Heat Transfer and Pressure Drop Measurements in an Air/Molten Direct-Contact Exchanger

This paper presents a comparison of experimental data with a recently published model of heat exchange in irrigated packed beds. Heat transfer and pressure drop were measured in a 150 mm (ID) column with a 610-mm bed of metal Pall rings. Molten nitrate salt and preheated air were the working fluids with a salt inlet temperature of approximately 440 degrees C and air inlet temperof approximately230 degrees C. A comparison between the experimental data and the heat transfer model is made on the basis of heat transfer from the salt. For the range of air and salt flow rates tested, 0.3 to 1.2 k/m2s air flow and 6 to 18 kg/m2s salt flow, the data agree with the model within 22% standard deviation. In addition, a model for the column pressure drop was validated, agreeing with theexperimental data within 18% standard deviation over the range of column pressure drop from 40 to 1250 Pa/m.