AN EVAPORATOR IN A COOLING FURNITURE

The present invention relates to an evaporator that improves the efficiency of a cooling furniture that is used for both cooling and freezing of food, e.g. in a supermarket.

BACKGROUND OF THE INVENTION In supermarkets, hypermarkets, etc., it is often desirable that a cooling furniture for the display and handling of food is capable of operating as a freezing counter for frozen food during some time periods and as a chilling counter for chilled food during other time periods. Cooling systems for freezing and chilling, respectively, typically constitute separate systems with different refrigerants. In known systems, a cooling furniture that may operate both at a freezing temperature, e.g. - 18 ⁰ C, and at a chilling temperature, e.g. 4 ⁰ C, the evaporator of the cooling furniture is coupled to the freezing system, and the temperature control in the furniture is switched between two thermostats so that easy selection between the two desired temperatures is provided. However, during operation at a chilling temperature, the cooling furniture operates with the efficiency of the freezing system, which is considerably lower than the efficiency of the chilling system.

SUMMARY OF THE INVENTION

Thus, it is an object of the present invention to provide a cooling furniture that is adapted for operation both at a freezing temperature and at a chilling temperature with improved efficiency at the chilling temperature. According to the present invention the above-mentioned and other objects are fulfilled by a refrigeration system comprising a freezing system and a chilling system with flow circuits for recirculation of separate refrigerants, each of the flow circuits comprising a compressor for generation of a refrigerant flow from a low-pressure side to a high-pressure side of the compressor and, in the order defined by the flow direction, connected in series with a condenser for cooling of the refrigerant towards the ambient temperature, a pressure reducing device, such as a reduction valve, cooperating with the compressor for generation of the low-pressure side and the high pressure side of the compressor, and an evaporator for evaporation of the refrigerant, e.g. in a cooling furniture.

The evaporator is a shared evaporator that is shared by the freezing system and the chilling system and provides a separate flow path through the evaporator for each of the refrigerants of the freezing system and the chilling system.

The evaporator may selectively be coupled into the flow circuit of the freezing system allowing the refrigerant of the freezing system to flow through the evaporator cooling the surroundings to a freezing temperature, e.g. - 18 ⁰ C, and the evaporator may selectively be

coupled into the flow circuit of the chilling system allowing the refrigerant of the chilling system to flow through the evaporator cooling the surroundings to a chilling temperature, e.g. 4 ⁰ C. In this way, the evaporator may selectively cool the surroundings to a freezing temperature with the efficiency of the freezing system and cool the surroundings to a chilling temperature with the efficiency of the chilling system.

In a preferred embodiment, one of the refrigerants is input to the respective flow path at a first end of the evaporator and the other of the refrigerants is input to the other respective flow path at a second end of the evaporator opposite the first end.

The evaporator may comprise a plurality of cooling fins for provision of an air flow path with a large cooling area, and an array of rows and columns of tubular flow channels extending linearly through and substantially perpendicular to the cooling fins, the tubular flow channels being interconnected with U-shaped tubes at the first and second end of the evaporator to form the separate flow paths for the refrigerants of the freezing system and the chilling system. The flow channels may be interconnected in such a way that every second column of flow channels form part of one of the flow paths, and every other second column of flow channels form part of the other of the flow paths.

One of the refrigerants may be CO ₂ .

The freezing system and/or the chilling system may be a transcritical system, such as a transcritical CO ₂ system.

Similar to the shared evaporator, the gas cooler or condenser may be a shared gas cooler or condenser that is shared by the freezing system and the chilling system and provides a separate flow path for each of the refrigerants of the freezing system and the chilling system through the shared condenser or gas cooler. The system may comprise a shared gas cooler or condenser and separate evaporators. BRIEF DESCRIPTION OF THE DRAWINGS

Below the invention will be described in more detail with reference to the exemplary embodiments illustrated in the drawing, wherein

Fig. 1 is a blocked schematic of an embodiment of a refrigeration system according to the present invention, and

Fig. 2 shows in perspective an evaporator according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig. 1 is a blocked schematic of an embodiment 10 of a refrigeration system according to the present invention. The system 10 comprises a freezing system 12 and a chilling system 14. The freezing system 12 has a refrigerant flow circuit 16 for recirculation of a refrigerant 18, the flow circuit 16 comprising a compressor 20 for generation of a refrigerant flow in the direction of the arrow 22 from a low-pressure side to a high-pressure side of the compressor 20 and, in the order defined by the flow direction, connected in series with a condenser, or, in a transcritical system, a gas cooler 24 for cooling of the refrigerant 18 towards the ambient temperature, a receiver 26 for accommodation of the refrigerant 18. The receiver 26 is connected to a magnet valve 27 in series with an expansion valve 28 that cooperates with the compressor 20 for generation of the low-pressure side and the high-pressure side of the compressor 20, and a shared evaporator 30 for evaporation of the refrigerant 18. Likewise, the chilling system 14 has a refrigerant flow circuit 32 for recirculation of a refrigerant 34, the flow circuit 32 comprising a compressor 36 for generation of a refrigerant flow in the direction of the arrow 38 from a low-pressure side to a high-pressure side of the compressor 36 and, in the order defined by the flow direction, connected in series with a condenser, or, in a transcritical system, a gas cooler 40 for cooling of the refrigerant 34 towards the ambient temperature, a receiver 42 for accommodation of the refrigerant 34. The receiver 42 is connected to a magnet valve 43 in series with an expansion valve 44 that cooperates with the compressor 36 for generation of the low-pressure side and the high-pressure side of the compressor 36, and the evaporator 30 for evaporation of the refrigerant 34.

The shared evaporator 30 may selectively be coupled into the flow circuit 16 of the freezing system 12 by opening magnet valve 27 and closing magnet valve 43 thereby allowing the refrigerant 18 of the freezing system 12 to flow through the shared evaporator 30 cooling the surroundings of the shared evaporator 30 to a freezing temperature, e.g. - 18 ⁰ C, and the shared evaporator 30 may selectively be coupled into the flow circuit 32 of the chilling system 14 by opening magnet valve 43 and closing magnet valve 27 thereby allowing the refrigerant 34 of the chilling system 14 to flow through the shared evaporator 30 cooling the surroundings of the shared evaporator 30 to a chilling temperature, e.g. 4 ⁰ C. In this way, the shared evaporator 30 may selectively cool the surroundings to a freezing temperature with the efficiency of the freezing system and cool the surroundings to a chilling temperature with the efficiency of the chilling system.

Fig. 2 shows in perspective a shared evaporator 50 according to the present invention. For illustration purposes, a part of the evaporator 50 shown in perspective from the left and a part of the evaporator 50 shown in perspective from the right is shown side by side. The left part of Fig. 2 shows the first end 52 of the evaporator 50 where the refrigerant 18 of the freezing

system 12 enters into the evaporator 50 at the input of flow channel 54 and flows through the evaporator 50 and is guided into flow channel 56 through a U-shaped tube 58 at the other end 60 of the evaporator. The refrigerant flows back and forth through the evaporator 50 through the column 62 of flow channels until the refrigerant 18 is guided to the next column 64 of flow channels through U-shaped tube 66, etc. Finally, the refrigerant 18 leaves the evaporator 50 at the output of flow channel 68. In the illustrated example, the refrigerant 18 is CO ₂ .

Likewise, the right part of Fig. 2 shows the second end 60 of the evaporator 50 where the refrigerant 34 of the chilling system 14 enters into the evaporator 50 at the input of flow channel 70 and flows through the evaporator 50 and is guided into flow channel 72 through a U-shaped tube 74 at the first end 52 of the evaporator 50. The refrigerant 34 flows back and forth through the evaporator 50 through the column 76 of flow channels until the refrigerant 34 is guided to the next column 78 of flow channels through U-shaped tube 80, etc. Finally, the refrigerant 34 leaves the evaporator 50 at the output of flow channels 82, 84. In the illustrated example, the refrigerant 34 is R134a.

The evaporator 50 also comprises a plurality of cooling fins 90, preferably made of aluminium, for provision of an airflow path with a large cooling area.

The person skilled in the art will appreciate that the evaporator according to the present invention may be manufactured substantially at the same cost as a prior art evaporator since the only difference between the evaporator according to the present invention and the prior art evaporator may reside in a different way of connecting the U-shaped tubes to the flow channels, and the inputs and outputs for the refrigerants.

A shared gas cooler or condenser may also be constructed as illustrated in Fig. 2.