Simulation of a pebble-bed heat regenerator

A mathematical model to simulate the operational behaviour of a pebble-bed heat regenerator has been developed, and an experimental study performed to test the model predictions. The model is based on finite heat balances for the solid and the fluid applied to a bed which is divided into several sec tions insulated from each other. Within each section, there is no radial or axial temperature gradient, i.e. the temperature of all the pebbles in a g iven section are the same. As the fluid stream flows through the idealized compartmented bed, there is heat exchange in each section between the pebbl es and the fluid. The model, which is applicable both to the heating and co oling cycles, has been used to simulate the behaviour of a heat regenerator . To test the predictions of the model, experiments have been performed on a 7 ft by 8 in cylindrical column using a hot air stream of approximately 2 00 degrees C at an average flow rate of 365 l min(-1). A special technique, wherein a pebble is fixed to a thermocouple, was used to measure the tempe rature at different bed positions. Experimental conditions were such that i nteresting results have been generated. The model was able to predict with good accuracy all the unusual operational behaviour encountered. The deviat ions between the model and the experimental results can be explained by the fact that the model does not consider heat loss from the column wall. Copy right (C) 2000 John Wiley & Sons, Ltd.