Refrigeration appliance with suction line heat exchanger and method for operating a refrigeration appliance with suction line heat exchanger

Abstract

A refrigeration appliance (10) has a refrigerant circuit (20, 80, 90) with a compressor (22), a first evaporator group (26) having at least one first evaporator (28) and a high-pressure line (48) connected upstream of the first evaporator group (26), a second evaporator group (32) connected in parallel to the first evaporator group (26) having at least one second evaporator (34), a low-pressure line (49, 49') connected downstream of the first evaporator group (26) and the second evaporator group (32), and a suction line heat exchanger (50, 50') in which a high-pressure line section (52, 52') of the high-pressure line (48) and a low-pressure line section (54, 54') of the low-pressure line (49, 49') are thermally coupled. The suction line heat exchanger (50, 50') has three temperature sensors at three positions from a set of positions (60, 60'; 62, 62'; 56, 56'; 58, 58') including positions at an inlet and an outlet of the low-pressure line section (54, 54') and at an inlet and an outlet of the high-pressure line section (52, 52'). The refrigeration appliance and the associated method achieve determining a ratio of a mass flow of refrigerant to the first evaporator group to a total mass flow of refrigerant.

Description

Technical Field

[0001] The present invention relates to a refrigeration appliance, particularly a household refrigeration appliance, and a method for operating such a refrigeration appliance, the refrigeration appliance having a refrigerant circuit having a suction pipe heat exchanger. Background Technology

[0002] A refrigeration appliance with an internal heat exchanger is known from DE102016202565. Summary of the Invention

[0003] The objective of this invention is to provide a refrigeration appliance having two parallel evaporators or evaporator groups and a suction pipe heat exchanger, and a method for operating such a refrigeration appliance, wherein an estimate of the mass flow rate of refrigerant through one evaporator or evaporator group relative to the total mass flow rate of the refrigerant can be obtained.

[0004] This task is solved by the refrigeration appliance and the method for operating the refrigeration appliance according to the present invention.

[0005] This invention relates to a refrigeration appliance having a refrigerant circuit, the refrigerant circuit comprising a compressor, a first evaporator assembly, a second evaporator assembly connected in parallel with the first evaporator assembly, a low-pressure pipe connected downstream of the first and second evaporator assemblies, and a suction pipe heat exchanger. The first evaporator assembly has at least one first evaporator and a high-pressure pipe connected upstream of the first evaporator assembly. The second evaporator assembly has at least one second evaporator. The high-pressure section of the high-pressure pipe and the low-pressure section of the low-pressure pipe are thermally coupled in the suction pipe heat exchanger. The suction pipe heat exchanger has three temperature sensors located at three of a set of positions: the inlet and outlet of the low-pressure pipe section and the inlet and outlet of the high-pressure pipe section.

[0006] Such refrigeration appliances are particularly common in households, where a number of storage units are stored in different compartments at different temperatures and may undergo temperature control. By utilizing evaporators that operate at different temperatures, the storage compartments can be maintained or operated at varying temperatures.

[0007] This invention can be advantageously used in parallel-connected evaporators or evaporator groups, wherein the evaporator group has evaporators each having a variablely selectable temperature. Storage cells that can operate at variablely selectable temperatures are hereinafter referred to as flexible cells, and the associated evaporators are referred to as flexible cell evaporators.

[0008] This invention is particularly advantageous for use in parallel-connected evaporators or evaporator groups, wherein the first evaporator or evaporator group operates at a low temperature, and the second evaporator or evaporator group selectively operates at a temperature lower or higher than ambient temperature. In such an appliance, the flexible temperature setting can be adjusted to a temperature over a particularly wide range.

[0009] In general, this invention describes a refrigeration appliance having a refrigerant circuit with two parallel branches, each branch having at least one evaporator. An important application is that there is only one evaporator in one or both branches. Hereinafter, for the sake of simplicity, the invention is described with respect to a first and a second evaporator. Those skilled in the art will appreciate the generalization regarding the branches.

[0010] In the description of this invention, the terms "suction pipe" and "low-pressure pipe" are used synonymously, and similarly, the terms "suction pipe heat exchanger" and "internal heat exchanger" are used synonymously. In such appliances, parallel evaporators typically have adjustable throttling points, particularly expansion valves at the inlet and outlet of the evaporator. Hereinafter, the expansion valve is referred to as a representative of adjustable throttling points. The valve position can thus affect the pressure in the evaporator, causing the corresponding cells to be cooled to varying degrees.

[0011] From the perspective of the refrigerant circuit, the evaporator group is considered a branch of the refrigerant circuit. Advantageously, the evaporators are grouped such that in the first evaporator group there are only evaporators with storage cells operating below ambient temperature, and in the second evaporator group there are only evaporators with storage cells selectively operating below or above ambient temperature.

[0012] The storage compartments of the first evaporator group are, for example, refrigerator compartments, cold storage compartments, freezer compartments, or simple flexible compartments. Since all these compartments are cooled, it is advantageous that the refrigerant branch of the first evaporator group is part of an internal heat transfer device or a suction pipe heat transfer device.

[0013] A characteristic of the refrigerant branch line leading to the second evaporator assembly is that it is not part of the internal heat transfer system, so that the flexible cell, which has an extended temperature range, can be heated by the refrigerant liquefied in the flexible cell evaporator. An advantage here is that it is possible to supply the second evaporator with warm or hot refrigerant at approximately the condenser temperature.

[0014] In parallel refrigerant branches, the distribution of mass flow rate depends not only on the valve position but also on the gas ratio or subcooling at the respective valve inlet. The gas ratio and subcooling are unavailable for appliance regulation, making it difficult to determine the precise distribution of mass flow rate on each evaporator.

[0015] This invention is based on the idea that if the two mass flows are essentially single-phase and at least three temperatures are known at the inlet and outlet of the internal heat exchanger, the ratio of the mass flow rates in an internal heat exchanger with two branches can be determined. The calculation is simplified if the four temperatures at the inlet and outlet of the internal heat exchanger are known.

[0016] In the internal heat exchanger, the refrigerant branch transfers heat to the suction line. Because different mass flow rates on the warm and cold sides cause different temperatures in the suction gas, this can be used to determine the mass flow rate ratio flowing through the first evaporator, as this ratio is essentially single-phase in the high-pressure section. The refrigerant in the suction line should be completely vaporized and thus exist in a single-phase gaseous state.

[0017] Therefore, the temperature distribution at the suction pipe heat exchanger is used as an internal heat transfer medium to deduce the mass flow rate ratio through the first evaporator. There, a liquid refrigerant with a corresponding specific heat capacity is applied to the warm side, and a gaseous refrigerant with a corresponding specific heat capacity is applied to the suction pipe side. Using thermodynamic considerations, it is now possible to determine the mass flow rate ratio with good accuracy using the three temperatures at the inlet and outlet of the suction pipe heat exchanger. See, for example, the University of Magdeburg lecture notes "Fundamentals of Heat and Mass Transfer" (Grundlagen der Magdeburg). -und Stoffübertragung)”, WS2009 / 2010.

[0018] In the case of a third evaporator following a parallel evaporator and flowing through it by the total mass flow of refrigerant, with its suction pipe directly connected to the suction pipe heat exchanger, it is possible to use the temperature of the third evaporator as the temperature at the inlet of the suction pipe branch, or, if no heat transfer occurs between the third evaporator and the suction pipe, to use a temperature sensor in the third evaporator instead of a temperature sensor at the inlet of the suction pipe branch.

[0019] The density of the suction gas can be determined by the evaporation temperature in the third evaporator and the suction gas temperature at the outlet of the internal heat transfer device, and the delivery mass flow rate can be determined by the compressor speed, thus allowing the determination of the total mass flow rate. Therefore, this method also provides the absolute value of the mass flow rate through the first evaporator line from the ratio of the mass flow rate to the total mass flow rate. Then, the mass flow rate through the second evaporator line is derived from the difference between this and the total mass flow rate. Thus, when the second evaporator line has only one evaporator, the mass flow rate is determined by this single evaporator.

[0020] According to one configuration of the invention, the high-pressure pipe section leads only to the first evaporator group and not to the second evaporator group. This has the advantage that the high-pressure pipe section has exactly the mass flow rate that flows through the first evaporator group.

[0021] Since the high-pressure section is located after the condenser, it primarily carries liquid refrigerant. Therefore, the mass flow rate through the high-pressure section is essentially the mass flow rate of liquid refrigerant with at most a very small proportion of gas.

[0022] According to another configuration of the invention, throttling elements, particularly expansion valves, that can be variably adjusted are connected upstream and downstream of the first and second evaporators, respectively. This achieves the advantage that the mass flow rates in the first and second evaporators can be adjusted independently of the other evaporator. Each of these evaporators can operate as an evaporator with a variable temperature. The refrigerant pressure, and therefore the evaporator temperature, can be adjusted for each evaporator independently of the others.

[0023] According to another configuration of the invention, the suction tube heat exchanger has a temperature sensor at each of a set of locations. This has the advantage of simplifying the calculation of the mass flow rate ratio.

[0024] According to another configuration of the invention, the refrigeration appliance has means for determining the ratio of the mass flow rate in the high-pressure section to that in the low-pressure section. Such means can be advantageously integrated into the control device of the refrigeration appliance.

[0025] According to another configuration of the invention, the refrigeration appliance has means for determining the ratio of the mass flow rates flowing to the first evaporator group and the second evaporator group. This is because the total mass flow rate is the sum of the mass flow rates flowing to the first evaporator group and the second evaporator group.

[0026] According to another configuration of the invention, the refrigeration appliance has a third evaporator arranged in parallel between first and second evaporators and a low-pressure pipe. This enables a further cooling compartment, preferably one with a lower temperature than the preceding compartments.

[0027] According to another configuration of the invention with a third evaporator, the refrigeration appliance has another suction pipe heat exchanger in which another high-pressure section of the high-pressure pipe and another low-pressure section of the low-pressure pipe are thermally coupled. This improves energy efficiency. However, it should be noted that the other suction pipe heat exchanger cannot be used to determine the mass flow rate if there is no substantially single-phase flow there.

[0028] According to another configuration of the invention, the third evaporator has a temperature sensor instead of the temperature sensor at the inlet of the low-pressure pipe section. Furthermore, the outlet of the third evaporator is directly connected to the inlet of the suction pipe heat exchanger. In the case where another suction pipe heat exchanger is not arranged between the third evaporator and the suction pipe heat exchanger, the refrigerant temperature in the third evaporator and at the inlet of the suction pipe heat exchanger is the same. Therefore, a temperature sensor for the temperature at the inlet of the suction pipe of the heat exchanger can also be arranged in the third evaporator. This is particularly advantageous in frost-free evaporators, which typically already have a temperature sensor for controlling the defrosting process.

[0029] The third evaporator is preferably assigned to the freezer compartment.

[0030] According to another configuration of the invention, the refrigeration appliance has a fourth evaporator directly in front of the third evaporator in the direction of refrigerant flow. This achieves further cooling to obtain a grid.

[0031] The fourth evaporator can advantageously be assigned to a refrigeration compartment or cold storage compartment, which is supplied with gaseous refrigerant from the preceding refrigeration compartment evaporator. This achieves very good energy efficiency.

[0032] According to another configuration of the invention, the compressor is a permanently operating compressor with a variable speed. This has the advantage that a constant temperature can be set in the evaporator, which avoids the temperature hysteresis common in intermittently operating compressors.

[0033] In another configuration of the invention, the evaporators of the first evaporator group need not be assigned to a flexible cell, but can also be assigned to a cell with a narrow desired temperature range, such as a refrigerator cell, a cold storage cell, or a freezer cell.

[0034] The present invention also relates to a method for determining a ratio of mass flow rates in a refrigeration appliance having a refrigerant circuit, the refrigerant circuit having a compressor, a first evaporator assembly, a second evaporator assembly connected in parallel with the first evaporator assembly, a low-pressure pipe connected downstream of the first and second evaporator assemblies, and a suction heat exchanger, the first evaporator assembly having at least one first evaporator and a high-pressure pipe connected upstream of the first evaporator assembly, the second evaporator assembly having at least one second evaporator, and a high-pressure section of the high-pressure pipe and a low-pressure section of the low-pressure pipe being thermally coupled in the suction heat exchanger. Here, the suction heat exchanger has a set of locations at the inlet and outlet of the low-pressure pipe section and at the inlet and outlet of the high-pressure pipe section, and the method comprises the following steps:

[0035] a) Determine the temperature at three locations from the set of locations;

[0036] b) Using the determined temperature, determine the ratio of the mass flow rate through the high-pressure pipe section to the mass flow rate through the low-pressure pipe section.

[0037] In the suction heat exchanger, after a certain compressor running time, a stationary state is reached where the refrigerant flow and temperature at the inlet and outlet of the suction heat exchanger are constant. Here, the temperature changes in the two refrigerant pipe sections of the heat exchanger are also constant and interdependent. This thermodynamically known dependence can be used to determine the ratio of the refrigerant mass flow rates from the inlet and outlet temperatures. Another application of thermodynamics can be used to determine the ratio of the refrigerant mass flow rates from only three temperatures at the inlet and outlet.

[0038] One configuration of the method includes an additional methodological step: determining the temperature at all locations from a set of locations. With three temperatures determined by sensors, a fourth temperature can be determined by another sensor or well estimated using thermodynamics.

[0039] In another configuration of the method, it is assumed that the refrigerant is liquid in the high-pressure section and gaseous in the low-pressure section, and the ratio of the mass flow rate through the high-pressure section to the mass flow rate through the low-pressure section is determined by means of the specific heat capacity of the refrigerant.

[0040] Another configuration of the method includes the additional step of determining the mass flow rate of the delivery from the compressor through the low-pressure section. The delivery mass flow rate is a function of rotational speed, displacement, volumetric efficiency, and suction gas density. The suction gas density is a function of the evaporation temperature of the evaporator upstream of the suction heat exchanger and the temperature at the outlet of the suction heat exchanger. The volumetric efficiency is a function of the condenser pressure and the evaporator pressure.

[0041] Another configuration of the method includes an additional step: determining the mass flow rate through the second evaporator assembly by the ratio of the mass flow rate through the high-pressure pipe section to the mass flow rate through the low-pressure pipe section. Therefore, the mass flow rate is determined by the ratio of the mass flow rate to the delivered mass flow rate. This has the advantage that the mass flow rate, which would otherwise be difficult to determine, can be absolutely determined through the second evaporator assembly.

[0042] Another configuration of the method includes additional method steps: controlling the refrigeration appliance based on the determined temperature. This knowledge can be used to better control the second evaporator assembly or the second evaporator if the mass flow rate through the second evaporator assembly or the second evaporator is known.

[0043] Another configuration of the method includes additional method steps: controlling the refrigeration appliance based on the ratio of the mass flow rate through the high-pressure pipe section to the mass flow rate through the low-pressure pipe section. This advantageously enables the control of refrigeration appliances with improved energy efficiency. Attached Figure Description

[0044] Further features and advantages of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings. The drawings show:

[0045] Figure 1 A schematic diagram of a refrigeration appliance according to the present invention;

[0046] Figure 2 A schematic diagram of a refrigerant circuit with parallel evaporator branches in a refrigeration appliance according to the present invention;

[0047] Figure 3 A schematic diagram of the internal heat exchanger of the refrigerant circuit in a refrigeration appliance according to the present invention;

[0048] Figure 4 A schematic diagram of a refrigerant circuit for a refrigeration appliance according to the present invention, having parallel evaporator branches and evaporators connected in series;

[0049] Figure 5 A schematic diagram of a refrigerant circuit of a refrigeration appliance according to the present invention, having parallel evaporator branches and additional evaporators connected in series.

[0050] Figure 6 A flowchart of one embodiment of the method according to the present invention; and

[0051] Figure 7 A flowchart of another embodiment having a configuration according to the method of the present invention. Detailed Implementation

[0052] In various embodiments, elements with the same function are indicated by the same reference numerals, and similar elements are indicated by reference numerals with apostrophes.

[0053] Figure 1 A refrigerator representing a refrigeration appliance 10 according to the invention is shown, having a refrigerator door 12 leading to a refrigerator compartment 15, a flexible compartment door 13 with an extended temperature range leading to a flexible compartment 16, and a door 14 leading to a simple flexible compartment 17. The refrigerator is used, for example, for food storage and includes a refrigerator compartment as a storage compartment, a flexible compartment with an extended temperature range, and a simple flexible compartment. These storage compartments are each cooled by an associated evaporator. The refrigeration appliance 10 also has a display and control unit 18 for controlling the refrigeration appliance. The display and control unit 18 has a means 19 for determining the ratio of mass flow rates. The refrigeration appliance 10 has a refrigerant circuit that can be configured in different configurations of the invention.

[0054] Figure 2 A refrigerant circuit 20 of a refrigeration appliance according to the present invention is shown. The refrigerant circuit 20 has a compressor 22, a condenser 24, a first evaporator group 26 and a second evaporator group 32 parallel to the first evaporator group 26, the first evaporator group having a first evaporator 28 and another evaporator 30 of the first evaporator group 26, and the second evaporator group having a second evaporator 34.

[0055] A compressor is a speed-regulated compressor with variable speed. Compressors are designed to operate continuously.

[0056] In the first evaporator group 26, the first evaporator 28 and another evaporator 30 of the first evaporator group 26 are arranged in parallel to each other. An expansion valve 36 is arranged in the flow direction in front of the first evaporator 28, which controls the inflow of refrigerant into the evaporator 28. An expansion valve 38 is arranged in the flow direction behind the first evaporator 28, which controls the outflow of refrigerant from the first evaporator 28.

[0057] Expansion valves 40 and 42 are also arranged in front of and behind the other evaporator 30 in the first evaporator group 26. In the first evaporator group, the other evaporators of the first evaporator group can be arranged in parallel with the first evaporator so as to provide their own evaporators for other storage cells.

[0058] Evaporators 28 and 30 of the first evaporator group 26 are assigned to storage compartments that can be cooled to temperatures below ambient temperature. Therefore, the first evaporator 28 is assigned to a refrigeration compartment, and the other evaporator 30 of the first evaporator group 26 is assigned to a simple, flexible compartment with variable temperature, allowing this compartment to be selectively operated as another refrigeration compartment, a cold storage compartment, or a freezer compartment. The variable temperature of the evaporators in the first evaporator group 26 is achieved via expansion valves at the front and rear of the evaporators, which allows adjustment of the refrigerant evaporation pressure in the evaporators to achieve the desired temperature independently of the temperatures in the other evaporators.

[0059] exist Figure 2 In the illustrated embodiment, there is only one evaporator in the second evaporator group 32, namely the second evaporator 34. An expansion valve 44 is arranged in the flow direction in front of the second evaporator 34, which controls the inflow of refrigerant into the evaporator 34. An expansion valve 46 is arranged in the flow direction behind the second evaporator 34, which controls the outflow of refrigerant from the second evaporator 34.

[0060] The second evaporator 34 of the second evaporator group 32 is assigned to a flexible compartment with a wide temperature range, which can operate over a wide temperature range below and above ambient temperature. The variable temperature of the second evaporator 34 can be achieved via expansion valves before and after the second evaporator 34, which allows the refrigerant evaporation pressure to be adjusted so that the desired temperature is reached independently of the temperatures in the other evaporators.

[0061] Figure 2 The arrangement shown with evaporators 28, 30, and 32 corresponds to the [from] Figure 1 In one embodiment of the refrigeration appliance 10, evaporators 28, 30 and 32 are assigned to storage compartments 15, 17 and 16.

[0062] The refrigerant circuit 20 has a piping system that connects the described components of the refrigerant circuit 20 to each other. The refrigerant circuit 20 has a high-pressure region between the outlet of the compressor 22 and expansion valves 36, 40, and 44. The refrigerant circuit 20 has a low-pressure region between valves 36, 40, and 46 and the inlet of the compressor 22.

[0063] In the second evaporator 34, the assignment of the piping region between the expansion valve 44 upstream of the second evaporator 34 and the expansion valve 46 downstream of the second evaporator 34 to either a high-pressure region or a low-pressure region depends on the corresponding operating state of the second evaporator 34 and the dominant pressure therein. If the second evaporator 34 operates at a temperature higher than ambient temperature, then the second evaporator functions as a condenser under this operating state and is capable of operating at high pressure.

[0064] The refrigerant circuit 20 has a high-pressure pipe 48, which is connected upstream of the evaporator of the first evaporator assembly. The high-pressure pipe 48 terminates at the throttling section of the evaporator of the first evaporator assembly, that is, at the expansion valves 36 and 40.

[0065] The refrigerant circuit 20 has a low-pressure line 49 that connects downstream of the first evaporator assembly 26 and the second evaporator assembly 32. The low-pressure line 49 runs between the expansion valves 38, 42, and 46 and the inlet of the compressor 22.

[0066] The refrigerant circuit 20 also has a suction pipe heat exchanger 50, in which the high-pressure pipe section 52 of the high-pressure pipe 48 and the low-pressure pipe section 54 of the low-pressure pipe 49 are thermally coupled.

[0067] The suction pipe heat exchanger 50 has four preferred locations for a temperature sensor: position 56 at the inlet of the high-pressure pipe section 52, position 58 at the outlet of the high-pressure pipe section 52, position 60 at the inlet of the low-pressure pipe section 54, and position 62 at the outlet of the low-pressure pipe section 54. These locations are preferred because, during operation of the refrigeration appliance, the maximum temperature difference of the refrigerant in the high-pressure pipe section 52 occurs between positions 56 and 58 due to heat exchange in the heat exchanger 50, and the maximum temperature difference of the refrigerant in the low-pressure pipe section 54 occurs between positions 60 and 62.

[0068] In one embodiment of the invention, the refrigerant circuit 20 has temperature sensors at all four locations 56, 58, 60, and 62. This embodiment has the advantage that the temperature difference between the high-pressure section 52 and the low-pressure section 54 can be determined by simple temperature measurement using the temperature sensors.

[0069] Therefore, the display and control unit 16 of the refrigeration appliance 10 can determine the ratio between the mass flow rate in the high-pressure section and the mass flow rate in the high-pressure section.

[0070] Therefore, in Figure 2 In the arrangement shown, which has only one evaporator 34 in the second evaporator group 32, the ratio of the mass flow rate through the evaporator 34 to the total mass flow rate can be calculated.

[0071] In another embodiment of the invention, the refrigerant circuit 20 has temperature sensors at three locations from the group of locations 56, 58, 60, and 62. This embodiment has the advantage of requiring fewer temperature sensors. The temperature at locations lacking temperature sensors can be determined by thermodynamic considerations. All four temperatures are then known, and the ratio of mass flow rates can be determined as in the previously described embodiment.

[0072] Corresponding to the present invention, in Figure 2 In the refrigerant circuit 20 shown, the evaporators of the first evaporator group 26, i.e., evaporators 28 and 30 here, are configured only as cells for cooling, such that evaporators 28 and 30 also operate as evaporators. Correspondingly, in this invention, the second evaporator group 32, having a single evaporator 34, is configured as a flexible cell with a wider temperature range, such as... Figure 1 The flexible compartment 16 is used. Since the evaporator of the second evaporator group 32 can operate not only as an evaporator but also as a condenser, the refrigerant for the second evaporator group 32 is supplied through a branch 64 of the high-pressure pipe 48, which does not participate in the heat exchange of the suction pipe. Therefore, the second evaporator group can obtain refrigerant at approximately the temperature of the condenser 24.

[0073] On the other hand, the energy efficiency improvement achieved through heat exchange in the suction pipe is utilized by additionally cooling the refrigerant supplied to the first evaporator assembly through heat exchange in the suction pipe.

[0074] In the refrigerant circuit 20, the condenser 24 has a fan 66. The task of the fan 66 is to prevent excessively high condenser temperatures, and the fan is able to cool the condenser 24 if there is no evaporator in the second evaporator group operating in heating mode to reach a temperature higher than the ambient temperature in the evaporator or in a flexible grid with a wide temperature range.

[0075] Evaporators 28, 30, and 34 are equipped with fans 68, 70, and 72. These fans are used not only to improve heat transfer between the evaporator and each cell but also to control humidity within each cell.

[0076] In the second evaporator group, additional evaporators of the second evaporator group can be arranged in parallel with the second evaporator to provide their own evaporators for additional storage compartments, especially flexible compartments with a widened temperature range. These compartment evaporators are preferably also arranged in parallel with the second evaporator 34, each with an expansion valve in front of and behind it.

[0077] Figure 3 Schematic illustration of from Figure 3 The suction pipe heat exchanger 50, also known as an internal heat exchanger or suction pipe heat transfer device, has a high-pressure pipe section 52 of a high-pressure pipe 48 and a low-pressure pipe section 54 of a low-pressure pipe 49. The direction of refrigerant flow is indicated by arrows 74 and 76. The suction pipe heat exchanger 50 has four preferred locations for a temperature sensor: outside the pipes of each section, at position 56 at the inlet of the high-pressure pipe section 52, at position 58 at the outlet of the high-pressure pipe section 52, at position 60 at the inlet of the low-pressure pipe section 54, and at position 62 at the outlet of the low-pressure pipe section 54.

[0078] Alternatively, it is possible to place the temperature sensor inside the pipe in each pipe section.

[0079] An exemplary coordinate line 77 is provided, which has endpoints 78 and 79 of a segment on which heat exchange occurs in the suction pipe heat exchanger 50. Using coordinate line 77, the temperature change process within the suction pipe heat exchanger 50 can be determined thermodynamically.

[0080] Figure 4 Schematic illustration of in relation to Figure 2 The refrigerant circuit 80 of a refrigeration appliance according to one embodiment of the present invention is described in contrast to configurations with different evaporator arrangements. Therefore, a description is essentially provided that... Figure 2The difference lies in the fact that the first evaporator group 26' has only the first evaporator 28, and the second evaporator group 32 has only the second evaporator 34. Expansion valves, as described, are arranged before and after the evaporators 28 and 34. The suction pipe heat exchanger 50' is also arranged in the same location with respect to the first evaporator group.

[0081] In this configuration, the refrigerant circuit has a third evaporator 82 located between the first and second evaporator groups 26', 32 arranged in parallel and the low-pressure pipe 49'. In the direction of refrigerant flow, the third evaporator 82 is connected in series after the evaporators 28, 34 of the parallel evaporator groups 26', 32.

[0082] The low-pressure pipe 49' extends from the third evaporator 82 to the compressor 22. The low-pressure pipe section 54' of the low-pressure pipe 49' is located in the suction pipe heat exchanger 50'.

[0083] The refrigerant circuit 80 has an optional additional internal heat transfer device 84, in which another section 81 of the low-pressure pipe 49' and the refrigerant pipe section 83 at the outlet of the first evaporator 28 are thermally coupled. However, this additional internal heat transfer device 84 does not provide information about the mass flow distribution, and the refrigerant is two-phase at the outlet of the evaporator 28. The pumped gas can then be considered as an isothermal heat source in this additional internal heat transfer device 84.

[0084] Refrigerant circuit 80 is suitable for use according to Figure 1 The refrigeration appliance 10. In this configuration of the invention, the evaporator 28 is assigned to the refrigeration compartment 15, the evaporator 34 is assigned to the flexible compartment having an extended temperature range 16, and the evaporator 82 is assigned to the simple flexible compartment, which can operate, for example, as a cold storage compartment or a freezer compartment. The evaporator 82 has a fan 85.

[0085] The refrigerant circuit 80 advantageously utilizes the low suction pressure of the compressor 22 for the evaporator 82 arranged in series, which is then equipped with a particularly cold grid.

[0086] The evaporator 82 is equipped with a cold compartment, preferably a freezing compartment, and has a temperature sensor 86.

[0087] The refrigerant circuit 80, when combined with temperature sensor 86, offers the following advantages: At the location of temperature sensor 86, the total refrigerant mass flow rate, temperature, and pressure are known, and thus the density of the suction gas at that location can be determined using a temperature sensor at the end of the low-pressure section, position 62'. This, in turn, allows the absolute total mass flow rate to be determined by the compressor's speed and the compressor's delivery.

[0088] This makes it possible to determine the absolute total mass flow rate through evaporator 34.

[0089] The present invention also achieves a configuration without another internal heat exchanger 84, in which a temperature sensor 86 is used at position 60' instead of a temperature sensor at the inlet of the low-pressure pipe section 54' to determine the temperature at the inlet of the low-pressure pipe section 54'.

[0090] Figure 5 A refrigerant circuit is shown in another embodiment, which is based on Figure 4 The embodiment shown is established. Now, a fourth evaporator 88 is added downstream of the third evaporator 82' in a series arrangement. The third evaporator 82' has a temperature sensor 86'.

[0091] The third evaporator 82' has a fan 85', and the fourth evaporator 88 has a fan 90.

[0092] In this arrangement, evaporator 86' operates as an evaporator for the freezer compartment to supply the freezer compartment, and an additional evaporator 88 operates as an evaporator for the cold storage compartment or refrigerator compartment. The refrigeration appliance with this refrigerant circuit is controlled such that the refrigerant supplied to evaporator 86' evaporates substantially in evaporator 86' and the next evaporator 88 is cooled by the cold gaseous refrigerant.

[0093] Temperature sensor 86' is located in the coldest cell, so the temperature and evaporation pressure can be determined based on the dominant temperature at that coldest cell location. This information can then be used to determine the suction gas density at the end of the low-pressure pipe section, at position 62'. The absolute total mass flow rate can then be determined by the compressor speed and the compressor's delivery.

[0094] Figure 6 A flowchart 100 illustrates an embodiment of a method according to the present invention for determining the ratio of mass flow rates in a refrigeration appliance. The refrigeration appliance, for example, is from... Figure 1 The refrigeration appliance 10 has a refrigerant circuit, for example from... Figure 2 The refrigerant circuit 20 in the middle or from Figure 4The refrigerant circuit 80, refrigerant circuits 20 and 80 include a compressor 22, a first evaporator group 26, 26', a second evaporator group 32 connected in parallel with the first evaporator group 26, 26', low-pressure pipes 49, 49' connected downstream of the first evaporator group 26, 26' and the second evaporator group 32, and suction pipe heat exchangers 50, 50'. The first evaporator group has at least one first evaporator 28 and a high-pressure pipe 48 connected upstream of the first evaporator group 26, 26'. The second evaporator group has at least one second evaporator 34. High-pressure pipe sections 52, 52' of the high-pressure pipe 48 and low-pressure pipe sections 54, 54' of the low-pressure pipes 49, 49' are thermally coupled in the suction pipe heat exchangers. The suction tube heat exchanger has a set of positions 60, 60'; 62, 62'; 56, 56'; 58, 58' at the inlet and outlet of the low-pressure tube section and at the inlet and outlet of the high-pressure tube section.

[0095] The method comprises the following steps:

[0096] a) Determine the temperature of 102 at three locations from the set of locations;

[0097] b) Using the determined temperature, determine the ratio of the mass flow rate of 104 flowing through the high-pressure pipe section to the mass flow rate flowing through the low-pressure pipe section.

[0098] One configuration of the method replaces method step a) with method step a'): determining the temperature at all locations from a set of locations 102.

[0099] Temperature determination at one of the locations of the suction pipe heat exchanger is typically performed using a temperature sensor located at the suction pipe heat exchanger location. However, alternatively, if no heat transfer from or to the suction pipe occurs between the two locations, temperature determination can also be performed using a temperature sensor located at the suction pipe, outside the suction pipe heat exchanger, at an adjacent location in the refrigerant circuit. The assumption that the same temperature exists at both locations is then reasonable.

[0100] Figure 7 A flowchart 110 illustrates another embodiment of a configuration having the method according to the invention. (See reference...) Figure 6 The added method steps are each optional and can be combined. The method again begins with method steps:

[0101] a) Determine the temperature at three locations from a set of locations for 102;

[0102] Next, proceed with the following steps:

[0103] c) Determine the mass flow rate of 112 delivered from the compressor through the low-pressure section.

[0104] In another method step:

[0105] d) The mass flow rate through the second evaporator group is determined by the ratio of the mass flow rate through the high-pressure pipe section to the mass flow rate through the low-pressure pipe section.

[0106] If the refrigeration appliance 10 is stationary during operation, i.e., the temperatures in the evaporators 28, 30, and 34 and the suction heat exchanger 50 are substantially constant, then the total mass flow rate of the refrigerant delivered by the compressor 22 flows through the low-pressure section 52 of the suction heat exchanger 50. The total mass flow rate can then be determined from the delivery from the compressor 22.

[0107] In another method step:

[0108] e) Based on the determined temperature, control 116 refrigeration appliances 10.

[0109] Instead of method step e), the following steps are performed:

[0110] e') The refrigeration appliance 10 is controlled based on the ratio of the mass flow rate through the high-pressure pipe section to the mass flow rate through the low-pressure pipe section. Here, the ratio of the mass flow rate through the high-pressure pipe section to the mass flow rate through the low-pressure pipe section is determined by means of the temperature from method step a).

[0111] List of reference numerals

[0112] 10 Refrigeration appliances

[0113] 12 Refrigerated compartments

[0114] 13 Flexible lattice doors

[0115] 14 doors

[0116] 15 Refrigerated Compartments

[0117] 16 Flexible grid

[0118] 17 Simple and flexible grid

[0119] 18 Display and Control Unit

[0120] 19. Apparatus for determining the ratio of mass flow rates

[0121] 20 Refrigerant Circuit

[0122] 22 Compressor

[0123] 24 Condenser

[0124] 26, 26' First Evaporator Group

[0125] 28 First Evaporator

[0126] 30 Another evaporator

[0127] 32 Second Evaporator Group

[0128] 34 Second Evaporator

[0129] Expansion valves 36, 38, 40, 42, 44, 46

[0130] 48 high-pressure pipe

[0131] 49, 49' low-pressure pipe

[0132] 50, 50' suction pipe heat exchanger

[0133] 52, 52' high-pressure pipe section

[0134] 54, 54' low-pressure pipe section

[0135] The positions of 56, 56', 58, 58', 60, 60', 62, and 62' at the suction pipe heat exchanger.

[0136] Branch of 64 high-pressure pipe

[0137] Fans 66, 68, 70, and 72

[0138] Arrows 74 and 76

[0139] 77 coordinate lines

[0140] Endpoints 78 and 79

[0141] 80 Refrigerant Circuit

[0142] 81 Another section of the jurisdiction

[0143] 82, 82' Third Evaporator

[0144] 83 Refrigerant Piping Section

[0145] 84 Another internal heat transfer device

[0146] 85' fan

[0147] 86, 86' temperature sensor

[0148] 90 Refrigerant Circuit

[0149] 92 Fourth Evaporator

[0150] 94 Fan

[0151] 100 Flowchart

[0152] 102 Determine the temperature

[0153] 104 Determine the ratio of mass flow rate

[0154] 110 Flowchart

[0155] 112 Determine the mass flow rate

[0156] 114 Determine the mass flow rate

[0157] 116, 118 Control refrigeration appliances

Claims

1. Method for determining a ratio of mass flows in a refrigeration appliance, the refrigeration appliance having a refrigerant circuit with a compressor, a first evaporator group (26) having at least one first evaporator and a high-pressure line (48) connected upstream of the first evaporator group (26), a second evaporator group (32) having at least one second evaporator connected in parallel to the first evaporator group (26), a low-pressure line (49, 49') connected downstream of the first evaporator group (26) and the second evaporator group, and a suction line heat exchanger (50, 50') in which a high-pressure line section (52, 52') of the high-pressure line (48) and a low-pressure line section (54, 54') of the low-pressure line (49, 49') are thermally conductively coupled, wherein, The suction pipe heat exchanger (50, 50') has a set of positions (60, 60'; 56, 56'; 58, 58') at the inlet and at the outlet of the low-pressure pipe section (54, 54') and at the inlet and at the outlet of the high-pressure pipe section (52, 52'). 62、62'； 56, 56'; 58, 58') and determining the ratio of the mass flow through the high-pressure pipe section (52, 52') to the mass flow through the low-pressure pipe section (54, 54') from the determined temperatures.

2. The method of claim 1, wherein, A further method step a') is provided: determining the temperature at all positions of the set of positions (60, 60'; 62, 62'; 56, 56'; 58, 58') is provided.

3. The method according to claim 1 or 2, characterized in that, The ratio of the mass flow through the high-pressure pipe section (52, 52') to the mass flow through the low-pressure pipe section (54, 54') is determined by means of the specific heat capacity of the refrigerant, assuming liquid refrigerant in the high-pressure pipe section (52, 52') and gaseous refrigerant in the low-pressure pipe section (54, 54').

4. The method according to claim 1 or 2, characterized in that, A further method step c) is provided: determining the mass flow (112) through the low-pressure pipe section (54, 54') delivered from the compressor (22).

5. The method according to claim 1 or 2, characterized in that, A further method step d) is provided: determining the mass flow through the second evaporator group (32) from the ratio of the mass flow through the high-pressure pipe section (52, 52') to the mass flow through the low-pressure pipe section (54, 54').

6. The method of claim 1 or 2, wherein, A further method step e') is provided: controlling the refrigeration appliance (10) based on the ratio of the mass flow through the high-pressure pipe section (52, 52') to the mass flow through the low-pressure pipe section (54, 54').

7. Refrigeration appliance (10) having a refrigerant circuit (20, 80, 90) for carrying out the method according to any one of claims 1 to 6, the refrigerant circuit having a compressor (22), a first evaporator group (26) having at least one first evaporator (28) and a high-pressure line (48) connected upstream of the first evaporator group (26), a second evaporator group (32) connected in parallel to the first evaporator group (26) having at least one second evaporator (34), a low-pressure line (49, 49') connected downstream of the first evaporator group (26) and of the second evaporator group (32), and a suction line heat exchanger (50, 50') in which a high-pressure line section (52, 52') of the high-pressure line (48) and a low-pressure line section (54, 54') of the low-pressure line (49, 49') are thermally coupled, characterized in that The suction pipe heat exchanger (50, 50') has three temperature sensors in three positions of the set of positions (60, 60'; 62、62'； 56, 56'; 58, 58') at the inlet and at the outlet of the low-pressure pipe section (54, 54') and at the inlet and at the outlet of the high-pressure pipe section (52, 52').

8. The refrigeration appliance of claim 7, wherein, The high-pressure pipe section (52, 52') leads only to the first evaporator group and not to the second evaporator group (32).

9. The refrigeration appliance of claim 7 or 8, wherein, Variable throttle elements are connected upstream and downstream of the first evaporator (28) and the second evaporator (34), respectively.

10. The refrigeration appliance of claim 7 or 8, wherein, The suction pipe heat exchanger (50, 50') has a temperature sensor at each position of the set of positions (60, 60'; 62、62'； 56, 56'; 58, 58').

11. The refrigeration appliance of claim 7 or 8, wherein, The refrigeration appliance has means for determining the ratio of the mass flow in the high-pressure pipe section (52, 52') and in the low-pressure pipe section (54, 54').

12. The refrigeration appliance of claim 11, wherein, The refrigeration appliance has means (19) for determining the ratio of the mass flow to the first evaporator group (26) and to the second evaporator group (32).

13. The refrigeration appliance of claim 7 or 8, wherein, The refrigeration appliance (10) has a third evaporator (82, 82') between the first and second evaporators arranged in parallel and the low-pressure line (49, 49').

14. The refrigeration appliance of claim 13, wherein, The refrigeration appliance has a further suction line heat exchanger in which a refrigerant line section (83) at the outlet of the first evaporator (28) and a further line section (81) of the low-pressure line (49, 49') are thermally conductively coupled, or the third evaporator has a temperature sensor (86) instead of a temperature sensor at the inlet of the low-pressure line section (54, 54').

15. The refrigeration appliance of claim 9, wherein, The throttling element is an expansion valve (36; 38; 44; 46).

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