US 12,168,957 B2
Fuel oil heat exchange
Craig W Bemment, Derby (GB); Benjamin J Keeler, Chesterfield (GB); Kevin R McNally, Derby (GB); and Andrea Minelli, Derby (GB)
Assigned to ROLLS-ROYCE PLC, London (GB)
Filed by ROLLS-ROYCE PLC, London (GB)
Filed on Jun. 20, 2023, as Appl. No. 18/337,603.
Claims priority of application No. 2219391 (GB), filed on Dec. 21, 2022.
Prior Publication US 2024/0209786 A1, Jun. 27, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. F02C 7/224 (2006.01); F23R 3/28 (2006.01)
CPC F02C 7/224 (2013.01) [F23R 3/28 (2013.01); F05D 2260/20 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of operating a gas turbine engine installed on an aircraft, the gas turbine engine comprising:
a fuel delivery system arranged to provide fuel;
a combustor arranged to combust the fuel;
a primary fuel-oil heat exchanger arranged to have the fuel provided by the fuel delivery system flow therethrough; and
a secondary fuel-oil heat exchanger arranged to have a proportion of the fuel from the primary fuel-oil heat exchanger flow therethrough, and wherein the proportion of the fuel is arranged to flow from the primary fuel-oil heat exchanger to the secondary fuel-oil heat exchanger and oil is arranged to flow from the secondary fuel-oil heat exchanger to the primary fuel-oil heat exchanger; and
wherein the method comprises
operating the gas turbine engine while the aircraft is at cruise conditions, and
controlling the fuel delivery system, the primary fuel-oil heat exchanger and the secondary fuel-oil heat exchanger so as to transfer heat to the fuel from the oil in the primary fuel-oil heat exchanger in an amount between 200-600 KJ/m3 of heat per unit volume of fuel reaching the combustor when operating the gas turbine engine while the aircraft is operating at the cruise conditions.