A New Approach for Explicit Construction of Moldability Based Feasibility Boundary for Polymer Heat Exchangers

2011 ◽  
Author(s):  
Timothy Hall ◽  
Madan Mohan Dabbeeru ◽  
Satyandra K. Gupta
Keyword(s):  
Heat Exchangers ◽  
Intelligent Design ◽  
Nonlinear Process ◽  
Explicit Construction ◽  
Computational Experiments ◽  
Design Parameters ◽  
New Approach ◽  
Highly Nonlinear ◽  
Computationally Intensive ◽  
Polymer Heat Exchangers

Incorporating manufacturing feasibility is a very important consideration during the design optimization process and this paper is interested in investigating the molding feasibility of polymer heat exchangers. This application requires the explicit construction of the boundary, represented as a surface based on the parameter space, which separates the feasible and infeasible design space. The feasibility boundary for injection molding in terms of the design parameters is quite complex due to the highly nonlinear process physics, which, consequently, makes molding simulation computationally-intensive and time-consuming. Moreover, in heat exchanger applications, the optimal design often lies on the feasibility boundary. This paper presents a new approach for the explicit construction of a moldability-based feasibility boundary for polymer heat exchangers. The proposed approach takes inspiration from intelligent design of experiments and incorporates ideas from the field of active learning to minimize the number of computational experiments needed to construct the feasibility boundary. Our results show that the proposed approach leads to significant reduction in the number of computational experiments needed to build an accurate model of the feasibility boundary.

Probabilistic Performance of Helical Compound Planetary System in Wind Turbine

2015 ◽  
Vol 10 (4) ◽  
Author(s):  
Fisseha M. Alemayehu ◽  
Stephen Ekwaro-Osire
Keyword(s):  
Wind Turbine ◽  
Multibody Systems ◽  
Planetary System ◽  
Design Parameters ◽  
Wind Turbine Gearbox ◽  
New Approach ◽  
Highly Nonlinear ◽  
Multibody Dynamic ◽  
Input Variables ◽  
Maintenance Process

The dynamics of contact, stress and failure analysis of multibody systems is highly nonlinear. Nowadays, several commercial and other analysis software dedicated for this purpose are available. However, these codes do not consider the uncertainty involved in loading, design, and assembly parameters. One of these systems with a combined high nonlinearity and uncertainty of parameters is the gearbox of wind turbines (WTs). Wind turbine gearboxes (WTG) are subjected to variable torsional and nontorsional loads. In addition, the manufacturing and assembly process of these devices results in uncertainty of the design parameters of the system. These gearboxes are reported to fail in their early life of operation, within three to seven years as opposed to the expected twenty years of operation. Their downtime and maintenance process is the most costly of any failure of subassembly of WTs. The objective of this work is to perform a probabilistic multibody dynamic analysis (PMBDA) of a helical compound planetary stage of a selected wind turbine gearbox that considers ten random variables: two loading (the rotor speed, generator side torque), and eight design parameters. The reliability or probabilities of failure of each gear and probabilistic sensitivities of the input variables toward two performance functions have been measured and conclusions have been drawn. The results revealed that PMBDA has demonstrated a new approach of gear system design beyond a traditional deterministic approach. The method demonstrated the components' reliability or probability of failure and sensitivity results that will be used as a tool for designers to make sound decisions.

Analog Circuit Failure Analysis Using Time-Resolved Emission

2005 ◽  
Author(s):  
B.J. Cain ◽  
G.L. Woods ◽  
A. Syed ◽  
R. Herlein ◽  
Toshihiro Nomura
Keyword(s):  
Analog Circuits ◽  
Integrated Circuit ◽  
Analog Circuit ◽  
Photon Emission ◽  
Nonlinear Process ◽  
Time Resolved ◽  
Non Invasive ◽  
Highly Nonlinear ◽  
Excellent Spatial Resolution ◽  
5 Ghz

Abstract Time-Resolved Emission (TRE) is a popular technique for non-invasive acquisition of time-domain waveforms from active nodes through the backside of an integrated circuit. [1] State-of-the art TRE systems offer high bandwidths (> 5 GHz), excellent spatial resolution (0.25um), and complete visibility of all nodes on the chip. TRE waveforms are typically used for detecting incorrect signal levels, race conditions, and/or timing faults with resolution of a few ps. However, extracting the exact voltage behavior from a TRE waveform is usually difficult because dynamic photon emission is a highly nonlinear process. This has limited the perceived utility of TRE in diagnosing analog circuits. In this paper, we demonstrate extraction of voltage waveforms in passing and failing conditions from a small-swing, differential logic circuit. The voltage waveforms obtained were crucial in corroborating a theory for some failures inside an 0.18um ASIC.

scholarly journals Application and Design Aspects of Ground Heat Exchangers

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2134
Author(s):  
Luka Boban ◽  
Dino Miše ◽  
Stjepan Herceg ◽  
Vladimir Soldo
Keyword(s):  
Renewable Energy ◽  
Heat Exchangers ◽  
Geothermal Energy ◽  
Energy Demand ◽  
Design Parameters ◽  
Direct Expansion ◽  
Alternative Source ◽  
Ground Heat Exchangers ◽  
Point Of Interest ◽  
Constant Source

With the constant increase in energy demand, using renewable energy has become a priority. Geothermal energy is a widely available, constant source of renewable energy that has shown great potential as an alternative source of energy in achieving global energy sustainability and environment protection. When exploiting geothermal energy, whether is for heating or cooling buildings or generating electricity, a ground heat exchanger (GHE) is the most important component, whose performance can be easily improved by following the latest design aspects. This article focuses on the application of different types of GHEs with attention directed to deep vertical borehole heat exchangers and direct expansion systems, which were not dealt with in detail in recent reviews. The article gives a review of the most recent advances in design aspects of GHE, namely pipe arrangement, materials, and working fluids. The influence of the main design parameters on the performance of horizontal, vertical, and shallow GHEs is discussed together with commonly used performance indicators for the evaluation of GHE. A survey of the available literature shows that thermal performance is mostly a point of interest, while hydraulic and/or economic performance is often not addressed, potentially resulting in non-optimal GHE design.

Scalable 3D Bicontinuous Fluid Networks: Polymer Heat Exchangers Toward Artificial Organs

2015 ◽  
Vol 27 (15) ◽  
pp. 2479-2484 ◽  
Author(s):  
Christopher S. Roper ◽  
Randall C. Schubert ◽  
Kevin J. Maloney ◽  
David Page ◽  
Christopher J. Ro ◽  
...  
Keyword(s):  
Heat Exchangers ◽  
Artificial Organs ◽  
Fluid Networks ◽  
Polymer Heat Exchangers

Subpixel determination of wormhole tip position in 4D tomography of dissolving limestone cores

2021 ◽  
Author(s):  
Rishabh Prakash Sharma ◽  
Max P. Cooper ◽  
Anthony J.C. Ladd ◽  
Piotr Szymczak
Keyword(s):  
Flow Field ◽  
Pore Space ◽  
Nonlinear Process ◽  
Linear Interpolation ◽  
Flow Fields ◽  
Porous Rocks ◽  
Dissolution Experiment ◽  
Novel Approach ◽  
Highly Nonlinear ◽  
Computed Microtomography

<p>Dissolution of porous rocks by reactive fluids is a highly nonlinear process resulting in a variety of dissolution patterns, the character of which depends on physical conditions such as flow rate and reactivity of the fluid. Long, finger-like dissolution channels, “wormholes”, are the main subject of interest in the literature, however, the underlying dynamics of their growth remains unclear. </p><p>While analyzing the tomography data on wormhole growth.  one open question is to define the exact position of the tip of the wormhole. Near the tip the wormhole gradually thins out and the proper resolution of its features is hindered by the finite spatial resolution of the tomographs. In particular, we often observe in the near-tip region several disconnected regions of porosity growth, which - as we hypothesized - are connected by the dissolution channels at subpixel scale. In this study, we show how these features can be better resolved by using numerically calculated flow fields in the reconstructed pore-space. </p><p>We used 70 micrometers, 16-bit grayscale X-ray computed microtomography (XCMT) time series scans of limestone cores, 14mm in diameter and 25mm in length. Scans were performed during the entire dissolution experiment with an interval of 8 minutes. These scans were further processed using a 3-phase segmentation proposed by Luquot et al.[1], in which grayscale voxels are converted to macro-porosity, micro-porosity and grain phases from their grayscale values. The macro-porous phase is assigned a porosity of 1, while the grain phase is assigned 0. Micro-porous regions are assigned an intermediate value determined by linear interpolation between pore and grain threshold using grayscale values. An OpenFOAM based, Darcy-Brinkman solver, porousFoam, is then used to calculate the flow field in this extracted porosity field. </p><p>Porosity contours reconstructed from the tomographs show some disconnected porosity growth near the tip region which later become part of the wormhole in subsequent scans. We have used a novel approach by including the micro-porosity phase in pore-space to calculate the flow-fields in the near-tip region. The calculated flow fields clearly show an extended region of focused flow in front of the wormhole tip, which is a manifestation of the presence of a wormhole at the subpixel scale. These results show that micro-porosity plays an important role in dissolution and 3-phase segmentation combined with the flow field calculations is able to capture the sub-resolved dissolution channels. </p><p> </p><p> [1] Luquot, L., Rodriguez, O., and Gouze, P.: Experimental characterization of porosity structure and transport property changes in limestone undergoing different dissolution regimes, Transport Porous Med., 101, 507–532, 2014</p>

Real-Time Robot Capability Analysis

2005 ◽  
Author(s):  
Chalongrath Pholsiri ◽  
Chetan Kapoor ◽  
Delbert Tesar
Keyword(s):  
Decision Making ◽  
Path Planning ◽  
Real Time ◽  
Computationally Efficient ◽  
New Approach ◽  
Ellipsoid Method ◽  
Capability Analysis ◽  
Computationally Intensive ◽  
Planar Robots

Robot Capability Analysis (RCA) is a process in which force/motion capabilities of a manipulator are evaluated. It is very useful in both the design and operational phases of robotics. Traditionally, ellipsoids and polytopes are used to both graphically and numerically represent these capabilities. Ellipsoids are computationally efficient but tend to underestimate while polytopes are accurate but computationally intensive. This article proposes a new approach to RCA called the Vector Expansion (VE) method. The VE method offers accurate estimates of robot capabilities in real time and therefore is very suitable in applications like task-based decision making or online path planning. In addition, this method can provide information about the joint that is limiting a robot capability at a given time, thus giving an insight as to how to improve the performance of the robot. This method is then used to estimate capabilities of 4-DOF planar robots and the results discussed and compared with the conventional ellipsoid method. The proposed method is also successfully applied to the 7-DOF Mitsubishi PA10-7C robot.

scholarly journals Intelligent Design Optimization System for Additively Manufactured Flow Channels Based on Fluid–Structure Interaction

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 100
Author(s):  
Haonan Ji ◽  
Bin Zou ◽  
Yongsheng Ma ◽  
Carlos F. Lange ◽  
Jikai Liu ◽  
...  
Keyword(s):  
Design Optimization ◽  
Intelligent Design ◽  
Fluid Structure Interaction ◽  
Parametric Modeling ◽  
Flow Channel ◽  
Design Parameters ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Optimization System ◽  
Flow Channels

Based on expert system theory and fluid–structure interaction (FSI), this paper suggests an intelligent design optimization system to derive the optimal shape of both the fluid and solid domain of flow channels. A parametric modeling scheme of flow channels is developed by design for additive manufacturing (DfAM). By changing design parameters, a series of flow channel models can be obtained. According to the design characteristics, the system can intelligently allocate suitable computational models to compute the flow field of a specific model. The pressure-based normal stress is abstracted from the results and transmitted to the solid region by the fluid–structure (FS) interface to analyze the strength of the structure. The design space is obtained by investigating the simulation results with the metamodeling method, which is further applied for pursuing design objectives under constraints. Finally, the improved design is derived by gradient-based optimization. This system can improve the accuracy of the FSI simulation and the efficiency of the optimization process. The design optimization of a flow channel in a simplified hydraulic manifold is applied as the case study to validate the feasibility of the proposed system.

scholarly journals Simulation of the effectiveness of longitudinal rectangular fins on the efficiency of the double pipe heat exchanger

2019 ◽  
Vol 21 (4) ◽  
pp. 48-57
Author(s):  
N. F. Timerbaev ◽  
A. K. Ali ◽  
Omar Abdulhadi Mustafa Almohamed ◽  
A. R. Koryakin
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cold Water ◽  
Tube Diameter ◽  
Hot Water ◽  
Outer Tube ◽  
Design Parameters ◽  
Double Pipe ◽  
Central Pipe ◽  
Pipe Heat

In this article, a mathematical simulation of a double pipe heat exchanger is carried out, having the longitudinal rectangular fins with the dimension of (2*3*1000) mm, mounted on the outer surface of the inner tube of the heat exchanger. In this paper, the advantage of using of that type of fins and its effect on the effectiveness of the heat exchanger are studied with the help of the computer program. The carried out research allowsmaking the calculation to find the optimum design parameters of heat exchangers. The outer tube diameter is (34.1mm) while the inner tube diameter is (16.05mm). The tubes wall thickness is (1.5mm) and the model length was (1 m). The hot water is flowing through the inner tube in parallel with the cold water that passing the outer tube. The hot and cold water temperature at the inlet is (75°C & 30°C) respectively. The mass flow rate inside the central pipe is (0.1 kg/s) while the annular pipe carrying (0.3 kg/s). In the present work, the program ANSYS Workbench 15.0 was used to find out the results of heat transfer as well as the behavior of liquids inside the heat exchangers.

scholarly journals Design Parameters for a South African Iceberg Power and Water Project

1980 ◽  
Vol 1 ◽  
pp. 129-133 ◽  
Author(s):  
David J. DeMarle
Keyword(s):  
South Africa ◽  
Functional Analysis ◽  
South African ◽  
Heat Exchangers ◽  
Design Parameters ◽  
Ice Storage ◽  
Processing Plant ◽  
Water Project ◽  
Tidal Forces ◽  
Exchange Medium

Construction of an iceberg processing plant at Saldanha Bay, Republic, of South Africa, is proposed. A reservoir would be constructed at Rieibaai for ice storage. Tidal forces would be harnessed to pump the warm water of Saldanha Lagoon over heat exchangers (using ammonia or propane gas as a heat exchange medium), thus providing power for electrical generators and for melting ice. A functional analysis of operations is presented, together with proposed costs. It is suggested that the fresh water and electricity produced by this system will cost 6¢/m3 and 3¢/kwH, respectively.

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