High-Temperature Heat Pump for Aircraft Engine Oil Cooling

Oil heat management must be reviewed globally as an integrated function as a consequence of the development of the next generation of aeroengines because of its strong effect on the cooling strategy applied in aircraft. Here, oil system cooling is provided in part by an air oil heat exchanger. Such an approach generates aerodynamic penalties in the turbomachine. Thus, new technological solutions should be inspected to meet the requirements. The present study investigates the feasibility of using heat pump technology for oil cooling to provide temperature lift as a means to reduce the air oil heat exchanger surface area, which should offset the effect of adding the heat pump components mass and the compressor power consumption. For this purpose, a proper thermodynamic optimization coupled with a working fluid selection method is conducted for the heat pump system. However, the heat pump cooling solution remains less attractive than a direct air oil heat exchanger. A novel optimized oil-cooling configuration that combines both the air oil heat exchanger and the heat pump system is proposed. Compared to the direct air oil heat exchanger, the new oil-cooling configuration shows merit from a certain threshold of oil heat dissipation, which is defined by the engine sizing.