– The idea that one can build a solid-state device that lets heat flow more easily in one way than in the other, forming a heat valve, is counter-intuitive. However the design of a thermal rectifier can be easily understood from the basic laws of heat conduction. Here we show how it can be done. This analysis exhibits several ideas that could in principle be implemented to design a thermal rect...

1. Despite escalating conflict over fresh water, recent years have witnessed a growing realisation that human society must modify its behaviour to ensure long-term ecological vitality of riverine ecosystems. In response, ecologists have been increasingly asked to guide instream flow management by providing ‘environmental flow’ prescriptions for sustaining the ecological integrity of riverine sy...

In this paper we explore theory, design, and fabrication of photonic crystal (PhC) based selective thermal emitters. In particular, we focus on tailoring spectral and spatial properties by means of resonant enhancement in PhC’s. Firstly, we explore narrow-band resonant thermal emission in photonic crystals exhibiting strong spectral and directional selectivity. We demonstrate two interesting de...

in this research a flat plate solar air collector was investigated under direct solar radiation consisted of a slatted glass cover, perforated absorber aluminum sheets (porosity 0.0177, 0.0314 and absorber thickness of 2.5 mm). the effect of porosity on absorber efficiency of collector was evaluated. six levels of air mass flow rates (0.0056 to 0.0385 kg m-2 s-1) were adopted.average solar ener...

In this work, we present a system of equations which describes non-isothermal flow in a bidispersive porous medium under conditions of local thermal non-equilibrium. The porous medium consists of macro pores, and in the solid skeleton are cracks or fissures which give rise to micro pores. The temperatures in the solid skeleton and in the fluids in the macro and micro pores are all allowed to be...

Thermal transpiration flows of rarefied gases in annular channels are considered, where the driving force for the flow is a temperature gradient applied in the channel walls. The influence of gas rarefaction, aspect ratio of the annulus, and surface accommodation coefficient on mass and heat transfer in the process are investigated. For this, the linearized Navier– Stokes–Fourier (NSF) and regu...

Miniaturized flow sensors composed of a thin membrane supporting appropriately positioned heating resistors and temperature sensors were studied by computer-numeric analysis. Significant improvements of the steady-flow transduction characteristics as well as the responses to step-like changes of the dissipated power are feasible by design modifications and new transduction schemes.

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A microelectromechanical systems (MEMS) thermal flow sensing array constructed of biocompatible materials has been designed, fabricated, nd tested. In addition to the construction, the electronic biasing conditions were selected such that sensor operation was compatible with biological uids. The device comprises several thin film platinum sensing elements sandwiched in a Parylene C membrane. Th...

The entropy generation during hydromagnetic boundary layer flow of a viscous incompressible electrically conducting fluid due to radial stretching sheet with Newtonian heating in the presence of a transverse magnetic field and the thermal radiation has been analyzed. The governing equations are then solved numerically by using the fourth order Runge-Kutta method with shooting technique. The eff...