Cooling systems for operation with a two-phase refrigerant are known from DE 10 2006 005 035 B3, WO 2007/088012 A1, DE 10 2009 011 797 A1 and US 2010/0251737 A1 and may be used for example to cool food that is stored on board a passenger aircraft and intended to be supplied to the passengers. Typically, the food provided for supplying to the passengers is kept in mobile transport containers. These transport containers are filled and precooled outside the aircraft and after loading into the aircraft are deposited at appropriate locations in the aircraft passenger cabin, for example in the galleys. In order to guarantee that the food remains fresh up to being issued to the passengers, in the region of the transport container locations cooling stations are provided, which are supplied with cooling energy from a central refrigerating device and release this cooling energy to the transport containers, in which the food is stored.
In the cooling systems known from DE 10 2006 005 035 B3, WO 2007/088012 A1, DE 10 2009 011 797 A1 and US 2010/0251737 A1 the phase transitions of the refrigerant flowing through the circuit that occur during operation of the system allow the latent heat consumption that then occurs to be utilized for cooling purposes. The refrigerant mass flow needed to provide a desired cooling capacity is therefore markedly lower than for example in a liquid cooling system, in which a one-phase liquid refrigerant is used. Consequently, the cooling systems described in DE 10 2006 005 035 B3, WO 2007/088012 A1, DE 10 2009 011 797 A1 and US 2010/0251737 A1 may have lower tubing cross sections than a liquid cooling system with a comparable cooling capacity and hence have the advantages of a lower installation volume and a lower weight. What is more, the reduction of the refrigerant mass flow makes it possible to reduce the conveying capacity needed to convey the refrigerant through the cooling circuit of the cooling system. This leads to an increased efficiency of the system because less energy is needed to operate a corresponding conveying device, such as for example a pump, and moreover less additional heat generated by the conveying device during operation of the conveying device has to be removed from the cooling system.
In the prior art cooling systems the two-phase refrigerant typically is stored, in the form of a boiling liquid, in an accumulator which is disposed in a cooling circuit allowing circulation of the two-phase refrigerant therethrough. So as to avoid excess wear of a conveying device for discharging the two-phase refrigerant from the accumulator, which may, for example, be designed in the form of a pump, conveying gaseous refrigerant through the conveying device and the formation of gas bubbles (cavitation) in the conveying device should be prevented as far as possible. Cavitation typically is the result of a pressure decrease in the refrigerant due to an abrupt increase of the flow speed caused by rapidly moving pump components.
Non-published DE 10 2011 014 954 therefore proposes an accumulator arrangement for use in a cooling system suitable for operation with a two-phase refrigerant wherein the refrigerant is liquefied and subcooled in a condenser. The subcooled refrigerant exiting the condenser is guided through a heat exchanger disposed within the accumulator and thereafter is discharged into the accumulator. While flowing through the heat exchanger the subcooled refrigerant releases cooling energy to the refrigerant already received in the accumulator.
Further, non-published DE 10 2011 121 745 proposes an accumulator arrangement for use in a cooling system suitable for operation with a two-phase refrigerant, wherein a conveying device for conveying refrigerant from an accumulator is formed integral with the accumulator. The integration of the conveying device into the accumulator allows to dispense with a tubing connecting the accumulator to the conveying device, which, in particular during start-up of the cooling system might contain gaseous refrigerant.
USPTO Backgrounds
USPTO Backgrounds