# US 9,521,786 B2 · Thermosiphon systems for electronic devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,521,786 B2 - Document ID: US9521786B2 - Status: Granted - Kind: B2 - Application number: 14/291,812 - Filed: 2014-05-30 - Published: 2014-09-18 - Granted: 2016-12-13 - Earliest claimed: 2011-04-25 - Assignees: Google Inc. - Applicants: Google Inc. - Inventors: Jeremy Rice; Bill Dailey; Jeffrey S. Spaulding - Web page: https://patentgrep.com/patent/US9521786B2 ## CPC - H05K 7/20809: {within server blades for removing heat from heat source} - F25B 21/02: using Peltier effect; using Nernst-Ettinghausen effect - F28D 15/04: with tubes having a capillary structure - G06F 1/20: Cooling means - H05K 7/20: Modifications to facilitate cooling, ventilating, or heating - H05K 7/20245: {by natural convection; Thermosiphons} - H05K 7/20309: {Evaporators} - H05K 7/20318: {Condensers} - H05K 7/20327: {Accessories for moving fluid, for connecting fluid conduits, for distributing fluid or for preventing leakage, e.g. pumps, tanks or manifolds} - H05K 7/20336: {Heat pipes, e.g. wicks or capillary pumps} - H05K 7/20727: {within server blades for removing heat from heat source} - H05K 7/20736: {within cabinets for removing heat from server blades} - H05K 7/20818: {within cabinets for removing heat from server blades} - F28D 15/0233: {the conduits having a particular shape, e.g. non-circular cross-section, annular (F28D15/0241, F28D15/0266 take precedence)} - F28D 15/043: {forming loops, e.g. capillary pumped loops} - G06F 2200/201: Cooling arrangements using cooling fluid - H05K 7/20672: {within sub-racks for removing heat from electronic boards} - H10W 40/73: for cooling by change of state - Y02D 10/00: Energy efficient computing, e.g. low power processors, power management or thermal management - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS - F28D: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of general) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract A thermosiphon system includes a condenser and an evaporator fluidically coupled to the condenser by a condensate line. The evaporator includes a housing having an opening to the condensate line, a wick located in the housing, and a flow restrictor located in the housing configured to restrict flow of a working fluid from the condensate line onto a portion of the wick. ## Claims ### Claim 1 A server rack sub-assembly, comprising: a tray configured for slidable insertion into a server rack; a motherboard mounted on the tray and a heat-generating device mounted on the motherboard; and a thermosiphon system including: an evaporator supported on the heating generating device, a condenser supported on the tray, the condenser comprising a body, the body including: a cavity, and a plurality of walls that divide the cavity into a central channel that extends laterally through the body along a first axis and a plurality of parallel chambers extending laterally away from the central channel along a second axis perpendicular to the first axis, each chamber having a length along the second axis greater than a width along the first axis and a height along a vertical axis greater than the width along the first axis, and a condensate line fluidically coupling the central channel of the condenser to the evaporator, the condensate line extending laterally from the condenser body and the central channel and perpendicular to the chambers. ### Claim 2 (depends on 1) The server rack sub-assembly of claim 1, wherein the chambers have closed off top ends. ### Claim 3 (depends on 1) The server rack sub-assembly of claim 1, wherein a first set of the plurality of chambers extend laterally from a first side of the central channel and a second set of the plurality of chambers extend laterally from an opposite second side of the central channel. ### Claim 4 (depends on 1) The server rack sub-assembly of claim 1, further comprising a plurality of heat conducting fins projecting outwardly from the body. ### Claim 5 (depends on 4) The server rack sub-assembly of claim 4, wherein the plurality of heat conducting fins project vertically from the body. ### Claim 6 (depends on 5) The server rack sub-assembly of claim 5, wherein the plurality of heat conducting fins extend along the first axis. ### Claim 7 (depends on 1) The server rack sub-assembly of claim 1, wherein the condensate line extends perpendicular to the second axis. ### Claim 8 (depends on 7) The server rack sub-assembly of claim 7, wherein the condensate line is coupled to an end of the central channel. ### Claim 9 (depends on 1) The server rack sub-assembly of claim 1, wherein the plurality of walls comprises undulations projecting inwardly into the chambers. ### Claim 10 (depends on 9) The server rack sub-assembly of claim 9, wherein the undulations project inwardly on the first axis with peaks of the undulations spaced apart along the second axis. ### Claim 11 (depends on 1) The server rack sub-assembly of claim 1, further comprising a fan mounted on the tray and oriented to generate an airflow over the motherboard and between a plurality of heat conducting fins that projecting outwardly from the condenser. ### Claim 12 (depends on 1) The server rack sub-assembly of claim 1, wherein the heat-generating device comprises a computer chip. ### Claim 13 (depends on 1) The server rack sub-assembly of claim 1, wherein the central channel has a same height as the parallel chambers. ### Claim 14 (depends on 1) The server rack sub-assembly of claim 1, wherein the central channel comprises two parallel channel walls extending from a bottom surface to a top surface of the condenser body, the channel walls having a plurality of openings from the bottom surface to the top surface, the openings extending laterally off the central channel to a wall of the condenser body to create the chambers. ### Claim 15 A server rack sub-assembly, comprising: a tray configured for slidable insertion into a server rack in a horizontal orientation; a motherboard mounted on the tray and a heat-generating device mounted on the motherboard; and a thermosiphon system including: an evaporator supported on the heating generating device, a condenser supported on the tray at a height above the evaporator, the condenser comprising a body having a plurality of parallel chambers connected to a common channel, and a single condensate line fluidically coupling the condenser to the evaporator, the condensate line extending from the common channel of the condenser body, the condensate line including a first horizontal portion extending from the evaporator and a second portion tilted at an angle greater than zero relative to horizontal that fluidically couples the first portion to the condenser, wherein an interior of the single condensate line includes a lower section coupled to the condenser at a position to receive liquid working fluid from the condenser such that the first horizontal portion and the second portion tilted at the angle greater than zero carry liquid working fluid from the condenser to the evaporator primarily by gravity and an upper section coupled to the condenser at a position to return gaseous working fluid to the condenser. ### Claim 16 (depends on 15) The server rack sub-assembly of claim 15, further comprising a second heat-generating device mounted on the motherboard, wherein the thermosiphon system includes a second evaporator supported on the second heat-generating device. ### Claim 17 (depends on 16) The server rack sub-assembly of claim 16, comprising a horizontal second condensate line fluidically coupling the second evaporator to the evaporator. ### Claim 18 (depends on 15) The server rack sub-assembly of claim 15, wherein the tray is configured for insertion into a 13 inch or 19 inch server rack. ### Claim 19 (depends on 15) The server rack sub-assembly of claim 15, wherein the condenser includes fins projecting from a top of the body, and wherein a total height from a bottom of the tray to a top of the heat conducting fins is at most 6 inches. ### Claim 20 (depends on 15) The server rack sub-assembly of claim 15, wherein the chambers have a length greater than a width and a width greater than a depth, and the length of the chambers is parallel to the tray and perpendicular to the condensate line, and the depth of the chambers is parallel to the tray and the condensate line. ### Claim 21 (depends on 15) The server rack sub-assembly of claim 15, comprising a fan to blow air across the condenser, the fan positioned between the motherboard and the condenser.