scholarly journals Environmental Response of 2D Thermal Cloak under Dynamic External Temperature Field

Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 461
Author(s):  
Yiyi Li ◽  
Haochun Zhang ◽  
Mingyuan Sun ◽  
Zhenhuan Zhang ◽  
Haiming Zhang
Keyword(s):  
Heat Dissipation ◽  
Dynamic Environment ◽  
Engineering Application ◽  
Amplitude Distribution ◽  
Entropy Production Rate ◽  
The Novel ◽  
Environmental Response ◽  
External Temperature ◽  
Response Entropy ◽  
Energy Processes

As a typical representative of transformation thermodynamics, which is the counterpart of transformation optics, the thermal cloak has been explored extensively while most current research focuses on the structural design instead of adaptability and practicability in a dynamic environment. The evaluation of energy processes involved in the thermal cloak under dynamic conditions are also lacking, which is essential to the engineering application of this functional structure. In this paper, based on the dynamic environment of a sinusoidal form with ambient amplitude, distribution density, phase, and temperature difference as variables, we evaluated the cloaking performance and environmental response of a 2D thermal cloak. Considering the heat dissipation and energy loss in the whole procedure, local entropy production rate and response entropy were introduced to analyze the different influences of each environmental parameter on the cloaking system. Moreover, we constructed a series of comprehensive schemes to obtain the fitting equation as well as an appropriate scope to apply the thermal cloak. The results are beneficial to the novel use of the concept of entropy and valuable for further improving the working efficiency and potential engineering applications of the thermal cloak.

scholarly journals Estimations on Properties of Redox Reactions to Electrical Energy and Storage Device of Thermoelectric Pipe (TEP) Using Polymeric Nanofluids

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1812
Author(s):  
Qin Gang ◽  
Rong-Tsu Wang ◽  
Jung-Chang Wang
Keyword(s):  
Thermal Conductivity ◽  
Power Density ◽  
Heat Dissipation ◽  
Electrical Energy ◽  
Steel Tube ◽  
Storage Device ◽  
Stainless Steel Tube ◽  
The Novel ◽  
Empirical Formulas ◽  
Dissipative Heat

A thermoelectric pipe (TEP) is constructed by tubular graphite electrodes, Teflon material, and stainless-steel tube containing polymeric nanofluids as electrolytes in this study. Heat dissipation and power generation (generating capacity) are both fulfilled with temperature difference via the thermal-electrochemistry and redox reaction effects of polymeric nanofluids. The notion of TEP is to recover the dissipative heat from the heat capacity generated by the relevant machine systems. The thermal conductivity and power density empirical formulas of the novel TEP were derived through the intelligent dimensional analysis with thermoelectric experiments and evaluated at temperatures between 25 and 100 °C and vacuum pressures between 400 and 760 torr. The results revealed that the polymeric nanofluids composed of titanium dioxide (TiO2) nanoparticles with 0.2 wt.% sodium hydroxide (NaOH) of the novel TEP have the best thermoelectric performance among these electrolytes, including TiO2 nanofluid, TiO2 nanofluid with 0.2 wt.% NaOH, deionized water, and seawater. Furthermore, the thermal conductivity and power density of the novel TEP are 203.1 W/(m·K) and 21.16 W/m3, respectively.

Heat and Mass Transfer to Air in a Cross Flow Heat Exchanger with Surface Deluge Cooling

2016 ◽  
Vol 24 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Andrea Diani ◽  
Luisa Rossetto ◽  
Roberto Dall’Olio ◽  
Daniele De Zen ◽  
Filippo Masetto
Keyword(s):  
Heat Exchanger ◽  
Heat Flow ◽  
Flow Rate ◽  
Data Center ◽  
Heat Dissipation ◽  
Cross Flow ◽  
Critical Conditions ◽  
Heat Flow Rate ◽  
External Temperature ◽  
Flow Heat

Cross flow heat exchangers, when applied to cool data center rooms, use external air (process air) to cool the air stream coming from the data center room (primary air). However, an air–air heat exchanger is not enough to cope with extreme high heat loads in critical conditions (high external temperature). Therefore, water can be sprayed in the process air to increase the heat dissipation capability (wet mode). Water evaporates, and the heat flow rate is transferred to the process air as sensible and latent heat. This paper proposes an analytical approach to predict the behavior of a cross flow heat exchanger in wet mode. The theoretical results are then compared to experimental tests carried out on a real machine in wet mode conditions. Comparisons are given in terms of calculated versus experimental heat flow rate and evaporated water mass flow rate, showing a good match between theoretical and experimental values.

Accurate LBM appraising of pin-fins heat dissipation performance and entropy generation in enclosures as application to power electronic cooling

2019 ◽  
Vol 30 (2) ◽  
pp. 742-768 ◽  
Author(s):  
Ridha Djebali ◽  
Abdallah Jaouabi ◽  
Taoufik Naffouti ◽  
Said Abboudi
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Entropy Generation ◽  
Heat Dissipation ◽  
Engineering Application ◽  
Industrial Applications ◽  
Cooling Performance ◽  
Content Type ◽  
Depth Analysis ◽  
Pin Fins

Purpose The purpose of this paper is to carry out an in-depth analysis of heat dissipation performance by natural convection phenomenon inside light-emitting diode (LED) lamps containing hot pin-fins because of its significant industrial applications. Design/methodology/approach The problem is assimilated to heat transfer inside air-filled rectangular cavity with various governing parameters appraised in ranges interesting engineering application and scientific research. The lattice Boltzmann method is used to predict the dynamic and thermal behaviors. Effects of monitoring parameters such as Rayleigh number Ra (103-106), fin length (0-0.25) and its position, pin-fins number (1-8), the tilting-angle (0-180°) and cavity aspect ratio Ar (0.25-4) are carried out. Findings The rising behaviors of the dynamic and thermal structures and heat transfer rate (Nu), the heatlines distribution and the irreversibility rate are appraised. It was found that the flow is constantly two contra-rotating symmetric cells. The heat transfer is almost doubled by increasing Ra. A lack of cooling performance was identified between Ar = 0.5 and 0.75. The inclination 45° is the most appropriate cooling case. At constant Ra, the maximum stream-function and the global entropy generation remain almost unchanged by increasing the pin number from 1 to 8 and the entropy generation is of thermal origin for low Ra, so that the fluid friction irreversibility becomes dominant for Ra larger than 105. Research limitations/implications Improvements may include three-dimensional complex geometries, accounting for thermal radiation, high unit power and turbulence modelling. Such factors effects will be conducted in the future. Practical implications The cooling performance/heat dissipation in LED lamps is a key manufacturing factors, which determines the lifetime of the electronic components. The best design and installation give the opportunity to increase further the product shelf-life. Originality/value Both cooling performance, irreversibility rate and enclosure configuration (aspect ratio and inclination) are taken into account. This cooling scheme will give a superior operating mode of the hot components in an era where energy harvesting, storage and consumption is met with considerable attention in the worldwide.

scholarly journals Improved Multiobjective Harmony Search Algorithm with Application to Placement and Sizing of Distributed Generation

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Wanxing Sheng ◽  
Ke-yan Liu ◽  
Yunhua Li ◽  
Yuan Liu ◽  
Xiaoli Meng
Keyword(s):  
Distributed Generation ◽  
Search Algorithm ◽  
Harmony Search ◽  
Engineering Application ◽  
Test System ◽  
Harmony Search Algorithm ◽  
Optimal Placement ◽  
The Novel ◽  
Nsga Ii ◽  
Intelligent Optimization Algorithm

To solve the comprehensive multiobjective optimization problem, this study proposes an improved metaheuristic searching algorithm with combination of harmony search and the fast nondominated sorting approach. This is a kind of the novel intelligent optimization algorithm for multiobjective harmony search (MOHS). The detailed description and the algorithm formulating are discussed. Taking the optimal placement and sizing issue of distributed generation (DG) in distributed power system as one example, the solving procedure of the proposed method is given. Simulation result on modified IEEE 33-bus test system and comparison with NSGA-II algorithm has proved that the proposed MOHS can get promising results for engineering application.

The Response of Rotating Machinery to External Random Vibration

1974 ◽  
Vol 96 (2) ◽  
pp. 477-489 ◽  
Author(s):  
J. M. Tessarzik ◽  
T. Chiang ◽  
R. H. Badgley
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
High Speed ◽  
Thrust Bearing ◽  
Dynamic Environment ◽  
Amplitude Distribution ◽  
Random Vibrations ◽  
Mass Model ◽  
Power Spectral ◽  
Rotor Axis

A high-speed turbogenerator employing gas-lubricated hydrodynamic journal and thrust bearings was subjected to external random vibrations for the purpose of assessing bearing performance in a dynamic environment. The pivoted-pad type journal bearings and the step-sector thrust bearing supported a turbine-driven rotor weighing approximately twenty-one pounds at a nominal operating speed of 36,000 rpm. The response amplitudes of both the rigid-supported and flexible-supported bearing pads, the gimballed thrust bearing, and the rotor relative to the machine casing were measured with capacitance type displacement probes. Random vibrations were applied by means of a large electrodynamic shaker at input levels ranging between 0.5 g (rms) and 1.5 g (rms). Vibrations were applied both along and perpendicular to the rotor axis. Response measurements were analyzed for amplitude distribution and power spectral density. Experimental results compare well with calculations of amplitude power spectral density made for the case where the vibrations were applied along the rotor axis. In this case, the rotor-bearing system was treated as a linear, three-mass model.

scholarly journals A Novel Geo-Inspired Earthquake Optimization Algorithm

2018 ◽  
Author(s):  
Efrain Mendez ◽  
Alexandro Ortiz ◽  
Pedro Ponce ◽  
Arturo Molina
Keyword(s):  
Dynamic Balance ◽  
Engineering Application ◽  
Bat Algorithm ◽  
Search Space ◽  
Optimization Method ◽  
The Novel ◽  
Exploration And Exploitation ◽  
Swarm Optimization ◽  
The Earth ◽  
Early Results

A novel metaheuristic optimization method is proposed based on an earthquake that is a geology phenomenon. The novel Earthquake Algorithm (EA) proposed, adapts the principle of propagation of geology waves P and S through the earth material composed by random density to ensure the dynamic balance between exploration and exploitation, in order to reach the best solution to optimization complex problems by searching for the optimum into the search space. The performance and validation of the EA are compared against the Bat Algorithm (BA) and the Particle Swarm Optimization (PSO) by using 10 diverse benchmark functions. In addition, an experimental engineering application is implemented to evaluate the proposed algorithm. Early results show a feasibility of the proposed method with a clearly constancy and stability. It is important highlight the fact that the main purpose of this paper is to present a new line of research, which is opened from the novel EA.

Wavelet Robust Filtering of Out-Trajectory Data

2013 ◽  
Vol 756-759 ◽  
pp. 344-348
Author(s):  
Ling Jing Meng ◽  
Hai Bo Liu
Keyword(s):  
Engineering Application ◽  
Original Data ◽  
Robust Filtering ◽  
The Novel ◽  
Trajectory Data ◽  
Process Data ◽  
Filtering Method ◽  
Noise Simulation ◽  
Simulation Calculation ◽  
Suppress Noise

Wavelet-based robust filtering of process data is proposed in order to reduce the influence of the outliers and noise in Out-trajectory data. We utilize the moving median filtering method to reject outliers in the original data and then combine wavelet de-noising method with empirical Wiener threshold to suppress noise. Simulation calculation and real engineering application has shown that the novel algorithm reliably preserves the information encapsulated in a process signal corrupted with noise and outliers. The methodology has been proved to be reliable and robust.

Optimization of Cooled Shields in Insulations

1984 ◽  
Vol 106 (4) ◽  
pp. 871-875 ◽  
Author(s):  
J. C. Chato ◽  
J. M. Khodadadi
Keyword(s):  
Dissipation Rate ◽  
Heat Dissipation ◽  
Absolute Temperature ◽  
Entropy Production Rate ◽  
Insulation Layer ◽  
Temperature Ratio ◽  
Insulation System ◽  
Simple Method ◽  
Practical Applications ◽  
Cooling Loads

A relatively simple method has been developed to optimize the location, temperature, and heat dissipation rate of each cooled shield inside an insulation layer. The method is based on the minimization of the entropy production rate, which is proportional to the heat leak across the insulation. The results show that the maximum number of shields to be used in most practical applications is three. However, cooled shields are useful only at low values of the overall, cold wall to hot wall absolute temperature ratio. The performance of the insulation system is relatively insensitive to deviations from the optimum values of temperature and location of the cooling shields. Design curves are presented for rapid estimates of the locations and temperatures of cooling shields in various types of insulations, and an equation is given for calculating the cooling loads for the shields.

A Novel Overhead Ground Wire with Winded Insulated Conductors for Ice-Melting

2012 ◽  
Vol 614-615 ◽  
pp. 1168-1171
Author(s):  
Jia Zheng Lu ◽  
Chun Zhao ◽  
Bo Li ◽  
Zhen Fang ◽  
Hong Xian Zhang
Keyword(s):  
Engineering Application ◽  
Galvanized Steel ◽  
Economic Power ◽  
The Novel ◽  
Ice Melting ◽  
Insulation Layer ◽  
Effective Power ◽  
Steel Wires ◽  
The Wire ◽  
Melting Experiments

Serious icing on overhead ground wires threatens the safe running of power system. Common overhead ground wires are difficult to realize ice-melting. A novel overhead ground wire structure for ice-melting is proposed. Some conductors coated with insulation layer are winded around the galvanized steel wires in a special way. Ice-melting experiments are performed on the novel overhead ground wire. Experimental results show that 30 W per meter of the wire is an economic power while 40 W per meter of the wire is an effective power for ice-melting. Engineering application of the novel overhead ground wire with insulated conductors is carried out. With the light moveable de-icer, onsite experiment is performed. Under the power of 40 W per meter of the wire, a temperature rise of 10 °C is achieved in 30 minutes. The result shows that the novel overhead ground wire can meet the demands of engineering application.

scholarly journals Comparative Analysis of Free Natural Convection Heat Transfer on Rectangular and Triangular Fins with and without Perforation

2018 ◽  
Vol 3 (5) ◽  
pp. 60
Author(s):  
Ogie Nosa Andrew ◽  
Joel Oluwayomi Oyejide
Keyword(s):  
Heat Transfer ◽  
Comparative Analysis ◽  
Natural Convection ◽  
Heat Dissipation ◽  
Nuclear Reactors ◽  
Research Work ◽  
Temperature Drop ◽  
Convection Heat Transfer ◽  
Engineering Application ◽  
Cylindrical Pipe

The importance of heat transfer by free natural convection can be found in many engineering application such as energy transfer in buildings, solar collectors, nuclear reactors and electronic packaging.  In this research work, we carried out the investigation and comparative analysis of heat transfer by natural convection on rectangular and triangular fins with and without circular perforation. A total of six (6) specimens were used.  Other materials that were used in this research work include four digital thermometers, one heating element, four thermocouple K-type and a power source.   The fins used in this research work were welded to a cylindrical pipe which served as the heat sink. The heat supplied was maintained at 2500C and the temperature drop through the fin was recorded for duration of 30minutes with intervals of 5minutes. It was observed that the temperature dropped more rapidly with the triangular fins than the rectangular fin. Also, the rate of heat dissipation increase with a corresponding increase in the number of perforation.

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