Saiied M. Aminossadati

Natural Convection Heat Transfer in an Inclined Enclosure Filled with a Water-Cuo Nanofluid

This article presents the results of a numerical study on natural convection heat transfer in an inclined enclosure filled with a water-CuO nanofluid. Two opposite walls of the enclosure are insulated and the other two walls are kept at different temperatures. The transport equations for a Newtonian fluid are solved numerically with a finite volume approach using the SIMPLE algorithm. The influence of pertinent parameters such as Rayleigh number, inclination angle, and solid volume fraction on the heat transfer characteristics of natural convection is studied. The results indicate that adding nanoparticles into pure water improves its heat transfer performance; however, there is an optimum solid volume fraction which maximises the heat transfer rate. The results also show that the inclination angle has a significant impact on the flow and temperature fields and the heat transfer performance at high Rayleigh numbers. In fact, the heat transfer rate is maximised at a specific inclination angle depending on Rayleigh number and solid volume fraction.

A Numerical Study on the Forced Convection of Laminar Nanofluid in a Microchannel with Both Slip and No-Slip Conditions

This article provides numerically study of the thermal performance of a microchannel, cooled with either pure water or a Cu-water nanofluid, while considering the effects of both slip and no-slip boundary conditions on the flow field and heat transfer. The microchannel is partially heated at a constant temperature and cooled by forced convection of a laminar flow at a relatively lower temperature. The effects of pertinent parameters such as Reynolds number, solid volume fraction, and slip velocity coefficient on the thermal performance of the microchannel are studied. The results of the numerical simulation indicate that the heat transfer rate is significantly affected by the solid volume fraction and slip velocity coefficient at high Reynolds numbers.

Enhanced natural convection in an isosceles triangular enclosure filled with a nanofluid

Natural convection is studied in an isosceles triangular enclosure with a heat source located at its bottom wall and filled with an Ethylene Glycol-Copper nanofluid. This paper examines the effects of pertinent parameters such as the Rayleigh number, the solid volume fraction, the heat source location, and the enclosure apex angle on the thermal performance of the enclosure. The thermal performance of the enclosure is improved with an increase in the Rayleigh number and solid volume fraction. The results also show that the variation of heat transfer rate with respect to the enclosure apex angle and heat source position and dimensions is different at low and high Rayleigh numbers. A comparison is also presented between the results obtained from the modified and original Maxwell models. The results show that the heat transfer is generally higher based on the modified Maxwell model.

Comparison of Mixed Convection in a Square Cavity with an Oscillating versus a Constant Velocity Wall

This article presents a numerical investigation of unsteady laminar mixed convection heat transfer in a two-dimensional square cavity. The cavity is configured such that one of the vertical walls is cooled and slides either with a constant speed or with a sinusoidal oscillation. A portion of the opposite stationery wall is heated by a constant temperature heat source while, the remaining walls of the cavity are thermally insulated. Different configurations of sliding wall movement and a series of Richardson numbers and Strouhal numbers are tested. The results indicate that the direction and magnitude of the sliding wall velocity affect the heat transfer rate. At low Richardson numbers, the average heat transfer rate for the cavity with an oscillating wall is found to be lower compared to that for the cavity with a constant velocity wall. In addition, at a fixed Richardson number, as the Strouhal number decreases the oscillation frequency of average Nusselt number on the vertical walls decreases; however, the oscillation amplitude of average Nusselt number increases.

Conjugate natural convection in an inclined nanofluid‐filled enclosure

Purpose – The purpose of this paper is to numerically examine the conjugate natural convection in an inclined enclosure with a conducting centred block. This enclosure is filled with an Ethylene Glycol‐copper nanofluid. This study utilises numerical simulations to quantify the effects of pertinent parameters such as the Rayleigh number, the solid volume fraction, the length and the thermal conductivity of the centred block and the inclination angle of the enclosure on the conjugate natural convection characteristics.Design/methodology/approach – The SIMPLE algorithm is utilised to solve the governing equations with the corresponding boundary conditions. The convection‐diffusion terms are discretised by a power‐law scheme and the system is numerically modelled in FORTRAN.Findings – The results show that the utilisation of the nanofluid enhances the thermal performance of the enclosure and that the length of the centred block affects the heat transfer rate. The results also show that the higher block therma...

An Artificial Neural Network Approach to Cooling Analysis of Electronic Components in Enclosures Filled With Nanofluids

Computational fluid dynamics (CFD) and artificial neural network (ANN) are used to examine the cooling performance of two electronic components in an enclosure filled with a Cu-water nanofluid. The heat transfer within the enclosure is due to laminar natural convection between the heated electronic components mounted on the left and right vertical walls with a relatively lower temperature. The results of a CFD simulation are used to train and validate a series of ANN architectures, which are developed to quickly and accurately carry out this analysis. A comparison study between the results from the CFD simulation and the ANN analysis indicates that the ANN accurately predicts the cooling performance of electronic components within the given range of data. ©2011 American Society of Mechanical Engineers

An experimental study on aerodynamic performance of turbine nozzle guide vanes with trailing-edge span-wise ejection

The present experimental study is to examine the influence of trailing-edge coolant ejection with the span-wise inclination on the aerodynamic loss of turbine nozzle guide vanes. This study uses a cascade of five vanes located in the test section of a low-speed wind tunnel. The vanes have the profile of high-pressure nozzle guide vanes, and the central vane is equipped with the internal cooling and the trailing-edge coolant ejection. The coolant is ejected through trailing-edge slots that are inclined in the span-wise direction at angles varying from 0 deg to 45 deg in 15 deg increments. The results indicate an optimum ejection rate, at which the aerodynamic loss is minimum. There is a little variation in loss as the span-wise inclination is varied when the ratio of coolant to mainstream gas mass flow rate is less than 1.5%. For higher coolant flow rates, however, the loss increases with increases in the span-wise ejection angle.

A microfabricated fibre optic sensor for methane gas measurement in underground coal mines

The mining industry requires a reliable system to accurately and safely measure methane concentrations at various locations in underground coal mines. This paper aims to investigate the potential for an all-fibre optic based methane sensor. Various types of all-fibre sensors are studied and side drilled hollow core fibres have been experimentally tested. The results show that hollow core fibre has the potential to be developed as a methane sensor and implemented in an underground coal mine environment to accurately and safely measure methane concentrations with acceptable response time and accuracy.

Magnetohydrodynamic Mixed Convection of a Cu-Water Nanofluid in a Vertical Channel

This technical brief numerically examines the mixed convection heat transfer of a Cu-water nanofluid in a parallel-plate vertical channel that is influenced by a magnetic field. An upward flow of Cu-water nanofluid enters the channel at a relatively low temperature and a uniform velocity. It is found that the magnetic field has dissimilar effects on the heat transfer rate at different Richardson numbers. The increase of solid volume fraction results in an increase of the heat transfer rate especially at low Richardson numbers.

Fibre Optic Sensing Based Slope Crest Tension Crack Monitoring System for Surface Mines

The stability of slopes in surface mines is of high concern due to the risk to both personnel and excavation plant. A variety of slope stability monitoring systems have been developed and implemented in the industry in order to predict slope failures before they occur and to minimise the damage to peopleand plant. This paper examines the technical challenges of the current slope tension crack monitoringsystems and demonstrates the feasibility of an innovative FBG-based crack sensing system. The results of preliminary experiments show that with the application of the mechanical displacement converter, the slope crack generation can be measured using FBG strain sensors.