US 12,241,415 B1
Gas turbine engine heat exchange
Benjamin J Keeler, Chesterfield (GB); Craig W Bemment, Derby (GB); Andrea Minelli, Derby (GB); Alastair G Hobday, Derby (GB); and Andrew T Smith, Derby (GB)
Assigned to ROLLS-ROYCE plc, London (GB)
Filed by ROLLS-ROYCE plc, London (GB)
Filed on Jun. 25, 2024, as Appl. No. 18/753,128.
Claims priority of application No. 2319120 (GB), filed on Dec. 14, 2023.
Int. Cl. F02C 7/14 (2006.01); F28D 21/00 (2006.01)
CPC F02C 7/14 (2013.01) [F05D 2260/213 (2013.01); F05D 2270/303 (2013.01); F28D 2021/0026 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method of operating a gas turbine engine, the gas turbine engine comprising:
an engine core comprising a turbine, a compressor, a combustor arranged to combust a fuel, and a core shaft connecting the turbine to the compressor;
a fan located upstream of the engine core;
a gearbox that receives an input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft;
an oil loop system arranged to supply oil to the gearbox; and
a heat exchange system comprising:
a refrigeration cycle apparatus;
an air-oil heat exchanger through which the oil in the oil loop system flows; and
a fuel-oil heat exchanger through which the oil in the oil loop system and the fuel flow such that heat is transferred between the oil and the fuel, and wherein the oil loop system branches such that a proportion of the oil can flow along each branch and the air-oil and fuel-oil heat exchangers are arranged in a parallel configuration on different branches of the oil loop system; and
a modulation valve arranged to allow the proportion of the oil sent via each branch to be varied,
the method comprising controlling the heat exchange system using the refrigeration cycle apparatus to provide thermal lift by transferring further heat from the oil to the fuel such that temperature of the fuel is raised above temperature of the oil such that, under cruise conditions, a heat transfer ratio of:

OG Complex Work Unit Math
is in the range from 0 to 0.67.