Thermal mixing between subchannels: measurement method and applications

A new thermal tracing technique is presented for the measurement of enthalpy interchange between connected subchannels in one-phase axial flow. The method is simple and versatile, being capable of implementation on compact and non-homogeneous bundles using water as fluid. To present the technique, measurements of turbulent mixing were performed on a triangular array bundle with a relation of pitch to diameter of 1.33, at Reynolds numbers between 104 and 6.8×104. For this simple arrangement the precision of the method is discussed showing that accuracies better than 10% can be readily achieved. Measurements are also performed in presence of a mixing vane showing another field were the method can be advantageously applied.