Development of Loop Heat Pipes for Cryogenic Applications

Publisher Summary Since loop heat pipe was first invented in 1987 by a Japanese inventor, some efforts have been made to extend it for cryogenic use. In 1991, a loop heat pipe had been demonstrated to work at liquid nitrogen temperature levels. This chapter shows that loop heat pipes can be put into operation at any temperature level fight down to 4 K level. To distinguish it from a capillary-pumped loop, which uses a wick, which is just a pipe coiled in a closed loop configuration. Having selected the loop pipe diameters close to 1.5 to 2 times Laplace constant, it was demonstrated that a loop heat pipe can function even at cryogenic temperatures as low as 30 K, 15 K and 4 K. Further optimizing is necessary for the helium loop heat pipe to have a higher heat transport capacity.