scholarly journals Research on heat transfer enhancement of variable cross sectional conformal cooling of injection mold based on fluent

2018 ◽  
Vol 10 (2) ◽  
pp. 7-20
Author(s):  
Zhihong YAN ◽  
Yingping QIAN ◽  
Wei HUANG ◽  
Xizhi ZHOU ◽  
Xuedan GONG
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Injection Mold ◽  
Variable Cross ◽  
Transfer Enhancement ◽  
Cross Sectional ◽  
Conformal Cooling

Heat Transfer Enhancement in Wavy Micro-Channels Through Multiharmonic Surfaces

2018 ◽  
Author(s):  
Justin Moon ◽  
J. Rafael Pacheco ◽  
Arturo Pacheco-Vega
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Enhancement ◽  
Numerical Solutions ◽  
Cold Water ◽  
Bottom Surface ◽  
Transfer Enhancement ◽  
Cross Sectional ◽  
Single Wave ◽  
Micro Channels

In this study, three-dimensional numerical simulations are performed to investigate heat transfer enhancement in multi-harmonic micro-scale wavy channels. The focus is on the influence of channel surface-topography, modeled as multi-harmonic sinusoidal waves of square cross-sectional area, on the enhancing mechanisms. A single-wave device of 0.5 mm × 0.5 mm × 20 mm length, is used as baseline, and new designs are built with harmonic-type surfaces. The channel is enclosed by a solid block, with the bottom surface within the sinusoidal region being exposed to a 47 W/cm2 heat flux. The numerical solutions of the governing equations for an incompressible laminar flow and conjugate heat transfer are obtained via finite elements. By using the ratio of the Nusselt number for wavy to straight channels, a parametric analysis — for a set of cold-water flowrates (Re = 50, 100, and 150) — shows that the addition of harmonic surfaces enhances the transfer of energy and that such ratio achieves the highest value with wave harmonic numbers of n = ±2. Use of a performance factor (PF), defined as the ratio of the Nusselt number to the pressure drop, shows that, surprisingly, the proposed wavy multi-harmonic channels are not as efficient as the single-wave geometries. This outcome is thought to be, primarily, due to the uncertainty associated with the definition of the Nusselt number used in this study, and establishes a direction to investigate the development of a more accurate definition.

Heat transfer enhancement in a tube using circular cross sectional rings separated from wall

2008 ◽  
Vol 85 (10) ◽  
pp. 988-1001 ◽  
Author(s):  
Veysel Ozceyhan ◽  
Sibel Gunes ◽  
Orhan Buyukalaca ◽  
Necdet Altuntop
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Transfer Enhancement ◽  
Cross Sectional

Thermal Characteristics in a Curved Rectangular Channel With Variable Cross-Sectional Area

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Avijit Bhunia ◽  
C. L. Chen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Sink ◽  
Rectangular Channel ◽  
Variable Cross ◽  
Entry And Exit ◽  
Transfer Enhancement ◽  
Curved Channel ◽  
Dean Number ◽  
Cross Sectional

Heat transfer due to steady, laminar air flow through a curved rectangular channel with a variable cross-sectional (c/s) area is investigated computationally. Such a flow passage is formed between two fin walls of a curved fin heat sink with a 90 deg bend, used in avionics cooling. Simulations are carried out for two different configurations: (a) a variable c/s area curved channel with inlet and outlet sections (entry and exit lengths) that are straight and constant c/s area—termed as the long channel and (b) a variable c/s area curved channel with no entry and exit lengths—termed as the short channel. Multiple secondary flow patterns develop in the curved section of the channel, which in conjunction with the bulk axial flow, lead to the formation of multiple vortices and separation bubbles. The complex 3-D flow structures, as well as the variable c/s area of the curved channel (diverging–converging) significantly alter the heat transfer characteristics, compared to the straight fin heat sink. Secondary flow strengthens with increasing axial (bulk) flow velocity, or Dean number in dimensionless form. This in turn improves heat transfer from all walls, particularly, the outer curvature (concave) wall and the heat sink base. At the highest Dean number condition, the local heat transfer coefficient at certain locations of the outer curvature wall is augmented by as much as 3.5 times, compared to the straight fin walls. The overall channel average heat transfer coefficient is improved by about 40% for the long channels, and about 10% for the short ones. However, the heat transfer enhancement is associated with a penalty of higher pressure drop, compared to the straight channels. To quantify the effectiveness of thermal performance enhancement a system Figure of Merit (FOM) is defined. A greater than unity FOM value is observed for all curved channel geometries and flow rate conditions. This indicates that heat transfer enhancement in the variable c/s area curved channel outweighs the penalty of additional pressure drop, compared to a straight channel of similar length.

Detailed Investigation on Rib Turbulated Flow Inside a Rectangular Duct

2012 ◽  
Author(s):  
Md. Shaukat Ali ◽  
A. Tariq ◽  
B. K. Gandhi
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Heat Transfer Enhancement ◽  
Field Investigation ◽  
Wall Turbulence ◽  
Internal Cooling ◽  
Rectangular Duct ◽  
Transfer Enhancement ◽  
Cross Sectional ◽  
Rib Turbulators

Rib turbulators are the most intensively studied passive technique, which promotes near wall turbulence in the internal cooling passages of heat transfer devices. However, there exists the tradeoff between the pressure penalty and heat transfer enhancement. For suggesting a correct rib configuration for particular application, it is necessary to understand the flow mechanism behind rib tabulators. For this purpose an experimental setup has been designed to investigate the detailed flow field and corresponding effect on heat transfer characteristics using Particle Image Velocimetry and Liquid Crystal Thermography respectively. In the literature the detailed flow field investigation as well as the thermal characterizations behind the rib other than rectangular/square cross sectional shape is found to be limited. The present work is an experimental investigation inside a rectangular duct for flow behind the trapezoidal type of rib with changing angle at different Reynolds numbers. The emphasis is towards assessing the potential impact of varying chamfering angle over the flow structures and its subsequent effect on heat transfer enhancement as well as in obviating the hot spots in the vicinity behind the chamfered rib turbulators.

Heat Exchanger Improvement via Curved Microfluidic Channels: Part 1 — Impact of Cross-Sectional Geometry and Channel Design on Heat Transfer Enhancement

2016 ◽  
Author(s):  
Samuel D. Marshall ◽  
Rerngchai Arayanarakool ◽  
Lakshmi Balasubramaniam ◽  
Bing Li ◽  
Poh Seng Lee ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Enhancement ◽  
Unit Cost ◽  
Superior Performance ◽  
Microfluidic Channels ◽  
Transfer Enhancement ◽  
Cross Sectional ◽  
Rate Condition ◽  
Curved Channels

The efficiency of conventional heat exchangers is restricted by many factors, such as effectiveness of convective heat transfer and the cost of their operation. The current research deals with these issues by developing a novel method for building a lower-cost yet more efficient heat sink. This method involves using a specially designed curved microchannel to utilise the enhanced fluid mixing characteristics of Dean vortices, and thus transferring heat efficiently. Numerical models have been employed to investigate the heat transfer enhancement of curved channels over straight equivalents, with the aim of optimising the heat exchanger design based on the parameters of maximising heat transfer whilst minimising pressure drop and unit cost. A range of cross-sectional geometries for the curved channels were compared, showing significantly higher Nusselt Numbers than equivalent straight channels throughout, and finding superior performance factors for square, circular and symmetrical trapezoidal profiles. Due the difficulty and expense in manufacturing circular microchannels, the relatively simple to fabricate square and symmetrical trapezoidal channels are put forward as the most advantageous designs. These results take into account both constant wall temperature and constant heat flux conditions. For a given set of channel dimensions, an optimal input flow rate condition is also determined.

Heat Transfer Enhancement in Spirally Corrugated Tube

2014 ◽  
Vol 7 (6) ◽  
pp. 970 ◽  
Author(s):  
Tholudin Mat Lazim ◽  
Zaid Sattar Kareem ◽  
M. N. Mohd Jaafar ◽  
Shahrir Abdullah ◽  
Ammar F. Abdulwahid
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Transfer Enhancement ◽  
Corrugated Tube
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