U.S. patent application 20190145359 (assignee Ford Global Technologies LLC, Dearborn, Mich.):
"Methods and systems are provided for an EGR [exhaust gas recirculation] cooler comprising a phase-change material. In one example, exhaust gas may be conducted through the EGR cooler when an engine is deactivated to maintain an engine temperature. ... The phase-change material may extract heat from the hot exhaust gas conducted through the cooler, and thus serves as an additional heat sink but also as an energy store. In other words, the cooler equipped with the phase-change material according to the disclosure may extract more energy from the exhaust gas than a conventional cooler which uses only coolant. This offers advantages in the case of large exhaust-gas quantities which occur at high engine speeds or loads, and in particular at the high exhaust-gas temperatures which occur at high loads."