HEAT TRANSFER ENHANCEMENT IN A HELICALLY COILED TUBE WITH Al2O3/WATER NANOFLUID UNDER LAMINAR FLOW CONDITION

2012 ◽  
Vol 11 (05) ◽  
pp. 1250029 ◽  
Author(s):  
P. C. MUKESH KUMAR ◽  
J. KUMAR ◽  
S. SURESH ◽  
K. PRAVEEN BABU
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Laminar Flow ◽  
Transfer Coefficient ◽  
Flow Condition ◽  
Volume Concentration ◽  
Dean Number ◽  
Particle Volume ◽  
Coiled Tube ◽  
Helically Coiled Tube

In this experimental investigation, the heat transfer coefficients of a shell and helically coiled tube heat exchanger using Al2O3 /water nanofluid under laminar flow condition were studied. The Al2O3 nanoparticles were characterized by X-Ray diffraction (XRD). The Al2O3 /water nanofluid at 0.1%, 0.4% and 0.8% particle volume concentration were prepared by using two step method. The prepared nanofluid was characterized by scanning electron microscope (SEM). It is observed that the overall heat transfer coefficient, inner heat transfer coefficient and experimental inner Nusselt number increase while increasing particle volume concentration and increasing inner Dean number. The enhancement of overall heat transfer coefficient was found to be 7%, 16.9% and 24.2% at 0.1%, 0.4% and 0.8% Al2O3 /water nanofluid respectively when compared with water. The enhancement of tube side experimental Nusselt number was found to be 17%, 22.9% and 28% at 0.1%, 0.4% and 0.8% particle volume concentration of Al2O3 /water nanofluid respectively when compared with water at fixed Dean number. The tests were conducted in the range of 1600 < De < 2700, and 5200 < Re < 8600 under laminar flow condition and counter flow configuration. These enhancements are due to higher thermal conductivity of nanofluid while increasing particle volume concentration and Brownian motion of nanoparticles. It is studied that there is no negative impact on formation of secondary flow and mixing of fluid when nanofluid passes through the helically coiled tube.

scholarly journals Numerical analysis of heat transfer enhancement with the use of γ-Al2O3/water nanofluid and longitudinal ribs in a curved duct

2012 ◽  
Vol 16 (2) ◽  
pp. 469-480 ◽  
Author(s):  
Hosseinali Soltanipour ◽  
Parisa Choupani ◽  
Iraj Mirzaee
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Base Fluid ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Transfer Enhancement ◽  
Dean Number ◽  
Particle Volume ◽  
The Heat Transfer Coefficient

This paper presents a numerical investigation of heat transfer augmentation using internal longitudinal ribs and ?-Al2O3/ water nanofluid in a stationary curved square duct. The flow is assumed 3D, steady, laminar, and incompressible with constant properties. Computations have been done by solving Navier-Stokes and energy equations utilizing finite volume method. Water has been selected as the base fluid and thermo- physical properties of ?- Al2o3/ water nanofluid have been calculated using available correlations in the literature. The effects of Dean number, rib size and particle volume fraction on the heat transfer coefficient and pressure drop have been examined. Results show that nanoparticles can increase the heat transfer coefficient considerably. For any fixed Dean number, relative heat transfer rate (The ratio of the heat transfer coefficient in case the of ?- Al2o3/ water nanofluid to the base fluid) increases as the particle volume fraction increases; however, the addition of nanoparticle to the base fluid is more useful for low Dean numbers. In the case of water flow, results indicate that the ratio of heat transfer rate of ribbed duct to smooth duct is nearly independent of Dean number. Noticeable heat transfer enhancement, compared to water flow in smooth duct, can be achieved when ?-Al2O3/ water nanofluid is used as the working fluid in ribbed duct.

Energy and Exergy Analysis of Shell and Coil Heat Exchanger Using Water Based Al2O3 Nanofluid Including Diverse Coil Geometries: An Experimental Study

2020 ◽  
Vol 9 (1) ◽  
pp. 13-23
Author(s):  
Samir M. Elshamy ◽  
Mohamed T. Abdelghany ◽  
M. R. Salem ◽  
O. E. Abdellatif
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Exergy Analysis ◽  
Volume Concentration ◽  
Pure Water ◽  
Cone Angle ◽  
Particle Volume ◽  
Water Based ◽  
Coil Heat

The aim of this research is to investigate experimentally the characteristics of the convective heat transfer and exergy analysis of pure water and water based Al2O3 nanofluid through helical coiled tubes (HCTs) and conical coiled tubes (CCTs) inside shell and coil heat exchangers. HCT and CCT fabricated with different coil torsions (λ) ranges from 0.0202 to 0.052 with different two angles (0° and 45°) while have the same curvature ratio (δ = 0.0564). The effects of mean coil torsion, the cone angle and nanoparticles volume concentration on the thermal performance were investigated. Results indicated that the overall heat transfer coefficient (Uov), convection heat transfer coefficient (ht), the tube side Nusselt number (Nut), effectiveness (ɛ) and exergy efficiency (ηex) of nanofluids are higher than those of the pure water at same flow condition, and this increase goes up with the increase in particle volume concentration (ϕ). The results also showed that Uov, ht, Nut, ɛ and ηex increases by decreasing the coil torsion from 0.052 to 0.0202. Correlations for Nut as a function of the investigated parameters are obtained.

scholarly journals Analysis of the effect of ultrasonic vibration on nanofluid as coolant in engine radiator

2021 ◽  
Vol 5 (5 (113)) ◽  
pp. 6-13
Author(s):  
Sudarmadji Sudarmadji ◽  
Santoso Santoso ◽  
Sugeng Hadi Susilo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Fluid Flow ◽  
Transfer Coefficient ◽  
Ultrasonic Vibration ◽  
Flow Rate ◽  
Volume Concentration ◽  
Aluminum Oxide Nanoparticles ◽  
Particle Volume ◽  
Overall Heat Transfer Coefficient

The paper discusses the combined methods of increasing heat transfer, effects of adding nanofluids and ultrasonic vibration in the radiator using radiator coolant (RC) as a base fluid. The aim of the study is to determine the effect of nanoparticles in fluids (nanofluid) and ultrasonic vibration on the overall heat transfer coefficient in the radiator. Aluminum oxide nanoparticles of 20–50 nm in size produced by Zhejiang Ultrafine powder & Chemical Co, Ltd China were used, and the volume concentration of the nanoparticles varied from 0.25 %, 0.30 % and 0.35 %. By adjusting the fluid flow temperature of the radiator from 60 °C to 80 °C, the fluid flow rate varies from 7 to 11 lpm. The results showed that the addition of nanoparticles and ultrasonic vibration to the radiator coolant increases the overall heat transfer coefficient by 62.7 % at a flow rate of 10 liter per minute and temperature of 80 °C for 0.30 % particles volume concentration compared to pure RC without vibration. The effect of ultrasonic vibration on pure radiator coolant without vibration increases the overall heat transfer coefficient by 9.8 % from 385.3 W/m2·°C to 423.3 W/m2·°C at a flow rate of 9 liter per minute at a temperature of 70 °C. The presence of particles in the cooling fluid improves the overall heat transfer coefficient due to the effect of ultrasonic vibrations, nanofluids with a volume concentration of 0.25 % and 0.30 % increased about 10.1 % and 15.7 %, respectively, compared to no vibration. While, the effect of nanoparticles on pure radiator coolant at 70 °C enhanced the overall heat transfer coefficient by about 39.6 % at a particle volume concentration of 0.35 % compared to RC, which is 390.4 W/m2·°C to 545.1 W/m2·°C at 70 °C at a flow rate of 10 liter per minute

scholarly journals Energetic and Exergetic Assessment of Spiral Heat Exchanger Using Mineral and Oxide Mineral Oil Nanofluid

2021 ◽  
Vol 39 (2) ◽  
pp. 531-540
Author(s):  
Khalid Faisal Sultan ◽  
Mohammed Hassan Jabal ◽  
Ameer Abed Jaddoa
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Base Fluid ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Coiled Tube ◽  
Helically Coiled Tube ◽  
The Heat Transfer Coefficient

This paper presents an experimental analysis on the heat transfer and pressure drop enhancement of oil nanofluid flow. In this analysis, the first method has used the helically coiled tube and shell, the oil nanofluids were employed instead of the base fluid (oil) in the second process. the two techniques were used to improve the heat transfer and pressure drop. Nanofluid oil concentrations utilized within range from 1 to 5 percent vol. This paper applied two forms of nanoparticles: copper (Cu (20 nm)) and zirconium oxide (ZrO2 (40 nm)) and base fluid (oil). The influence on the heat transfer coefficient for different factors such as the flow number of Reynolds, the temperature of the nanofluid oil, the concentration and shape of the nanoparticle, and the pressure gradient of the flow have examined. The results indicated that the value of a 40.35 percent in the heat transfer coefficient for Cu + oil and 28.42 percent for ZrO2 + oil increased compared with the base fluid (oil) at 5 percent vol concentration. Using oil nanofluids (Cu, ZrO2 – oil) instead of the base fluid (oil) led to increasing in the heat transfer coefficient and decreasing the pressure. In addition, the result showed that the heat transfer efficiency has enhanced using the helically coiled tube and shell, as well as increasing in the pressure drop was due to the curvature of the tube. Baes on the relationship between viscosity and shear intensity, the oil nanofluid behaviors were similar to the standard Newtonian fluids. Moreover, the related flow and heat transfer methods are used to present the output index. The exergy inflow, exergy destruction and exergy efficiency of oil nanofluid (Cu +oil) were greater than the oil nanofluid (ZrO2 +oil) and oil. The exergy inflow, exergy destruction, and exergy efficiency for the two type of oil nanofluid increased with increasing of nanoparticles concentration.

Experimental Investigations to Study the Effect on Coefficient of Friction and Heat Transfer Coefficient in the Lubricants With Nano Blending

2017 ◽  
Author(s):  
Lvrsv Prasad Chilamkurti ◽  
Isai Dharma Rao ◽  
K. Santarao
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Coefficient Of Friction ◽  
Frictional Force ◽  
Room Temperature ◽  
Volume Concentration ◽  
Nano Particles ◽  
Average Particle ◽  
Particle Volume

Worm gears are unique in their ability to achieve large speed reductions in a compact space with gear ratios of 20:1, 60:1 and 200:1 or even higher in some cases and have transmission efficiency between 50% and 70%. One of the major drawback in worm drive design is the relative motion between the two mating elements is entirely sliding. This sliding motion continuously expels the lubricant aside leading to higher wear and increase in temperature. This phenomenon leads to high wear and higher temperatures, which are the limiting factors in the worm drives. Nano particles have gained a greater attention in the recent years because of their highly enhanced thermal and tribological properties when blended with conventional lubricants. In the present investigations the addition of Al2O3 nano particles with average particle size of 30 nm in SAE 140 gear oil resulted in reducing the coefficient of friction, wear and enhanced the heat transfer coefficient. It is observed that coefficient of friction is decreased by 8.98%, 10.11% and 16.85% at nano particle volume concentration of 0.1%, 0.2% and 0.5% respectively at room temperature. Frictional force was found reduced by 26.02% at room temperature for 0.5% volume concentration. Further it was also noted 32.25% and 18.55% reduction in frictional force at the temperatures 60°C and 90°C respectively for 0.2% volume concentration. Convective heat transfer coefficient is increased with increasing particle volume concentration and maximum enhancement of 46.35% in heat transfer coefficient observed at 0.5% volume fraction. The results depict that lubricants blended with nano particles exhibit enhanced tribological and heat transfer properties.

scholarly journals Numerical Study of Laminar Flow Forced Convection of Water-Al2O3Nanofluids under Constant Wall Temperature Condition

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Hsien-Hung Ting ◽  
Shuhn-Shyurng Hou
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Volume Concentration ◽  
Numerical Study ◽  
Pure Water ◽  
Particle Volume ◽  
Constant Wall Temperature ◽  
Water Based

This numerical study is aimed at investigating the forced convection heat transfer and flow characteristics of water-based Al2O3nanofluids inside a horizontal circular tube in the laminar flow regime under the constant wall temperature boundary condition. Five volume concentrations of nanoparticle, 0.1, 0.5, 1, 1.5, and 2 vol.%, are used and diameter of nanoparticle is 40 nm. Characteristics of heat transfer coefficient, Nusselt number, and pressure drop are reported. The results show that heat transfer coefficient of nanofluids increases with increasing Reynolds number or particle volume concentration. The heat transfer coefficient of the water-based nanofluid with 2 vol.% Al2O3nanoparticles is enhanced by 32% compared with that of pure water. Increasing particle volume concentration causes an increase in pressure drop. At 2 vol.% of particle concentration, the pressure drop reaches a maximum that is nearly 5.7 times compared with that of pure water. It is important to note that the numerical results are in good agreement with published experimental data.

Thermal and Hydrodynamic Performance of Aqueous CuO and Al2O3 Nanofluids in an Annular Coiled Tube Under Constant Wall Temperature and Laminar Flow Conditions

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Wael I. A. Aly
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Laminar Flow ◽  
Transfer Coefficient ◽  
Wall Temperature ◽  
Base Fluid ◽  
Hydrodynamic Performance ◽  
Constant Wall Temperature ◽  
Coiled Tube ◽  
Tube Heat Exchanger

Laminar flow and heat transfer behaviors of two different metal oxide, Al2O3 (36 nm) and CuO (29 nm), nanofluids flowing through an annular coiled tube heat exchanger (ACTHE) with constant wall temperature boundary condition have been numerically studied to evaluate their superiority over the base fluid (water). Simulations covered a range of nanoparticles volume concentrations of 1.0–6.0% and mass flow rates from 0.025 to 0.125 kg/s. Numerical results indicated that a considerable heat transfer enhancement is achieved by both nanofluids. Results at the same Reynolds number for the pressure drop and heat transfer coefficient show an increase with increasing particle volumetric concentration. The maximum enhancements in heat transfer coefficient were 44.8% and 18.9% for CuO/water and Al2O3/water, respectively. On the other hand, the pressure loss was seven times in comparison to water for CuO/water and about two times for Al2O3/water nanofluid. Also, comparing to the base fluid, nanofluids at low concentrations (up to 3%) can provide the same heat transfer amount at lower pumping power. The overall performance of the enhanced heat transfer technique utilized has been evaluated using a thermohydrodynamic performance index which indicated that Al2O3/water nanofluid is a better choice than CuO/water nanofluid. Moreover, conventional correlations for helical circular tubes for predicting friction factor and average heat transfer in laminar flow regime such as the correlations of Mori and Nakayam and Manlapaz and Churcill, respectively, are also valid for water and the tested nanofluids with small nanoparticle loading in the ACTHE.

scholarly journals Numerical investigation of flow boiling heat transfer in helically coiled tube under constant heat flux

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Mohammad Ali Abdous 1 ◽  
Shahriyar Ghazanfari Holagh ◽  
Hamid Saffari
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Boiling ◽  
Tube Diameter ◽  
Cfd Modeling ◽  
Vapor Quality ◽  
Coiled Tube ◽  
Helically Coiled Tube ◽  
Coil Diameter

Numerical study of subcooled and saturated flow boiling in the curved and helically  coiled tubes in presence of phase change is one of the challenging area of CFD studies. In this paper, the CFD modeling of the nucleate and convective flow boiling in the small helically coiled tube at low vapor quality (up to the 18.93 percent) region is studied. A proper Eulerian-based mathematical model is used for interphase exchange forces and heat transfer between two phases in CFD modeling using Bulk boiling model. The results show that, the inner and the bottom wall of the helically coiled tube have the lowest and the highest heat transfer coefficient, respectively. The effect of change in coil diameter, helical pitch and tube diameter is investigated on the counters of vapor volume fraction. It is seen that at low vapor quality flows, the heat transfer coefficient is enhanced by decreasing in coil diameter, tube diameter and increasing in coil pitch of helically coiled tube. 

Energy Efficient Hybrid Nanofluids for Tubular Cooling Applications

2014 ◽  
Vol 592-594 ◽  
pp. 922-926 ◽  
Author(s):  
Devasenan Madhesh ◽  
S. Kalaiselvam
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Volume Concentration ◽  
Thermal Characteristics ◽  
Hybrid Nanofluid ◽  
Tubular Heat Exchanger ◽  
Overall Heat Transfer Coefficient ◽  
Flow Through ◽  
Hybrid Nanofluids

Analysis of heat transfer behaviour of hybrid nanofluid (HyNF) flow through the tubular heat exchanger was experimentally investigated. In this analysis the effects of thermal characteristics of forced convection, Nusselt number, Peclet number, and overall heat transfer coefficient were investigated.The nanofluid was prepared by dispersing the copper-titania hybrid nanocomposite (HyNC) in the water. The experiments were performed for various nanoparticle volume concentrations addition in the base fluid from the range of 0.1% to 1.0%. The experimental results show that the overall heat transfer coefficient was found to increases maximum by 30.4%, up to 0.7% volume concentration of HyNC.

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