Abstract: A method of cooling a biological material includes providing a vessel. The vessel includes a generally vertical inner wall disposed at an inner radius from a vertically disposed center axis. The generally vertical inner wall defines in part an interior volume. A medium including a biological material is provided. A plurality of heat transfer surfaces is positioned within the interior volume. Each of the plurality of heat transfer surfaces is oriented generally vertically through the interior volume. Each of the heat transfer surfaces is arranged such that it does not extend into the portion of the interior volume defined by a distance from the center axis greater than 90% of the inner radius. The medium is introduced into the vessel. A heat transfer fluid is circulated through the plurality of heat transfer surfaces. The heat transfer surfaces conduct heat out of the medium.