Thermal-Hydraulic Performance Analysis of Fluid Flow in Tube With Helical Screw Inserts in Transition Flow

2020 ◽  
Author(s):  
Shashank Ranjan Chaurasia ◽  
R. M. Sarviya
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Performance Analysis ◽  
Hydraulic Performance ◽  
Transition Flow ◽  
Maximum Enhancement ◽  
Transition Flow Regime ◽  
Twist Ratio ◽  
Single Strip

Abstract An experimental analysis is arranged to evaluate thermal hydraulic performance analysis on fluid flow in helical screw inserts in tube with number of strips and different twist ratios in Transition flow regime. Single strip insert is also compared with double strip inserts of helical screw inserts with three values of twist ratios. Heat transfer enhancement is achieved with fluid flow in double strip as compared to single strip helical screw insert at decreases values of twist ratios and increases values of Reynolds number (Re). Maximum enhancement in the value of Nusselt number is achieved with double strip inserts at low value of twist ratio and Reynolds number as compared to Single strip inserts. Common correlations of Nusselt number and friction factor are generated. Thermal performance factor (TPF) is achieved maximum values with double strip insert at all flow rates at 2.5 of twist ratio than single strip inserts. Double strip inserts show suitability of helical screw insert in heat exchangers to compact the size of thermal applications.

Thermal Performance With Entropy Generation Analysis of Fluid Flow in a Heat Exchanger Pipe With Single and Double Strip Helical Screw Tape Inserts

2020 ◽  
Author(s):  
Shashank Ranjan Chaurasia ◽  
R. M. Sarviya
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Twisted Tape ◽  
Maximum Enhancement ◽  
Twist Ratio ◽  
Single Strip

Abstract In heat exchangers, twisted tape insert is a technique to enhance heat transfer. In this paper, the experimental investigation is arranged to analyse thermal performance and entropy generation analysis on fluid flow in helical screw inserts with number of strips. The Nusselt number is achieved enhancement with double strip as compared to single strip helical screw inserts at decreased values of twist ratio and increased values of flow rates. The Nusselt number is achieved maximum enhancement of 112% with double strip helical screw insert than plain tube at 4000 of Reynolds number, whereas it is found higher value at Reynolds number of 16000. The common correlations of Nusselt number and friction factor with repect of Reynolds number, number of the strips and twist ratio are generated. The entropy generation analysis is also performed. The thermal performance factor is found increment with double strip than single strip helical screw inserts at twist ratio of 2.5 and 3, whereas, it is attained maximum value of 1.5 at twist ratio 2.5 and Reynolds number of 16000 with double strip helical screw insert. The double strip helical screw inserts are suitable for reducing the size of heat exchanger, which could dercrease the size of many thermal applications as solar water heater, radiator, electronic cooling systems.

Numerical and experimental thermal performance with entropy generation analysis on tube with helical screw tape inserts at number of strips in turbulent flow

2020 ◽  
pp. 095440622093773
Author(s):  
Shashank Ranjan Chaurasia ◽  
RM Sarviya
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Twisted Tape ◽  
Maximum Enhancement ◽  
Twist Ratio ◽  
Plain Tube ◽  
Volume Method ◽  
Single Strip

In the heat exchangers, twisted tape insert is a technique to enhance heat transfer. In this paper, the experimental and numerical investigations are arranged to analyze thermal performance with entropy generation analysis on single and double strip helical screw tape inserts. The finite volume method is used with shear stress transport K-ω model to analyze fluid flow in tube with inserts. The Nusselt number attained enhancement with double strip as compared to single strip helical screw inserts at decreased values of twist ratio and increased values of Reynolds number. However, the Nusselt number attained maximum enhancement of 112% with double strip helical screw insert than plain tube at 4000 of Reynolds number (Re). The common correlations for Nusselt number and friction factor are generated with respect to Reynolds number, number of the strips and twist ratio. Entropy generation analysis is also performed. The thermal performance factor attained its enhancement with double strip than single strip helical screw inserts at twist ratio of 2.5 and 3; whereas, double strip helical screw insert attained maximum value of 1.5 at twist ratio of 2.5 and Reynolds number of 16000. The double strip helical screw inserts are suitable for miniaturization of heat exchanger.

Experimental and numerical thermal performance analysis with exergy destruction on nanofluid flow in tube with double strip helical screw inserts

2021 ◽  
pp. 095765092098214
Author(s):  
Shashank Ranjan Chaurasia ◽  
RM Sarviya
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Thermal Performance ◽  
Power Plants ◽  
Exergy Destruction ◽  
Water Heater ◽  
Nanofluid Flow ◽  
Maximum Enhancement ◽  
Twist Ratio ◽  
Single Strip

Experimental and numerical analysis is arranged with exergy destruction to evaluate thermal performance of system on nanofluid flow in tube with single and double strip helical screw inserts at different values of twist ratio in laminar flow regime. CFD analysis has occurred on the fluent workbench of ANSYS software. The Nusselt number attained enhancement with the flow of nanofluid in double strip helical screw inserts as compared with single strip helical screw inserts at decreasing values of twist ratio and increasing values of Reynolds number. Maximum enhancement of 421% is found with Nusselt number in the flow of nanofluid in tube with double strip helical screw insert at 1.5 of twist ratio and lower value of Reynolds number as compared with the flow of water in plain tube. Common correlations of Nusselt number and friction factor are generated. Exergy destruction number is attained less than one value for both types of inserts at different values of twist ratio and Reynolds number, whereas attained lower value with the flow of nanofluid in tube with double strip helical screw insert at twist ratio of 1.5 and low value of Reynolds number. Heat transfer enhancement number is attained more than one value for both types of inserts with different values of twist ratio and Reynolds number, whereas double strip helical screw inserts attained maximum value at twist ratio of 1.5 in the range of Reynolds number. Therefore, double strip helical screw inserts are the best inserts as compared with single strip helical screw inserts to compact the size of heat exchangers, whereby size of many thermal applications could be compact such as solar water heater, electronic cooling devices, automobile radiator, power plants etc.

Experimental analysis on thermal and friction factor characteristics of fluid flow in tube with novel double strip helical screw tape

2019 ◽  
Vol 234 (6) ◽  
pp. 874-886
Author(s):  
Shashank R Chaurasia ◽  
RM Sarviya
Keyword(s):  
Nusselt Number ◽  
Fluid Flow ◽  
Friction Factor ◽  
Experimental Analysis ◽  
Flow Characteristics ◽  
Performance Ratio ◽  
Working Fluid ◽  
Flow Rates ◽  
Twist Ratio ◽  
Single Strip

An experimental analysis has been carried out to investigate the thermal and friction factor characteristics of fluid flow in a tube with double strip helical screw tape (DS-HST) inserts with different values of twist ratio and compared with single strip helical screw tape inserts and plain tube. Water is used as a working fluid at different flow rates with constant heat flux conditions. CFD analysis is also carried out to visualize thermal and fluid flow characteristics of fluid flow in tube with inserts. Experimental results have showed that Nusselt number and friction factor have attained excellent enhancement with double strip helical screw tape inserts in the range of flow rates than single strip helical screw tape inserts at the value of twist ratio 1.5. Correlation is also developed for Nusselt number with a range of Reynolds number, twist ratio and number of strips. Moreover, the performance ratio has attained maximum value at twist ratio of 2.5 with high values of flow rate. It is concluded that DS-HST is able to attain enhancement in the efficiency of heat exchanger, causing a reduction in size for thermal applications.

Comparative Thermal Performance Analysis on Helical Screw Insert in Tube With Number of Strips With Nanofluid at Laminar Flow Regime

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Shashank Ranjan Chaurasia ◽  
R. M. Sarviya
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Flow Regime ◽  
Thermal Performance ◽  
Power Plants ◽  
Nanofluid Flow ◽  
Laminar Flow Regime ◽  
Twist Ratio ◽  
Single Strip

Abstract The experimental analysis is arranged to evaluate the thermal hydraulic performance on nanofluid flow in helical screw insert with tube at a number of strips and different twist ratios in laminar flow regime. The single strip (SS) helical screw inserts are also compared with the double strip (DS) helical screw inserts. The heat transfer enhancement is achieved with nanofluid flow in double strip as compared with single strip helical screw insert at decreased values of twist ratio and increased values of Reynolds number. A maximum enhancement of 421% is found in the value of Nusselt number with double strip helical screw insert at twist ratio of 1.5 and low value of Reynolds number in the flow of nanofluid than water in plain tube. The common correlations of Nusselt number and friction factor are generated. The thermal performance factor (TPF) is achieved at a maximum value of 2.42 with double strip than single strip helical screw inserts at twist ratio of 2.5 and low value of Reynolds number. The present analysis shows suitability of the double strip helical screw insert to enable miniaturization of the heat exchangers. A compact heat exchanger decreases the size of thermal application such as solar water heater, solar power plants, electronic cooling systems, radiator, etc., which could save environment by pollution reduction with utilization of energy.

Static Performance of Smooth Liquid Annular Seals in the Transition and Turbulent Regimes

2021 ◽  
Author(s):  
Dara W. Childs ◽  
Joshua Bullock
Keyword(s):  
Reynolds Number ◽  
Flow Regime ◽  
Operating Conditions ◽  
Radial Clearance ◽  
Turbulent Regime ◽  
Swirl Ratio ◽  
Transition Flow ◽  
Transition Flow Regime ◽  
San Andres ◽  
Annular Seals

Abstract Static test results are presented for smooth annular seals with a length-to-diameter ratio of 0.50, radius R = 51.00 mm, at the nominal radial clearance Cr = 0.2032 mm. Tests were conducted for angular shaft speeds; ω = 2, 4, 6, 8 krpm, axial pressure drops; ΔP = 2.1, 4.13, 6.21, 8.27 bars, and eccentricity ratios ϵ0 = e0/Cr = 0.00, 0.27, 0.53, 0.8 where e0 is the static eccentricity. Three pre-swirl inserts were used to target zero, medium, and high (0., 0.4, and 0.8) pre-swirl ratios for a set of pre-determined operating conditions with ISO VG 2 oil at 46.1°C. Pitot tubes measured the circumferential velocity at separate upstream and downstream seal locations and were used to calculate pre-swirl ratio, PSR = vinlet/Rω, and outlet-swirl ratio, OSR = voutlet/Rω. For all tested pre-swirl inserts, PSR tended to converge to 0.4∼0.5 as ω increased. PSR and OSR were poorly correlated. Volumetric leakage rate Q ˙ versus pressure differential ΔP was measured. The measured vector Reynolds number Re, combining the axial and circumferential Reynolds numbers ranged from ∼1000 to ∼3500. Based on Zirkelback and San Andrés 1996 publication, almost all of the flow regime is predicted to lie in the transition regime, with fewer points in the turbulent regime. Generally, the seals’ static centering properties were obtained by applying a static load Fs and measuring the resulting displacement vector e0. At many low-speed, low-ΔP test conditions, the seal would not remain in the desired centered or near-centered position and had to be forced into place with a centering force Fs. The authors believe that the observed de-centering effects resulted from test operations in the transition flow regime where the friction factor λ does not drop with increasing ΔP and increasing Re. A positive centering Lomakin effect requires that λ drop with increasing axial Reynolds number. The seals had positive centering effects over a large portion of the predicted transition flow regime, supporting the view that the shift from transition-to-turbulent flow regularly occurred at lower Re values than the Re = 3000 boundary used by Zirkleback and San Andrés.

Investigations on Fluid Flow and Heat Transfer Performances Within a Real Turbine Blade Channel

2014 ◽  
Author(s):  
Zhaoqing Ke ◽  
Jian Pu ◽  
Jianhua Wang ◽  
Lei Wang ◽  
Zhiqiang Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Secondary Flow ◽  
Reynolds Numbers ◽  
Numerical Investigations ◽  
Serpentine Channel ◽  
Flow And Heat Transfer ◽  
Working Medium

The characteristics of fluid flow and heat transfer within a smooth three-pass channel of a real low pressure (LP) turbine blade have been investigated through experimental and numerical approaches. The serpentine channel consists of two inlet passes, two dividing walls, two 180 degree bends, twenty-five exits at the trailing edge, and two exits at the blade tip. In the experiments, purified water was used as working medium, the secondary flow patterns at five cross-sections were captured by a particle image velocimetry (PIV) system, the inlet Reynolds number was controlled by a turbine flow meter, and the mass flow rate ejected from each exit was measured by rotameters. Using the commercial software ANSYS CFX 13.0, numerical investigations were carried out. The practicability of four turbulence models, the SSG RSM, SST k-ω, RNG k-ε and standard k-ε models, were estimated. Through qualitative and quantitative comparisons of the secondary flow patterns, local velocity variation trends and mass flow rates between the experimental data and numerical results, the SSG RSM was selected as the most appropriate model in the following numerical investigations. Using ideal gas as working medium, the impacts of Reynolds numbers and rotation numbers on the heat transfer performances were numerically investigated. The numerical results predicted three interesting phenomena: 1) The locally averaged Nusselt number increases generally with the inlet Reynolds numbers. However, the increasing amplitude is significantly different from the correlation suggested by Dittus-Boelter, Nuo = 0.023Re0.8Pr0.4. The effect of the Reynolds number on the Nusselt number is substantially enhanced due to the serpentine channel design with two 180 degree-bends. The enhancement amplitude is described by two fitted coefficients based on Dittus-Boelter correlation. 2) Under a rotation condition, in the 1st and 3rd passes, the enhancement amplitude of the average Nusselt number on the pressure side (PS) is more significant than that on the suction side (SS), whereas in the 2nd pass, the enhancement amplitude on the PS is lower than that on the SS. 3) In the 3rd pass, a higher rotation number leads to a more uniform distribution of the local Nusselt number along the streamwise direction on both the PS and SS.

scholarly journals Double-Layer Metal Foams for Further Heat Transfer Enhancement in a Channel: An Analytical Study

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 672
Author(s):  
Sinem Donmus ◽  
Moghtada Mobedi ◽  
Fujio Kuwahara
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Equilibrium Analysis ◽  
Interfacial Heat Transfer Coefficient ◽  
Thermal Dispersion ◽  
Pore Density ◽  
Aluminum Foams ◽  
Heat And Fluid Flow

A local thermal non-equilibrium analysis of heat and fluid flow in a channel fully filled with aluminum foam is performed for three cases: (a) pore density of 5 PPI (pore per inch), (b) pore density of 40 PPI, and (c) two different layers of 5 and 40 PPI. The dimensionless forms of fully developed heat and fluid flow equations for the fluid phase and heat conduction equation for the solid phase are solved analytically. The effects of interfacial heat transfer coefficient and thermal dispersion conductivity are considered. Analytical expressions for temperature profile of solid and fluid phases, and also the channel Nusselt number (NuH) are obtained. The obtained results are discussed in terms of the channel-based Reynolds number (ReH) changing from 10 to 2000, and thickness ratio between the channel height and sublayers. The Nusselt number of the channel with 40 PPI is always greater than that of the 5 PPI channel. It is also greater than the channel with two-layer aluminum foams until a specific Reynolds number then the Nusselt number of the channel with two-layer aluminum foams becomes greater than the uniform channels due to the higher velocity in the outer region and considerable increase in thermal dispersion.

scholarly journals Effect of baffle shape in heat transfer for jet impingement on a solid block

2018 ◽  
Vol 240 ◽  
pp. 01025
Author(s):  
Muthukannan Marimuthu ◽  
Uthayakumar ◽  
Rajesh Kanna P ◽  
Paweł Ocłoń ◽  
Jan Taler ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Jet Impingement ◽  
Reattachment Length ◽  
Heat Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Wide Range ◽  
Solid Block

The numerical solution solution is obtained for fluid flow and heat transfer in a confined impinging slot on a solid block with the presence of baffles. In order to consider the effect of baffle shape the rectangular and semi circular baffles are considered and for the effect for Reynolds number the Reynolds number is varied from 100 to 300 with the step of 50. The present study reveals the vital impact of Baffle shape and Reynolds number (Re) on the fluid flow and heat transfer characteristics over a wide range. It is finally added that the presence of baffle improves the Nusselt number. The Nusselt number increases with the increase of Reynolds number. The present study proved that, the primary peak of Nusselt number occurs nearer to the reattachment length. The secondary peak of Nusselt number occurs nearer to the baffle. It is observed that for semi circle baffle the velocity attains maximum one compared to rectangular baffle.

Sign in / Sign up

Export Citation Format

Share Document