# US 2013/0152576 A1 · Closed Cycle System for Recovering Waste Heat > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0152576 A1 - Document ID: US20130152576A1 - Status: Published application - Kind: A1 - Application number: 13/711,954 - Filed: 2012-12-12 - Published: 2013-06-20 - Earliest claimed: 2011-12-14 - Assignees: Nuovo Pignone S.p.A. - Inventors: Rajesh Mavuri; Bhaskara KOSAMANA - Web page: https://patentgrep.com/patent/US20130152576A1 ## CPC - F02G 5/02: Profiting from waste heat of exhaust gases - F01K 7/32: the engines using steam of critical or overcritical pressure - F01K 25/06: using mixtures of different fluids (plants using mixtures of steam and gas F01K21/04) - F01K 25/10: the vapours being cold, e.g. ammonia, carbon dioxide, ether - Y02E 20/16: Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT] - Y02P 80/15: On-site combined power, heat or cool generation or distribution, e.g. combined heat and power [CHP] supply - F02G: HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS (steam engine plants, special vapour plants, plants operating on either hot gas or combustion-product gases together with other fluid F01K; gas-turbine plants F02C; jet-propulsion plants F02K); USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR - F01K: STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES (gas-turbine or jet-propulsion plants F02; nuclear power plants, engine arrangements therein G21D) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A closed cycle system for waste heat recovery is provided. The system comprises: a heat exchanger configured to transfer heat from an external heat source to a working fluid; an expander fluidly connected to an outlet of the heat exchanger and configured to expand the working fluid and produce mechanical energy; a recuperator fluidly connected to an outlet of the expander and configured to remove heat from the working fluid; a condensing unit fluidly connected to an outlet of the recuperator and configured to condense the working fluid; and a pump fluidly connected to an outlet of the condensing unit and configured to pump the condensed working fluid back to the recuperator, wherein the recuperator is fluidly connected to the heat exchanger such that the working fluid follows a closed path. ## Claims ### Claim 1 A closed cycle system for waste heat recovery, the system comprising: a heat exchanger configured to transfer heat from an external heat source to a working fluid; an expander fluidly connected to an outlet of the heat exchanger and configured to expand the working fluid and produce mechanical energy; a recuperator fluidly connected to an outlet of the expander and configured to remove heat from the working fluid; a condensing unit fluidly connected to an outlet of the recuperator and configured to condense the working fluid; and a pump fluidly connected to an outlet of the condensing unit and configured to pump the condensed working fluid back to the recuperator, wherein the recuperator is fluidly connected to the heat exchanger such that the working fluid follows a closed path. ### Claim 2 (depends on 1) The system of claim 1, wherein the condensing unit comprises: a multistage compressor configured to compress the working fluid; and a cooler mechanism fluidly connected to the multistage compressor and configured to cool the working fluid. ### Claim 3 (depends on 2) The system of claim 2, wherein the cooler mechanism comprises: a first cooler mechanism disposed upstream of the multistage compressor and configured to cool the working fluid to achieve a predetermined temperature; and a second cooler mechanism disposed downstream of the multistage compressor and configured to cool and condense the working fluid. ### Claim 4 (depends on 2) The system of claim 2, wherein the multistage compressor comprises at least one inter-cooler mechanism between adjacent stages. ### Claim 5 (depends on 1) The system of claim 1, wherein the condensing unit is configured to change a state of the working fluid to a supercritical state. ### Claim 6 (depends on 5) The system of claim 5, wherein the change of the state of the working fluid to the supercritical state occurs in a multistage compressor. ### Claim 7 A method of waste heat recovery that is part of a closed cycle system, the method comprising: transferring heat from an external heat source to a working fluid; expanding the heated working fluid for producing mechanical energy; cooling the expanded working fluid; condensing the cooled working fluid to change a phase of the working fluid to a liquid phase; pumping the condensed working fluid; and heating the pumped working fluid by transferring heat from the expanded working fluid. ### Claim 8 (depends on 7) The method of claim 7, wherein condensing the working fluid comprises: cooling the working fluid to a pre-determined temperature; compressing the working fluid; and further cooling the working fluid to condense it. ### Claim 9 A closed cycle system for waste heat recovery, the system comprising: a heat exchanger configured to transfer heat from an external heat source to a working fluid; an expander fluidly connected to an outlet of the heat exchanger and configured to expand the working fluid and produce mechanical energy; a recuperator fluidly connected to an outlet of the expander and configured to remove heat from the working fluid; a refrigeration unit fluidly connected to an outlet of the recuperator and configured to condense the working fluid; and a pump fluidly connected to an outlet of the refrigeration unit and configured to pump the condensed working fluid back to the recuperator, wherein the recuperator is fluidly connected to the heat exchanger such that the working fluid follows a closed path. ### Claim 10 A transcritical closed cycle system for waste heat recovery and configured to follow a phase curve plotted in a pressure versus enthalpy space, the system comprising: a heat exchanger configured to transfer heat from an external heat source to a working fluid; an expander fluidly connected to an outlet of the heat exchanger and configured to expand the working fluid and produce mechanical energy; a recuperator fluidly connected to an outlet of the expander and configured to remove heat from the working fluid; a condensing unit fluidly connected to an outlet of the recuperator and configured to condense the working fluid; and a pump fluidly connected to an outlet of the condensing unit and configured to pump the condensed working fluid back to the recuperator, wherein the recuperator is fluidly connected to the heat exchanger such that the working fluid follows a closed path, and wherein the phase curve comprises: a first part which lies above the critical point of the working fluid; a second part which lies below the critical point of the working fluid and at the right side of a vapor dome of the working fluid; and at least one point near the critical point of the working fluid.