PTAB

IPR2025-00196

Green Revolution Cooling, Inc. v. Midas Green Technologies, LLC

Log In

1. Case Identification

2. Patent Overview

  • Title: Appliance Immersion Cooling System
  • Brief Description: The ’457 patent discloses an immersion cooling system for electronic appliances, such as computer servers. The system uses a tank filled with a dielectric fluid, a plenum to dispense the fluid, and a weir with an overflow lip to facilitate uniform recovery and recirculation of the heated coolant.

3. Grounds for Unpatentability

Ground 1: Obviousness over Best-2008 and Osada - Claims 1-16 are obvious over Best-2008 in view of Osada.

  • Prior Art Relied Upon: Best-2008 (Application # 2011/0132579) and Osada (Japanese Patent Application Publication No. 2001-181898).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Best-2008 teaches a complete immersion cooling system with a tank, vertically oriented appliance slots, a primary circulation facility (pump, heat exchanger), and a controller. However, Best-2008 removes fluid via outlet pipes. Osada, which addresses similar challenges in open-top immersion tanks, discloses using a conventional, "widely-used" rectangular weir that extends along the tank wall to manage fluid level, remove impurities, and promote uniform overflow into an external recovery reservoir. The combination of Best-2008’s system with Osada’s weir and reservoir arrangement allegedly supplies the missing limitations of a "weir, integrated horizontally into the long wall of the tank" and a "dielectric fluid recovery reservoir positioned vertically beneath the overflow lip."
    • Motivation to Combine: A POSITA would combine Best-2008 with Osada to solve known problems in open-tank systems, namely improving filtration and achieving uniform temperature and fluid level control. Osada expressly teaches using a weir system for these purposes. Petitioner asserted it would have been an obvious design choice to apply this known, predictable solution from Osada to the similar system of Best-2008 to achieve the same benefits.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because implementing Osada’s weir and overflow box in Best-2008’s tank is a simple mechanical reconfiguration. Both systems are open-air immersion tanks using dielectric fluids for similar purposes, making the integration straightforward and predictable.

Ground 2: Obviousness over Best-2008, Osada, and Best-2012 - Claims 1-16 are obvious over Best-2008 in view of Osada and Best-2012.

  • Prior Art Relied Upon: Best-2008 (Application # 2011/0132579), Osada (Japanese Patent Application Publication No. 2001-181898), and Best-2012 (Application # 2014/0211412).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on the combination of Best-2008 and Osada. Best-2012, filed by the same inventor as Best-2008, discloses an updated tank design using a suction manifold with nozzles distributed uniformly along the entire length of the tank, "adjacent all appliance slots." Petitioner argued that Best-2012 confirms the obviousness of arranging Osada’s weir/notches along the full length of the tank wall adjacent to all slots to achieve the claimed "substantially uniform recovery of the dielectric fluid."
    • Motivation to Combine: The motivation is the same as in Ground 1. Best-2012 provides further rationale for why a POSITA would implement a fluid recovery mechanism (like Osada's weir or Best-2012's manifold) across the full length of the tank—to achieve uniform coolant flow, a goal already present in Best-2008.
    • Expectation of Success: The expectation of success remains high, as Best-2012 simply reinforces a design principle for achieving uniform flow that was already evident from the combination of Best-2008 and Osada.

4. Key Claim Construction Positions

  • "a weir, integrated into the long wall of the tank adjacent all appliance slots": Petitioner noted that during prosecution, the Examiner contended "adjacent all appliance slots" modifies "the long wall of the tank," not the "weir." However, in a prior IPR, the Patent Owner argued the phrase modifies the "weir," requiring the weir itself to extend adjacent all slots. Petitioner contended the claims are obvious under either construction but adopted the Patent Owner's broader interpretation for its arguments.
  • "a weir... having an overflow lip": Petitioner adopted the Examiner's prosecution-era position that a "weir" can be a simple opening in a wall, and its "lip" is merely the bottom surface of that opening. Petitioner argued the patent specification provides no further structural limitation for these terms, and the prior art discloses such structures even if it does not use the exact terminology.

5. Arguments Regarding Discretionary Denial

  • §314(a) (Fintiv Factors): Petitioner argued against discretionary denial based on parallel district court litigation. The core arguments were that Petitioner filed a broad Sotera stipulation agreeing not to pursue the same grounds in district court, which should be dispositive. Further, the litigation is in a very early stage, with the trial date nearly two years away and likely to be postponed, and no significant investment has occurred (e.g., Markman briefing has not begun).
  • §325(d) (Advanced Bionics Framework): Petitioner argued against denial based on the Examiner having previously considered some of the art. Petitioner asserted that the new combinations present arguments and art not before the Examiner. Specifically, the Examiner never considered Osada or Best-2012. Osada was argued to be critical, as it discloses the very "dielectric fluid recovery reservoir" limitation that the Examiner found lacking in the art during prosecution and which led to the final amendments. Therefore, Petitioner contended the Examiner erred in the initial search and analysis.

6. Relief Requested

  • Petitioner requests institution of inter partes review and cancellation of claims 1-16 of the ’457 patent as unpatentable.