Abstract: A ladder-structural gravity-assisted-heat-pipe geothermal energy recovery system without liquid-accumulation effect, comprises a ladder-structural gravity-assisted heat pipe, a condenser, and a liquid tank. The ladder-structural gravity-assisted heat pipe comprises a return pipe, an outer pipe and an inner pipe. The return pipe is provided in a space between the outer pipe and the inner pipe and communicated with the liquid tank, and the space between the outer pipe and the inner pipe is divided to form a ladder structure. A liquid working medium flows from the liquid tank through the return pipe into each section sequentially, absorbs heat from a high-temperature rock through a wall of the outer pipe, vaporizes into a gaseous working medium, gets into the inner pipe, and rises to the condenser to condense and flows to the liquid tank to circulate. Such design greatly improves the heat transfer efficiency in geothermal energy recovery using ultra-long heat pipes.

Abstract: A method and apparatus for measuring scour depth in a waterway bed is described. The apparatus utilizes magnetic attraction between a weight resting on the waterway bed and a magnetic probe within a guide chamber to which the weight is attached. Magnetic attraction between the probe and the weight retains the probe in an aligned position with the weight, enabling a user to detect a reduced force in the support line to identify the location of the weight and thus the riverbed. In a second embodiment, the inventive device includes a second weight slidably attached to the guide enabling a measurement of infill in a waterway bed scour. In the method according to the invention, the weight is placed upon the waterway bed and allowed to rest there. A probe is then inserted into the chamber and allowed to descend to the level of the weight where magnetic attraction supports the probe.