Numerical investigation of turbulent CuO–water nanofluid inside heat exchanger enhanced with double V-cut twisted tapes

Journal of Thermal Analysis and Calorimetry - This numerical investigation aims to study the turbulent characteristics and thermal enhancement parameter of CuO–water nanofluids through heat...     

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.

     

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...     

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.

     

Entropy analysis of a hydromagnetic micropolar dusty carbon NTs-kerosene nanofluid with heat generation: Darcy–Forchheimer scheme

Journal of Thermal Analysis and Calorimetry - The current paper on carbon nanotubes suspended magnetohydrodynamics micropolar dusty nanofluid impinging on a permeable extending sheet placed in a...     

Entropy generation in electrical magnetohydrodynamic flow of Al2O3–Cu/H2O hybrid nanofluid with non-uniform heat flux

Journal of Thermal Analysis and Calorimetry - This paper explores the influence of entropy production on MHD hybrid nanofluid (Al2O3–Cu/H2O) flow due to permeable stretching sheet with...     

Role of entropy generation on thermal management of a porous solar collector using Al2O3–Cu/water nanofluid and magnetic field

Journal of Thermal Analysis and Calorimetry - The purpose of this study is a presentation of the thermal management of a flat plate solar collector via employing entropy generation analysis. The...     

Thermal–hydraulic efficiency management of spiral heat exchanger filled with Cu–ZnO/water hybrid nanofluid

Journal of Thermal Analysis and Calorimetry - In this paper, the effect of different channel spacing in spiral heat exchanger filled with Cu–ZnO–water hybrid nanofluid was investigated...     

Entropy analysis of Powell–Eyring hybrid nanofluid including effect of linear thermal radiation and viscous dissipation

Journal of Thermal Analysis and Calorimetry - Hybrid nanofluids are introduced as heat transfer fluids with greater surface stability, diffusion and dispersion capabilities compared to traditional...     

Effects of partial slip on entropy generation and MHD combined convection in a lid-driven porous enclosure saturated with a Cu–water nanofluid

Journal of Thermal Analysis and Calorimetry - In this work, the influences of heat generation/absorption and nanofluid volume fraction on the entropy generation and MHD combined convection heat...     

Numerical investigation and multi-criteria optimization of the thermal–hydraulic characteristics of turbulent flow in conical tubes fitted with twisted tape insert

Journal of Thermal Analysis and Calorimetry - The ever-growing interest in developing compact and more effective heat exchangers necessitates the investigation of combined passive solutions....     

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...     

MHD mixed convection in an inclined cavity containing adiabatic obstacle and filled with Cu–water nanofluid in the presence of the heat generation and partial slip

Journal of Thermal Analysis and Calorimetry - In the present paper, the performance of the graphene oxide in the solar steam generation has experimentally been examined. For this purpose, a setup...     

Numerical simulation of transient mixed convection of water–Cu nanofluid in a square cavity with multiple rotating cylinders having harmonic motion

Journal of Thermal Analysis and Calorimetry - Mixed convection in a lid-driven square cavity with different walls temperature in the existence of four rotating cylinders having harmonic motion is...     

Experimental investigation and modeling of thermal conductivity of CuO–water/EG nanofluid by FFBP-ANN and multiple regressions

The purpose of this study is to predict the thermal conductivity of copper oxide (CuO) nanofluid by using feed forward backpropagation artificial neural network (FFBP-ANN). Thermal conductivity of CuO nanofluid is measured experimentally using transient hot-wire technique in temperature range of 20–60 °C and in volume fractions of 0.00125, 0.0025, 0.005 and 0.01% for neural network training and modeling. In addition, in order to evaluate accuracy of modeling in predicting the coefficient of nanofluid thermal conductivity, indices of root-mean-square error, coefficient of determination (R ²) and mean absolute percentage error have been used. FFBP-ANN with two input parameters (volume fraction and nanofluid temperature) and one output parameter (nanofluid thermal conductivity) in addition to two hidden layers and one outer layer which purelin, logsig and tansig functions are used was considered as the most optimum structure for modeling with neuron number of 4–10–1. In this study, among common methods of theoretical modeling of nanofluid thermal conductivity, theoretical method of Maxwell and also multivariate linear regression model was used for explaining the importance of modeling and predicting the results using neural network. According to this research, the results of indices and predictions show high accuracy and certainty of ANN modeling in comparison with empirical results and theoretical models.     

Entropy generation of graphene–platinum hybrid nanofluid flow through a wavy cylindrical microchannel solar receiver by using neural networks

Journal of Thermal Analysis and Calorimetry - Analyzing microchannel heat sinks (MCHS) in terms of the second thermodynamic law is useful, and it is necessary to examine MCHSs in terms of...     

Effect of MWCNT–Fe3O4/water hybrid nanofluid on the thermal performance of ribbed channel with apart sections of heating and cooling

Journal of Thermal Analysis and Calorimetry - A two-dimensional (2D) numerical simulation is performed to simulate the laminar forced convection of a nanofluid in a ribbed channel with apart...     

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.