Mathematical Modeling and Multi-Objective Optimization of a Mini-Channel Heat Exchanger Via Genetic Algorithm

Author(s):  
Tommaso Selleri ◽  
Behzad Najafi ◽  
Fabio Rinaldi ◽  
Guido Colombo

In the present paper a mathematical model for a mini-channel heat exchanger is proposed. Multiobjective optimization using genetic algorithm is performed in the next step in order to obtain a set of geometrical design parameters, leading to minimum pressure drops and maximum overall heat transfer coefficient. Multiobjective optimization procedure provides a set of optimal solutions, called Pareto front, each of which is a trade-off between the objective functions and can be freely selected by the user according to the specifications of the project. A sensitivity analysis is also carried out to study the effects of different geometrical parameters on the considered functions. The whole system has been modeled based on advanced experimental correlations in matlab environment using a modular approach.

Author(s):  
Hassan Hajabdollahi ◽  
Babak Masoumpour

Modeling and optimization of a multi tube heat exchanger (MTHE) network considering the effects of different nanoparticles on the tube side are carried out using Fast and elitist non-dominated sorting genetic algorithm. After thermal modeling in [Formula: see text] method, optimization is performed by increasing the effectiveness and decreasing total annual cost as two objective functions using eight design parameters such as number of MTHE and particles volumetric concentration. In addition, optimization is performed at three various cold mass flow rates and different nanoparticles including Al2O3, CuO and ZrO2 and results are compared with the base fluid (water). For the reliability of the present code, the modeling results are validated with the results obtained from both the numerical and experimental model. The results show that the optimal Pareto front is improved in nanoparticles case, and the rate of improvement in CuO nanoparticles case, especially in higher effectiveness and lower cold mass flow rate is more significant compared with the other studied cases. In addition, because of improvement in the thermal performance of MTHE network with nanoparticles, the heat transfer surface area and consequently the total volume of MTHE network for the fixed values of effectiveness are noticeably reduced. Finally, the effects of design parameters versus effectiveness are demonstrated and discussed.


Author(s):  
Sayed M. Metwalli ◽  
Hesham A. Hegazi

Abstract This paper is concerned with the application of CAD to design disc brakes using multi-objective form optimization. Temperature and disc (rotor) volume are two competing design objective functions used to obtain the optimum design parameters of disc brakes. The geometrical parameters affecting disk brake design such as the outer and inner disc diameters, disc thickness, pad thickness and pad angle are considered. The exponents of the two competing objective functions are to be optimized for better results. A sensitivity analysis of the two exponents (A and B) is used for this optimization procedure. The design vector for optimizing disc brakes includes the outer disc diameters, diameter ratio, disc thickness, and pad angle. The multi-objective formulation satisfies maximum attained torque; minimum actuating force; minimum thermal stresses; minimum temperature and minimum disc volume. A comparison with two previous optimization results indicates a marked improvement of the present design since previous results did not consider all design parameters or optimized objectives.


Author(s):  
Adel Ghenaiet

This paper presents an evolutionary approach as the optimization framework to design for the optimal performance of a high-bypass unmixed turbofan to match with the power requirements of a commercial aircraft. The parametric analysis had the objective to highlight the effects of the principal design parameters on the propulsive performance in terms of specific fuel consumption and specific thrust. The design optimization procedure based on the genetic algorithm PIKAIA coupled to the developed engine performance analyzer (on-design and off-design) aimed at finding the propulsion cycle parameters minimizing the specific fuel consumption, while meeting the required thrusts in cruise and takeoff and the restrictions of temperatures limits, engine size and weight as well as pollutants emissions. This methodology does not use engine components’ maps and operates on simplifying assumptions which are satisfying the conceptual or early design stages. The predefined requirements and design constraints have resulted in an engine with high mass flow rate, bypass ratio and overall pressure ratio and a moderate turbine inlet temperature. In general, the optimized engine is fairly comparable with available engines of equivalent power range.


Author(s):  
Andrew J. Robison ◽  
Andrea Vacca

A computationally efficient gerotor gear generation algorithm has been developed that creates elliptical-toothed gerotor gear profiles, identifies conditions to guarantee a feasible geometry, evaluates several performance objectives, and is suitable to use for geometric optimization. Five objective functions are used in the optimization: minimize pump size, flow ripple, adhesive wear, subsurface fatigue (pitting), and tooth tip leakage. The gear generation algorithm is paired with the NSGA-II optimization algorithm to minimize each of the objective functions subject to the constraints to define a feasible geometry. The genetic algorithm is run with a population size of 1000 for a total of 500 generations, after which a clear Pareto front is established and displayed. A design has been selected from the Pareto front which is a good compromise between each of the design objectives and can be scaled to any desired displacement. The results of the optimization are also compared to two profile geometries found in literature. Two alternative geometries are proposed that offer much lower adhesive wear while respecting the size constraints of the published profiles and are thought to be an improvement in design.


Author(s):  
Gizem Gulben ◽  
Selin Aradag ◽  
Nilay Sezer-Uzol ◽  
Ufuk Atamturk

In this study, a computer program is developed to calculate characteristics of a Chevron type gasketed plate heat exchanger (CTGPHEX) such as: the number of plates, the effective surface area and total pressure drops. The main reason to prefer the use of CTGPHEXs to other various types of heat exchangers is that the heat transfer efficiency is much higher in comparison. Working conditions such as the flow rates and inlet and outlet temperature of both flow sides and plate design parameters are used as an input in the program. The Logarithmic Mean Temperature Method and the different correlations for convective heat transfer coefficient and Fanning factor that are found in the literature are applied to calculate the minimum necessary effective heat transfer area, the number of plate and pressure drops due to friction for both fluid sides of fulfill the desired heat transfer rate. This Turkish / English language optioned user friendly computer program is targeted to be used in domestic companies to design and select CTGPHEXs for any desired working conditions.


2014 ◽  
Vol 18 (suppl.2) ◽  
pp. 375-391 ◽  
Author(s):  
Sepehr Sanaye ◽  
Davood Modarrespoor

Cost and effectiveness are two important factors of heat pipe heat exchanger (HPHE) design. The total cost includes the investment cost for buying equipment (heat exchanger surface area) and operating cost for energy expenditures (related to fan power). The HPHE was thermally modeled using e-NTU method to estimate the overall heat transfer coefficient for the bank of finned tubes as well as estimating pressure drop. Fast and elitist non-dominated sorting genetic algorithm (NSGA-II) with continuous and discrete variables was applied to obtain the maximum effectiveness and the minimum total cost as two objective functions. Pipe diameter, pipe length, numbers of pipes per row, number of rows, fin pitch and fin length ratio were considered as six design parameters. The results of optimal designs were a set of multiple optimum solutions, called ?Pareto optimal solutions?. The comparison of the optimum values of total cost and effectiveness, variation of optimum values of design parameters as well as estimating the payback period were also reported for various inlet fresh air volume flow rates.


Author(s):  
Stefanie Bade ◽  
Michael Wagner ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer ◽  
Bruno Schuermans

A Design for Thermo-Acoustic Stability (DeTAS) procedure is presented, that aims at selecting a most stable burner geometry for a given combustor. It is based on the premise that a thermo-acoustic stability model of the combustor can be formulated and that a burner design exists, which has geometric design parameters that sufficiently influence the dynamics of the flame. Describing the flame dynamics in dependence of the geometrical parameters an optimization procedure involving a linear stability model of the target combustor maximizes the damping and thereby yields the optimal geometrical parameters. To demonstrate the procedure on an existing annular combustor a generic burner design was developed that features a significant variability of dynamical flame response in dependence of two geometrical parameters. In this paper the experimentally determined complex burner acoustics and complex flame responses are described in terms of physics based parametric models with excellent agreement between experimental and model data. It is shown that these model parameters correlate uniquely with the variation of the burner geometrical parameters, allowing to interpolate the model with respect to the geometrical parameters. The interpolation is validated with experimental data.


Author(s):  
Renaud Henry ◽  
Damien Chablat ◽  
Mathieu Porez ◽  
Frédéric Boyer ◽  
Daniel Kanaan

This paper addresses the dimensional synthesis of an adaptive mechanism of contact points ie a leg mechanism of a piping inspection robot operating in an irradiated area as a nuclear power plant. This studied mechanism is the leading part of the robot sub-system responsible of the locomotion. Firstly, three architectures are chosen from the literature and their properties are described. Then, a method using a multi-objective optimization is proposed to determine the best architecture and the optimal geometric parameters of a leg taking into account environmental and design constraints. In this context, the objective functions are the minimization of the mechanism size and the maximization of the transmission force factor. Representations of the Pareto front versus the objective functions and the design parameters are given. Finally, the CAD model of several solutions located on the Pareto front are presented and discussed.


Author(s):  
Huajin Yu ◽  
Lina Zhu ◽  
Zhenxing Zhang ◽  
Ziyu Liao

The passive design for decay heat removal system of future fast reactor will put forward higher requirement for air heat exchanger (AHX), which is directly relevant to the structure and anti-seismic design of stack. Under considering the heat exchanger ability and the structure compactness comprehensively, a strategy for the optimization design of AHX based on genetic algorithm was developed in this paper. The air resistance in shell side of vertical fin tube AHX was chosen as the objective function, and the effect of design parameters including fin pitch, number of tube rows, tube pitch and tube length on the air resistance was discussed. The results of the study show that the method for the optimization design of AHX based on genetic algorithm can effectively optimize the structure of AHX and improve the resistance characteristic of the shell side evidently, which leads to design the fast reactor plant, stack structure and seismic resistance simply.


2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Andrej Sarjaš ◽  
Rajko Svečko ◽  
Amor Chowdhury

This paper describes the use of a multiobjective genetic algorithm for robust motion controller design. Motion controller structure is based on a disturbance observer in an RIC framework. The RIC approach is presented in the form with internal and external feedback loops, in which an internal disturbance rejection controller and an external performance controller must be synthesised. This paper involves novel objectives for robustness and performance assessments for such an approach. Objective functions for the robustness property of RIC are based on simple even polynomials with nonnegativity conditions. Regional pole placement method is presented with the aims of controllers’ structures simplification and their additional arbitrary selection. Regional pole placement involves arbitrary selection of central polynomials for both loops, with additional admissible region of the optimized pole location. Polynomial deviation between selected and optimized polynomials is measured with derived performance objective functions. A multiobjective function is composed of different unrelated criteria such as robust stability, controllers’ stability, and time-performance indexes of closed loops. The design of controllers and multiobjective optimization procedure involve a set of the objectives, which are optimized simultaneously with a genetic algorithm—differential evolution.


Sign in / Sign up

Export Citation Format

Share Document