Solar energy collection system with symmetric wavy absorber pipe

A solar thermal energy collection system comprising a solar energy concentrator, a heat transfer fluid, and an absorber pipe through which the heat transfer fluid flows for absorbing concentrated solar energy incident on the absorber pipe from the solar energy concentrator, the absorber pipe comprising a pipe wall that extends about and around a central longitudinal axis that extends between each end of the absorber pipe, the pipe wall comprising an inner surface and an outer surface, the inner surface defining a first contour defining alternating peaks and troughs along a length of the absorber pipe, and the outer surface defining a second contour defining alternating peaks and troughs along the length of the absorber pipe, wherein:

• the inner surface defines an entire flow path for the heat transfer fluid through the absorber pipe, wherein the entire flow path is defined between an inlet and an outlet of the absorber pipe,
• the first contour, as viewed through an axial cross section of the absorber pipe, forms sinusoidal waves on each side of and spaced apart from the central longitudinal axis, wherein the sinusoidal waves on each side of the central longitudinal axis are symmetrical with respect to the central longitudinal axis,
• at least a portion of the absorber pipe is disposed along a focal line of the solar energy concentrator, and
• the second contour, as viewed through the axial cross section of the absorber pipe, forms sinusoidal waves on each side of and spaced apart from the central longitudinal axis, wherein the sinusoidal waves of the second contour on each side of the central longitudinal axis are symmetrical with respect to the central longitudinal axis.