Investigation of thermal characteristics of high-capacity loop heat pipes after a long-term storage

• Loop heat pipes were tested after long-term storage.
• The devices were made of stainless steel with water and ammonia as working fluids.
• The maximum capacity remained the same: 1200 and 800 W, respectively.
• Some increase in thermal resistance was recorded at low heat loads.

Repeat thermal tests of two high-capacity LHPs (loop heat pipes) have been conducted after their long-term storage under normal conditions. The first of them 1820 mm long with a capacity of 1200 W and water as a working fluid was made and first tested in 1985. The other device with a length of 2750 mm and a capacity of 800 W, which consisted of two ammonia LHPs joined in series, was made and tested for the first time in 1988. Both the devices were made of stainless steel and equipped with a titanium and nickel capillary structures. The tests, which were conducted in conditions similar to the initial ones, have shown that a long-term storage has not had any considerable impact on the LHP thermal characteristics. Such devices may be used in systems of utilization of low-potential heat and solar energy, and also for heating and cooling various objects.