Experimental Comparison of Staggered and In-line Tube-bank Thermal Performance.

Experimental investigation of fluid flow and heat transfer were performed for cross-flow tube-type heat exchanger in staggered and in-line arrangement. The purpose of this work was to determine the process of forced convection heat transfer of air over a heated cylindrical pure copper rod. Also, the work was to compare the performance of both staggered and in-line tube bundle configurations. Tube bank with staggered arrangement consisted of 25 mm transverse pitch, 18.75 mm longitudinal pitch, 20 cylindrical rods of diameter12.5 mm, in a 125 x 125 mm cross section. An in-line tube arrangement was constructed based on the staggered tube bank dimensions. During the test, the working sections were placed one after the other in a specially design testing rig air channel through which the fluid flowed normal to the tube. A complete set of test were taken with the heated element in each of the four banks of tube for ten different throttle openings in the range of 10 to 100%. The test results show that the heat transfer coefficient associated with the tube is a function of its position in the tube bank. Higher heat transfer coefficients were obtained in the subsequent tube bank downstream of the first row. However, the heat transfer coefficients stabilize, such that little change occurs for tube beyond the fourth row. The overall heat transfer coefficient for staggered tube arrangement was found to be 4.28% higher than of the in-line tube arrangement