

环保用板翅式换热器的数值模拟与试验研究

为了应对目前国内电煤供应日趋紧张、价格不断上涨、煤质不稳定的局面,必须对国内外电煤供应市场进行调研和分析,探索相对稳定并具有一定灵活性的煤炭供应渠道。在确保锅炉掺烧国产及进口煤种安全性和经济性,同时满足日益严格的环保要求的前提下,选择印度尼西亚、澳大利亚和俄罗斯等国的部分动力煤与900MW超临界锅炉设计（校核）煤掺烧运行。鉴于储煤场地的局限性及进口动力煤与国内动力煤的煤质有着较大差异,为了使进口动力煤进场后在有效的时间内与锅炉的设计煤种适时掺烧,对进口动力煤在储煤场地的存放特性变化进行了探索,为建立和完善进口煤堆放制度提供理论依据。     

环保用板翅式换热器的数值模拟与试验研究

选取矩形截面平直翅片板翅式换热器的矩形单通道运用fluent软件进行数值模拟。首先对不同波高和波距的三组九种几何尺寸的翅片在同一工况下进行数值模拟,选出每组中传热和阻力综合性能最优者。然后对选出的三种翅片在不同工况下进行数值模拟,最终选出一种传热和阻力综合性能最优的。并对实物换热器进行试验研究,同时将试验结果和数值模拟结果进行对比分析,验证了数值模拟的正确性。     

Measurement of performance of plate-fin heat sinks with cross flow cooling

This work assesses the performance of plate-fin heat sinks in a cross flow. The effects of the Reynolds number of the cooling air, the fin height and the fin width on the thermal resistance and the pressure drop of heat sinks are considered. Experimental results indicate that increasing the Reynolds number can reduce the thermal resistance of the heat sink. However, the reduction of the thermal resistance tends to become smaller as the Reynolds number increases. Additionally, enhancement of heat transfer by the heat sink is limited when the Reynolds number reaches a particular value. Therefore, a preferred Reynolds number can be chosen to reduce the pumping power. For a given fin width, the thermal performance of the heat sink with the highest fins exceeds that of the others, because the former has the largest heat transfer area. For a given fin height, the optimal fin width in terms of thermal performance increases with Reynolds number. As the fins become wider, the flow passages in the heat sink become constricted. As the fins become narrower, the heat transfer area of the heat sink declines. Both conditions reduce the heat transfer of the heat sink. Furthermore, different fin widths are required at different Reynolds numbers to minimize the thermal resistance.     

Experimental investigation of header configuration on flow maldistribution in plate-fin heat exchanger

In this paper, the concept of second header installation is put forward. The experimental investigation on the effects of the inlet pipe diameter (Φ_1(in)), the first header’s diameter of equivalent area (Φ_1(out)) and the second header’s diameter of equivalent area (Φ_2(in) and Φ_2(out)) on the flow maldistribution in plate-fin heat exchanger (PFHE) is performed. The results indicate that the flow distribution in PFHE becomes more uniform when Φ_1(out)/Φ_1(in) is equal to Φ_2(out)/Φ_2(in). The correlation of the dimensionless flow maldistribution parameter S and Reynolds number is obtained under different header configurations. The ratio of the maximum flow velocity and the minimum flow velocity drops from 2.08–2.81 to 1.2–1.4 for various Reynolds numbers. The experimental studies prove that the performance of flow distribution in PFHE is effectively improved by the optimum design of the header configuration.     

Thermal-economic multi-objective optimization of plate fin heat exchanger using genetic algorithm

Thermal modeling and optimal design of compact heat exchangers are presented in this paper. ε–NTU$\epsilon ''–''\mathit{NTU}$ method was applied to estimate the heat exchanger pressure drop and effectiveness. Fin pitch, fin height, fin offset length, cold stream flow length, no-flow length and hot stream flow length were considered as six design parameters. Fast and elitist non-dominated sorting genetic-algorithm (NSGA-II) was applied to obtain the maximum effectiveness and the minimum total annual cost (sum of investment and operation costs) as two objective functions. The results of optimal designs were a set of multiple optimum solutions, called ‘Pareto optimal solutions’. The sensitivity analysis of change in optimum effectiveness and total annual cost with change in design parameters of the plate fin heat exchanger was also performed and the results are reported. As a short cut for choosing the system optimal design parameters the correlations between two objectives and six decision variables with acceptable precision were presented using artificial neural network analysis.     

Thermodynamic optimization of a coiled tube heat exchanger under constant wall heat flux condition

In this paper the second law analysis of thermodynamic irreversibilities in a coiled tube heat exchanger has been carried out for both laminar and turbulent flow conditions. The expression for the scaled non-dimensional entropy generation rate for such a system is derived in terms of four dimensionless parameters: Prandtl number, heat exchanger duty parameter, Dean number and coil to tube diameter ratio. It has been observed that for a particular value of Prandtl number, Dean number and duty parameter, there exists an optimum diameter ratio where the entropy generation rate is minimum. It is also found that with increase in Dean number or Reynolds number, the optimum value of the diameter ratio decreases for a particular value of Prandtl number and heat exchanger duty parameter.     

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.     

Prediction of boiling heat transfer duty in a compact plate-fin heat exchanger using the improved local assumption

A previous study presented a design method for compact plate-fin heat exchangers having flow passages with frequent interruptions. The local assumption was applied whereby the local boiling heat transfer coefficient was assumed to be fixed by the local metal-to-liquid ΔT. The present study extends the local assumption to include the effect of velocity on the local heat transfer coefficient. Confirmation of the new method is provided by a comparison of prediction and data for Freon-113 in an actual heat exchanger.     

基于改进粒子群算法的多目标无功优化

提出了一种基于粒子群算法的多目标优化方法,该算法采用Pareto支配关系来更新粒子的个体最优和全局最优值,用存储池保存搜索过程中发现的非支配解;采用聚类算法裁剪非支配解,以保持解的分散性;采用动态惯性权重来平衡粒子的局部和全局搜索能力,并将该算法应用于IEEE14节点系统的多目标无功优化。     

Optimization of an inertance pulse tube refrigerator using the particle swarm optimization algorithm

In this study, a particle swarm optimization method is employed to find the optimal operating parameters and geometrical parameters, which maximize the coefficient of performance (COP) of an inertance pulse tube refrigerator (IPTR). The considered decision variables of the IPTR are the charging pressure, which varies from 15 to 25 bar, operating frequency varying from 20 to 60 Hz, geometrical parameters, such as diameter varying from 15.0 to 25.00 mm, and length varying from 40.0 to 70 mm of the regenerator; diameter varying from 12.0 to 20.00 mm and length varying from 40.0 to 80 mm of the pulse tube; and diameter varying from 2.0 to 6.00 mm and length varying from 1.0 to 3.0 m of the inertance tube. A 1D numerical model, based on the finite volume discretization of governing equations has been selected to build the initial design matrix and solve the governing continuity, momentum, and energy equations. Analysis of variance is performed using the result obtained from the numerical simulation to visualize the variations of COP as a combination of various input parameters. It is observed that after optimizing the input parameters, the COP of the IPTR increases by 15.14%.     

Estimation of unknown heat source function in inverse heat conduction problems using quantum-behaved particle swarm optimization

The estimation of temporal dependent heat source in transient heat conduction problem is investigated. A stochastic method known as quantum-behaved particle swarm optimization (QPSO) is used to estimate the heat source without a priori information on its functional form, which is classified as the function estimation by inverse calculation. Because of the ill-posedness of this kind of inverse problems, Tikhonov regularization method is applied in this paper to stabilize the solution. Numerical experiments indicate the validity and stability of the QPSO method. Comparison with the conjugate gradient method (CGM) is also presented in this paper.     

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.     

Estimating soot volume fraction and temperature in flames using stochastic particle swarm optimization algorithm

A simulation investigation for simultaneous reconstruction of distributions of temperature and soot volume fraction from multi-wavelength emission in a sooting flame using the stochastic particle swarm optimizer (PSO) algorithm is presented. The self-absorption of the flame is considered. The selection of parameters of the stochastic PSO algorithm and detection wavelengths is analyzed. The effects of measurement errors and optical thickness of the flame on the accuracy of the reconstruction are investigated. It proved that the stochastic PSO algorithm is robust and can obtain accurate distributions of temperature and soot volume fraction from line-of-sight intensities in only several wavelengths, especially in the flame with large optical thickness, while other methods neglecting self-attenuation of the flame will take some errors.     

Multi-objective shape optimization of a heat exchanger using parallel genetic algorithms

We perform in this paper a multi-objective design optimization concerning the blade shape of a heat exchanger, considering the coupled solution of the flow/heat transfer processes. For this, a genetic algorithm is used. The aim of the procedure is to find the geometry most favorable to simultaneously maximize heat exchange while obtaining a minimum pressure loss. An in-house computer package, called OPAL, performs the optimization process in a fully automatic manner. It calls the pre-processor to generate the computational geometry as well as the mesh, it then performs the numerical simulation of the coupled fluid flow/heat transfer problem using Fluent, calculates the output parameters, and iterates the procedure. The genetic algorithm relies on a relatively large number of simulations, which may result in a considerable computational effort, depending on the configuration. The procedure can thus be performed in parallel on a Linux PC cluster to reduce user waiting time. A nearly optimal speed-up is obtained for the present configuration.     

Optimal design of power-system stabilizers using particle swarm optimization

In this paper, a novel evolutionary algorithm-based approach to optimal design of multimachine power-system stabilizers (PSSs) is proposed. The proposed approach employs a particle-swarm-optimization (PSO) technique to search for optimal settings of PSS parameters. Two eigenvalue-based objective functions to enhance system damping of electromechanical modes are considered. The robustness of the proposed approach to the initial guess is demonstrated. The performance of the proposed PSO-based PSS (PSOPSS) under different disturbances, loading conditions, and system configurations is tested and examined for different multimachine power systems. Eigenvalue analysis and nonlinear simulation results show the effectiveness of the proposed PSOPSSs to damp out the local and interarea modes of oscillations and work effectively over a wide range of loading conditions and system configurations. In addition, the potential and superiority of the proposed approach over the conventional approaches is demonstrated.