U.S. patent application 20170131014 (applicant Sonoco Development Inc., Hartsville, S.C.):
"Temperature controlled cargo containers may include thermal masses conditioned to temperatures above and/or below a target temperature. Example thermal masses may include plates including phase change materials, such as eutectic materials. One or more fans may be selectively operated to circulate air in the cargo container across one or more of the thermal masses to maintain the temperature within the cargo container within a prescribed temperature band. Some example temperature controlled cargo containers may include refrigeration units and/or heaters for regenerating the thermal masses when receiving power from an external power source and/or may include one or more rechargeable batteries for providing power during transport or storage independent of external power sources."