Heat transfer enhancement in the novel wavy shaped heat exchanger channel with cylindrical vortex generators

Abstract

The enhancement characteristics of heat transfer in conjunction with a low pressure drop were experimentally and numerically investigated for the novel geometry wavy shaped heated channel with cylindrical vortex generators. To visualize the temperature distribution there was used the holographic interferometry method while the Ansys Fluent software was used to evaluate the temperature, velocity, and pressure field in the wavy channel. The study is focused on the analysis of the heat transfer coefficients, Nusselt numbers, thermal performance, Colburn factor, and friction factor for the wavy channel and the wavy channel with cylindrical vortex generators of 15 mm diameter located in five different horizontal positions. Moreover, we have performed a comparison with the smooth channel. The results are presented for the surface temperature Ts = 318.15 K, Reynolds number 778 ≤ Re ≤ 7,930, and channel height 0.04 m ≤ H ≤ 0.06 m. At the wavy channel with position “2” of cylindrical vortex generators for the channel height of 0.04 m and Re = 1,669 was noticed the maximum thermal performance factor TPF́ = 0.8167. For this configuration, the novel asymmetric curve geometry in combination with cylindrical vortex generators at position “2” brought the enhancement of the Colburn factor j by 2.48 and 3.28 times compared to the wavy and smooth channels, respectively. The new correlating equations for all investigated channel height and volumetric flow rate in the range of 10 m3/h to 50 m3/h were created. The results show that inserting cylindrical vortex generators into the investigated channels is significant to achieve more efficient heat transfer and thus reducing energy consumption.