Helical coil heat exchangers are widely used in industrial applications ranging fromcryogenic processes, air-conditioning, and nuclear reactors to waste heat recovery due totheir compact size and high heat transfer coefficient. In this kind of heat exchangers, flowand heat transfer are complicated. This paper reports a numerical investigation of theinfluence of different parameters such as coil...

In this study, condensation heat transfer coefficients of R-410A were obtained in flattened stainless tubes made from 5.0 mm inner diameter round tubes. The test range covered saturation temperature 45 , heat flux 10 °C kW/m, mass flux 100~400 kg/ms and quality 0.2~0.8. Results showed the effect of aspect ratio on condensation heat transfer coefficient was dependent on the flow pattern. For ann...

The present study deals with the analysis of the effects of radiative heat transfer of micropolar fluid flow over a porous and stretching sheet in the presence of magnetic field. The dynamic viscosity and thermal conductivity coefficient have formulated by temperature-dependent relations to obtain more exact results. The flow is supposed two-dimensional, incompressible, steady and laminar and t...

the present work is an experimental study of steady state convective heat transfer of de-ionized water with a (0.04% by volume) volume fraction of al2o3 nanoparticles dispersed to form a nanofluid that flows through an aluminium tube.laminar fully developed flow heat transfer coefficient of al2o3 nanoparticles are dispersed in water in circular tube is discussed in this paper. in order to valid...

the presence of particles in liquid-solid fluidized beds enhances the bed heat transfer, because the movement of the particles leads to an increased turbulence in the system. moreover, the violent movement of the particles has a positive effect on fouling of the heat transfer surface. the aim of this investigation was to perform systematic measurements of bed voidage and heat transfer coefficie...

In the current study, non-Newtonian flow pattern and heat transfer in an enclosure containing a tilted square are examined. In order to numerically simulate the problem, the mesoscopic lattice Boltzmann method is utilized. The non-Newtonian Carreau-Yasuda model is employed. It is able to adequately handle the shear-thinning case. The simulation results of flow and heat transfer have been ...

Using of nanofluids and ducts with corrugated walls are both supposed to enhance heat transfer, by increasing the heat transfer fluid conductivity and the heat transfer area respectively. Use of a diverging duct with a jet at inlet section may further increase heat transfer by creating recirculation zones inside the duct. In this work two-dimensional incompressible laminar flow of a nanofluid e...

the present experimental study reports on enhancement of heat transfer by addition of nanoparticles to the working fluid of commercial swimming pool heat exchangers under laminar flow condition. three different concentrations of titanium dioxide nanoparticles were added to the water as working fluid of a typical forced convective heat exchanger used to transfer heat to public swimming pools. th...

The present article focuses on the evaluation of a first-moment closure model applicable to film cooling flow and heat transfer computations. The present first-moment closure model consists of a higher level of turbulent heat flux modeling in which two additional transport equations for temperature variance kθ and its dissipation rate εθ are ...