scholarly journals Designing and Optimising the Parameters of Micro Channels

2020 ◽  
Vol 8 (2S12) ◽  
pp. 71-76
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Convective Heat Transfer Coefficient ◽  
Volume Flow ◽  
Micro Channel ◽  
Micro Channels ◽  
Good Agreement

This paper documents the optimization of different parameters of micro channel heat sink which enhance the heat transfer. The objective is to find the major thermal resistance in micro channel and its effect on other parameters. Water is used as a coolant and the initial values of convective heat transfer coefficient and volume flow rate are 30000 W/m2K and 1 lpm respectively. Different graph are plotted between pressure drop,heat transfer co-efficient, pressure drop,thermal resistance and flow rate to finally achieve the optimized valus of channel width and height, hydraulic diameter, thermal resistance and pressure drop. The result achieved are in good agreement with the previous researches.

scholarly journals Experimental study on heat transfer of an engine radiator with TiO2/EG-water nano-coolant

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Mohd Muzammil Zubair ◽  
Md. Seraj ◽  
Mohd. Faizan ◽  
Mohd Anas ◽  
Syed Mohd. Yahya
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Ethylene Glycol ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Convective Heat Transfer Coefficient ◽  
Volume Flow ◽  
Nanoparticle Concentration

AbstractNanofluid as a transport medium displays a great potential in engineering applications involving heat transfer. In this paper, the execution of water and ethylene glycol-based TiO2 nanofluid as a radiator coolant is resolved experimentally. The convective heat transfer coefficient of TiO2/EG-Water nanocoolant has been estimated and contrasted with the information acquired experimentally. Nanocoolant were set up by taking 25% ethylene glycol and 75% water with low volume concentration of TiO2 nanoparticles. All the experiments were led for the distinctive volume flow rates in the range going from 30 to 180 L/h (LPH). The nanocoolant made to flow through curved radiator tubes in every experiment, so that it can exchange heat effectively. Result shows that increasing the volume flow rate of nanocoolant flowing in the radiator tubes, increases the heat transfer as well as the convective heat transfer coefficient of nanocooant. Maximum heat transfer enhancement of 29.5% was recorded for nanocoolant with 0.03% nanoparticle concentration as compared to water at 150 LPH. Apart from this nanoparticle concentration into the base fluid, no further enhancement in heat transfer has been observed at any volume flow rate.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Identification of Design Criteria for Converter Cooling System of Permanent Magnet Direct-Drive Wind Turbine Generator

2016 ◽  
Author(s):  
Gerardo L. Augusto ◽  
Alvin B. Culaba ◽  
Laurence A. Gan Lim
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Cooling System ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Design Criteria ◽  
Direct Drive ◽  
Turbine Generator ◽  
Wind Turbine Generator ◽  
System Volume

The design criteria of converter cooling system for a 2.5 MW permanent magnet direct-drive wind turbine generator were investigated. Two (2) distribution networks with pipe sizes of DN40 and DN50 were used as basis for fluid flow analysis. The theoretical system pressure drop and system volume flow rate of converter cooling system were calculated using the governing equations of mass conservation, pump performance curve and distribution network characteristics. The system of nonlinear equations was solved using multivariable Newton-Raphson method with the solution vector determined using LU decomposition method. Numerical results suggest that the DN50 pipe provides a pressure drop limit of less than 300 Pa/m in the converter cooling system better than the pressure drop obtained from a DN40 pipe. The system volume flow rate of DN50 pipe was found to be above the operating limit of heat exchanger requirement of 135.30 L/min which needs to dissipate heat with a minimum of 50 kW.

Thermal Performance Intensification of Car Radiator using SiO2/Water and ZnO/Water Nanofluids

2021 ◽  
pp. 1-25
Author(s):  
Hussein Maghrabie ◽  
Hamouda Mousa
Keyword(s):  
Heat Transfer ◽  
Working Conditions ◽  
Flow Rate ◽  
Thermal Performance ◽  
Cooling System ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Coolant Temperature ◽  
Inlet Temperature ◽  
The Impact

Abstract Recent progress in nanotechnology has lead to a revolution in the automotive cooling system. In the present work, enhancement of car radiator thermal performance was investigated using different nanofluids named SiO2/water, ZnO/water nanofluids as cooling mediums. The present study mainly aims to investigate the impact of (5 wt.%) from SiO2 and ZnO nanoparticles (NPs) dispersed in water based on car radiator heat transfer with spherical and hexagonal morphology, respectively. The experiments were performed in two working conditions of the nanofluids i.e coolant temperature and volume flow rate, moreover the present results were compared with the previous studies. The experimental working conditions were set at coolant inlet temperature (tc,i) ranged from 45 oC to 80 oC and the coolant volume flow rate (V) ranged from 3.5 lit/min to 6.5 lit/min. The experimental results show that the hexagonal ZnO/water nanofluid was superior towards enhancement of car radiator thermal performance comparing to that of SiO2 NPs. Additionally, at 6.5 lit/min and 45 °C, the enhancements of car radiator effectiveness due to using SiO2 and ZnO based water nanofluids and compared with that for the based water were 13.9% and 16%, respectively. The present study used the multiple regression analysis (MRA) and hence empirical correlations are suggested to estimate the overall heat transfer coefficient (U) for all coolants as functions of volume flow rate (V) and the coolant inlet temperature (tc,i) with a maximum STDEV of ± 1.85%.

Effects of heat transfer and the endoscope on Jeffrey fluid peristaltic flow in tubes

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
A.M. Abd-Alla ◽  
S.M. Abo-Dahab ◽  
M.A. Abdelhafez ◽  
Esraa N. Thabet
Keyword(s):  
Heat Transfer ◽  
Pressure Gradient ◽  
Flow Rate ◽  
Analytical Solutions ◽  
Volume Flow Rate ◽  
Peristaltic Flow ◽  
Volume Flow ◽  
Jeffrey Fluid ◽  
Temperature Profiles ◽  
Content Type

PurposeThis article aims to describe the effect of an endoscope and heat transfer on the peristaltic flow of a Jeffrey fluid through the gap between concentric uniform tubes.Design/methodology/approachThe mathematical model of the present problem is carried out under long wavelength and low Reynolds number approximations. Analytical solutions for the velocity, temperature profiles, pressure gradient and volume flow rate are obtained.FindingsThe results indicate that the effect of the wave amplitude, radius ratio, Grashof number, the ratio of relaxation to retardation times and the radius are very pronounced in the phenomena. Also, a comparison of obtaining an analytical solution against previous literatures shows satisfactory agreement.Originality/valueAnalytical solutions for the velocity, temperature profiles, pressure gradient and volume flow rate are obtained. Numerical integration is performed to analyze the pressure rise and frictional forces on the inner and outer tubes.

Transport Phenomena in Two-Phase Micro-Channel Heat Sinks

2002 ◽  
Author(s):  
Weilin Qu ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Hydrodynamic Instability ◽  
Transport Phenomena ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Micro Channel ◽  
Two Phase ◽  
Convective Boiling ◽  
Micro Channels

The design and reliable operation of a two-phase micro-channel heat sink require a fundamental understanding of the complex transport phenomena associated with convective boiling in small, parallel coolant passages. This understanding is the primary goal of this paper. This goal is realized by exploring the following aspects of boiling in micro-channels: hydrodynamic instability, two-phase flow patterns, pressure drop, and convective boiling heat transfer. High-speed photographic methods were used to determine dominant flow patterns and explore as well as characterize hydrodynamic instabilities. Two types of dynamic instability were identified, a severe pressure drop oscillation and a mild parallel channel instability, and a simple method is recommended to completely suppress the former. Predictions of three popular two-phase pressure drop models and correlations were compared to micro-channel water data, and only a separated flow (Lockhart-Martinelli) correlation based on the assumption of laminar flow in both phases gave acceptable predictions. Several popular heat transfer correlations were also examined and deemed unsuitable for micro-channel heat sinks because all these correlations are based on turbulent flow assumptions, and do not capture the unique features of micro-channel flow such as abrupt transition to slug flow, hydrodynamic instability, and high droplet entrainment in the annular regime. These findings point to the need for further study of boiling behavior and new predictive tools specifically tailored to micro-channel heat sinks.

Generalized Two-Phase Pressure Drop and Heat Transfer Correlations in Evaporative Micro/Mini-Channels

2007 ◽  
Author(s):  
Hee Joon Lee ◽  
Dongyao Liu ◽  
Shi-Chune Yao ◽  
Y. Alyousef
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Bond Number ◽  
Micro Channel ◽  
Two Phase ◽  
Working Fluids ◽  
Operational Conditions ◽  
Micro Channels ◽  
Wide Range ◽  
Existing Data

Existing data base and correlations in literature on the micro-channel pressure drop and heat transfer are reviewed. None of the existing correlations can cover the wide range of working fluids, operational conditions and different microchannel dimensions. The importance of the Bond number, which relates the nominal bubble dimension or capillary parameter with the channel size, is revealed. Using the Bond number, improved correlations of pressure drop and heat transfer are established. The new correlations predict the existing data well over wide ranges of working fluids, operational conditions and dimensions of micro-channels. Furthermore, Bond number could be used as a criterion to classify a flow path as a micro-channel or conventional macro-channel.

Multi-Objective Optimization Design of Multi-Layer Rectangle Micro-Channel Heat Sink for Single-Phase Flow and Heat Transfer

2013 ◽  
Vol 709 ◽  
pp. 286-291 ◽  
Author(s):  
Li Feng Wang ◽  
Bao Dong Shao ◽  
He Ming Cheng
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Optimization Design ◽  
High Heat ◽  
Micro Channel ◽  
Compact Structure ◽  
Total Thermal Resistance ◽  
High Heat Transfer

The purpose of this paper is to optimize the structural sizes of multi-layer rectangle micro-channel heat sink, which has been widely used to cool electronic chip for its high heat transfer coefficient and compact structure. Taking the thermal resistance and the pressure drop as goal functions, a binary-objective optimization model was proposed for the multi-layer rectangle micro-channel heat sink based on Sequential Quadratic Programming (SQP) method. The number of optimized micro-channel in width n1 and that in height n2 are 21 and 7, the width of optimized micro-channel Wc and fin Wf are 340 and 130μm, the height of optimized micro-channel Hc is 415μm, and the corresponding total thermal resistance of the whole micro-channel heat sink is 1.3354 °C/W. The corresponding pressure drop is about 1.3377 Pa. When the velocity of liquid is larger than 0.3 m/s, the effect of change of velocity of liquid on the thermal resistance and pressure drop can be neglected.

scholarly journals Design Optimization and Validation of Single-Phase Rectangular Micro Channels With Axial Non-Uniform Width

2010 ◽  
Author(s):  
Tijs Van Oevelen ◽  
Martine Baelmans
Keyword(s):  
Heat Transfer ◽  
Simple Model ◽  
Numerical Model ◽  
Thermal Resistance ◽  
Single Phase ◽  
Analytical Models ◽  
Micro Channel ◽  
Hydraulic Behaviour ◽  
Developing Flow ◽  
Micro Channels

A simple model for the simulation of the hydraulic behaviour and heat transfer of a single micro channel is formulated, assessed and optimized. The model is based on a thermally developing flow regime. The results of the optimization show that a reduction of 7.8% in thermal resistance can be achieved using non-uniform channels instead of uniform channels. Furthermore, the assumptions of the simple model are validated by comparing the results with a more accurate, numerical model. It is shown that the simple model is sufficiently accurate to simulate the hydraulic and thermal behaviour of micro channels as such. However, the effective improvement of channel width optimization cannot accurately be determined by the analytical models.

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