U.S. patent application 20180185189 (applicant Zeltiq Aesthetics Inc., Pleasanton, Calif.):
"A treatment system for cooling subcutaneous lipid-rich cells  in a human subject includes an applicator  and a control unit. The treatment system has a cooling mode for cooling tissue and a heating mode for warming tissue. The control unit includes a circulation circuit in fluid communication with the applicator, a chiller apparatus configured to chill fluid from the applicator circulation circuit, and a heater apparatus to warmed fluid from the applicator circulation circuit. ... The chilled reservoir can hold coolant (referred to as 'chilled coolant') at a relatively low temperature and the chiller fluidic circuit can include, without limitation, a refrigeration unit, a cooling tower, a thermoelectric chiller, a cartridge of phase change material, or any other device capable of removing heat from coolant."