<b>Experimental evaluation of the global heat transfer coefficient in a fixed bed, percolated by water</b> - DOI: 10.4025/actascitechnol.v26i1.1551

Abstract

Many experiments were performed in a fixed bed heat exchanger, packed with stainless steel spheres, percolated by water and heated through the wall. Wall and center temperatures were measured for several experimental conditions: 3 mm < d_p < 6.3 mm, 50 L/h < water flow rate < 190 L/h. The global heat transfer coefficient (U) was evaluated fitting an unidimensional pseudo-homogeneous model to the fixed bed measured temperatures. Results show that both the techniques of adjustment and the model used are adequate. The analysis of the global heat transfer coefficient indicates that this parameter varies linearlly with water flow rate, but does not influence significantly the diameter at the range of experimental conditions explored. U as a function of water flow rate ( ) could be represented by the following linear equation: U = 232645 +1182.2 (R² = 0.99). Additionally, it was observed that the temperatures near the wall are more influenced by the water flow rate than those at the center of the fixed bed