Numerical simulation of heat exchanger
Principally, heat exchangers are devices used for transfer of heat from one fluid to another one.
The main object of improving a heat exchanger is the enhancement of the efficiency of heat transfer. That means, that the colder fluid flow has to be heated up as effectively as possible and the warmer one has to be cooled down as much as possible. The thermal processes occurring in heat exchangers are analysed with particular attention to uniform inflow, optimal heat transfer and reduction of thermal loads of its components.
With CFD (Computational Fluid Dynamics) methods, powerful alternative tools are available for development of new heat exchanger designs and optimisation of existing ones. By simulating the global and local three-dimensional flow behaviour in a heat exchanger, very complex designs can be analysed in great detail. This particularly applies to special heat exchangers where effects like natural or mixed convection, temperature-dependent fluid properties or non-Newtonian rheology of the fluids need to be considered. Additionally, more demanding processes like boiling heat transfer or the combination of a laminar and a turbulent fluid flow are generally not captured by empirical design methods but can be investigated by a numerical flow simulation. Structure-mechanical analyses permit the prediction of the mechanical properties of the solid walls and the built-in components as well as their interaction with the fluid.
As result of the flow simulation, detailed three-dimensional information on velocity, pressure, temperature and heat transfer rate distributions are visualised for the entire heat exchanger. At the same time, simulations enable an insight into thermal and mechanical loading of its parts. Using these advanced virtual design tools, new designs or optimisation of existing heat exchangers can be performed very effectively and target-orientated.