Air-Sand Heat Exchanger

Kurzfassung

This Paper summarizes research activities that analyse the thermodynamic behaviour of an Air / Sand Heat Exchanger, developed by Solar-Institut Jülich (SIJ) and the German Aerospace Centre (DLR). The numerical 3-D model, new results and a model validation of this particular cross-flow heat exchanger are presented. Simulation results were obtained for sand with 1-2 mm grain size. The simulation was validated with a new 15 kW prototype unit. Ansys, including Ansys-CFX, is used as modelling and simulation platform. Validation is made using a new test rig system. The bulk material is modelled by a porous solid medium without structural dynamic interaction between fluid and solid phase. For bulk material pressure drop model from Ergun is used. The model parameters were validated and fitted with measured values of a separate pressure drop test rig. The validation was done with quartz sand. To determine suitability of available granular products for the mentioned application, tests have been conducted regarding the thermomechanical properties as well as their attrition behaviour and abrasion on various wall materials.