The effect of cavity formation on the casting heat dissipation rate

2014 ◽  
pp. 351-358 ◽  
Keyword(s):  
Dissipation Rate ◽  
Heat Dissipation ◽  
Cavity Formation

Ocean Turbulent Mixing in Northern Bohai Strait, China

2013 ◽  
Author(s):  
Shu-xiu Liang ◽  
Zhao-chen Sun ◽  
Song-lin Han ◽  
Hong-qiang Yin ◽  
Bo Bai
Keyword(s):  
Turbulent Mixing ◽  
Yellow Sea ◽  
Dissipation Rate ◽  
Bohai Sea ◽  
Heat Dissipation ◽  
Strong Mixing ◽  
Observation Data ◽  
Diffusivity Coefficient ◽  
Division Line ◽  
Bohai Strait

The measurements of ocean microstructure through which ocean internal mixing mechanism is revealed are taken more often recently. Free-falling turbulence microstructure profiler TurboMAP-9 is used to take a field observation on the area of northern Bohai Strait. 13 stations distributed in Bohai Sea, Yellow Sea and the “division line” between them are measured. Turbulent mixing characteristics of northern Bohai Strait for different seasons are described by analyzing the observation data of ocean turbulence microstructure profile. The results show that the northern Bohai Strait is a strong mixing area during non-stratification period. Turbulent energy dissipation rate ε of winter is bigger than that of autumn and it is strongest near the bottom layers which is in the order of 10−5W/kg. Heat dissipation rate χθ is in the same order of 10−6–10−5°C2/s in autumn as ε and 2–3 orders smaller than ε in winter. Thermal diffusivity coefficient kθ is a little bigger than turbulent mixing rate kρ in autumn and 1–2 orders smaller than kρ in winter. Both the kρ and kθ along the “division line” of Bohai Sea and Yellow Sea are bigger than that of the Bohai Sea and Yellow Sea. Base on the measured data and the analysis, heat dissipation rate and thermal dispersion coefficient can change 2–3 orders in non-stratification seasons which should be paid much attention to, especially for ocean model parameterization and pollutant discharge modeling.

“A REVIEW OF HEAT DISSIPATION ANALYSIS BY VARYING GEOMETRICAL CONDITION OF CYLINDRICAL FIN”

IJOSTHE ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 7
Author(s):  
Swarnik Mehar ◽  
Pankaj Mishra
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heat Transfer Rate ◽  
Dissipation Rate ◽  
Transfer Rate ◽  
Heat Dissipation ◽  
Heat Engine ◽  
Total Heat Flow ◽  
Geometrical Condition ◽  
Interesting Task

If the heat in the heat engine is not removed properly, it causes the development of the detonation and eventually reduces the efficiency of the engine, so that the heat dissipation rate of the cylinder an important and interesting task is the option. The cylinder of the engine is one of the most important automotive components, variations of high temperature and thermal loads. To cool the cylinder, the ribs are provided on the surface of the cylinder, to increase the rate of heat transfer. By a thermal analysis of the motor cylinder and the ribs that surround it, it is useful to know the heat transfer rate and the temperature distribution inside the cylinder. We know that we can increase the heat dissipation rate by increasing the surface so it is very difficult to design such a complex motor. The main objective of this project is to analyze thermal properties such as thermal directed flow, total heat flow and temperature distribution. The cooling mechanism of the air cooled engine depends mainly on the design of the cylinder head and the block ribs. The cooling fins are used to increase the heat transfer rate of the specified surface. The life and efficiency of the engine can be improved by efficient cooling. The finite element method was used using the ANSYS software as a simulation tool for analysis.

Measurement of Heat Dissipation Rate Based on Optic-Thermo Oscillations in CaF2 Optical Micro-Cavity

2019 ◽  
Vol 39 (5) ◽  
pp. 0512004
Author(s):  
郭栋 Guo Dong ◽  
邹长铃 Zou Changling ◽  
任宏亮 Ren Hongliang ◽  
卢瑾 Lu Jin ◽  
覃亚丽 Qin Yali ◽  
...  
Keyword(s):  
Dissipation Rate ◽  
Heat Dissipation ◽  
Micro Cavity

Research of Relations between Thermodynamic Quantities of Building Materials in Connection with Heat Dissipation

2015 ◽  
Vol 244 ◽  
pp. 48-53
Author(s):  
Milena Kušnerová ◽  
Jan Valíček ◽  
Vojtěch Václavík ◽  
Marta Harničárová ◽  
Lukáš Gola
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Capacity ◽  
Dissipation Rate ◽  
Building Materials ◽  
Material Parameter ◽  
Heat Dissipation ◽  
Temporal Change ◽  
Point Of View ◽  
Physical Point

This paper proposes the evaluation of material coefficient of heat dissipation rate for building materials, in particular using partial entropies, a temporal change in entropy upon heating a sample of a studied material and a temporal change in entropy upon overheating a sample of a studied material, in order to evaluate the rate of heat dissipation on samples of building materials with thermal insulating properties. From a physical point of view, the material parameter “specific heat capacity” generally refers to the ability of material to “conceive heat” so it can be said that the illustrated material Ytong has a slightly higher specific heat capacity than that of polyurethane. From a physical point of view, the material parameter “thermal conductivity” generally refers to the ability of a given material to “conduct heat through the material in connection with stationary heat flux”, so it can be assumed as well as verified by measuring that Ytong also has a higher thermal conductivity than that of polyurethane. From a physical point of view, the newly proposed material parameter “heat dissipation rate” generally indicates the “rate of heat loss to the external environment in connection with non-stationary heat flux”, so it may also be assumed and verified by measuring that the heat dissipation rate of Ytong will be higher than that of polyurethane.

scholarly journals Heat dissipation rate constrains reproductive investment in a wild bird

2018 ◽  
Vol 33 (2) ◽  
pp. 250-259 ◽  
Author(s):  
Andreas Nord ◽  
Jan‐Åke Nilsson
Keyword(s):  
Dissipation Rate ◽  
Wild Bird ◽  
Heat Dissipation ◽  
Reproductive Investment

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.

Molecular Dynamic Computer Simulation of Thin Film's Heat Dissipation Rate

2006 ◽  
Vol 910 ◽  
Author(s):  
Ya-Yun Cheng ◽  
Horng-Ming Hsieh ◽  
Cheng-Chung Lee
Keyword(s):  
Thin Film ◽  
Thermal Diffusivity ◽  
Constant Temperature ◽  
Dissipation Rate ◽  
Md Simulation ◽  
Heat Dissipation ◽  
Film Growth ◽  
Average Temperature ◽  
Dynamic Computer Simulation ◽  
Molecular Dynamic Computer Simulation

AbstractHeat dissipation rate of the thin film is theoretically related to the thickness of the film. As the film grows on a substrate of constant temperature, the heat dissipation rate would be lower when the film becomes thicker. It is difficult to observe rate change during the film growth through experiment. With MD simulation, this rate can be "observed". A system including Platinum substrate at constant temperature 300K is setup. The constant temperature is obtained by Phantom method.The average temperature of aluminum thin film is 600K. For various thickness of the film: 3.656nm, 5.302nm, and 7.567nm. The average temperature decays exponentially. Through the simple equation T=(T0-Ts)exp(-kt/d2PCp)+Ts, the dissipation rate should follow the parameter R=k/d2PCp and the parameter α=k/£Cp is the thermal diffusivity. It is observed that the thermal diffusivity increases with film thickness increases.

scholarly journals Recent Advances in High-Flux, Two-Phase Thermal Management

2013 ◽  
Author(s):  
Issam Mudawar
Keyword(s):  
Dissipation Rate ◽  
Heat Dissipation ◽  
Future Research ◽  
Air Cooling ◽  
High Flux ◽  
Computer Algorithms ◽  
Two Phase ◽  
Computer Data ◽  
Predictive Tools ◽  
Two Phase Cooling

Recent developments in applications such as computer data centers, electric vehicle power electronics, avionics, radars and lasers have led to alarming increases in heat dissipation rate, which now far exceeds the capability of air cooling schemes and even the most aggressive single-phase liquid cooling schemes. This trend is responsible for a recent transition to two-phase cooling, which capitalizes upon the coolant’s latent heat rather than sensible heat alone to achieve several order-of-magnitude increases in heat transfer coefficient. Three two-phase cooling configurations have surfaced as top contenders for the most demanding applications: mini/micro-channel, jet and spray. This study will explore the implementation of these configurations into practical cooling packages, assess available predictive tools, and identify future research needs for each. It is shown that the design and performance assessment of high-flux, two-phase cooling systems are highly dependent on empirical or semi-empirical predictive tools and, to a far lesser extent, theoretical mechanistic models. A major challenge in using such tools is the lack of databases for coolants with drastically different thermophysical properties, and which cover broad ranges of such important parameters as flow passage size, mass velocity, quality and pressure. Recommendations are therefore made for future research to correct any critical knowledge gaps, including the need for robust computer algorithms. Also discussed is a new class of ‘hybrid’ cooling schemes that capitalize upon the merits of multiple cooling configurations. It is shown that these hybrid schemes not only surpass the basic cooling configurations in heat dissipation rate, but they also provide better surface temperature uniformity.

scholarly journals Impact of Heat Shield Thickness on Performance of Roll through Simulation

2019 ◽  
Vol 9 (2) ◽  
pp. 3105-3109
Keyword(s):  
Dissipation Rate ◽  
Heat Dissipation ◽  
Electrical Energy ◽  
Power Input ◽  
Surface Coatings ◽  
Heat Shield ◽  
Steady Temperature ◽  
Time Saving ◽  
Heat Shields ◽  
Stainless Steel 316

Rolls of the packing machine undertakes an imperative job in packing industries. So as to decrease the power input and reducingthe heat dissipation rate, there are numerous methodologies, for example, surface coatings, surface boronizing and with heat shields and so forth. This work is expected to reducethe power contribution to heaters by diminishing the heat dissemination rate utilizing heat shields with simulation of different thicknesses. There is a decrease of dissipation of heat by using Stainless steel 316 Ti (0.7 mm thickness) heat shields and there is a reduction of 13.9% in power input, 28% time saving and14% in heat dissipation rate is noticedwhencompared to standard rolls up to steady surface temperature where there is saving of 198W per hour in power after steady temperature. Hence an attempt is being made for improving results that are obtained from experiments by using simulation through ANSYS steady state thermal analysis. From the results it is inferred that as thickness of heat shield increases the input electrical energy for the heater goes on reducing and results shows that 0.7 mm thickness shield is 4.28% efficient than 0.8 mm heat shield. Further through simulation optimum thickness is was observed. But thickness is restricted to 1mm only because of machine specification complexity. Further the results of simulation for varying thickness are presented with contours of temperature distribution and heat flux.

Sign in / Sign up

Export Citation Format

Share Document