scholarly journals Proposal, Robustness Analysis and Equivalent Implementation of Optimization Method for Row-By-Row Fin Distribution in Multi-Row Frosting Evaporator

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6069
Author(s):  
Yu Sun ◽  
Rijing Zhao ◽  
Siyuan Wu ◽  
Dong Huang
Keyword(s):  
Pressure Drop ◽  
Three Dimensional ◽  
Robustness Analysis ◽  
Optimization Method ◽  
Operating Conditions ◽  
Air Pressure ◽  
Capacity Loss ◽  
Distribution Scheme ◽  
Increase Rate ◽  
Quantitative Design

The evaporator in a frost-free refrigerator typically has more tube rows, but frost deposition reduces along the airflow direction. Correspondingly, the evaporator fin distribution is thinner in the upstream rows but denser downstream, and a good match between frost and fin distribution is achieved to recover evaporator capacity loss. However, quantitative design principles of non-uniform fin distribution are lacking. A quasi-static frosting evaporator model is established and experimentally verified considering a three-dimensional (3D) evaporator, 1D frost growth and 1D non-uniform fin distribution. An optimization method for row-by-row fin distribution of a multi-row frosting evaporator is proposed based on the air pressure drop’s increase rate. When the increase rate in the air pressure drop of each row is almost equal, the smallest overall evaporator pressure drop is obtained, leading to the highest air flowrate and the greatest evaporator capacity. By applying the method, the air flowrate and the evaporator capacity increase by 5.5% and 4.6%, respectively, compared to the original fin distribution scheme. Moreover, the robustness of the optimization method is validated under wide temperature and humidity operating conditions. An equivalent implementation under an initial no-frost condition is also proposed to facilitate the optimization method without calculating the whole frosting process.

Motion Analysis of McKibben Type Pneumatic Rubber Artificial Muscle with Finite Element Method

2014 ◽  
Vol 8 (2) ◽  
pp. 147-158 ◽  
Author(s):  
Takashi Nozaki ◽  
◽  
Toshiro Noritsugu ◽  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
3D Model ◽  
Design Method ◽  
Three Dimensional ◽  
Artificial Muscle ◽  
Optimization Method ◽  
Artificial Muscles ◽  
3D Finite Element ◽  
Quantitative Design

This study aims to use three-dimensional (3D) Finite Element Modeling (FEM) to establish a quantitative design optimization method forMcKibben-type pneumatic rubber artificial muscle. First, a simple 3D model that does not account for the friction between the tube and the fiber braid strands and or that between the strands themselves is developed. The model is validated through experimentation, and the usefulness of the model is examined. With this model, the effects of various parameters, e.g., the braid angle, on the operation of the artificial muscle is investigated. It is found that the characteristics of the artificial muscle can be predicted. Thus, the proposed analysis may be a useful design method for braided artificial muscles.

Aero-Mechanical Optimization Method With Direct CAD Access: Application to Counter Rotating Fan Design

2006 ◽  
Author(s):  
S. Pierret ◽  
H. Kato ◽  
R. Filomeno Coelho ◽  
A. Merchant
Keyword(s):  
Three Dimensional ◽  
Integrated Design ◽  
Optimization Method ◽  
Optimization Techniques ◽  
Operating Conditions ◽  
Design System ◽  
Cad System ◽  
Design Variables ◽  
Automatic Optimization ◽  
Turbomachinery Blades

The detailed design of three-dimensional turbomachinery blades is a very challenging problem requiring multi-disciplinary analysis (MDA), efficient numerical optimization techniques and efficient shape parameterization techniques. Moreover, CAD systems have become an integral and critical part of the complete design process in various fields, and in particular in the field of turbomachine design. The connection of an automated design system to drive CAD geometry directly in the native CAD software is therefore mandatory in order to obtain an integrated design system that can be used in an industrial design chain. This paper presents and discusses an effort to incorporate these technologies into a single and integrated design system for the automatic optimization of turbomachinery blades. First, a brief summary of the algorithms and software used in this design system is presented. Then, the performance of this design system is first demonstrated on the automatic optimization of a counter-rotating fan stage. The fan is redesigned for several aerodynamic operating conditions as well as for multi-disciplinary objectives with constraints involving a CFD solver and structural mechanics FEM solver. The fan geometry is parameterized using 70 design variables and an optimum solution is found in 300 optimization cycles. The peak efficiency is increased by 1.5%, while the static stresses and dynamic vibration modes satisfy the constraints imposed during the optimization. Finally, a second application demonstrates the design optimization of a CAD model of the counter-rotating fan performed with direct integration to the CAD system using the CAPRI middleware. In this case the tip section of the first rotor is parameterized using 7 design variables. The efficiency is increased by 0.5% and the CAD integration in the optimization cycle is demonstrated.

Modeling Laminar Fluid Flows in Rectangular Vapor Grooves of Evaporators Used in Loop Heat Pipes

2010 ◽  
Author(s):  
Nirmalakanth Jesuthasan ◽  
B. Rabi Baliga
Keyword(s):  
Pressure Drop ◽  
Three Dimensional ◽  
Fluid Flows ◽  
Heat Pipes ◽  
Cost Effective ◽  
Operating Conditions ◽  
Pressure Drops ◽  
One Dimensional ◽  
Loop Heat Pipes ◽  
Dimensional Models

Loop heat pipes (LHPs) are devices in which capillary forces in a wick and liquid-vapor phase-change phenomena are used to achieve continuous and relatively high rates of transfer of thermal energy from a heat source to a heat sink. Quasi one-dimensional models of the fluid flow and heat transfer within LHPs, with empirical correlations as inputs, are commonly used as the basis of cost-effective computer simulations for the design and optimization of these devices for specific applications. The focus in this work is on laminar fluid flows in straight rectangular vapor grooves of flat evaporators used in LHPs. The pressure drops for such fluid flows are computed in available quasi one-dimensional models of LHPs using correlations for a friction factor that applies strictly only in the fully-developed region of flows in straight rectangular ducts with impermeable walls. The resulting errors can become serious if the pressure drop in the vapor grooves is a significant contributor to the overall pressure drop in the LHP. Thus, to enhance the capabilities of current quasi one-dimensional models of LHPs, more accurate correlations for predicting the aforementioned pressure drop are needed. In this work, a three-dimensional parabolic finite volume method is used to simulate laminar Newtonian fluid flows in straight rectangular vapor grooves of flat evaporators, for a representative range of LHP operating conditions. The mathematical model, computational methodology, results, and suitable correlations for the pressure drops are presented and discussed in this paper.

Numerical Analysis of Nozzle and Afterbody Flow of Hypersonic Transport Systems

1995 ◽  
Vol 117 (3) ◽  
pp. 389-393
Author(s):  
T. Esch ◽  
M. Giehrl
Keyword(s):  
Three Dimensional ◽  
Exhaust System ◽  
Optimization Method ◽  
Operating Conditions ◽  
Transport Systems ◽  
Navier Stokes ◽  
Nozzle Flow ◽  
Two Dimensional ◽  
Direct Optimization ◽  
Hypersonic Aircraft

Using an implicit Finite-Volume Navier–Stokes code, the flow field in a Single Expansion Ramp Nozzle (SERN) for a hypersonic aircraft is studied. Comparisons between experimental data and CFD calculations for certain components of the integrated exhaust system (cold two-dimensional nozzle flow, high temperature reacting three-dimensional combustion chamber flow, and two-dimensional nozzle flow with external flow) are presented. To show the sensitivity of the considered components to off-design operating conditions, comprehensive numerical studies have been carried out. For the determination of nozzle performance a detailed two-dimensional analysis from transonic to hypersonic flight Mach numbers has been performed. A direct optimization method has been used to investigate the influence of the lower nozzle flap shape on the thrust vector.

Novel Arrangement of Rough Tubes for Heat Flux Improvement

2012 ◽  
Vol 326-328 ◽  
pp. 81-86
Author(s):  
Farshad Farahbod ◽  
Sara Farahmand ◽  
Farzaneh Farahbod
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Crude Oil ◽  
Transfer Coefficient ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Set Up ◽  
The Heat Transfer Coefficient

The objective of the research is to represent a novel arrangement of conical three dimensional rough tubes (FS3D) for heat transfer coefficient enhancement. Experiments were performed with 316 stainless steel tubes of FS3D roughness and hot crude oil was circulated in constant heat flux condition in the related set up. The pressure drop is measured in this set up and compared with the pressure drop in a smooth tube with the same operating conditions. The heat transfer coefficient is one of essential parameters for design of heat transfer equipments and in this experimental work this is investigated for an Iranian crude oil in the FS3D rough tube. The heat transfer coefficient in FS3D rough tubes is higher than in other commercial enhanced tubes. FS3D rough tubes improve the performance of heat transfer equipments and also optimize the size of the mentioned devices. Consequently this type, the FS3D rough tube, is advantageous in energy and cost saving.

Experiment Study and Simulation Research for the Atomization Characteristics of the Internal-Mixing Twin-Fluid Atomizer

2014 ◽  
Vol 1049-1050 ◽  
pp. 1075-1082
Author(s):  
Peng Bo Bai ◽  
Yu Ming Xing ◽  
Ze Wang
Keyword(s):  
Droplet Size ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Air Pressure ◽  
Experimental Result ◽  
Hydraulic Pressure ◽  
Liquid Ratio ◽  
Energy Field ◽  
Internal Mixing ◽  
Atomization Characteristics

The internal-mixing twin-fluid atomizer has found wide application in aerospace, industrial gas turbine, oil-fired boiler, energy field and so on. The atomization characteristics of internal mixing nozzle under different operating conditions are studied by utilizing the Malvern laser particle size analyzer. According to the experiment results, the influence of air pressure, hydraulic pressure and air-liquid ratio to droplet size and uniformity are analyzed. The three-dimensional flow field model of internal mixing nozzle is built to simulate the droplet size of mixing room and outlet by Fluent. The simulation results show that the droplet size decreases along with the increase of the air pressure and the air-liquid ratio, moreover, the air pressure plays a main actor. The droplet size increases in the mixing room, and then decrease sharply at the domain of the outlet. The droplet size of the nozzle’s outlet obtained in simulation matches the experimental result.

scholarly journals Experimental Investigation of Hybrid Airblast Atomizer

1996 ◽  
Author(s):  
J. S. Chin ◽  
N. K. Rizk ◽  
M. K. Razdan
Keyword(s):  
Experimental Investigation ◽  
Pressure Drop ◽  
Fuel Injection ◽  
Simple Calculation ◽  
Operating Conditions ◽  
Air Pressure ◽  
Spray Angle ◽  
Engine Operation ◽  
Fuel Atomization ◽  
Pilot Fuel

As a means of overcoming the difficulties of achieving a satisfactory fuel atomization over the entire range of engine operation, both airblast forces and high pressure fuel injection are used in one hybrid atomizer design. The objectives of the present effort are to further improve the understanding of the important process of spray interaction in the hybrid atomizer flowfield, and to develop a relatively simple calculation approach that can relate the net effect of the interaction to the atomizer operating conditions. The ratio of the calculated average SMD for both the pilot and main prefilming device of the hybrid atomizer, each operating separately, to the SMD measured for the overall spray, obtained when both fuel devices were operating simultaneously, was used as an indication of the interaction between the two sprays. The experimental investigation demonstrated that stronger interaction between the pilot pressure nozzle spray and the prefilming main spray of the hybrid airblast atomizer occurred at higher pilot fuel pressure, larger pilot spray angle, or lower air pressure drop. It was also noticed that there was an optimum value of main fuel pressure, beyond which a decline in spray interaction was observed. The results indicated that by carefully selecting the pilot spray angle and flow capacities of the atomization devices, satisfactory atomization could be achieved even at lower air pressure drop. The interaction between the pilot and main sprays of the hybrid atomizer in configurations that utilized air swirlers surrounding the atomizer, was strongly dependent on swirler geometry. The extent of the interaction was attributed to changes in the air flowfield around and between the two sprays and the main filming process, all significantly affected the degree of utilization of the airblast effects.

Three-dimensional asymmetric maximum weight lifting prediction considering dynamic joint strength

2021 ◽  
pp. 095441192098703
Author(s):  
Rahid Zaman ◽  
Yujiang Xiang ◽  
Jazmin Cruz ◽  
James Yang
Keyword(s):  
Experimental Data ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Three Dimensional ◽  
Optimization Method ◽  
Weight Lifting ◽  
Joint Torque ◽  
Maximum Weight ◽  
Angular Velocities ◽  
Asymmetric Lifting

In this study, the three-dimensional (3D) asymmetric maximum weight lifting is predicted using an inverse-dynamics-based optimization method considering dynamic joint torque limits. The dynamic joint torque limits are functions of joint angles and angular velocities, and imposed on the hip, knee, ankle, wrist, elbow, shoulder, and lumbar spine joints. The 3D model has 40 degrees of freedom (DOFs) including 34 physical revolute joints and 6 global joints. A multi-objective optimization (MOO) problem is solved by simultaneously maximizing box weight and minimizing the sum of joint torque squares. A total of 12 male subjects were recruited to conduct maximum weight box lifting using squat-lifting strategy. Finally, the predicted lifting motion, ground reaction forces, and maximum lifting weight are validated with the experimental data. The prediction results agree well with the experimental data and the model’s predictive capability is demonstrated. This is the first study that uses MOO to predict maximum lifting weight and 3D asymmetric lifting motion while considering dynamic joint torque limits. The proposed method has the potential to prevent individuals’ risk of injury for lifting.

scholarly journals Optimization of Polymer Extrusion Die Based on Response Surface Method

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1043 ◽  
Author(s):  
Amin Razeghiyadaki ◽  
Dichuan Zhang ◽  
Dongming Wei ◽  
Asma Perveen
Keyword(s):  
Three Dimensional ◽  
Theoretical Work ◽  
Optimization Method ◽  
Extrusion Die ◽  
Surface Method ◽  
Spline Fitting ◽  
Die Profile ◽  
Response Optimization ◽  
Geometric Variables ◽  
Volume Method

A coupled surface response optimization method with a three-dimensional finite volume method is adopted in this study to identify five independent geometric variables of the die interior that provides a design with the lowest velocity variance at the exit of the coat-hanger extrusion die. Two of these five geometric variables represent the manifold dimension while the other three variables represent the die profile. In this method, B-spline fitting with four points was used to represent the die profile. A comparison of the optimized die obtained in our study and the die with a geometry derived by a previous theoretical work shows a 20.07% improvement in the velocity distribution at the exit of the die.

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