Silver–water nanofluid flow and convective heat transfer in a microfin tube equipped with loose-fit twisted tapes

Heat transfer enhancement and performance of compact heat exchangers have been extensively studied in the past century for the purpose of promoting energy efficiency. Microfin tubes in single/two/multiple-phase flow heat exchangers into which twisted tape swirl generators are installed can promote heat transfer with a moderate pressure loss penalty. This article reports on the enhanced heat transfer of silver–water nanofluids in a microfin tube into which loose-fit twisted tapes are installed in a counter-flow arrangement. The experiments were carried out using nanofluids with various silver concentrations (0.007–0.03 vol%), loose-fit twisted tapes with clearance ratios (c/D) of 0.0 (tight-fit), 0.05, 0.075 and 0.1, for a twist ratio, y/W, of 2.0. The results indicate that the heat transfer rate (Nu) and pressure drop (f) increase with a decrease in clearance ratio (c/D) and increase in silver (Ag) nanoparticle concentration. Additionally, the thermal performance factor tends to increase with the decrease in Reynolds numbers.

     

Effect of magnetic field on laminar forced convective heat transfer of MWCNT–Fe3O4/water hybrid nanofluid in a heated tube

Journal of Thermal Analysis and Calorimetry - A numerical investigation is carried out to assess the hydrothermal performance of a water-based hybrid nanofluid containing both Fe3O4 (magnetite)...     

Heat transfer enhancement in hydromagnetic alumina–copper/water hybrid nanofluid flow over a stretching cylinder

Journal of Thermal Analysis and Calorimetry - In the current study, heat transfer performances and flow characteristics of alumina–copper/water (Al2O3–Cu/H2O) hybrid nanofluid over a...     

Application of SiO2–water nanofluid to enhance oil recovery

The present study aims to investigate effects of nanofluid flooding on EOR and also compares its performance with water flooding in field scale using the published experimental data provided from core-scale studies. The nanofluid is based on water including silica nanoparticles. The relative permeability curves of water, nanofluid and oil for a light crude oil core sample obtained in an experimental study are used in this numerical investigation. A 2D heterogeneous reservoir model is constructed using the permeability and porosity of the last layer of SPE-10 model. It has been shown that nanofluid flooding can substantially improve the oil recovery in comparison with the water flooding case. Afterward, the operational parameters of the 13 injection and production wells have been optimized in order to meet the maximum cumulative oil production. First, pattern search (PS) algorithm was implemented which has a good convergence speed, but with a high probability of trapping in local optimum points. Particle swarm optimization (PSO) approach has also been employed, which requires a large number of population (to approach the global optimum) with so many simulations. Accordingly, a hybrid PSO–PS algorithm with confined domain is proposed. The hybrid algorithm starts with PSO and depending on the distribution density of the values of each parameter, confines the searching domain and provides a proper initial guess to be used by PS. It is concluded that the hybrid PSO–PS method could obtain the optimal solution with a high convergence speed and reduced possibility of trapping in local optimums.

     

An experimental investigation on the heat transfer characteristics of closed-loop pulsating heat pipe with graphene–water nanofluid

Journal of Thermal Analysis and Calorimetry - The heat transfer performance of a closed-loop pulsating heat pipe (CLPHP) having 2.2 mm inner diameter is experimentally studied at different...     

Experimental analyses on heat transfer performance of TiO2–water nanofluid in double-pipe counter-flow heat exchanger for various flow regimes

Journal of Thermal Analysis and Calorimetry - Nanofluids are widely used in heat transfer applications. This article presents the effect of heat transfer and pressure drop of the TiO2–water...     

Free convection of copper–water nanofluid in a porous gap between hot rectangular cylinder and cold circular cylinder under the effect of inclined magnetic field

Journal of Thermal Analysis and Calorimetry - Natural convection heat transfer of copper–water nanofluid in a porous gap between hot internal rectangular cylinder and cold external circular...     

Simulation of the heat transfer performance of Al2O3–Cu/water binary nanofluid in a homogenous copper metal foam

Journal of Thermal Analysis and Calorimetry - The present study analyzed the behavior of a hybrid nanofluid with the aim of improving its heat transfer in tubes filled with a porous medium, which...     

Experimental investigation of TiO2–water nanofluid flow and heat transfer inside wavy mini-channel heat sinks

Journal of Thermal Analysis and Calorimetry - The present study comprises experimental investigation on heat transfer and hydrodynamic characteristics of TiO2 nanofluid as coolant in wavy channel...     

Melting heat transfer in squeezing flow of basefluid (water), nanofluid (CNTs + water) and hybrid nanofluid (CNTs + CuO + water)

Journal of Thermal Analysis and Calorimetry - Unsteady squeezed flow of hybrid nanofluid is investigated in this analysis. Comparison of hybrid nanofluid (using CNTs?+?CuO) and...     

Entropy generation on magneto-convective flow of copper–water nanofluid in a cavity with chamfers

Journal of Thermal Analysis and Calorimetry - The irreversibility in convective nanofluid flow in the occurrence of a magnetic field (MHD) in a cavity with chamfers is calculated by numerical...     

Effect of volume concentration and temperature on viscosity and surface tension of graphene–water nanofluid for heat transfer applications

In the present study, the effect of volume concentration (0.05, 0.1 and 0.15 %) and temperature (10–90 °C) on viscosity and surface tension of graphene–water nanofluid has been experimentally measured. The sodium dodecyl benzene sulfonate is used as the surfactant for stable suspension of graphene. The results showed that the viscosity of graphene–water nanofluid increases with an increase in the volume concentration of nanoparticles and decreases with an increase in temperature. An average enhancement of 47.12 % in viscosity has been noted for 0.15 % volume concentration of graphene at 50 °C. The enhancement of the viscosity of the nanofluid at higher volume concentration is due to the higher shear rate. In contrast, the surface tension of the graphene–water nanofluid decreases with an increase in both volume concentration and temperature. A decrement of 18.7 % in surface tension has been noted for the same volume concentration and temperature. The surface tension reduction in nanofluid at higher volume concentrations is due to the adsorption of nanoparticles at the liquid–gas interface because of hydrophobic nature of graphene; and at higher temperatures, is due to the weakening of molecular attractions between fluid molecules and nanoparticles. The viscosity and surface tension showed stronger dependency on volume concentration than temperature. Based on the calculated effectiveness of graphene–water nanofluids, it is suggested that the graphene–water nanofluid is preferable as the better coolant for the real-time heat transfer applications.     

Entropy generation of turbulent Cu–water nanofluid flow in a heat exchanger tube fitted with perforated conical rings

Entropy generation analysis for the Cu–water nanofluid flow through a heat exchanger tube equipped with perforated conical rings is numerically investigated. Frictional and thermal entropy generation rates are defined as functions of velocity and temperature gradients. Governing equations are solved by using finite volume method, and Reynolds number is in the range of 5000–15,000. The effects of geometrical and physical parameters such as Reynolds number, number of holes and nanoparticles volume fraction on the thermal and viscous entropy generation rates and Bejan number are investigated. The results indicate that the thermal irreversibility is dominant in most part of the tube. But it decreases with increasing the nanoparticle volume fraction. Frictional entropy generation reduces with increasing the number of holes from 4 to 10. This is because of stronger velocity gradient near the perforated holes. Bejan number decreases with augment of Reynolds number.

     

Effects of novel hybrid nanofluid (TiO2–Cu/EG) and geometrical parameters of triangular rib mounted in a duct on heat transfer and flow characteristics

Journal of Thermal Analysis and Calorimetry - Heat transfer and flow characteristics have been numerically analyzed by using four different fluids [pure ethylene glycol (EG), TiO2/EG and Cu/EG...     

Comparative study of mixed convection heat transfer of water–Cu nanofluid in an enclosure having multiple rotating circular cylinders with different configurations and considering harmonic cylinders rotation

Journal of Thermal Analysis and Calorimetry - In the present study, heat transfer in a lid-driven square cavity in the existence of four rotating cylinders having harmonic motion was investigated...     

Adsorption of carbon oxide on tetrahedral bimetallic gold–copper clusters

The interaction between carbon oxide and [Au_20–nCu_n]_q clusters (n = 0, 1, 19, 20 and q = 0, ±1) is studied by means of DFT/PBE in the scalar relativistic approximation. To establish the composition and structure of an adsorption site, isomers of bimetallic Au₁₉Cu and AuCu₁₉ particles with different positions of the heteroatom at an apex, edge, and face of the tetrahedral framework are considered. The optimized structures are used as the basis to determine the electronic properties of clusters (average bond energy per atom, difference of energies between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), ionization potential, electron affinity energy). The calculated parameters shrink as the copper content in clusters grows. Among the uncharged models, the highest CO adsorption energy is typical of Au₁₉Cu, the heteroatom of which lies at a cluster’s apex. The CO adsorption energy for cationic and anionic clusters grows in comparison to neutral clusters.     

ANN modeling,cost performance and sensitivity analyzing of thermal conductivity of DWCNT–SiO2/EG hybrid nanofluid for higher heat transfer

Journal of Thermal Analysis and Calorimetry - In this study, the thermal conductivity of SiO2–DWCNT/ethylene glycol hybrid nanofluid has been experimentally investigated on 0.03–1.71%...     

MHD free convection heat transfer of a water–Fe3O4 nanofluid in a baffled C-shaped enclosure

Journal of Thermal Analysis and Calorimetry - In this paper, the effect of a baffle on free convection heat transfer of a water–Fe3O4 nanofluid in a C-shaped enclosure in the presence of a...     

Wall properties and convective conditions in MHD radiative peristalsis flow of Eyring–Powell nanofluid

Journal of Thermal Analysis and Calorimetry - Present study examines the impacts of wall flexibility on MHD peristaltic flow of Eyring–Powell nanofluid with convective conditions. No slip...