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Indentations And Starting Points In Traveling Sales Tour Problems: Implications For Theory, James N. Macgregor
Indentations And Starting Points In Traveling Sales Tour Problems: Implications For Theory, James N. Macgregor
The Journal of Problem Solving
A complete, non-trivial, traveling sales tour problem contains at least one “indentation”, where nodes in the interior of the point set are connected between two adjacent nodes on the boundary. Early research reported that human tours exhibited fewer such indentations than expected. A subsequent explanation proposed that this was because the observed human tours were close to the optimal, and the optimal tours happened to have few indentations. The present article reports two experiments. The first was designed to test the “few indentations” hypothesis under more stringent conditions than previously, by including point sets with two (near) optimal solutions that …
The Influence Of Optimization Algorithm On Suction Muffler Design, Talita Wajczyk, Rodrigo Link
The Influence Of Optimization Algorithm On Suction Muffler Design, Talita Wajczyk, Rodrigo Link
International Compressor Engineering Conference
The standards for refrigerators energy consumption are increasing faster in the recent past years, so, the situation demands compressor with a higher efficiency level. To develop such compressors the performance of the most important compressor´s components must be increased. However, the pressure for fast time to market are turning more difficulty the optimization process of a big amount of components, specially using experimental validations. One of the most important components in the compressor is the suction muffler. The main suction muffler functions are the thermal insulation of gas from the evaporator and noise attenuation. To increase the performance of muffler …
Rigid-Frame Porous Material Acoustic Attenuation On Compressor Discharge, Paulo Henrique Mareze, Arcanjo Lenzi, Claudio Pellegrini
Rigid-Frame Porous Material Acoustic Attenuation On Compressor Discharge, Paulo Henrique Mareze, Arcanjo Lenzi, Claudio Pellegrini
International Compressor Engineering Conference
Standards have limited the allowable noise levels in different situations, requiring the study of solutions at the source, in the path or the receiver. Muffler is the major factor influencing the noise of rotary compressor. Control and analyze the acoustic characteristics of muffler is essential. Porous materials have been studied and widely applied to reduce aircraft and vehicular noise or industrial problems in general. Generally, designers use absorbing materials available on the market, however they are not always adequate to the problem when there is the presence of another gas, for example in hermetic compressors. Thus it is proposed to …
Investigation Of The Centrifugal Force Effect To A Revolving Vane (Rv) Machine, Alison Subiantoro, Kim Tiow Ooi
Investigation Of The Centrifugal Force Effect To A Revolving Vane (Rv) Machine, Alison Subiantoro, Kim Tiow Ooi
International Compressor Engineering Conference
The Revolving Vane (RV) machine is unique because the cylinder rotates together with the rotor at their respective axis. This causes various unique behaviors that are not previously observed in the conventional rotary machines. In this paper, the effects of the centrifugal force to the behavior of the machine are investigated. It is found that the centrifugal force affects the average output torque through the shaft bearing load and friction loss. Interestingly, if the center of mass is set properly, the centrifugal force can help to offset the pressure force acting at the shaft. This helps to reduce the bearing …
Clustering, Randomness, And Regularity: Spatial Distributions And Human Performance On The Traveling Salesperson Problem And Minimum Spanning Tree Problem, Matthew Dry, Kym Preiss, Johan Wagemans
Clustering, Randomness, And Regularity: Spatial Distributions And Human Performance On The Traveling Salesperson Problem And Minimum Spanning Tree Problem, Matthew Dry, Kym Preiss, Johan Wagemans
The Journal of Problem Solving
We investigated human performance on the Euclidean Traveling Salesperson Problem (TSP) and Euclidean Minimum Spanning Tree Problem (MST-P) in regards to a factor that has previously received little attention within the literature: the spatial distributions of TSP and MST-P stimuli. First, we describe a method for quantifying the relative degree of clustering, randomness or regularity within point distributions. We then review evidence suggesting this factor might influence human performance on the two problem types. Following this we report an experiment in which the participants were asked to solve TSP and MST-P test stimuli that had been generated to be either …
Topological Design Of Channels For Squeeze Flow Optimization Of Thermal Interface Materials, Nikhil Bajaj, Ganesh Subbarayan, S V. Garimella
Topological Design Of Channels For Squeeze Flow Optimization Of Thermal Interface Materials, Nikhil Bajaj, Ganesh Subbarayan, S V. Garimella
CTRC Research Publications
No abstract provided.
Performance Characteristics And Optimization Of A Dual-Loop Cycle For A Domestic Refrigerator-Freezer, Won Jae Yoon, Hyun Joon Chung, Yongchan Kim
Performance Characteristics And Optimization Of A Dual-Loop Cycle For A Domestic Refrigerator-Freezer, Won Jae Yoon, Hyun Joon Chung, Yongchan Kim
International Refrigeration and Air Conditioning Conference
A dual-loop cycle for a domestic refrigerator-freezer (RF) has a large energy saving potential because of lower compression ratio due to higher evaporating temperature in the fresh food compartment (R)-operation, and the individual optimization flexibility for each loop, compared to a conventional refrigeration cycle. In this study, the optimization of the dual-loop cycle was carried out. The optimization process included both the theoretical analysis and experimental investigation. The theoretical analysis was conducted to optimize the specifications of cycle components for each loop of the dual-loop cycle. Based on the experimental results, the energy consumptions of the optimized dual-loop cycle was …
Thermodynamic Design Of Condensers And Evaporators: Thermodynamic Design Of Condensers And Evaporators: Formulation And Applications, Christian Hermes
Thermodynamic Design Of Condensers And Evaporators: Thermodynamic Design Of Condensers And Evaporators: Formulation And Applications, Christian Hermes
International Refrigeration and Air Conditioning Conference
This paper assesses the approach introduced in a prior publication for the optimum design of condensers and evaporators aimed at balancing the heat transfer and pressure drop tradeoffs. Case studies carried out with different heat exchanger configurations for light commercial and household refrigeration applications are reported. The analysis indicated that a heat exchanger design with a high aspect ratio is preferable to a low aspect ratio one as the former produces a dramatically lower amount of entropy. In addition, since the refrigeration system COP obeys the Te/(Tc–Te) scale, it was found that the heat exchanger design that presents the best …
Unsteady State Simulation Of Vapor Compression Heat Pump Systems With Modular Analysis (This Paper Will Not Be Presented.), Kuniyasu Matsumoto, Kiyotaka Ueno, Kiyoshi Saito, Keisuke Ohno
Unsteady State Simulation Of Vapor Compression Heat Pump Systems With Modular Analysis (This Paper Will Not Be Presented.), Kuniyasu Matsumoto, Kiyotaka Ueno, Kiyoshi Saito, Keisuke Ohno
International Refrigeration and Air Conditioning Conference
Due to worldwide demand for energy saving, many new technologies have been developed in the air conditioning field. Packaged indoor unit and outdoor unit vapor compression refrigerating heat pump system using the change of refrigerant’s condition between liquid and gas is a recently developed air conditioning system. The cooling cycle is composed of an evaporator, a condenser, a compressor, an accumulator, pipe and an expansion valve. These components are controlled by the equation of continuity, the equation of energy and the equation of motion and so on. We can solve these equations by giving numerical boundary conditions. In this study, …
Fast Refrigerant Property Calculations Using Interpolation-Based Methods, Christopher Laughman, Yiming Zhao, Daniel Nikovski
Fast Refrigerant Property Calculations Using Interpolation-Based Methods, Christopher Laughman, Yiming Zhao, Daniel Nikovski
International Refrigeration and Air Conditioning Conference
An interpolation-based method for computing refrigerant properties which can be used in simulations of vaporcompression air-conditioning equipment is presented. This method uses bicubic functions to interpolate between samples of the Helmholtz energy surface as a function of temperature and density. Three beneficial characteristics of this method are discussed: speed, accuracy, and consistency, as well as a means for using a variety of different independent variables are also presented. The implementation of this method is discussed, and experimental results for property calculations for refrigerant R-134a are presented which compare favorably to standard Newton-based equation of state methods.
Simulation-Based Design And Optimization Of Frost-Free Refrigerators: A Thermoeconomic Approach, Rodrigo Mitishita, Eduardo Barreira, Cezar Negrao, Christian Hermes
Simulation-Based Design And Optimization Of Frost-Free Refrigerators: A Thermoeconomic Approach, Rodrigo Mitishita, Eduardo Barreira, Cezar Negrao, Christian Hermes
International Refrigeration and Air Conditioning Conference
A steady-state simulation model was devised and its predictions for energy consumption were compared with experimental data obtained elsewhere, with differences not exceeding a 9% error band. The model was used to find out the evaporator air flow rate, the number of evaporator and condenser fins, the compressor size and efficiency, and the insulation thicknesses of both compartments which yield the minimum energy consumption when the total cost is constrained. The optimization led to a refrigeration system with energy consumption 18% lower than that observed for the baseline system without any cost penalty. The system performance for four different compressors …
Optimization Of Peripheral Finned-Tube Evaporators Using Entropy Generation Minimization, Bruno Pussoli, Jader Barbosa Jr., Luciana Da Silva, Massoud Kaviany
Optimization Of Peripheral Finned-Tube Evaporators Using Entropy Generation Minimization, Bruno Pussoli, Jader Barbosa Jr., Luciana Da Silva, Massoud Kaviany
International Refrigeration and Air Conditioning Conference
The peripheral finned-tube (PFT) is a new geometry for enhanced air-side heat transfer under moisture condensate blockage (evaporators). It consists of individual hexagonal (peripheral) fin arrangements with radial fins whose bases are attached to the tubes and tips are interconnected with the peripheral fins. In this paper, experimentally validated semi-empirical models for the air-side heat transfer and pressure drop are combined with the entropy generation minimization theory to determine the optimal characteristics of PFT heat exchangers. The analysis is based on three independent parameters, i.e., porosity, equivalent particle diameter and particle-based Reynolds number. The total heat transfer rate is a …
Effectiveness Of Entransy Dissipation Metric And Entropy Generation Units In The Design Of Fin-Tube Heat Exchangers, Yunho Hwang, Suxin Qian, Long Huang, Vikrant Aute, Reinhard Radermacher
Effectiveness Of Entransy Dissipation Metric And Entropy Generation Units In The Design Of Fin-Tube Heat Exchangers, Yunho Hwang, Suxin Qian, Long Huang, Vikrant Aute, Reinhard Radermacher
International Refrigeration and Air Conditioning Conference
Several techniques and metrics based on the Second Law of Thermodynamics have been used in the past for the analysis of heat exchangers. The terms used for these techniques include irreversibility analysis, entropy generation minimization, exergy analysis and thermodynamic efficiency. Entransy is a recently developed concept reflecting the heat transfer potential, rather than the ability to convert heat to work. Entransy is transferred along with heat flux in the heat transfer process, and subsequently dissipates. The entransy dissipation extremum principle is applicable to heat transfer enhancement. Entropy on the other hand is a thermodynamic state-based quantity. This study focuses on …
Use Of Phase Change Material In A Building Wall Assembly: A Case Study Of Technical Potential In Two Climates, Kenneth W. Childs, Therese K. Stovall
Use Of Phase Change Material In A Building Wall Assembly: A Case Study Of Technical Potential In Two Climates, Kenneth W. Childs, Therese K. Stovall
International High Performance Buildings Conference
Phase change material (PCM), placed in an exterior wall, alters the temperature profile within the wall and thus influences the heat transport through the wall. This may reduce the net energy transport through the wall via interactions with diurnal temperature swings in the external environment or reduce the electricity needed to meet the net load through the wall by shifting the time of the peak load to a time when the cooling system operates more efficiently. This study covers a broad range of parameters that can influence the effectiveness of such a merged thermal storage-thermal insulation system. These parameters included …