Abstract: A fluid conduit system, including a central fluid channel having an entrance for a working fluid flowing in a first direction at one end and an exit for the working fluid at an opposite end, a circumferential fluid channel surrounding the central fluid channel adapted for receiving the working fluid exiting the central fluid channel and directing the working fluid in a second direction opposite the first direction, at least one device positioned in the central fluid channel for having the working fluid flow therethrough, and fluid communication between the device and outside the circumferential fluid channel, wherein thermal energy supplied by the working fluid is used by a thermal energy consumption system.

Abstract: A solar thermal system comprising at least one solar system including a solar system working fluid flowing therethrough, and a solar receiver for heating the solar system working fluid by solar radiation admitted into the solar receiver, and a thermal energy system in fluid communication with the solar system and receiving the heated solar system working fluid so as to produce thermal energy.