Maximum Enhancement In Nusselt Number Research Articles

Experimental investigation on effect of perforated double V-cut twisted tape on thermo-hydraulic characteristics of heat exchanger tube

ABSTRACT To enhance overall thermal performance factor of tubular heat exchanger, use of twisted tape has been very effective. Twisted tape creates turbulence in the flow which enhances rate of heat transfer and friction factor. Present experimental study aims to limit this penalty of increase in friction factor and achieve high thermal performance factor. For this, present article analyzes the effect of different design modifications in twisted tape on thermo-hydraulic performance of heat exchanger tube. Different inserts, i.e. Simple Twisted tape (STT), Double V-Cut Twisted Tape (DVCTT) and Perforated Double V-Cut Twisted Tape (PDVCTT), of varying twist ratio (TR) 3, 4 and 5 are considered for the investigation. Further design modification such as V-cut with width of cut (wc) 5 mm, depth of cut (dc) 4 mm, and perforation of 5 mm diameter is produced in twisted tape. Water is used as the working fluid for the study. Data pertaining to Nusselt number and friction factor is collected for the analysis in turbulent region where Reynolds number varied from 4000 to 16,000. Maximum enhancement in Nusselt number and friction factor is recorded 2.44 times and 3.71 times of plain tube respectively at Re = 4000 in case of TR = 3. Further PDVCTT leads to maximum decrement in Nusselt number and friction factor 3.83% and 27.35% when compared with DVCTT. Maximum thermal performance obtained is 1.71 in case of PDVCTT with TR of 3 at Re = 4000.

Thermo‐hydraulic performance investigation of solar air heater duct having staggered D‐shaped ribs: Numerical approach

AbstractThe thermohydraulic performance (THP) of a solar air heater (SAH) duct with staggered D‐shaped ribs as roughness geometry is examined in this work using three‐dimensional numerical investigation. The investigation is carried out at roughness parameters of radius of rib to transverse pitch (r/Ptv) ratios of 0.1–0.35 and longitudinal pitch to radius of rib (Plg/r) ratios of 4–10 under varied operating circumstances of Reynolds number (Re) from 10,200 to 20,200. The maximum Nusselt number (Nu) is obtained to be 81.3 at Re of 20,200, r/Ptv as 0.1, and Plg/r as 4. In contrast, the maximum friction factor (f) is obtained to be 0.0169 at Re of 10,200, r/Ptv as 0.35, and Plg/r as 4. In the range of parameters examined, the maximum enhancement in Nusselt number (Nu/Nus) is observed to be 1.35 at an optimal parameter of r/Ptv as 0.1, Plg/r as 4, and Re as 10,200. Correspondingly, the enhancement in the friction factor (f/fs) at this optimum parameter is 1.87. The maximum value of the THP parameter is found to be 1.1 at the same optimum range of parameters. In further analysis, correlations were developed for Nusselt number (Nu) and friction factor (f) in terms of r/Ptv, Plg/r, and Re with a deviation of ±2% and ±1.5%, respectively.

Mini-channel cooling system for solar PV Panels with hybrid magnetic nanofluid and magnetic field

This study delves into the interplay between magnetic fields, heat transfer, and fluid behavior within a 3D mini-channel. Exploring the effects of a magnetic field on a hybrid nanofluid (Fe3O4–TiO2) under varying intensities (1000–2000 Gauss) and positions. Using numerical simulations (finite volume method), key parameters like Nusselt number (Nu), Friction factor (f), and Thermal Enhancement Factor (TEF) have been analyzed to uncover how magnetic fields and nanofluids interact in complex geometries. Results showed that the application of a magnetic field significantly enhanced heat transfer performance, with a maximum Nusselt number enhancement of 230%. Moreover, it was shown that greater magnetic field intensities were associated with elevated friction factors, whereas friction factors exhibited a declining trend as Reynolds numbers increased. The thermal enhancement factor initially increased with Reynolds numbers, but declined after reaching a peak. However, higher magnetic field strengths mitigated this decline, intensifying heat transfer enhancement effects reaching a maximum of 2.18 at 2000G magnetic field. These findings provide quantitative insights into the effectiveness of magnetic fields in enhancing heat transfer in Fe3O4–TiO2 hybrid nanofluids.

Experimental analysis of thermal performance factor for double pipe heat exchanger with ZnO–water nanofluid

Nanofluid has attracted a large number of researchers in recent decades due to its exceptional heat transfer properties. In this study, a ZnO–H2O nanofluid with surfactant sodium dodecyl benzene sulphonate has been investigated to quantify heat transfer and frictional loss in a double-pipe heat exchanger. The turbulent zone was studied, with Reynolds numbers ranging from 5500 to 16,000 for fully developed flow. Volume fractions employed were 0.005%, 0.01%, 0.03% and 0.06%. Brownian motion and the interfacial layer, in addition to thermal conductivity, are the primary factor to influence heat transfer in heat exchangers. The maximum enhancement in Nusselt number and thermal performance achieved for a volume fraction of 0.06% at Reynolds number 5500 is 35% and 1.15, respectively.

Thermal and Flow Analysis of TiO2 Nanofluid Flow in Circular and Square Ducts with Multiple Twisted Tape Inserts

A numerical study is conducted to observe the thermal and flow performance of TiO2 nanofluid in the circular and square ducts with different twisted tape arrangements. The presence of the twisted tape in the tube induces swirl flow, which aids in the heat transfer, but at the penalty of a higher friction factor. The results also reveal that the maximum Nusselt number enhancement is obtained in the circular tube when the counter-triple twisted tape arrangement (C-TTs) is adopted while it is co-triple twisted tape arrangement (Co-TTs) for the case of square duct. Besides, the highest friction factor is observed for the Co-TTs for both circular and square ducts. The heat transfer and friction factor in the circular duct are greater than that of the square duct. The highest thermal performance factor of 1.286 is obtained when the single twisted tape and 1.5% nanofluid are used in the circular tube. However, multiple twisted tape inserts in the square duct contributes to improved thermal performance at a relatively lower friction factor when compared to the circular tube. Therefore, it is recommended to implement the square duct with multiple inserts for compact or microchannel heat exchanger for heat transfer application.

Experimental and numerical analysis of effect of combined drop-shape pin fins and plate fins type heat sink under natural convection

As the junction temperature of a light-emitting diode (LED) is inversely proportional to its lifespan and efficiency. This study investigates the thermal performance of heat sink-based model with a drop-shaped pin fin for LED cooling under natural convection, experimentally, and numerically. The study used three distinct drop form pin fin arrays with variable vertical fin spacing (Sv = 25, 50, and 75 mm), with the best array being used in subsequent studies with variations in drop-shaped pin fin size (diameter DD and apex length LD ). The heat transfer coefficient and Nusselt number were obtained in the quantitative analysis of thermal performance. A numerical model with Boussinesq approximation for natural convection is used for this study and well-validated with experimental results. A qualitative investigation was also carried out utilizing numerical research to investigate velocity streamlines and their impacts on heat transfer enhancement in various configurations. An experimental test with conventional plate fin, circular pin fins were done for the verification of the test setup results and their results were compared with results calculated from the standard correlations presented in previous well-known literature. The maximum heat transfer coefficient was found to be 12.80 W/m2K for drop form pin fins with vertical fin spacing (Sv ) equal to 75 mm, a diameter of 6 mm, and a length of 7.2 mm, and the corresponding Nusselt number was 94.85. Also, the maximum enhancement in Nusselt number was found to be (Nu/Nu plate fin) 3.11 corresponding to the conventional plate-fin heat sink. This comparison will help the industrialists determine innovative passive cooling technology for electronic devices such as LED street lights.

A numerical study of water based nanofluids in shell and tube heat exchanger

Abstract This numerical investigation is made to estimate the effect of Al2O3 and Cu nanofluids on heat transfer rate, friction factor and thermal performance factor of a shell and tube heat exchanger. Mass flow rates of shell side (water) fluid are varied. Water based nanofluids are used inside the tubes with 0.01, 0.03, and 0.05% volume concentrations of Al2O3 and Cu nanofluids. Nusselt number obtained from the present investigation is compared with Dittus–Bolter equation and Pongjet Pomvonge et al. and found to be in good agreement with a maximum deviation of 3%. The Nusselt number of the dispersed nanofluids increased with the increase of nanofluids volume concentrations and shell side mass flow rate. In this study, maximum enhancement in Nusselt number is 7.50%, 8.65%, and 9.61% for Al2O3, and 1.46%, 2.23%, and 3.18% for Cu nanofluid respectively at 0.01, 0.03, and 0.05% volume concentrations were compared to base fluid as water. Friction factor is highest by 58.00% at 0.05% volume concentration of Cu/H2O nanofluid when relate to Al2O3/H2O nanofluid. Thermal Enhancement factor achieved is highest for Al2O3/H2O nanofluid.

Comparative studies on convective heat transfer behaviour of nanofluids under turbulent flow with inserts

ABSTRACT In this paper, the thermal performance of novel spiraled rod inserts in the turbulent flow of Al2O3/water, CuO/water, and TiO2/water nanofluids through a circular tube with constant heat flux boundary conditions is compared. The nanofluids used in this study contain particle volume concentrations of 0.25 and 0.5%. According to the study's findings, nanofluids have a greater Nusselt number than deionised water. Among the nanofluids used, CuO nanofluid with a spiraled rod insert of the lesser pitch gives the maximum enhancement in Nusselt number, and the enhancement value is 49.6% for 0.5% volune concentration compared to deionised water. The increase in friction factor for the above condItion is 17.59%. The maximum thermal performance factor value with a pitch of 30 mm spiraled rod insert and 0.5% volume concentration of CuO nanofluids is about 1.41.The novelty of this present study is the simple and easily manufactured inserts used to enhance heat transfer.

Energy and exergy analysis of solar air heater with trapezoidal ribs based absorber: A comparative analysis

AbstractThe performance of a solar air heater (SAH) is computationally investigated in this study using COMSOL multiphysics software. The present study aims to enhance the performance of smooth SAH with the help of artificial roughness. To achieve the goal, trapezoidal ribs above (Model 1) and below (Model 2) the absorber were fixed. The thermo‐hydraulic characteristics of smooth SAH were compared with the thermo‐hydraulic performances of Model 1 and Model 2. The computations were made by varying the heat flux between 600 and 1000 W/m2, Reynolds number from 4000 to 7000, relative rib height (h/H) from 0.2 to 0.7, and a constant pitch of 15 mm. The maximum enhancement in Nusselt number (Nu) compared to smooth duct was 5.54 times for Model 1 and 5.42 times for Model 2 at a h/H = 0.7 at Re = 7000. The maximum increase in friction factor was 36.97 times more than the smooth duct. The thermal performance factor (TPF) at 1000 W/m2 ranged from 1.29 to 1.72 for Model 1 and 1.27 to 1.68 for Model 2. It is found that trapezoidal ribs of Model 1 with h/H of 0.6 has delivered a maximum TPF of 1.72 at Re = 7000. The optimized relative rib height was found to be 0.6. The maximum exergy efficiency of 10.40% was obtained for Model 1 with h/H of 0.6 and at 1000 W/m2.

Experimental investigation of heat transfer augmentation due to obstacles mounted in solar air heater duct

ABSTRACT In this paper, six different shape obstacles, namely, Isosceles trapezoid (Type 1), Triangular with curve apex (Type 2), Rectangular with chamfered edges (Type 3), Rectangular with curve edges (Type 4), Triangular with curve corner at bottom (Type 5) and Triangular shape (Type 6) have been tested in inline and staggered fashions in solar air heater (SAH) duct. This work aims to investigate the effect of obstacle shape on heat transfer and friction characteristics. All experiments have been carried out at eight different values of Reynolds number ranging from 2000 to 16000 and fixed value of heat flux of 1000 W/m2. As results, Nusselt number and friction factor characteristics have been presented and discussed. The maximum enhancement in Nusselt number and friction factor are observed in case isosceles trapezoid obstacles (Type 1) and rectangular with curve edges obstacles (Type 4) when mounted in staggered fashion, respectively and their respective average enhancement factor in Nusselt number and friction factor are observed as 2.95 and 4.37. Also, thermo-hydraulic performance parameter (η) of all obstacles in both arrangement have been evaluated and found to be average maximum values 1.88 in case of isosceles trapezoid obstacles (Type 1) in staggered manner.

Study on Performance Analysis of a Solar Air Heater with Aerofoil Shaped Rib Roughness Using CFD

Present study investigates the heat transfer, friction factor and fluid flow characteristics of fully developed turbulent flow in a rectangular duct of solar air heater having aerofoil shaped rib-roughness on underside of absorber plate. ANSYS 14.5 has been used to simulate air flow through roughened air heater duct. Effect of relative roughness height and roughness pitch on Nusselt number and friction factor of roughened duct have been investigated and compared with that of smooth duct. It is found that the Nusselt number improves by attaching the roughness. Maximum enhancement in Nusselt number has been found to be 3.15 times over the smooth duct for rib roughness pitch P=15 mm, rib height e=7 mm, relative roughness height e/Dh=0.128, and aspect ratio of duct W/H=10. It is observed that the thermo-hydraulic performance parameter for roughened duct is greater than that obtained for smooth duct.

Oriented square shaped pin-fin heat sink: Performance evaluation employing mixture based on ethylene glycol/water graphene oxide nanofluid

Based on effective heat dissipation in electronic devices, the current study deals with heat transfer characteristics of oriented square shaped pin fin heat sink having a fin angle of 22.5°. It has been investigated experimentally employing graphene oxide (GO) nanofluid under laminar flow regime. The performance of graphene oxide (GO) nanofluid having concentrations of 0.004%, 0.0065%, and 0.009 vol% is compared with a mixture of EG-water (50:50) as base fluid under three different heating powers of 20 W, 35 W, and 50 W. The experimental results revealed better thermal performance for all used concentrations of (GO) nanofluid compared to the base fluid due to the heat transfer augmentation and reduction in thermal resistance as a result of enhanced thermal conductivity of nanofluid. It was observed that the thermal performance of heat sink improved with increasing Reynolds number and heating power. Minimum wall temperature and maximum enhancement in Nusselt number of 30.75 °C and 19.68% respectively is associated with graphene oxide nanofluid having a concentration of 0.009 vol%. According to the results, nanofluid exhibited better trends of thermal enhancement in comparison of EG/water base fluid with an increase in nanoparticle concentration usually at low Reynolds number. Thus, graphene oxide nanofluid has proven to be the potential candidate for improving the thermal performance of heat sink.

A Numerical Simulation Study to Improve Heat Transfer Rate in a Double Pipe Heat Exchanger using Different ways.

In this work the thermo hydraulic performance of double pipe heat exchanger made of stainless-steel with inner and outer diameters are (11.43 and 16.83cm) respectively, 0.305cm thickness and150cm length, studied numerically by using Solid Works 2016 package. It is used to the purpose of preheat heavy fuel oil flow in the outer pipe by hot air flow inside the inner one. Helical tape with different pitches (11, 14, and 17) cm the inner side of the inner tube and helical fin with different fin spaces (10, 20, and 30) cm over the inner tube are used as an enhancement heat transfer device. The study was conducted with specific identifiers, Reynold’s number (Re) values are (31668, 47361, 63008, 78589) for air side (inner tube), oil inlet temperature is (313) K and flow with rate of oil (0.1 and 0.06 kg/s). The results were first verified by using both the inner helical tape and outer helical fin separately and comparing the results of them with the plain tube, and then combining each of the helical tape and helical fin together and indicating the improvement in heat transfer rate, the result show that the maximum heat transfer is (4559.726 W) obtained by merged the helical tape with smaller pitch (11 cm) and helical fin with low fin pitch (10 cm) at oil flow rate (0.1 kg/s) as compared with (2052.385W) for plain tube, the maximum enhancement percentage in heat transfer rate and overall heat transfer coefficient were is (122.167 % and 142.941%) at the same conditions. The maximum enhancement in Nusselt number (Nu) and convection heat transfer coefficient were (224.572 % and 129.523 % W/m2. K) respectively were achieved by using helical tape with pitch (11 cm). At higher Reynolds number, the higher-pressure drop for air side is (7437.8 pa) obtained when using minimum pitch for helical tape and it is (1086.26 pa) for oil side by using helical fin with pitch (10 cm).

Study of solar air heater with discrete arc ribs geometry: Experimental and numerical approach

In design of Solar Air Heaters (Sol-AHs) duct, the most efficient way to enhance the heat transfer is by providing artificial roughness on the absorber plate. In the present paper, experimental analyses perform on solar air heater (Sol-AHs) with novel discrete symmetrical arc rib geometry. The studied parameters are ratio of gap width to rib element diameter (g/e) of 2, 3, 4 and 5, ratio of rib diameter height to hydraulic diameter (e/Dh) as 0.045, ratio of rib pitch to rib element diameter as 10, air flow angle of attack as 30°, number of gaps 3 and Re in range of 3000–14000. The performance of novel discrete arc rib solar air heater has been compared with existing staggered V-rib geometry. Maximum enhancement in Nusselt number achieves at g/e equal to 4, which is 3.88 times more compared to the smooth plate, while the highest increment in the thermo-hydraulic performance also observes at g/e of 4. Correlations have been developed for ratio of gap width to rib element diameter and flow parameters. The mathematical model has been developed using a MATLAB code and validates with an experimental study, which further use to design the Solar Air Heater (Sol-AHs) under various operating parameters. Moreover, the new discrete symmetrical arc rib geometry has better performance than the existing best novel V-rib geometry.

Comparative studies on air, water and nanofluids based Rayleigh–Benard natural convection using lattice Boltzmann method: CFD and exergy analysis

The present study incorporates laminar natural convection and entropy generation in Rayleigh–Benard (R–B) convection with air, water and alumina–water nanofluid as working fluids. The fluid flow and energy equations are solved using D2Q9 and D2Q5 LBM models, respectively. The effects of Rayleigh numbers (Ra = 5 × 103, 104, 105) and volume fractions ( $$\emptyset$$ = 0 to 0.08) of nanoparticles on heat transfer and irreversibility are investigated. Results show that the heat transfer evaluated based on Nusselt number is enhanced due to addition of nanoparticles in the base fluid. The maximum enhancement in Nusselt number is found to be 13.93% at Ra = 105 with 8% of nanoparticle in base fluid. The various irreversibilities considered in this study are thermal, fluid flow and total irreversibility, where fluid flow and total irreversibilities in the study depend on irreversibility ratio. The irreversibility ratios taken into account are 10–2, 10–3, 10–4 and 10–5. One facet of study shows the deviation in onset of critical Rayleigh number for air is 1.58%. The other facet indicates dimensionless heat transfer, fluid flow and total irreversibility decrease with the increase in volume fraction of nanoparticles in the base fluid. The analyzed results of irreversibilities are presented in normalized form. In addition, dimensionless entropy generation maps and Bejan number contours are also plotted.

Numerical investigation of heat transfer and pressure drop for cooling of microchannel heat sink using MWCNT-CuO-Water hybrid nanofluid with different mixture ratio

Micro-channel heat sinks are gaining prominent importance in cooling of micro-electronic devices due to their high rate of heat dissipation and very high surface area. Also during the recent times, hybrid nanofluids have appeared as a innovative group of working fluids for many heat transfer applications owing to special heat carrying characteristics. In view of the importance, a numerical study is carried out to examine the heat transfer and pressure drop characteristics for laminar flow of hybrid nanofluid as a coolant in a circular micro-channel heat sink (MCHS) under forced convection conditions in the present work. The performance of heat sink is evaluated using Multi-Walled Carbon Nano Tubes (MWCNT)-CuO/water based hybrid nanofluid for different mass flow rates, with the volume fractions ranging from 1% to 3%. The law of mixtures and correlations existing in the literature are used to find the properties of hybrid nanofluids. The influence of Reynolds number on pumping power and the heat transport rate is studied for different mixture ratios of MWCNT-CuO/water based hybrid nanofluids and similar studies were carried out for MWCNT-water and CuO-water mono fluids. The results show a step up in heat transfer with hybrid nanofluids over mono nanofluids and the enhancement of heat transfer is observed with raise in volume fraction. The maximum enhancement in Nusselt number was found at 3% of hybrid MWCNT-CuO/water nanofluid. An enhancement of 4.68% and 12.64% was found, when compared with CuO/water and MWCNT/water mono nonofluids respectively. The pressure drop results indicate that hybrid MWCNT-CuO/water nanofluid possess less pressure drop when compared to CuO/water nanofluids and when compared to water an increase of pressure drop of 300 Pa was found. This indicates that there is no significant increase in pumping power with hybrid nanofluids compared to mono-nanofluids and water. The present model is validated by comparing the numerical results got for mono nanofluid with the data available in literature.

Experimental investigation on thermo-physical properties and heat transfer characteristics of green synthesized highly stable CoFe2O4/rGO nanofluid

The application of spinel ferrite decorated graphene hybrids in heat transfer has been limited mostly due to their poor stability in water. This study reports a straightforward strategy to synthesis a cobalt ferrite/reduced graphene oxide (CoFe2O4/rGO) nanocomposite with high water dispersibility characteristics through the treatment of synthesized hybrid material with Gallic acid (GA) as a green agent at room temperature. A π-π interaction between graphene and the aromatic ring of GA results in a suspension with high stability. The structure of the nanocomposite was investigated in detail by FTIR, XRD, TGA, VSM, Raman spectroscopy, FESEM, and TEM. Also, UV–vis spectroscopy is used to examine the stability of the stability of the CoFe2O4/rGO in the base fluid. The highly stable aqueous nanofluids were subsequently prepared from the products. Thermo-physical analyses of nanofluids revealed that the thermal conductivity ratio of ferrofluid prepared by the obtained CoFe2O4/rGO with 0.9 wt.% load of nanoparticles at 60 °C is rose to 1.46. Besides, the convective heat transfer in laminar flow regime conditions which passes a circular tube under uniform heat flux was examined. The nanofluid with the highest load of nanoparticles (0.9 wt.%) shown the maximum enhancement in Nusselt number of 27.8 % at Reynolds number of 1713.

Analysis of hydro-thermal and entropy generation characteristics of nanofluid in an aluminium foam heat sink by employing Darcy-Forchheimer-Brinkman model coupled with multiphase Eulerian model

The efficiency and the operational life of the modern high-tech electronics are essentially dependent on their effective thermal management. The metal foam heat sinks cooled by nanofluid are the potential candidate for electronic cooling applications. Therefore, this study investigates the hydrothermal and entropy generation aspects of nanofluid in an aluminum foam heat sink. The multiphase Eulerian model couple with the Darcy-Forchheimer-Brinkman model was introduced to model nanofluid in the metal foam. The performance of nanofluid dependent on substrate porosity and nanoparticles is analyzed for porosity and Reynolds number ranges of 0.5–0.8 and 600–1800, respectively. The probed nanofluid sample consisted of a 0.5% volume fraction of aqueous-based alumina nanoparticles with 40 nm diameter. The hydrothermal results are evaluated in terms of average Nusselt number, local heat transfer coefficient, pumping power and performance evaluation criteria of the heat sink. Additionally, the fluid dynamics and surface temperature distribution across the heat sink are illustrated with velocity streamlines, velocity, and thermal contours. The entropy generation aspects are discussed in the form of thermal, viscous and total entropy parameters. The results demonstrate that the heat transfer enhancement of the nanofluid is optimized by increasing the substrate porosity at the expense of the least pressure drop. The effect of media permeability on the performance of the nanofluid is more evident at a larger Reynolds number. At the Reynolds number of 1800, utilization of the nanofluid resulted in the maximum Nusselt number enhancement of 5%, 15% and 33% for the foam porosities of 0.5, 0.7 and 0.8, respectively.

Heat Transfer and Friction Factor Correlations for Solar Air Heater With Gap in V-Rib With Symmetrical Gap and Staggered Ribs

Abstract The present experimental study is concerned with heat transfer analysis of air flowing in solar air heater duct with a gap in V-rib with symmetrical gap and staggered ribs geometry. The investigated parameters are Reynolds number (Re) of 4000–14,000, relative roughness pitch (p/e) of 12, relative roughness height (e/Dh) of 0.043, angle of attack (α) of 60 deg, relative staggered rib pitch (p′/p) of 0.65, relative gap size (g/e) of 4, relative staggered rib size (r/e) of 4, relative gap position of additional gap in each symmetrical rib elements (d/w) of 0.65, relative gap size of additional gap in each symmetrical rib elements (g′/e) of 1, number of main gaps (Ng) of 1, 2, 3, 4, and number of additional gap (ng) varying from 1 to 5. Fourteen roughened absorber plates were tested. The maximum enhancement in Nusselt number (Nu) and friction factor (f) was 2.34 and 2.79 times that of smooth surface corresponding to the number of main gaps (Ng) of 4 with the number of additional gaps (ng) of 4. The performance of the gap in V-rib with symmetrical gap and staggered rib geometry has been compared with the existing latest V-rib geometry and smooth surface. The proposed gap in V-rib with symmetrical gap and staggered ribs geometry has a better performance than the existing latest V-rib geometry. The following correlations have been developed for heat transfer and friction factor in terms of roughness and operating parameters. Heat transfer:Nur=0.0073(Re)0.9788(Ng)0.2790(ng)0.0184exp[−0.1678(ln(Ng))2]exp[−0.0129(ln(ng))2] Friction factor:fr=0.0477(Re)−0.0678(Ng)0.5919(ng)−0.0562exp[−0.4922(ln(Ng))2]exp[−0.0487(ln(ng))2]

What dominates heat transfer performance of hybrid nanofluid in single pass shell and tube heat exchanger?

Influence of nanoparticle volume concentration and proportion on heat transfer performance (HTP) of Al2O3 – Cu/water hybrid nanofluid in a single pass shell and tube heat exchanger is analyzed. Multiphase mixture model is adopted to model the flow. Three-dimensional governing equations and associated boundary conditions are solved using finite volume method. The numerical results are validated with the experimental results. Results indicate that optimized nanoparticle volume concentration and proportion dominate HTP of hybrid nanofluid. Heat transfer coefficient and Nusselt number are monotonic increase functions of nanoparticle volume concentration and proportion. The percentage increase in heat transfer coefficient of hybrid nanofluid is 139% than water and 25% than Cu/water nanofluid. At higher Reynolds number, the increment in Number of Transfer Units (NTU) between water and hybrid nanofluid is close to 75%. Maximum enhancement in Nusselt number for hybrid nanofluid exceeds 90% when compared to nanofluid (Al2O3/Water nanofluid). Consequently, highest heat transfer performance is attained for hybrid nanofluid systems. Effectiveness of heat exchanger increases almost to 124% when hybrid nanofluid is employed. We show that it is higher than water as well (conventional coolant). Results are expected to be helpful in further industrial-scale deployment of nanofluids, which is an area that is currently relevant for ongoing academia-industry partnership efforts worldwide.