Loop heat pipes

Loop heat pipes (LHPs) are two-phase heat-transfer devices with capillary pumping of a working fluid. They possess all the main advantages of conventional heat pipes, but owing to the original design and special properties of the capillary structure are capable of transferring heat efficiency for distances up to several meters at any orientation in the gravity field, or to several tens of meters in a horizontal position. Besides, the LHP conception allows a wide variety of different design embodiments, which essentially extends the sphere of functional possibilities and practical application of these devices. The paper is a review of developments, results of theoretical analysis and tests of LHPs performed at the Institute of Thermal Physics and some other organizations. It gives examples of successful application of these highly efficient devices in space technology and electronics.