Abstract: A heat dissipation structure for a casting block assembly, which includes a tube extending through a casting block, and the tube has at least one turbulence generating device to promote turbulence inside the tube and reduce boundary layer thickness, and therefore increase the heat transfer coefficient. The turbulence generating device is one or more ribs or dimples integrally formed as part of the tube, before forming the casting block around a portion of the tube. The ribs or dimples promote turbulence to reduce boundary layer thickness, and therefore increase the heat transfer coefficient. The turbulence generating devices promote higher turbulence intensity, a thinner boundary layer thickness, increased heat transfer coefficient, and a stronger bond between the tube and the casting block. The tube may have an elliptical cross-section, which allows for increased spacing between various portions of the tube while maintaining the same cross-sectional flow area, enhancing heat transfer.