Patent ID: 12234020

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG.1thus schematically illustrates a first exemplary embodiment of a system100for combined heating and cooling, which is configured to implement heat exchanges in an aircraft such as the aircraft1represented inFIG.5.

The system100comprises a tank13storing dihydrogen1001in liquid form. The temperature of the dihydrogen1001in the tank13is, for example, −253° C. The system100furthermore comprises a pipe, referred to as the main pipe11, for transporting the dihydrogen1001from the tank13to a combustion chamber142of an engine14of the aircraft, where it is used as fuel. The dihydrogen1001is circulated with the aid of a circulator109, such as a pump, located on the main pipe11at the exit of the tank13. The main pipe11comprises a fuel metering valve112located at the entry of the combustion chamber142. The fuel metering valve112makes it possible to inject a predefined quantity of dihydrogen1001into the combustion chamber142.

The engine14is a turboprop, and it furthermore comprises a compressor141configured to compress air entering the combustion chamber142, as well as a turbine143located at the exit of the combustion chamber142.

The system100furthermore comprises a pipe, referred to as the bypass pipe12, separate from the main pipe11and located bypassing a predefined segment111of the main pipe11. The bypass pipe12is configured to transport a part of the flow of dihydrogen1001passing through the main pipe11and coming from the tank13, between an entry of the bypass pipe12and an exit of the bypass pipe12. The other part of the flow of dihydrogen1001passing through the main pipe11is transported in parallel in the predefined segment111of the main pipe11, between the entry of the bypass pipe12and the exit of the bypass pipe12.

Optionally, the system100furthermore comprises a flow controller121located on the bypass pipe12. The flow controller121is controlled by a control unit and makes it possible to regulate the flow of dihydrogen1001passing through the bypass pipe12.

The system100comprises a first closed circuit17, in which a first heat transfer fluid is circulated in a predefined direction, for example with the aid of a circulator107such as a pump.

The first closed circuit17comprises a first heat exchanger101and at least one second heat exchanger102, referred to as a secondary heat exchanger.

The system100furthermore comprises a second closed circuit18, in which a second heat transfer fluid is circulated in a predefined direction, for example with the aid of a circulator108such as a pump. The second closed circuit18comprises a third heat exchanger103and a fourth heat exchanger104.

Each heat exchanger101,102,103,104makes it possible to carry out a heat exchange between two fluids without mixing them, in other words to transfer heat from one fluid to the other fluid across an exchange surface.

The first heat exchanger101makes it possible to carry out a first heat exchange between the first heat transfer fluid and the dihydrogen1001passing through the bypass pipe12. The first heat exchange leads to a transfer of heat from the first heat transfer fluid to the dihydrogen1001passing through the bypass pipe12, and thus makes it possible to cool the first heat transfer fluid and to reheat a part of the flow of dihydrogen1001.

The secondary heat exchanger102makes it possible to carry out a second heat exchange, referred to as a secondary heat exchange, between the first heat transfer fluid and a fluid that is used in the aircraft and needs to be cooled, referred to as a working fluid. The working fluid is transported in a pipe15, which may be a closed circuit151(not represented inFIG.1but visible inFIG.3) or a pipe transporting the working fluid from a recovery zone1521(not represented inFIG.1but visible inFIG.3) to a working zone1522(not represented inFIG.1but visible inFIG.3). The working fluid is, for example, oil or compressed air.

The third heat exchanger103makes it possible to carry out a third heat exchange between the second heat transfer fluid and the dihydrogen1001transported by the main pipe11. The third heat exchange leads to a transfer of heat from the second heat transfer fluid to the dihydrogen1001, and thus makes it possible to cool the second heat transfer fluid and reheat the dihydrogen1001. The third heat exchange leads to a sufficient supply of heat to the dihydrogen1001so that the dihydrogen1001, which is liquid at the entry of the third heat exchanger103, vaporizes and reaches a temperature above 0° C., so as to allow stable combustion in the combustion chamber142. The dihydrogen1001is thus in the gas state at the exit of the third heat exchanger103and may then be used as fuel in the engine14. The dihydrogen1001is in a liquid state in the part of the main pipe11located between the tank13and the third heat exchanger103, and in a gas state in the part of the main pipe11located between the third heat exchanger103and the engine14.

According to the first exemplary embodiment, the third heat exchanger103is located downstream of the predefined segment111of the main pipe11. An element located downstream of an identified zone of a pipe is located on the opposite side of the identified zone from a source of a fluid circulating in the pipe. An element located upstream of an identified zone of a pipe is located on the same side of the identified zone as the source of a fluid circulating in the pipe. The source of the dihydrogen1001circulating in the main pipe11and the bypass pipe12is the tank13. For example, the third heat exchanger103is located on the side of the predefined segment111that is opposite to the tank13. The dihydrogen1001is then in a liquid state in the predefined segment111and in the bypass pipe12. The fourth heat exchanger104makes it possible to carry out a fourth heat exchange between the second heat transfer fluid and an exhaust gas that comes from the turbine143of the engine14and is transported in an exhaust gas pipe144. The fourth heat exchange leads to a transfer of heat from the exhaust gas to the second heat transfer fluid, and thus makes it possible to reheat the second heat transfer fluid.

The first heat transfer fluid may, for example, be water glycol. Water glycol comprises water and comprises a proportion of ethylene glycol or propylene glycol, and is used as a heat transfer fluid in the liquid state. The operating temperature of water glycol is defined between its melting temperature and is boiling temperature, and these vary according to the proportion of ethylene glycol or propylene glycol. Particularly, the higher the proportion of ethylene glycol, the lower the melting temperature of the water glycol. Alternatively, the first heat transfer fluid may be a gas such as dinitrogen or helium. The second heat transfer fluid may, for example, be a gas such as dinitrogen or helium.

Furthermore, the second heat transfer fluid must operate, on the one hand, at sufficiently low temperatures to withstand the loss of heat transmitted to the dihydrogen1001in the third heat exchanger103without freezing, in other words without the solidification temperature of the second heat transfer fluid being reached. Specifically, the temperature of the dihydrogen1001changes in the third heat exchanger103from about −253° C. to a temperature above 0° C. so as to allow stable combustion in the combustion chamber142. On the other hand, the second fluid must operate at sufficiently high temperatures to withstand the supply of heat received from the exhaust gas in the fourth heat exchanger104without reaching the boiling temperature of the second heat transfer fluid.

The first heat transfer fluid, conversely, has an operating temperature range narrower than that of the second heat transfer fluid. The first heat transfer fluid must be able to absorb an amount of heat in the secondary heat exchanger102which is sufficient for the working fluid to be cooled and small enough to avoid the working fluid freezing, in other words to avoid the solidification temperature of the working fluid being reached.

According to one embodiment, the flow of dihydrogen1001passing through the bypass pipe12is regulated by the flow controller121, under the control of the control unit, according to a measured temperature of the working fluid. The measured temperature of the working fluid is, for example, measured at the exit of the secondary heat exchanger102, in other words, measured after the secondary heat exchanger in the direction of circulation of the working fluid. If the measured temperature of the working fluid increases, the control unit sends a command for increasing the flow of dihydrogen1001to the flow controller121. The increase in the flow of dihydrogen1001passing through the bypass pipe12then leads to a rise in the cooling of the first heat transfer fluid, in other words, the amount of heat transferred by the first heat transfer fluid to the dihydrogen1001in the first heat exchanger101per unit volume of the first heat transfer fluid increases. Consequently, the cooling of the working fluid is enhanced, in other words, the amount of heat transferred by the working fluid to the first heat transfer fluid in the secondary heat exchanger102increases.

Conversely, if the measured temperature of the working fluid decreases, for example when the measured temperature of the working fluid falls below a first predefined threshold, the control unit sends a command for decreasing the flow of dihydrogen1001to the flow controller121. The decrease in the flow of dihydrogen1001passing through the bypass pipe12then leads to a decrease in the amount of heat per unit volume of the first heat transfer fluid transferred by the first heat transfer fluid to the dihydrogen1001in the first heat exchanger101. The cooling of the working fluid is consequently reduced, in other words, the amount of heat transferred by the working fluid to the first heat transfer fluid in the secondary heat exchanger102decreases. The regulation of the flow of dihydrogen thus makes it possible to optimize the cooling of the working fluid while avoiding the working fluid freezing.

The flow of dihydrogen1001passing through the bypass pipe12may furthermore, or alternatively, be regulated by the flow controller121, under the control of the control unit, according to a measured temperature of the first heat transfer fluid. The measured temperature of the first heat transfer fluid is, for example, measured at the entry of the first heat exchanger101, in other words, measured before the first heat exchanger101in the direction of circulation of the first heat transfer fluid. When the measured temperature of the first heat transfer fluid decreases, for example when the temperature falls below a second predefined threshold, the control unit sends a command for reducing the flow of dihydrogen1001to the flow controller121. Because of the decrease in the flow of dihydrogen1001passing through the bypass pipe12, the amount of heat transferred by the first heat transfer fluid to the dihydrogen1001decreases. The temperature of the first heat transfer fluid at the exit of the first heat exchanger thus remains above the solidification temperature of the first heat transfer fluid, and the first heat transfer fluid does not freeze.

FIG.2schematically illustrates the system100for combined heating and cooling according to a second exemplary embodiment.

The system100comprises the tank13storing the dihydrogen1001, the main pipe11transporting the dihydrogen between the tank13and the combustion chamber142of the engine14, and the bypass pipe12. The system comprises the first closed circuit17, which comprises the first heat exchanger101and the at least one secondary heat exchanger102. The system100furthermore comprises the second closed circuit18comprising the third and fourth heat exchangers103band104.

According to the second exemplary embodiment, the third heat exchanger103bis located upstream of the predefined segment111of the main pipe11, in other words, located on the same side of the predefined segment111as the tank13. The dihydrogen1001is then in a gas state in the predefined segment111and in the bypass pipe12.

The risk of the first heat transfer fluid freezing in the first heat exchanger101is therefore reduced in comparison with the first exemplary embodiment, since the temperature of the dihydrogen1001passing through the first heat exchanger101is higher.

Optionally, a fifth heat exchanger (not represented) may be added at an intersection between the second closed circuit18and the main pipe11. The fifth heat exchanger is located on the second closed circuit18and, in the direction of circulation of the second heat transfer fluid, between the fourth heat exchanger104and the third heat exchanger103b. The fifth heat exchanger is located on the main pipe11, downstream of the bypass pipe12, in other words, on the opposite side of the bypass pipe12from the tank13.

The liquid dihydrogen1001is thus initially heated partially in the third heat exchanger103b, then is partially transported through the bypass pipe12, where the first heat exchange is carried out with the first heat transfer fluid, with a sufficiently high temperature to avoid the first heat transfer fluid freezing. The heating of the dihydrogen1001is then completed in the fifth heat exchanger, where the second heat transfer fluid is hotter than in the third heat exchanger103b, in order to be used as fuel.

FIG.3schematically illustrates the system100for combined heating and cooling according to a third exemplary embodiment.

The system100comprises the tank13storing the dihydrogen1001, the main pipe11transporting the dihydrogen between the tank13and the combustion chamber142of the engine14, and the bypass pipe12. The system100furthermore comprises the second closed circuit18comprising the third and fourth heat exchangers103and104.

In the third exemplary embodiment, the system comprises the first closed circuit17which, successively in the direction of circulation of the first heat transfer fluid, comprises the first heat exchanger101, a first secondary heat exchanger1021and a second secondary heat exchanger1022.

In a similar way to the heat exchangers101,102,103,104, each heat exchanger1021,1022makes it possible to carry out a heat exchange between two fluids without mixing them, in other words, to transfer heat from one fluid to the other fluid across an exchange surface.

The first heat exchanger101makes it possible to carry out the first heat exchange between the first heat transfer fluid and the dihydrogen1001passing through the bypass pipe12.

The first secondary heat exchanger1021makes it possible to carry out a first secondary heat exchange between the first heat transfer fluid and oil circulating in a closed oil circuit151. The first secondary heat exchange leads to a transfer of heat from the oil to the first heat transfer fluid and thus makes it possible to cool the oil. The oil is transported in the oil circuit151between a working zone1511, where the oil is reheated, and the first secondary heat exchanger1021, where the oil is cooled.

The second secondary heat exchanger1022makes it possible to carry out a second secondary heat exchange between the first heat transfer fluid and compressed air that comes from the compressor141of the engine14and is transported through a compressed air pipe152. The second secondary heat exchange leads to a transfer of heat from the compressed air to the first heat transfer fluid, and thus makes it possible to cool the compressed air.

The compressed air is used in an air-conditioning system of the aircraft. The compressed air is compressed and heated in the compressor141of the engine14. The flow of the compressed air is regulated at the exit of the compressor141by a system of valves1521then sent through the second secondary heat exchanger1022. At the exit of the second secondary heat exchanger1022, the compressed air is transported to an air-conditioning system1522, where it is used to pressurize and air-condition the cabin of the aircraft.

In the third exemplary embodiment, the operating temperature range of the first heat transfer fluid is sufficiently narrow to be able to cool the oil in the first secondary heat exchanger1021and to cool the compressed air in the second secondary heat exchanger1022, and to avoid the oil freezing on the other hand, in other words, the oil falling below its solidification temperature.

The flow of dihydrogen1001is regulated by the flow controller121, under the control of the control unit, according to the temperature of the oil measured at the exit of the first secondary heat exchanger1021and/or the temperature of the compressed air measured at the exit of the second secondary heat exchanger1022.

For example, when the measured temperature of the oil increases, the control unit sends a command for increasing the flow of dihydrogen1001to the flow controller121.

When the measured temperature of the oil decreases, for example when the temperature of the oil decreases and passes below a third predefined threshold, the control unit sends a command for reducing the flow of dihydrogen1001to the flow controller121.

When the measured temperature of the compressed air increases, the control unit determines whether the measured temperature of the oil is above the third predefined threshold. If this is the case, the control unit sends an instruction for increasing the flow of dihydrogen1001to the flow controller121.

FIG.4schematically illustrates an example of the hardware architecture of an internal control unit of the flow controller121. The control unit internal to the flow controller121then comprises, connected by a communication bus410: a processor or central processing unit (CPU)401; a random-access memory (RAM)402; a read-only memory (ROM)403; a storage unit or a storage medium reader such as a hard disk drive (HDD)404; and a communication interface405for communicating with elements such as temperature sensors.

The processor401is capable of executing instructions loaded into the RAM402from the ROM403, an external memory (not represented), a storage medium or a communication network. When the control unit is powered up, the processor401is capable of reading instructions from the RAM402and executing them. These instructions form a computer program causing the processor401to implement all or some of the actions described above in connection with the control unit.

Thus, all or some of the actions described in connection with the control unit of the flow controller121may be implemented in software form via the execution of a set of instructions by a programmable machine, such as a DSP (digital signal processor) or a microcontroller, or in hardware form by a machine or a dedicated component, such as an FPGA (field-programmable gate array) or an ASIC (application-specific integrated circuit). According to one variant, the control unit described above is external to the flow controller121and comprises means for remote control of the flow controller121.

FIG.5illustrates the aircraft1equipped with the system for combined heating and cooling.

While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.