Experimental and Numerical Investigation of the Heat Transfer of Honeycomb-Structured Tubes

Abstract

Tube bundle recuperators are generally designed to operate with smooth tubes. Structured tubes can be used to increase the efficiency of recuperators. Compared to smooth tubes, the surface for heat transfer is increased and thus heat transfer is enhanced. This effect is accompanied by an increased pressure loss, which must be kept as low as possible. Four tube geometries with different honeycomb structures are examined. The results are compared with the performance of a smooth tube. The investigations were carried out both numerically and experimentally at different off-gas and combustion air velocities. The experimental results show that the highest heat transfer is achieved with the concave 6 mm structured tube. The greatest pressure loss also occurs here. The validation of the numerical model has shown issues in resolving the turbulence.