scholarly journals An Independent Internal Cooling System for Promoting Heat Dissipation during Dry Cutting with Numerical and Experimental Verification

2017 ◽  
Vol 7 (4) ◽  
pp. 332 ◽  
Author(s):  
Bin Yao ◽  
Weifang Sun ◽  
Binqiang Chen ◽  
Xiaojin Yu ◽  
Yuchao He ◽  
...  
Keyword(s):  
Experimental Verification ◽  
Heat Dissipation ◽  
Cooling System ◽  
Internal Cooling ◽  
Dry Cutting

Toolholder Internally Cooled by a Phase Change Fluid in Turning of SAE XEV-F

2015 ◽  
Vol 798 ◽  
pp. 486-490 ◽  
Author(s):  
Rubens Roberto Ingraci Neto ◽  
Renan Luis Fragelli ◽  
Arthur Alves Fiocchi ◽  
Vicente Luis Scalon ◽  
Luiz Eduardo de Angelo Sanchez
Keyword(s):  
Phase Change ◽  
Heat Dissipation ◽  
Cutting Tool ◽  
Cooling System ◽  
Cutting Fluid ◽  
Tool Geometry ◽  
Internal Cooling ◽  
Dry Cutting ◽  
Internally Cooled ◽  
Coated Cemented Carbide

An internal cooling system inside a toolholder was developed aiming to eliminate the need of using cutting fluid without compromising machining efficiency. A phase change coolant (R141-b), with boiling point of 32oC around 101.3 kPa (atmosphere pressure), was used to improve heat dissipation in the cutting tool. Turning tests on SAE XEV-F were carried out using coated cemented carbide inserts. The results showed that the cutting tools lives were greater with internally cooled method than in dry cutting conditions. Nevertheless, the results were limited due to the low thermal conductivity of the steel (14.5 W.m/K) that is similar to Inconel®, its abrasivity, and absence of lubricant effect of the internal cooling method. On the other hand, the cutting tool geometry was not modified as was done in others solutions found in literature and the cooling system operated in a closed loop. It has a great possibility of use by the industry because is an environmentally friendly technology.

The Impact of Cooling System on Surface Quality in Milling

2015 ◽  
Vol 809-810 ◽  
pp. 135-140 ◽  
Author(s):  
Bogdan Alexandru Chirita ◽  
Nicolae Catalin Tampu
Keyword(s):  
Heat Dissipation ◽  
Cooling System ◽  
Minimum Quantity Lubrication ◽  
Production Costs ◽  
Cutting Fluids ◽  
Cryogenic Machining ◽  
Machining Processes ◽  
Dry Cutting ◽  
Environment Quality ◽  
The Impact

In the last years there has been an increased demand to lower the impact of industrial activities on environment quality. Cutting fluids, among other products, are an important pollutant but they have often been associated with the need for a higher productivity of machining processes. Cutting fluids are a mean of reducing temperature in the cutting area, friction and tool wear but they also represent 7% to 17% of the production costs. Other problems raised by cutting fluids are: microorganism infestation, which can cause pulmonary and dermatological diseases and poor lubrication or corrosion caused by some of the chemicals. Dry cutting is regarded as the cleanest cooling method, but it has a reduced heat dissipation efficiency and practically there is no lubrication. Other relatively new green solutions concern the use of minimum quantity lubrication (MQL) and cryogenic machining.

scholarly journals The Study of Cooling Mechanism Design for High-Power Communication Module with Experimental Verification

2021 ◽  
Vol 11 (11) ◽  
pp. 5188
Author(s):  
Tsu-Ping Yu ◽  
Yung-Lung Lee ◽  
Ya-We Li ◽  
Shih-Wei Mao
Keyword(s):  
High Power ◽  
Experimental Verification ◽  
Communication Systems ◽  
Heat Dissipation ◽  
Cooling System ◽  
Heat Pipes ◽  
Communications Systems ◽  
Cooling Mechanism ◽  
Simulation Results ◽  
Cold Plates

With the continued development of 5G mobile communications technology, the implementation of high-power communication systems has become a key indicator of developed nations. Communication modules are also trending toward wide bandwidth and high-capacity Multi-Input and Multi-Output systems. As the signal transmission speed and resolution continue with the increasing trend, the power used to operate these communications systems increase, causing extreme heat generation by transmit/receive modules (T/R module). In conditions where computation load increases in micro design systems, chips must operate in environments that are narrow, sealed, and have no convection, which can drastically increase the thermal load within a system. If no proper cooling system is utilized, the system fails or operates at impacted performance due to excessive temperatures. To solve the aforementioned problem, this study aimed to optimize the design of the cooling system in the T/R modules of communications systems by integrating heat pipes, cooling fans, cooling fins, and cooling chips within a limited space. We also proposed four types of cold plates based on the different directional clamp-in configuration methods of heat pipes within copper panels and utilized the finite element method to simulate and analyze the heat dissipation performance. The simulation results reveal that cold plates of types I and II can achieve a better heat dissipation performance. Finally, types I and II cold plates were selected for production and experimental verification. The results show that heat dissipation performances were similar to simulation results. The results also confirmed that type II cold plate has a better temperature uniformity and heat transfer efficiency. Thus, the cooling mechanism depicted in this study is viable in practical applications. The proposed mechanisms can also provide a reference for heat dissipation design patterns in different electronic module settings.

scholarly journals Numerical Study of a Cooling System Using Phase Change of a Refrigerant in a Thermosyphon

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3634
Author(s):  
Grzegorz Czerwiński ◽  
Jerzy Wołoszyn
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat Dissipation ◽  
Cooling System ◽  
Numerical Study ◽  
Relaxation Parameter ◽  
Phase Changes ◽  
Transfer Time ◽  
Two Phase ◽  
Time Relaxation

With the increasing trend toward the miniaturization of electronic devices, the issue of heat dissipation becomes essential. The use of phase changes in a two-phase closed thermosyphon (TPCT) enables a significant reduction in the heat generated even at high temperatures. In this paper, we propose a modification of the evaporation–condensation model implemented in ANSYS Fluent. The modification was to manipulate the value of the mass transfer time relaxation parameter for evaporation and condensation. The developed model in the form of a UDF script allowed the introduction of additional source equations, and the obtained solution is compared with the results available in the literature. The variable value of the mass transfer time relaxation parameter during condensation rc depending on the density of the liquid and vapour phase was taken into account in the calculations. However, compared to previous numerical studies, more accurate modelling of the phase change phenomenon of the medium in the thermosyphon was possible by adopting a mass transfer time relaxation parameter during evaporation re = 1. The assumption of ten-fold higher values resulted in overestimated temperature values in all sections of the thermosyphon. Hence, the coefficient re should be selected individually depending on the case under study. A too large value may cause difficulties in obtaining the convergence of solutions, which, in the case of numerical grids with many elements (especially three-dimensional), significantly increases the computation time.

Multidisciplinary Optimization of Airfoil Cooling Structure

2008 ◽  
Author(s):  
Grzegorz Nowak
Keyword(s):  
Cooling System ◽  
Computational Cost ◽  
System Optimization ◽  
Multidisciplinary Optimization ◽  
Internal Cooling ◽  
Technical Problems ◽  
Thermal Boundary Conditions ◽  
Optimization Task ◽  
External Conditions ◽  
Cooling Air

This paper discusses the problem of cooling system optimization within a gas turbine airfoil regarding to thermo-mechanical behavior of the component, as well as some economical aspects of turbine operation. The main goal of this paper is to show the possibilities of evolutionary approach application to the cooling system optimization. This method, despite its relatively high computational cost, seems to be a valuable tool to such technical problems. The analysis involves the optimization of location and size of internal cooling passages within an airfoil. Initially cooling is provided with circular passages and heat is transported by convection. During the optimization the number of channels can vary. The task is approached in 3D configuration. Each passage is fed with cooling air of constant parameters at the inlet. Also a constant pressure drop is assumed along the passage length. The thermal boundary conditions in passages vary with diameter and local vane temperature (passage wall temperature). The analysis is performed by means of the genetic algorithm for the optimization task and FEM for the heat transfer predictions within the component. In the present study the airfoil profile is taken as aerodynamically optimal and the objective of the search procedure is to find cooling structure variant that at given external conditions provides lower stresses, material temperature and indirectly coolant usage.

Combined Experimental and CFD Study of a HP Blade Multi-Pass Cooling System

2009 ◽  
Author(s):  
D. Jackson ◽  
P. Ireland ◽  
B. Cheong
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Cooling System ◽  
Detailed Comparison ◽  
Bulk Temperature ◽  
Internal Cooling ◽  
3 Dimensional ◽  
Turbine Cooling ◽  
Cooling Hole ◽  
The Difference

Progress in the computing power available for CFD predictions now means that full geometry, 3 dimensional predictions are now routinely used in internal cooling system design. This paper reports recent work at Rolls-Royce which has compared the flow and htc predictions in a modern HP turbine cooling system to experiments. The triple pass cooling system includes film cooling vents and inclined ribs. The high resolution heat transfer experiments show that different cooling performance features are predicted with different levels of fidelity by the CFD. The research also revealed the sensitivity of the prediction to accurate modelling of the film cooling hole discharge coefficients and a detailed comparison of the authors’ computer predictions to data available in the literature is reported. Mixed bulk temperature is frequently used in the determination of heat transfer coefficient from experimental data. The current CFD data is used to compare the mixed bulk temperature to the duct centreline temperature. The latter is measured experimentally and the effect of the difference between mixed bulk and centreline temperature is considered in detail.

LES and RANS Assessment of Rib Cooled Channel Related to SGT-800 Combustor Liner

2011 ◽  
Author(s):  
Daniel Lo¨rstad
Keyword(s):  
Pressure Drop ◽  
Cooling System ◽  
Large Temperature ◽  
Internal Cooling ◽  
Low Frequencies ◽  
System Pressure ◽  
Model Size ◽  
Periodic Boundaries ◽  
Combustor Liner ◽  
Simulation Time

The main parts of the annular combustor liner walls of the Siemens gas turbine SGT-800 are convectively cooled using rib turbulated cooling. Due to the serial system of cooling and combustion air there is a potential of further reduction of total combustor pressure drop by improvements of the cooling system. Apart from the rib cooling, also the cooling channel bypass entrance is related to a significant part of the total cooling system pressure drop. In this study, an investigation is performed for a rib cooled channel which is related to the considered combustor liner and where empirical correlations are available in order to evaluate the methodology used. The study includes an assessment of the Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models available within commercial Computational Fluid Dynamics (CFD) codes and includes also an investigation of model size when using periodic boundaries for LES simulations. It is well known that a small geometrical distance in the direction of the periodic boundaries may have a strong effect on the flow field but is often neglected in practice in order to speed up LES calculations. Here the effect is assessed in order to show what size is required for accurate results, both for time averaged and transient results. In addition too small domains may be affected by spurious low frequencies originating from the periodic boundaries requiring additional simulation time for time converged statistics, but also the averages may be significantly affected. In addition the simulation period for time converged statistics is evaluated in order to show that larger model size in the periodic direction does not necessarily require longer practical simulation time, due to the fact that larger volumes may be used for the combined time and space averaging. The aim is to obtain practical guidelines for LES calculations for internal cooling flows. Then the study is extended step by step to investigate the importance due to high Reynolds number, variable fluid properties and large temperature gradients in order to cover the ranges and specifics required for SGT-800 engine conditions.

Thermo-mechanical analysis of an internal cooling system with various configurations of a combustion liner after shell

2015 ◽  
Vol 51 (12) ◽  
pp. 1779-1790 ◽  
Author(s):  
Hokyu Moon ◽  
Kyung Min Kim ◽  
Jun Su Park ◽  
Beom Seok Kim ◽  
Hyung Hee Cho
Keyword(s):  
Cooling System ◽  
Mechanical Analysis ◽  
Internal Cooling

Heat dissipation system based on electromagnetic driven rotational flow of liquid metal coolant

2021 ◽  
pp. 1-14
Author(s):  
Lei Wang ◽  
Xudong Zhang ◽  
Dr. Jing Liu ◽  
Yixin Zhou
Keyword(s):  
Liquid Metal ◽  
Thermal Resistance ◽  
Heat Dissipation ◽  
High Efficiency ◽  
Cooling System ◽  
Electric Heater ◽  
Power Relationship ◽  
Rotational Flow ◽  
Large Power ◽  
Dissipation System

Abstract Liquid metal owns the highest thermal conductivity among all the currently available fluid materials. This property enables it to be a powerful coolant for the thermal management of large power device or high flux chip. In this paper, a high-efficiency heat dissipation system based on the electromagnetic driven rotational flow of liquid metal was demonstrated. The velocity distribution of the liquid metal was theoretically analyzed and numerically simulated. The results showed that the velocity was distributed unevenly along longitudinal section and the maximum velocity appears near the anode. On the temperature distribution profile of the heat dissipation system, the temperature on the electric heater side was much higher than the other regions and the role of the rotated liquid metal was to homogenize the temperature of the system. In addition, the thermal resistance model of the experimental device was established, and several relationships such as thermal resistance-power curve were experimentally measured. The heating power could be determined from the temperature-power relationship graph once the maximum control temperature was given. The heat dissipation method introduced in the paper provides a novel way for fabricating compact chip cooling system.

scholarly journals Cooling Performance Enhancement of Air-Cooled Condensers by Guiding Air Flow

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3503
Author(s):  
Huang ◽  
Chen ◽  
Yang ◽  
Du ◽  
Yang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Dissipation ◽  
Performance Enhancement ◽  
Cooling System ◽  
Wind Effects ◽  
Cooling Performance ◽  
Air Cooled Condensers ◽  
Arc Shape

Adverse wind effects on the thermo-flow performances of air-cooled condensers (ACCs) can be effectively restrained by wind-proof devices, such as air deflectors. Based on a 2 × 300 MW coal-fired power generation unit, two types (plane and arc) of air deflectors were installed beneath the peripheral fans to improve the ACC’s cooling performance. With and without air deflectors, the air velocity, temperature, and pressure fields near the ACCs were simulated and analyzed in various windy conditions. The total air mass flow rate and unit back pressure were calculated and compared. The results show that, with the guidance of deflectors, reverse flows are obviously suppressed in the upwind condenser cells under windy conditions, which is conducive to an increased mass flow rate and heat dissipation and, subsequently, introduces a favorable thermo-flow performance of the cooling system. When the wind speed increases, the leading flow effect of the air deflectors improves, and improvements in the ACC’s performance in the wind directions of 45° and –45° are more satisfactory. However, hot plume recirculation may impede performance when the wind direction is 0°. For all cases, air deflectors in an arc shape are recommended to restrain the disadvantageous wind effects.

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