Speaker
Konstantinos Kouloulias
(Department of Mechanical Engineering)
Description
Increased cooling performance is eagerly required by the cutting edge engineering and industrial technology. Nanofluids have attracted considerable interest due to their potential to enhance the thermal performance of conventional heat transfer fluids. However, heat transfer in nanofluids is a controversial research theme as there is yet no conclusive answer to explain the underlying heat transfer mechanisms. The purpose of this study is to investigate the physics behind the heat transfer behavior of Al2O3 – deionised (DI) H2O nanofluids under natural convection. A high spatial resolution flow visualisation method (Particle Image Velocimetry - PIV) is employed in dilute nanofluids inside a classical Rayleigh-Benard configuration with appropriate optical access. The resulting mean and instantaneous velocity and flow structures of nanofluids and their overall heat transfer performance are compared with those of pure DI water, under a broad range of Rayleigh numbers. In this way, the possible modification of flow structures due to the addition of nanoparticles will be evaluated and its potential influence on the heat transfer rate in nanofluids assessed. Additional comparisons between current experiments and numerical studies of different modelling approaches and boundary conditions will be reported to assess the accuracy of the numerical and analytical tools. This paper aims to identify the contribution of the suspended nanoparticles on the heat and mass transfer mechanisms in low flow velocity applications, such as natural convection. In addition, the outcome of the current research is a first step towards the evaluation of the applicability of nanofluids in applications where more complex heat transfer modes, namely boiling and Critical Heat Flux, are involved that are of great importance for the cooling of Fusion reactors.
Co-authors
Antonis Sergis
(Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, United Kingdom)
Konstantinos Kouloulias
(Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, United Kingdom)
Yannis Hardalupas
(Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, United Kingdom)
