CH718262A1 - Cooling device with a cooling circuit for cooling the condenser. - Google Patents

Abstract

A refrigerator, in particular a domestic refrigerator, comprises a controller (12) and a heat pump with an evaporator (3a, 3b) for cooling a usable space (1, 2), a condenser for dissipating heat, a compressor (4), a throttle ( 6), and a first circuit (7) for the circulation of refrigerant. The cooling device has a second circuit (8) for circulating a cooling medium, in particular a liquid or a gas, with the condenser being designed as a heat exchanger (5) in order to transfer heat from the refrigerant to the cooling medium of the second circuit (8).

Description

field of invention

The invention relates to a refrigerator, in particular a household refrigerator with a controller and a heat pump. The heat pump includes an evaporator for cooling a useful space, a condenser for dissipating heat, a compressor, a throttle, and a first circuit for circulating refrigerant.

background

The demands on the energy consumption of conventional refrigerators in private households are constantly increasing. Known measures for reducing energy consumption are, for example, improved insulation of the utility rooms or an optimized design of the cooling unit. The energy consumption essentially depends on the ambient temperature at which the cooling device is operated. The greater the temperature difference between the usable space and the environment, the greater the energy consumption.

Presentation of the invention

The object is to provide a cooling device which has reduced energy consumption.

[0004] This object is solved by the subject matter of the independent claim. Accordingly, a refrigeration device, in particular a domestic refrigeration device, comprises a controller and a heat pump. The heat pump includes an evaporator for cooling a usable space, a condenser for dissipating heat, a compressor, a throttle, and a first circuit for circulating refrigerant between the individual components of the heat pump. The cooling device also includes a second circuit for circulating a cooling medium, in particular a liquid or a gas, with the condenser being designed as a heat exchanger in order to transfer heat from the refrigerant of the first circuit to the cooling medium of the second circuit.

The cooling device can be, for example, a refrigerator, a freezer or a combination of refrigerator and freezer or a wine cabinet.

[0006] Water, gray water, waste water, glycols, water-glycol mixtures, heat transfer oils, demineralized water or another refrigerant are used as the cooling medium, for example.

The cooling of the condenser by means of a cooling medium circulating in a second circuit has the advantage that the operation of the cooling device is less dependent on the thermal conditions of that room in which the cooling device is arranged. If the cooling device is installed in a kitchen, for example, and the circulation lines of the second circuit run from the cooling device as part of an anergy or geothermal network into the ground, the cooling medium can always, i.e. throughout the year, assume temperatures that are significantly below the kitchen room temperature. Compared to a cooling device that is cooled with ambient air, the cooling medium circulating in the second circuit is at a lower temperature on the one hand and in a narrower temperature range on the other. Because cooling devices are usually located in rooms with a room temperature of 20°C to 35°C, depending on the time of year.

The heat exchanger is advantageously configured as a plate heat exchanger. A plate heat exchanger requires relatively little space in a cooling device, so that more space is available for the usable space of the cooling device, for example. Alternatively, the use of a tube-to-tube heat exchanger, a tube-in-tube heat exchanger or a microchannel heat exchanger is also conceivable.

The second circuit is advantageously a closed circuit. This means that the same coolant constantly circulates within the second circuit, no coolant escapes from the second circuit or new one enters.

Furthermore, the controller can control the second circuit in such a way that the cooling medium has a certain, in particular constant, temperature in the heat exchanger or at its outlet or inlet. This has the advantage that the heat transfer from the refrigerant to the cooling medium can be precisely controlled and the heat transfer is independent of the ambient temperature. It also favors the equipment of the cooling device with passive throttling devices.

In particular, the temperature of the cooling medium in the heat exchanger or at its outlet or inlet depends on an ambient temperature, a usable space temperature, or a pressure prevailing in the first circuit, in particular a pressure in the evaporator or in the heat exchanger or a temperature at the respective inlet or outlets of the evaporator or the heat exchanger. This is advantageous because the usable space requires more or less cooling capacity depending on the ambient temperature. By measuring the status values of the device, this requirement can be determined and the temperature or the flow rate of the cooling medium can be adjusted in order to keep the temperature within the usable space at the desired target temperature.

In a particular embodiment, the controller controls the second circuit in such a way that the cooling medium flows at a specific volume flow in the heat exchanger, in particular with the volume flow depending on an ambient temperature and/or a usable space temperature and/or a pressure prevailing in the first circuit , in particular a pressure in the evaporator or in the heat exchanger or a pressure or temperature at the respective inlets or outlets of the evaporator or the heat exchanger. The heat transfer at the heat exchanger can also be influenced well by controlling the volume flow. The more volume of cooling medium is available at the heat exchanger, the more heat energy can be extracted from the refrigerant.

Furthermore, the second circuit has a bypass line for bypassing the heat exchanger, and/or the volume flow in the second circuit can be controlled by the controller, in particular by means of a valve. The bypass line means that not all of the cooling medium is routed through the heat exchanger, but some of it flows past the heat exchanger. Accordingly, the total volume flow of that cooling medium which circulates in the entire second circuit differs from that cooling medium which flows through the heat exchanger. The temperatures of the cooling medium in the heat exchanger and in the rest of the second circuit can be influenced as a result.

[0014] Examples of suitable valves are on/off valves, needle valves with a stepper motor, thermostatic expansion valves or other flow-dividing valves.

In a particular embodiment, the throttle has at least two capillaries connected in parallel, in particular with two different flow resistances. These can be opened or closed individually by means of valves, resulting in a flow through one or more capillaries and thus the flow resistance of the throttle can be adjusted. An expansion valve with a variable flow resistance can also be provided for the same purpose. Expansion valve and capillary can also be connected in series or in parallel.

Advantageously, the switchover of the at least two capillaries connected in parallel or the switchover of the expansion valve takes place as a function of the ambient temperature, a temperature of the cooling medium prevailing in the second circuit or a pressure of the refrigerant prevailing in the first circuit, in particular a pressure in the evaporator (3a, 3b) or in the heat exchanger (5).

Further protected is a building with an interior and an exterior, a cooling device arranged in the interior according to the present invention, wherein the second circuit is arranged at least partially in the exterior. In particular, the second circuit is arranged within a floor of the outdoor area, in particular deeper than one meter below the floor surface.

The cooling device according to the invention can be used not only in private households, but also, for example, in clean rooms or gray rooms. These are places where air circulation through ventilation is undesirable, which is why cooling by means of a second circuit is particularly well suited for such rooms.

The heat energy of the second circuit can be released, for example, into a ground, to a water reservoir, a third fluid circuit, to waste water or to groundwater.

The invention also relates to an arrangement with the cooling device according to the invention and at least one other household appliance to be cooled and/or a heat-related household appliance, in particular a dishwasher. In this case, the second circuit is connected to the other household appliance to be cooled and/or to the heat-related household appliance. The other household appliance to be cooled can give off heat to the cooling medium of the second circuit and/or the heat-related household appliance can absorb heat from the cooling medium and use it to cool it.

It should be noted that the cooling device according to the invention could also provide conventional cooling of the heat pump condenser by means of ambient air.

Brief description of the drawings

[0022] Further configurations, advantages and applications of the invention result from the dependent claims and from the following description with reference to the figures. 1 shows a schematic representation of a first embodiment of the cooling device according to the invention, and FIG. 2 shows a schematic representation of a second embodiment of the cooling device according to the invention.

Ways to carry out the invention

1 shows a refrigerator with a usable space, which consists of a freezer compartment 1 and a refrigerator compartment 2 . The temperatures in the freezer compartment 1 are below -18°C and the temperatures in the refrigerator compartment are between 2°C and 5°C. However, these are only examples and other usable space compartments with other temperature ranges can also be provided.

The cooling of the freezer compartment 1 and the refrigerator compartment 2 is carried out by means of a heat pump. The heat pump comprises two evaporators 3a and 3b, which are assigned to the freezer compartment 1 and the refrigerator compartment 2, a compressor 4, a heat exchanger 5, which serves as a condenser in the heat pump system, and a throttle 6 designed as a capillary. To transport the heat energy circulates between the individual components of the heat pump, a refrigerant in lines of a first circulation circuit 7. By evaporating the refrigerant, the evaporators 3a and 3b extract thermal energy from the freezer compartment 1 and the refrigerator compartment 2, which is released again by the heat pump on the heat exchanger 5 through condensation of the refrigerant.

At the heat exchanger 5 a heat exchange takes place between the refrigerant circulating in the heat pump and a cooling medium circulating in a second circuit 8 . Thermal energy is transferred from the refrigerant to the cooling medium. As a result, the refrigerant is cooled and expanded in the throttle 6, and is thus ready again to absorb thermal energy from the freezer compartment 1 and the refrigerator compartment 2 again in the evaporators 3a and 3b. Water or brine, for example, serves as a cooling medium. The heat exchanger 5 is designed as a plate heat exchanger. This enables efficient heat exchange between the refrigerant and the cooling medium. Furthermore, the plate heat exchanger is very space-saving compared to other forms of heat exchangers.

The second circuit 8 is a closed circuit, i.e. the cooling medium neither exits the circuit nor does new cooling medium enter the circuit. The second circuit 8 comprises a passage through the heat exchanger 5, a pump 9, cooling lines 10, two valves 11a and 11b and a circulation line 11c. Alternatively, these valves could be replaced by a single valve at the branch point.

The cooling medium is conveyed within the second circuit 8 by means of the pump 9 . The pump performance determines the total volume flow. This flows completely through the cooling lines 10. The cooling lines 10 can, for example, run 1.5 meters below the surface of the ground, i.e. at a location in which the ground has a sufficiently low temperature so that the cooling medium releases thermal energy to the ground while circulating through the cooling lines 10 can. If the cooling device is installed in a private household, for example, the cooling lines 10 can run in the ground in the garden.

[0028] In such an arrangement of the cooling lines, one speaks of a surface register arranged, in particular horizontally. Instead of borehole boreholes, cooling lines are laid flat under the ground. If such a surface register is used in combination with a heating heat pump, the cooling lines can also serve as heating lines. I.e. the cooling device helps to heat a fluid for the heating heat pump.

The flow through the heat exchanger 5 can be adjusted by adjusting the valves 11a and 11b. Either the total volume flow of the second circuit 8 flows completely through the heat exchanger 5, so that the cooling capacity is greatest. Alternatively, the total volume flow flows completely through the circulating line 11c, so that no heat exchange takes place at the heat exchanger 5. The total volume flow can also flow partly through the heat exchanger 5 and partly through the circulating line 11c. For example, the cooling medium can flow through the heat exchanger 5 with a volume flow of 0 to 100 liters, for example 20 liters, per hour.

While the best possible heat exchange with the ground is desired in the cooling lines 10, the remaining lines of the second circuit 8 are to be insulated as well as possible so that the cooling medium is not unnecessarily heated by the environment. In addition, the insulation prevents the formation of condensation, which would lead to damage to the building. To the extent that the lines of the second circuit 8 run within the housing of the cooling device, the lines can be foamed in, for example, or covered with well-insulating covers. The entire system, i.e. both the first circuit 7 and the second circuit 8, are controlled by a controller 12. The controller 12 receives measurement data from different sensors. For example, the temperatures in the freezer compartment 1 and in the refrigerator compartment 2 are measured by means of temperature sensors 13a and 13b. The temperature of the coolant of the first circuit 7 at the outlet of the heat exchanger 5 and the temperature of the cooling medium of the second circuit 8 at the outlet of the heat exchanger 5 are measured by means of temperature sensors 14 and/or 15 . A sensor 16 measures the ambient temperature.

The control could now be as follows: Depending on the ambient temperature, the need to extract thermal energy from the freezer compartment 1 and the refrigerator compartment 2 by means of the evaporators 3a and 3b is greater or smaller. Accordingly, the controller 12 has to adapt the power of the compressor 4 . The more thermal energy that reaches the first circuit at the evaporators 3a and 3b, the more thermal energy must also be dissipated at the heat exchanger 5 to the second circuit. In addition, the tuning of the temperature levels in 1 and 2 must remain guaranteed, which in conventional devices with a passive throttle occurs in a self-regulating manner as the ambient temperature 16 rises. The temperature sensor 15 measures the temperature of the coolant of the second circuit 8 at the outlet of the heat exchanger 5 and the temperature sensor 14 at the outlet of the heat exchanger 5 measures the temperature of the refrigerant of the first circuit 7. For example, it is determined that the temperature of the coolant at the outlet of the heat exchanger 5 is always the ambient temperature must be minus 13 Kelvin, i.e. Toutlet(15) = Tambient(16) - 13K. If the temperature at the temperature sensor 15 increases, the delivery rate of the pump 9 can be changed, or the valves 11 can be adjusted accordingly, so that the volume flow of the second circuit 8 through the heat exchanger 5 is adjusted. The overall cooling capacity increases and the temperatures in the freezer compartment 1 or in the refrigerator compartment 2 can be kept low even when the ambient temperature is higher.

Compared to a conventional refrigerator, in which thermal energy is released from the refrigerant to the heat exchanger to the ambient air, the present system has the advantage that a cooling medium is available on the heat exchanger 5, which has a significantly lower temperature and a significantly higher heat capacity exhibits than the ambient air. The heat exchange at the heat exchanger 5 is therefore significantly more efficient and compact. The low temperature of the cooling medium prevailing at the heat exchanger 5 makes it possible for the compressor to be operated with a lower output, because the refrigerant at the heat exchanger 5 can release thermal energy even at a comparatively low temperature. Accordingly, the system has a higher coefficient of performance and can be operated in a very energy-saving manner.

2 shows an almost identical structure of the cooling device according to the invention. The only difference is that the throttle 6 of the first circuit 7, in comparison to the embodiment according to FIG. 1, not only has a single capillary but two capillaries 6a and 6b connected in parallel. The flow of the refrigerant through the capillaries 6a and/or 6b can be controlled via a switch 6c. Capillaries connected in parallel allow different flow resistances to be set at the throttle 6. Different flow resistances can be generated by the two capillaries 6a and 6b having different lengths or different flow cross sections. For example, an internal diameter of 0.7 mm and a length of 3 m are conceivable. The flow resistances could also be switched over by means of an expansion valve. A serial arrangement of the capillaries 6a and 6b would also be conceivable.

Since the temperature of the cooling medium in the heat exchanger 5 always has a similar temperature, regardless of the ambient temperature, the refrigerant circulating in the heat exchanger 5 can also always have similar temperature and pressure conditions. However, since the cooling requirement is higher at higher ambient temperatures in the freezer compartment 1 and in the refrigerator compartment 2, the compressor 4 must be operated at a higher power. The performance ratio of freezer compartment 1 and refrigerator compartment 2 also changes. By switching the flow resistance of the throttle 6, i.e. by switching between the different capillaries 6a and 6b, it is possible to prevent the temperature and pressure conditions on the heat exchanger 5 and the Temperature levels in freezer compartment 1 and refrigerator compartment 2 remain almost unchanged. The energy consumption of the cooling device can be optimized as a result.

It should be noted that the line parts of the second circuit 8 are to be configured as flexibly as possible, so that the cooling device can be installed in a kitchen niche in a particularly simple manner. In a first step, the lines are pre-assembled in front of the niche on the refrigerator and in a second step, the refrigerator can be fixed in the correct position in the kitchen niche.

While in the present application preferred embodiments of the invention are described, it is to be understood that the invention is not limited thereto and may be otherwise embodied within the scope of the following claims.

Claims (11)

1. A refrigerator, in particular a household refrigerator, comprising a controller (12) and a heat pump - An evaporator (3a, 3b) for cooling a usable space (1, 2), – a condenser for dissipating heat, - a compressor (4), - a throttle (6), and - a first circuit (7) for the circulation of refrigerant, characterized in that the cooling device has a second circuit (8) for circulating a cooling medium, in particular a liquid or a gas, the condenser being designed as a heat exchanger (5) in order to transfer heat from the refrigerant to the cooling medium of the second circuit (8) to deliver. 2. Cooling device according to claim 1, wherein the heat exchanger (5) is a plate heat exchanger. 3. Cooling device according to one of the preceding claims, wherein the second circuit (8) is a closed circuit. 4. Cooling device according to one of the preceding claims, wherein the controller (12) controls the second circuit such that the cooling medium has a specific, in particular constant, temperature in the heat exchanger (5) or at its outlet or inlet. 5. Cooling device according to claim 4, wherein the temperature of the cooling medium in the heat exchanger (5) or at its outlet or inlet as a function – an ambient temperature, – a usable room temperature, - A pressure prevailing in the first circuit (7), in particular a pressure in the evaporator (3a, 3b) or in the heat exchanger (5) or a pressure at the respective inlets or outlets of the evaporator (3a, 3b) or the heat exchanger (5) , is determined. 6. Cooling device according to one of the preceding claims, wherein the controller (12) controls the second circuit (8) in such a way that the cooling medium flows in the heat exchanger (5) with a specific volume flow, in particular, the flow rate depending - an ambient temperature, and/or - a work space temperature, and/or - A pressure prevailing in the first circuit (7), in particular a pressure in the evaporator (3a, 3b) or in the heat exchanger (5) or a pressure at the respective inlets or outlets of the evaporator (3a, 3b) or the heat exchanger (5) , is determined. 7. Cooling device according to one of the preceding claims, wherein - The second circuit (8) has a bypass line (11c) for bypassing the heat exchanger (5), and/or - The volume flow in the second circuit (8) can be controlled by the controller (12), in particular by means of a valve (11a, 11b) and/or a pump (9). 8. Cooling device according to one of the preceding claims, wherein - The throttle (6) has at least two capillaries (6a, 6b) connected in parallel, in particular with two different flow resistances, which can be opened and closed individually, or wherein - The throttle (6) has an expansion valve with variable flow resistance. 9. Cooling device according to claim 8, wherein the switchover of the at least two parallel-connected capillaries (6a, 6b) or the switchover of the expansion valve as a function – the ambient temperature, - A temperature of the cooling medium prevailing in the second circuit (8) or a pressure of the refrigerant prevailing in the first circuit (7), in particular measured at the inlet or at the outlet of the heat exchanger (5), he follows. 10. Building comprehensive – an indoor area and an outdoor area, - An indoor cooling device according to any one of the preceding claims, characterized in that the second circuit (8) is at least partially arranged on the outside of the building, in particular within a floor of the outdoor area or below the building. 11. Arrangement comprising - The cooling device according to any one of claims 1 to 9, - at least one other household appliance to be cooled, in particular the cooling appliance according to one of claims 1 to 9, and/or a heat-related household appliance, in particular a dishwasher, characterized in that the second circuit (8) is connected to the other household appliance to be cooled and/or to the heat-related household appliance.