Abstract
Canadian wells are used for heating and cooling in residential buildings, agriculture and industry. They rely on the quasi-stable underground temperature at a certain depth throughout the year. One way to enhance the performance of this type of heat exchangers, is to implement internal Vortex Generators (VGs). The VGs contribute in disrupting the thermal boundary layer, intensifying turbulence and increasing the heat transfer coefficient.
Series of numerical simulations, using ANSYS FLUENT, were conducted to mimic the variable seasonal operational conditions of Canadian Wells during the year. One circumferential row of parallelepiped Vortex Generators was implemented in a real U-shaped tube Canadian Well geometry. The yearly ground and underground temperatures were implemented as sinusoidal functions of time and depth. The VGs were placed immediately downstream of the first bend close to the inlet. The Reynolds number was in the range 14975–42785. The ambient conditions were considered for the city of Constantine (Algeria) at an altitude of 600m over the sea level.
The VGs yielded an improvement of up to 8% of the heat transfer coefficient for different Reynolds numbers. The bend, upstream of the VGs, and the wake, downstream of them, play a key role in affecting the heat transfer locally.
