A cooling system includes a first cooling loop, a second cooling loop and a heat exchanger configured to transfer heat from the first cooling loop to the second cooling loop. The first cooling loop includes a flow restrictor, an inertial separator, and a pressure relief valve cooperating to effect diversion of vapor present in the first cooling loop due to a leak between the first cooling loop and the second cooling loop.

The cooling system includes an energy source, one or more heat exchangers for cooling a coolant, the one or more heat exchangers being connected to the energy source by a coolant circuit, one or more air channels inside which the one or more heat exchangers are placed, wherein the coolant circuit includes a bypass portion that recirculates the coolant to the energy source or circulates the coolant from the energy source to the one or more heat exchangers. The method includes decreasing the temperature of a portion of a coolant below an operating temperature, acting this portion of the coolant as a thermal buffer, and maintaining the rest of the coolant at the operation temperature. They allow enhancing the cooling capabilities of the system during the take-off phase, especially during the beginning of this phase.

The cooling system includes an energy source, one or more heat exchangers for cooling a coolant, the one or more heat exchangers being connected to the energy source by a coolant circuit, one or more air channels inside which the one or more heat exchangers are placed, wherein the coolant circuit includes a bypass portion that recirculates the coolant to the energy source or circulates the coolant from the energy source to the one or more heat exchangers. The method includes decreasing the temperature of a portion of a coolant below an operating temperature, acting this portion of the coolant as a thermal buffer, and maintaining the rest of the coolant at the operation temperature. They allow enhancing the cooling capabilities of the system during the take-off phase, especially during the beginning of this phase.

A cooling system for an aircraft comprises a gas turbine engine, an ancillary apparatus, and a heat exchanger. The gas turbine engine comprises, in axial flow sequence, a compressor module, a combustor module, and a turbine module, with a first electric machine being rotationally connected to the turbine module. The first electrical machine is configured to generate an electrical power P.sub.EM1 (W). The heat exchanger is configured to transfer a total waste heat energy Q (W) generated by the gas turbine engine and the ancillary apparatus, to an airflow passing through the heat exchanger, and a ratio S of:

[00001]$S=\frac{\left(\mathrm{Total}\mathrm{Electrical}\mathrm{Power}\mathrm{Generated}=P_{\mathrm{EM}1}\right)}{\left(\mathrm{Total}\mathrm{Heat}\mathrm{Energy}\mathrm{Rejected}\mathrm{to}\mathrm{Airflow}=Q\right)}$

is in a range of between 0.50 and 5.00.

A cooling system for an aircraft comprises a gas turbine engine, an ancillary apparatus, and a heat exchanger. The gas turbine engine comprises, in axial flow sequence, a compressor module, a combustor module, and a turbine module, with a first electric machine being rotationally connected to the turbine module. The first electrical machine is configured to generate an electrical power P.sub.EM1 (W). The heat exchanger is configured to transfer a total waste heat energy Q (W) generated by the gas turbine engine and the ancillary apparatus, to an airflow passing through the heat exchanger, and a ratio S of:

[00001]$S=\frac{\left(\mathrm{Total}\mathrm{Electrical}\mathrm{Power}\mathrm{Generated}=P_{\mathrm{EM}1}\right)}{\left(\mathrm{Total}\mathrm{Heat}\mathrm{Energy}\mathrm{Rejected}\mathrm{to}\mathrm{Airflow}=Q\right)}$

is in a range of between 0.50 and 5.00.

A combined cooling and humidifying system for a fuel cell system includes a first line strand, second line strand, gas separator, and water feed device. The first line strand has a supply line for feeding water to a heat exchanger of the fuel cell system and a return line for receiving a water-steam mixture from the fuel cell system. The gas separator is in the return line to at least partially separate the steam from the water-steam mixture and provide it at a steam connection. The second line strand has a fluid inlet for feeding a gaseous fluid to the fuel cell system. The steam connection is coupled to the second line strand downstream of the fluid inlet to admix steam with the fluid. The water feed device is coupled to the supply line to compensate for a separating mass flow of steam in the first line strand.

A combined cooling and humidifying system for a fuel cell system includes a first line strand, second line strand, gas separator, and water feed device. The first line strand has a supply line for feeding water to a heat exchanger of the fuel cell system and a return line for receiving a water-steam mixture from the fuel cell system. The gas separator is in the return line to at least partially separate the steam from the water-steam mixture and provide it at a steam connection. The second line strand has a fluid inlet for feeding a gaseous fluid to the fuel cell system. The steam connection is coupled to the second line strand downstream of the fluid inlet to admix steam with the fluid. The water feed device is coupled to the supply line to compensate for a separating mass flow of steam in the first line strand.

In an aspect of the present disclosure is a system for cooling a high voltage (HV) cable on an electric aircraft, including a fuselage configured to receive the HV cable, including a first side comprising a first venting closure movable between an open position and a closed position. The fuselage may further comprise a second side opposite the first side, the second side comprising a second venting closure movable between an open position and a closed position; wherein the first and second venting closures are configured to create a cooling channel between the first and second venting closures when the first and second venting closures are in the open position, wherein the cooling channel contacts the HV cable.

A system and method for adaptively controlling a cooldown cycle of an auxiliary power unit (APU) that is operating and rotating at a rotational speed includes reducing the rotational speed of the APU to a predetermined cooldown speed magnitude that ensures combustor inlet temperature has reached a predetermined temperature value, determining, based on one or more of operational parameters of the APU, when a lean blowout of the APU is either imminent or has occurred, and when a lean blowout is imminent or has occurred, varying one or more parameters associated with the shutdown/cooldown cycle.

A system and method for adaptively controlling a cooldown cycle of an auxiliary power unit (APU) that is operating and rotating at a rotational speed includes reducing the rotational speed of the APU to a predetermined cooldown speed magnitude that ensures combustor inlet temperature has reached a predetermined temperature value, determining, based on one or more of operational parameters of the APU, when a lean blowout of the APU is either imminent or has occurred, and when a lean blowout is imminent or has occurred, varying one or more parameters associated with the shutdown/cooldown cycle.