Prosecution Insights
Last updated: April 19, 2026
Application No. 18/848,124

THERMAL ENERGY CONVERSION METHOD AND SYSTEM

Non-Final OA §102§112
Filed
Sep 17, 2024
Examiner
NGUYEN, HOANG M
Art Unit
3746
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Hans Gude Gudesen
OA Round
1 (Non-Final)
76%
Grant Probability
Favorable
1-2
OA Rounds
2y 7m
To Grant
92%
With Interview

Examiner Intelligence

Grants 76% — above average
76%
Career Allow Rate
1292 granted / 1708 resolved
+5.6% vs TC avg
Strong +16% interview lift
Without
With
+16.4%
Interview Lift
resolved cases with interview
Typical timeline
2y 7m
Avg Prosecution
25 currently pending
Career history
1733
Total Applications
across all art units

Statute-Specific Performance

§101
0.6%
-39.4% vs TC avg
§103
57.5%
+17.5% vs TC avg
§102
10.0%
-30.0% vs TC avg
§112
8.6%
-31.4% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1708 resolved cases

Office Action

§102 §112
Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claim Objection Claim 5 is objected to because on line 2, the phrase “controlled opening and closing and valves” is not grammatically correct. 35 USC 112(a) rejections Claims 5, 6, 15, 16, are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. Independent claims 1 and 12 recites the subject matter “by the pressure differential, driving a hydraulic power conversion device fluidly connected to the two heat exchange volumes, thereby generating mechanical energy”, and “a hydraulic power conversion device fluidly connected to the two heat exchange volumes, and arranged to generate mechanical energy by a pressure differential between working fluid vapor pressures in the two heat exchange volumes”. Only the embodiments of figures 3-5 disclose the concept of using hydraulic device 21 to generate mechanical energy. The embodiments of figures 1, 6 use gas pressure to produce mechanical energy, and only the embodiment of figure 6 disclose valves 50-53, and fluid control device 24. Thus, it is unclear which figure/embodiment disclose a combination of a hydraulic power device with valves and fluid control device as claimed. Please explain. 35 USC 102 rejections The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. Claim(s) 1-26 are is/are rejected under 35 U.S.C. 102(a1) as being anticipated by US 3901033 (McAlister). Regarding independent claims 1, 12, McAlister discloses a method for converting thermal energy into mechanical energy, the method comprising the following steps (note figures 10-14, but figure 10 is used to explain the rejection): injecting heat into a working fluid in a heat exchange volume by a thermally connected heat exchanger (note the upper vessels with heated heat exchanger coils 220, 222; figure 11 discloses upper vessels 240, 242; figure 12 discloses vessels 276, 278; figure 13 discloses vessels 352, 354; figure 14 discloses vessels 410, 412), and extracting heat from a working fluid in another heat exchange volume by a thermally connected heat exchanger (note the cooling chambers 240, 242; when one of the vessel is heated, the other vessel is cooled by the cooling coil from chambers 240, 242), thereby establishing and maintaining within predefined ranges temperatures of respectively THigh and TLow < THigh and a pressure differential between working fluid vapor pressures in the two heat exchange volumes (the differential pressure between the upper vessels), where the heat exchange volume where heat is injected contains working fluid at least partially in the liquid phase, and the temperatures THigh and TLow lie between the triple point temperature and the critical point temperature of the working fluid (all the fluid in liquid and gas phase are between the triple point and the critical point temperatures), and by the pressure differential, driving a hydraulic power conversion device (note hydraulic motor 232) fluidly connected to the two heat exchange volumes, thereby generating mechanical energy. Again, all embodiments in figures 10-14 disclose similar systems, all having heating chambers, cooling chambers to generate gas pressure to drive hydraulic power devices. Regarding independent claim 12 only, the method steps of apparatus claim 1 are equivalent with the functions of the elements in apparatus claim 12. Regarding claim 2, McAlister discloses method according to claim 1, operating the hydraulic power conversion device 232 under load conditions such that the fluid is discharged from the hydraulic power conversion device at a pressure equal to or exceeding the liquid to vapor equilibrium pressure of the working fluid at the temperature TLow. Regarding claim 3, McAlister discloses the method according to claim 1, cyclically switching the injecting heat and the extracting heat between the two heat exchange volumes (the upper vessels are cyclically switching). Regarding claims 4, 13, 14, McAlister discloses the method according to claim 1, performing the injecting and the extracting heat respectively in the one and the other heat exchange volume, and cyclically switching the fluid connection between the two heat exchange volumes and the hydraulic power conversion device (the upper vessels are cyclically switching using valves). Regarding claims 5, 15, McAlister discloses the method according to claim 4, where the switching the fluid connection comprises controlled opening and closing and valves (note the check valves CV and fluid lines) and ducts between the hydraulic power conversion device 232 and the heat exchange volumes. Regarding claims 6, 16, McAlister discloses the method according to claim 4, further comprising transferring working fluid in liquid form from the heat exchange volume where heat is extracted to the heat exchange volume where heat is injected via a flow control device (upper check valves CV in figure 10; valves 266, 268 in figure 11, valves 282, 284 in figure 12, valve 360 in figure 13), where the transferring working fluid in liquid form is performed either continuously or intermittently. Regarding claims 7, 17, 18, 23, 24, McAlister discloses the method according to claim 1, where the driving the hydraulic power conversion device 232 comprises cyclically exposing one or more displacement elements (note the flexible diaphragm 410, 412 in figure 6, that can be used in all vessels in figures 10-14) comprised by the hydraulic power conversion device to working fluid from the two heat exchange volumes. Regarding claims 8, 19, McAlister discloses the method according to claim 1, where the driving the hydraulic power conversion device comprises allowing the pressure differential to sustain a flow of working fluid in liquid or gaseous phase through the hydraulic power conversion device 232 between the two heat exchange volumes. Regarding claims 9, 21, McAlister discloses the method according to claim 1, where the driving the hydraulic power conversion device 232 comprises sustaining a flow of a hydraulic liquid through the hydraulic power conversion device 232 by the differential pressure. Regarding claims 10, 26, McAlister discloses the method according to claim 9, where the sustaining the flow of the hydraulic liquid through the hydraulic power conversion device comprises transmitting working fluid vapor pressure via moveable separation elements (note the flexible diaphragm 410, 412 in figure 6, that can be used in all vessels in figures 10-14) to the hydraulic liquid. Regarding claims 11, 25, 26, McAlister discloses the method according to claim 9, where the sustaining the flow of the hydraulic liquid through the hydraulic device 232 comprises allowing the working fluid vapor pressures acting directly on a free surface of the hydraulic liquid (all vessels show the gas pressure applied directly on the liquid except for figure 6 showing a diaphragm). Regarding claim 20, McAlister discloses a water turbine and/or rotary screw device 50 in figure 2 that can be used in all of his embodiments in figures 10-14. Regarding claims 21-22, the hydraulic fluid is water. Claim(s) 1, 2, 10-12, 24-26, are is/are rejected under 35 U.S.C. 102(a1) as being anticipated by US 4816121 (Keefer). Regarding independent claims 1, 12, Keefer discloses a method for converting thermal energy into mechanical energy, the method comprising the following steps injecting heat into a working fluid in a heat exchange volume by a thermally connected heat exchanger (25), and extracting heat from a working fluid in another heat exchange volume by a thermally connected heat exchanger (32), thereby establishing and maintaining within predefined ranges temperatures of respectively THigh and TLow < THigh and a pressure differential between working fluid vapor pressures in the two heat exchange volumes (the differential pressure between the upper vessels), where the heat exchange volume where heat is injected contains working fluid at least partially in the liquid phase, and the temperatures THigh and TLow lie between the triple point temperature and the critical point temperature of the working fluid (all the fluid in liquid and gas phase are between the triple point and the critical point temperatures), and by the pressure differential, driving a hydraulic power conversion device (23) fluidly connected to the two heat exchange volumes, thereby generating mechanical energy. Regarding independent claim 12 only, the method steps of apparatus claim 1 are equivalent with the functions of the elements in apparatus claim 12. Regarding claim 2, McAlister discloses method according to claim 1, operating the hydraulic power conversion device 23 under load conditions such that the fluid is discharged from the hydraulic power conversion device at a pressure equal to or exceeding the liquid to vapor equilibrium pressure of the working fluid at the temperature TLow. Regarding claims 11, 18, 24-26, Keefer disclose vapor pressure acting on a free surface of the hydraulic fluid, and/or pistons as displacement elements. Prior Art of Record The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Lewellin, McBride, Benn, and US 3803847 disclose hydraulic device being powered by gas pressure. Conclusions Any inquiry concerning this communication or earlier communications from the Examiner should be directed to Examiner Nguyen whose telephone number is (571) 272-4861. The examiner can normally be reached on Monday--Thursday from 9:00 AM to 7:00 PM. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Mark Laurenzi, can be reached on (571) 270-7878. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of an application may be obtained from the Patent Application Information Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). /HOANG M NGUYEN/Primary Examiner, Art Unit 3746 HOANG NGUYEN PRIMARY EXAMINER ART UNIT 3746 Hoang Minh Nguyen 7/18/2025
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Prosecution Timeline

Sep 17, 2024
Application Filed
Jul 18, 2025
Non-Final Rejection — §102, §112 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
76%
Grant Probability
92%
With Interview (+16.4%)
2y 7m
Median Time to Grant
Low
PTA Risk
Based on 1708 resolved cases by this examiner. Grant probability derived from career allow rate.

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