U.S. patent application 20180216894 (applicant General Electric Co., Schenectady, N.Y.)
"A transient cooling system includes a first phase change material (PCM) element and a second PCM element. The first PCM element includes a first PCM, a first surface, and a second surface, the first surface complementary to a surface to be cooled. The second PCM element includes a second PCM and a third surface in thermal contact with the second surface. The first PCM and the second PCM may have different thermal characteristics."