The introduction of high powered LEDs has brought extensive challenges with regard to thermal design, from chip level to system level thermal management. With the increased efficiency of modern high power LEDs, it is important that the thermal modeling of an LED application calculate the actual thermal load produced by the component. In the case of high power LEDs; this will differ significantly from the total power consumed. In the following paper the advantage of implementing a detailed and computationally efficient LED model is assessed. The assessment compares the detailed model with thermal resistance models and considers its ability to model transient applications as well as an optimization tool.

If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -One-dimensional pipe network flow analysis can be used in many applications to satisfactorily solve various engineering problems. The paper aims to focus on this. Design/methodology/approach -A hybrid nodal method is detailed, which solves the pressure field prior to the elemental flows, and models both compressible gas and incompressible liquid and gas flows.Findings -The results obtained by the algorithm were verified against a number of published benchmark flow problems. The methodology was found to yield accuracy similar or improved, compared with that of others, while being applicable to both incompressible liquid and compressible gas flows. Convergence performance was found to be similar to other hybrid techniques. Originality/value -All flows are modelled via a single governing equation set. In the case of incompressible flow, the method is capable of dealing with both constant and variable cross-sectional area ducts. The latter includes geometrically complex pipes such as sudden expansions.

The numerical modeling of heat transfer on the suction side of a cooled gas turbine blade is one of the more difficult problems in engineering. The main reason is believed to be the transition from laminar to turbulent flow and the inability of standard Navier–Stokes solvers to predict the transition. This paper proves that sudden changes in heat transfer on the suction side of a turbine blade can indeed also be caused by localized shocks disrupting the boundary layer. In contrast to transition, the position of these shocks and the effect of the shocks on the pressure distribution and heat transfer rate can be predicted to within an acceptable degree of accuracy using standard Navier–Stokes solvers. Two well-documented case studies from the literature are used to prove that the pressure distribution around the profile can be predicted accurately when compared to experimental data. At the same time this method can be used to capture sudden changes in heat transfer rate caused by localized shocks. The conclusion from this study is that localized shock waves close to the suction side surface of a turbine blade can have the same effect on the heat transfer rate to the blade as transition.

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