# US 9,435,586 B2 · Controlled nucleation during freezing step of freeze drying cycle using pressure differential ice crystals distribution from condensed frost > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,435,586 B2 - Document ID: US9435586B2 - Status: Granted - Kind: B2 - Application number: 14/205,802 - Filed: 2014-03-12 - Published: 2014-07-24 - Granted: 2016-09-06 - Earliest claimed: 2012-08-13 - Assignees: Millrock Technology, Inc. - Applicants: Millrock Technology, Inc. - Inventors: Weijia Ling - Web page: https://patentgrep.com/patent/US9435586B2 ## CPC - F26B 5/06: the process involving freezing - F26B: DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM (drying devices for combines A01D41/133; racks for drying fruit or vegetables A01F25/12; drying foodstuffs A23; drying hair A45D20/00; body-drying implements A47K10/00; drying household articles A47L; drying gases or vapours B01D; chemical or physical processes for dewatering or like separating liquids from solids B01D43/00; centrifugal apparatus B04; drying ceramics C04B33/30; drying yarns or fabrics in association with some other form of treatment D06C; drying frames for laundry without heating or positive air circulation, domestic laundry-or spin-driers, wringing or hot pressing laundry D06F; furnaces, kilns, ovens F27) ## Abstract A method of controlling and enhancing the nucleation of product in a freeze dryer, wherein the product is maintained at a predetermined temperature and pressure in a chamber of the freeze dryer, and a predetermined volume of condensed frost is created on an inner surface of a condenser chamber separate from the product chamber and connected thereto by a vapor port. The opening of the vapor port into the product chamber when the condenser chamber has a pressure that is greater than that of the product chamber creates gas turbulence that breaks down the condensed frost into ice crystals that rapidly enter the product chamber for even distribution therein to create uniform and rapid nucleation of the product in different areas of the product chamber. ## Claims ### Claim 1 A method of controlling and enhancing the nucleation of product in a freeze dryer, comprising: maintaining the product at a predetermined temperature and pressure in a chamber of the freeze dryer; creating a predetermined volume of condensed frost on an inner surface of a condenser chamber separate from the product chamber and connected thereto by a vapor port; and opening the vapor port into the product chamber when the condenser chamber has a predetermined pressure that is greater than that of the product chamber to create gas turbulence that breaks down the condensed frost into ice crystals that rapidly enter the product chamber for even distribution therein to create uniform and rapid nucleation of the product in different areas of the product chamber. ### Claim 2 (depends on 1) The method of claim 1 wherein the vapor port has an isolation valve between the product chamber and the condenser chamber to open or close vapor flow therebetween. ### Claim 3 (depends on 1) The method of claim 1 wherein a vacuum pump is connected to the condenser chamber for selectively reducing the pressure within the product chamber and the condenser chamber when the isolation valve is opened. ### Claim 4 (depends on 1) The method of claim 1 wherein the pressure within the product chamber is about 50 Torr and the pressure within the condenser chamber is about atmospheric when the vapor port is opened into the product chamber. ### Claim 5 (depends on 4) The method of claim 4 wherein the temperature of the product is about −5.0° C. and the temperature of the condenser chamber is less than 0° C. when the vapor port is opened into the product chamber. ### Claim 6 (depends on 1) The method of claim 1 wherein a predetermined moisturized back fill gas is introduced into the condenser chamber to produce the condensed frost. ### Claim 7 (depends on 6) The method of claim 6 wherein the condenser chamber has a fill valve which is opened to enable the moisturized back fill gas to be introduced into the condenser chamber to produce the condensed frost. ### Claim 8 (depends on 6) The method of claim 6 wherein the back fill gas is filtered ambient atmospheric air and has a moisture content of about 50-80% by volume. ### Claim 9 (depends on 6) The method of claim 6 wherein the back fill gas is nitrogen or argon with moisture added thereto. ### Claim 10 (depends on 6) The method of claim 6 wherein the moisturized gas is introduced into the condenser chamber while it is under a vacuum. ### Claim 11 (depends on 10) The method of claim 10 wherein the vacuum is thereafter released in the condenser chamber and its pressure is increased to a pressure greater than the pressure in the product chamber. ### Claim 12 (depends on 11) The method of claim 11 wherein the vacuum is released in the condenser chamber by opening a vent valve on the condenser. ### Claim 13 (depends on 6) The method of claim 6 wherein the moisturized gas is introduced into the condenser chamber while it is under atmospheric pressure or another predetermined pressure greater than the pressure in the product chamber. ### Claim 14 (depends on 13) The method of claim 13 wherein the pressure in the product chamber is below atmospheric pressure. ### Claim 15 (depends on 1) The method of claim 1 wherein the inner surface of the condenser chamber is defined by a plurality of inner coils, plates or walls. ### Claim 16 (depends on 15) The method of claim 15 wherein the inner walls are in a coil configuration to maximize the size of the inner surface.