scholarly journals Numerical Investigation of Air-Side Heat Transfer and Pressure Drop Characteristics of a New Triangular Finned Microchannel Evaporator with Water Drainage Slits

Fluids ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 205 ◽  
Author(s):  
Brice Rogie ◽  
Wiebke Brix Markussen ◽  
Jens Honore Walther ◽  
Martin Ryhl Kærn
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Water Drainage ◽  
Cfd Simulations ◽  
F Factor ◽  
Computational Fluid Dynamics Cfd ◽  
Triangular Fin ◽  
Industrial Refrigeration ◽  
Tube Pitch ◽  
Thermal Entrance

The present study investigated a new microchannel profile design encompassing condensate drainage slits for improved moisture removal with use of triangular shaped plain fins. Heat transfer and pressure drop correlations were developed using computational fluid dynamics (CFD) and defined in terms of Colburn j-factor and Fanning f-factor. The microchannels were square 2.00 × 2.00 mm and placed with 4.50 mm longitudinal tube pitch. The transverse tube pitch and the triangular fin pitch were varied from 9.00 to 21.00 mm and 2.50 to 10.00 mm, respectively. Frontal velocity ranged from 1.47 to 4.40 m·s−1. The chosen evaporator geometry corresponds to evaporators for industrial refrigeration systems with long frosting periods. Furthermore, the CFD simulations covered the complete thermal entrance and developed regions, and made it possible to extract virtually infinite longitudinal heat transfer and pressure drop characteristics. The developed Colburn j-factor and Fanning f-factor correlations are able to predict the numerical results with 3.41% and 3.95% deviation, respectively.

Air-Side Performance Characterization of Air-to-Refrigerant Heat Exchangers Using Parallel Parameterized CFD

2013 ◽  
Author(s):  
Khaled Saleh ◽  
Weizhe Han ◽  
Vikrant Aute ◽  
Reinhard Radermacher
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Cfd Simulations ◽  
Cfd Models ◽  
F Factor ◽  
Wide Range ◽  
Different Types ◽  
Computational Fluid Dynamics Cfd ◽  
Friction Performance

The goal of the study presented in this paper is to use Computational Fluid Dynamics (CFD) to characterize the heat transfer and friction performance of fins used in air-to-refrigerant heat exchangers. Five different types of fins used in air-cooled heat exchangers (HXs) are studied using Parallel Parameterized CFD (PPCFD) approach described in this paper. The fin types considered in this paper are; Plain, Wavy, Slit, Super Slit, and Louver. 3-D CFD models are built and tested for these fin types. Based on the CFD results, air side heat transfer coefficient (HTC), Colburn j factor, Fanning f factor, and pressure drop are calculated. The results from CFD simulations are compared against experimental data from the literature for the different fin types and a good agreement is found between the two. In addition, the results from CFD simulations are used to evaluate the thermal and hydraulic performance for a wide range of heat exchanger parameters such as tube diameters, fin pitch, number of rows, and frontal air velocity. The results show the advantages of using PPCFD to efficiently develop correlations for different types of fins used in air-cooled HX, with significant reduction in engineering time. The PPCFD approach can be extended to efficiently optimize novel heat transfer surfaces.

Flow Simulations in Packed Beds by a Coupled DEM and CFD Approach

2012 ◽  
Author(s):  
Xiang Zhao ◽  
Trent Montgomery ◽  
Ping Lu ◽  
Sijun Zhang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Structural Parameters ◽  
Packed Beds ◽  
Local Behavior ◽  
Cfd Simulations ◽  
Flow Simulations ◽  
Packing Structure ◽  
Computational Fluid Dynamics Cfd

This paper presents flow simulations in packed beds by a coupled discrete element method (DEM) and computational fluid dynamics (CFD) approach. The realistic packing structure in packed beds is generated by DEM. Then the packing structure is imported into the CFD preprocessor to generate a mesh for flow simulations in packed beds. The subsequent CFD simulations are carried out. The predicted results reveal that not only the local behavior but also macroscopic quantities like the pressure drop depend remarkably on the local packing structural parameters, which is unable to be taken into account when using correlations with averaged values.

An Experimental and Numerical Study of Pressure Drop and Hydraulic Behavior in Scaled-Down Fuel Bundle

2013 ◽  
Vol 275-277 ◽  
pp. 409-412
Author(s):  
Duen Sheng Lee ◽  
Kai Ting Hsieh ◽  
Po Chih Tsao ◽  
Tzu Chen Hung ◽  
Yi Tung Chen ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Numerical Study ◽  
Spent Fuel ◽  
Rod Bundles ◽  
Cfd Simulations ◽  
Fuel Bundle ◽  
Acceptable Deviation ◽  
Spent Fuel Pool ◽  
Computational Fluid Dynamics Cfd ◽  
The Relationship

This study presents a scaled-down single fuel assembly experiment to simulate the fuel in the spent fuel pool (SFP). From experiment results, this study obtained the relationship among pressure drop and velocity, the viscous resistance and inertial resistance factor. In computational fluid dynamics (CFD) simulations, the large number of fuel rod bundles is approximated with porous medium technique that imposes similar flow resistance to the motion of the fluid. Difference of the pressure drop between numerical and experimental results is within acceptable deviation.

Heat Transfer and Pressure Drop Through Rectangular Helical Ducts

2009 ◽  
Author(s):  
Ahmad K. Sleiti ◽  
Edward J. Naimaster
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Centrifugal Force ◽  
Rectangular Cross Section ◽  
Fluid Flows ◽  
Lower Surface ◽  
Electric Machines ◽  
Turbulent Model ◽  
Small Pitch ◽  
Computational Fluid Dynamics Cfd

Optimization of heat transfer and flow in a helical duct of rectangular cross-section used to cool the stators of electric machines is studied using computational fluid dynamics (CFD) techniques. Realizable turbulent model is used with water and oil as working fluids for two different designs (Spiral (S) and Reverse Annulus (RA) designs) and total of five configurations of the helical duct at small pitch size of 0.00254 m. The Reverse Annulus (RA) is a new design proposed by the author. Due to the curvature of the ducts, as fluid flows through curved tubes, a centrifugal force is generated. A secondary flow induced by the centrifugal force has significant ability to enhance the heat transfer rate. Results showed that the spiral design provides better heat transfer in terms of lower surface temperatures at the expense of higher pressure drop for the same flow rate of fluid.

Numerical Study on Heat Transfer and Fluid Flow Characteristic of Tube Bank with Integral Wake Splitter-Effect of Wake Splitter Length

2013 ◽  
Vol 315 ◽  
pp. 650-654
Author(s):  
Abobaker Mohammed Alakashi ◽  
Hamidon Bin Salleh
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Flow Characteristic ◽  
Numerical Study ◽  
Heat Transfer Characteristics ◽  
Tube Bank ◽  
Computational Fluid Dynamics Cfd

The purpose of this research is to investigate effect of wake splitter to pressure drop and heat transfer characteristics in a tube bank with staggered arrangements. The pressure drop and averaged heat transfer coefficient of seven rows with five tubes in each row with integral wake splitter has been determined by means of 2-D simulation using commercial computational fluid dynamics (CFD) code Fluent. Two type of integral wake splitter length have been studied, 0.5D and 1D with different location. Simulations have been carried out at Reynolds number based on tube diameter from 5000 up to 27800. The results, presented in terms of pressure drop as well as averaged heat transfer coefficient values, show the influence of wake splitter length and direction. By adding 0.5D wake splitter at downstream direction leads to higher averaged heat transfer coefficient and reduction of the pressure drop.

Maximization of Solar Gains of an Air Collector by Simulations

2013 ◽  
Vol 284-287 ◽  
pp. 483-487 ◽  
Author(s):  
Ondrej Sikula ◽  
Vit Merka ◽  
Jiri Hirs ◽  
Josef Plášek
Keyword(s):  
Heat Transfer ◽  
Solar Energy ◽  
Solar Collector ◽  
Cfd Simulations ◽  
Ansys Fluent ◽  
Operation Conditions ◽  
Flow And Heat Transfer ◽  
Solar Air Collector ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

The paper deals with numerical simulations of the impact of design, shading, positioning and orientation of a solar air collector an efficiency of exploitation of solar energy. The solar collector is used to preheat of an air, which then is supplied into the building. There are various requirements for solar air collectors. We are focused on maximization of solar energy gain by optimizing geometry, orientation and positioning of a solar air collector. To achieve the desired objective was a combination of two methods used. The firs one is Computational Fluid Dynamics (CFD) simulations of flow and heat transfer by convection, conduction and radiation in software ANSYS Fluent. The second one is the numerical simulation of the annual operations of the collector in the software BSim. The result of this work is an optimal design and operation conditions of the air collector.

Heat Transfer of Springs in Oblique Crossflows

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Daniel B. Biggs ◽  
Christopher B. Churchill ◽  
John A. Shaw
Keyword(s):  
Heat Transfer ◽  
Convection Heat Transfer ◽  
Reynolds Numbers ◽  
Experimental Program ◽  
Convection Heat ◽  
Computational Tool ◽  
Cfd Simulations ◽  
Nonmonotonic Dependence ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

An experimental program is presented of heated tension springs in an external crossflow over a range of laminar Reynolds numbers, spring stretch ratios, and angles of attack. Extensive measurements of the forced convection heat transfer of helical wire within a wind tunnel reveal an interesting nonmonotonic dependence on angle of attack. Computational fluid dynamics (CFD) simulations, showing good agreement with the experimental data, are used to explore the behavior and gain a better understanding of the observed trends. A dimensionless correlation is developed that well captures the experimental and CFD data and can be used as an efficient computational tool in broader applications.

Heat Transfer and Pressure Drop of Laminar Flow in Horizontal Tubes With/Without Longitudinal Inserts

1999 ◽  
Vol 122 (3) ◽  
pp. 465-475 ◽  
Author(s):  
S.-S. Hsieh ◽  
I.-W. Huang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Visualization ◽  
Complex Flow ◽  
Enhancement Of Heat Transfer ◽  
Horizontal Tubes ◽  
Aspect Ratios ◽  
Mixed Mean ◽  
Thermal Entrance

Heat transfer and pressure drop characteristics of water flow in horizontal tubes with/without longitudinal inserts used as a heat exchanger tubing was experimentally studied. Testing was performed on bare tubes and tubes with square and rectangular as well as crossed-strip inserts with aspect ratios AR=1 and 4 and varied ratios of inlet mixed mean temperature to wall temperature of 0.88 to 0.97. The Reynolds number ranged from approximately 250 to 1750 for flow visualization and from 1700 to 4000 for the pressure drop and heat transfer measurements. Flow visualization, using a dye injection method, revealed a highly complex flow pattern including a secondary flow formed in the cross section for crossed-strip inserts. The thermal entrance length was found and correlated in terms of Re for this type of inserted tubes. The enhancement of heat transfer as compared to a conventional bare tube at the same Reynolds number based on the hydraulic diameter was found to be about a factor of 16 at Re⩽4000, while the friction factor rise was only about a factor of 4.5 at Re⩽4000. [S0022-1481(00)01303-7]

Thermal Simulations of Thermocouple Tips in Hot Jets

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Sassan Etemad
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Measurement Accuracy ◽  
Reynolds Numbers ◽  
Cfd Simulations ◽  
Hot Gas ◽  
Gas Jets ◽  
Spherical Bead ◽  
Computational Fluid Dynamics Cfd ◽  
Thermal Simulations

Computational fluid dynamics (CFD) simulations have been carried out for the turbulent convective heat transfer, conduction and radiation for metal thermocouple tips, accommodated in hot gas jets to study the measurement accuracy of the thermocouples. The study covers several thermocouple sizes, jet temperatures, and Reynolds numbers. The spherical bead, representing the tip, becomes so hot that it radiates some heat to the colder surrounding surfaces. This phenomenon is responsible for a gap between the jet temperature and the bead temperature. The mentioned temperature difference is significant. It grows both with bead size and gas temperatures but decreases with the Reynolds number.

Sign in / Sign up

Export Citation Format

Share Document