Flow resistance and forced convective heat transfer effects for various flow orientations in a packed channel

This study explores the flow resistance and forced convective heat transfer effect for three types of flow orientation in a packed channel. Experimental parameters include the copper bead diameter (dp = 3, 4, 5, and 6 mm) and the hydraulic Reynolds number (Re = 1349, 2697, 4046, 5394, and 6743). The results indicate that flow resistance approaches a minimum in O-II due to its inlet/outlet design, and the O-I case produces the largest friction in the three orientations. While the influence of flow orientation on convective heat transfer is not as strong as that of as flow resistance, O-I and O-II show almost the same performance, and O-III case can acquire a higher average Nusselt number value for its two outlets. Therefore, two dominated parameters (ε, Re) need to be compromised for their positive/negative effects in the abovementioned Cf and Nu. An empirical correlation equation of image vs. Re for O-I–O-III and dp = 3–6 mm is also proposed herein to offer a rapid and efficient guide in specifying appropriate parameters in relational applications.