Heat pump with optimized refrigerant circuit

Abstract

The invention relates to a heat pump having a refrigerant circuit (100) with a compressor (10), an expansion mechanism (20), a condenser (30) and an evaporator (40), which are connected to refrigerant lines, and a refrigerant contained in the refrigerant circuit (100), which is able to circulate in the refrigerant circuit (100) by means of the compressor (10). The condenser (30) and the evaporator (40) comprise heat exchangers (32, 42) having a refrigerant side and a medium side, wherein the heat exchanger (32) of the condenser (30) is a plate heat exchanger and the heat exchanger (42) of the evaporator (40) is a plate heat exchanger or a finned tube heat exchanger. It is furthermore proposed according to the invention that the heat exchangers (32, 42) of the condenser (30) and / or the evaporator (42) are designed asymmetrically between the refrigerant side and the medium side, such that the volume of the refrigerant side is reduced by at least 10% compared to the volume of the medium side.

Description

Technical Field

[0001] The present invention relates to a heat pump having a refrigerant circuit comprising: a compressor, an expansion mechanism, a condenser, and an evaporator connected to a refrigerant line; and a refrigerant contained in the refrigerant circuit, the refrigerant being circulated in the refrigerant circuit by means of the compressor. Background Technology

[0002] Flammable refrigerants (such as R-454-C) are often used in the refrigerant circuit of heat pumps because they are considered more environmentally friendly than those currently in use. However, when using newer, especially flammable, refrigerants, it is necessary to constantly monitor and comply with increased safety requirements, such as specific requirements for the installation site, which makes the manufacture and operation of the heat pump more expensive. This becomes more pronounced with the use of more refrigerants.

[0003] To date, reducing the amount of refrigerant has been achieved by reducing the size of the corresponding components; however, this leads to a decrease in the power coefficient of the heat pump. On the other hand, in order to achieve the desired pressure loss and power transfer when using, for example, a plate heat exchanger, the number of plates is increased until the desired process data are achieved in the refrigerant loop. However, a larger number of plates in a plate heat exchanger results in a higher refrigerant charge in the facility. Summary of the Invention

[0004] The objective of this invention is to provide a heat pump with a refrigerant circuit that overcomes the described drawbacks and enables a reduction in refrigerant charge while maintaining an acceptable power coefficient, thereby reducing refrigerant costs and the requirements for necessary safety design.

[0005] The objective is achieved according to the invention by means of the independent claim. Preferred designs are given in the dependent claims.

[0006] According to the present invention, a heat pump having a refrigerant circuit is provided, the refrigerant circuit comprising: a compressor, an expansion mechanism, a condenser, and an evaporator connected to a refrigerant pipeline; and a refrigerant contained in the refrigerant circuit, the refrigerant being circulated in the refrigerant circuit by means of the compressor. The condenser and evaporator include heat exchangers having a refrigerant side and a medium side, wherein the heat exchanger of the condenser is a plate heat exchanger, and the heat exchanger of the evaporator is a plate heat exchanger or a finned tube heat exchanger.

[0007] Furthermore, according to the invention, the heat exchangers of the condenser and / or evaporator, especially when they are configured as plate heat exchangers, are designed asymmetrically between the refrigerant side and the medium side, such that the volume of the refrigerant side is reduced by at least 10% compared to the volume of the medium side.

[0008] The asymmetric design of the heat exchanger according to the present invention results in a significant reduction in the required refrigerant charge and the reduction in the requirements for safety-related measures while maintaining an acceptable power coefficient.

[0009] Heat pumps can be configured as brine-water heat pumps, water-water heat pumps, or air-water heat pumps. In the case of brine-water heat pumps and water-water heat pumps, the heat exchanger of the evaporator is often configured as a plate heat exchanger, while in the case of air-water heat pumps, it is usually a finned tube heat exchanger.

[0010] In another design according to the invention, the plates of the heat exchanger of the condenser and / or evaporator have arrow-shaped pressed portions with a sweep angle of at least 45° (“high” pressed portions).

[0011] A large sweep angle (Pfeilungswinkel) or pressure angle can cause a strong deflection of the fluid, which may result in a higher power coefficient and greater pressure loss.

[0012] If the heat exchanger of the evaporator is a finned tube heat exchanger, according to the present invention, the inner diameter of the finned tube heat exchanger is 3 mm to 7 mm, and its outer diameter is 3.5 mm to 7.5 mm, thus reducing the amount of refrigerant.

[0013] To further improve the efficiency of finned tube heat exchangers, fins are provided on the inner side of the tubes.

[0014] To further optimize the process, the heat pump according to the present invention can include an internal heat exchanger, which is configured as a plate heat exchanger.

[0015] Furthermore, it can be suggested that the internal heat exchanger has a plate with an arrow-shaped pressing section having a sweep angle or pressing angle of less than 45°.

[0016] Furthermore, the internal heat exchanger can advantageously be configured with grooved pressing sections instead of arrow-shaped pressing sections. These grooved pressing sections reduce pressure loss on the medium side of the heat exchanger and decrease the amount of refrigerant required.

[0017] Furthermore, it can be proposed that the internal heat exchanger is constructed asymmetrically, reducing the volume of the liquid side compared to the volume of the gas side. This allows for a further reduction in the refrigerant charge.

[0018] Further reduction of refrigerant charge can be achieved by making the inner diameter of liquid lines, especially refrigerant lines, as small as possible.

[0019] Besides reducing the amount of refrigerant, acoustic requirements can also be met by specifically designing the liquid piping. This is done by designing the inner diameter of the liquid piping, especially the refrigerant piping, according to the following formula:

[0020]

[0021] At the maximum power of the heat pump or the highest speed of the compressor, the flow velocity in the liquid line shall be at least 0.5 m / s, but at most 3.5 m / s. At lower heat pump power or lower compressor speed, the minimum flow velocity is preferably not less than 0.05 m / s, 0.3 m / s, or a value between 0.05 m / s and 0.3 m / s.

[0022] The following formulas apply:

[0023]

[0024] In another embodiment, the heat pump according to the invention includes a regulator connected to an inverter that controls the compressor and to an expansion mechanism. The regulator is configured to control the compressor and the expansion mechanism such that the flow velocity in the liquid lines, particularly in the refrigerant lines, is at most 3.5 m / s. Attached Figure Description

[0025] Other advantages and preferred design schemes are described below with reference to the accompanying drawings. These are shown here:

[0026] Figure 1a A circuit diagram of a coolant circuit for a heat pump according to the present invention, having an evaporator as a plate heat exchanger and an internal heat exchanger, is shown.

[0027] Figure 1b A circuit diagram of a refrigerant circuit with an evaporator as a plate heat exchanger is shown for a heat pump according to the present invention.

[0028] Figure 1c A circuit diagram of a refrigerant circuit with an evaporator as a finned tube heat exchanger is shown for a heat pump according to the present invention.

[0029] Figure 1d A circuit diagram of a refrigerant circuit of a heat pump according to the present invention, having an evaporator as a finned tube heat exchanger and an internal heat exchanger, is shown.

[0030] Figure 2a A schematic enlarged cross-sectional view of a symmetrical plate heat exchanger is shown.

[0031] Figure 2b A schematic enlarged cross-sectional view of an asymmetric plate heat exchanger is shown.

[0032] Figure 2cA schematic enlarged cross-sectional view of the metal plates of an asymmetric plate heat exchanger is shown.

[0033] Figure 2d A schematic, enlarged three-dimensional cross-sectional view of the metal plates of an asymmetric plate heat exchanger is shown.

[0034] Figure 3a A portion of a plate in a plate heat exchanger is shown, the plate having arrow teeth with a sweep angle of less than 45°;

[0035] Figure 3b A portion of a plate in a plate heat exchanger is shown, the plate having arrow teeth with a sweep angle greater than 45°;

[0036] Figure 4 A portion of a plate in a plate heat exchanger is shown, the plate having a recessed pressing portion;

[0037] Figure 5 A partial view of the refrigerant circuit is shown;

[0038] Figure 6 The pipe guide section of the refrigerant circuit is shown. Detailed Implementation

[0039] According to Figure 1a , 1b The circuit diagrams of the refrigeration circuit 100 of the heat pump according to the invention shown in 1c and 1d include at least one compressor 10, a pressure reducing element 20, a condenser 30, an evaporator 40, and, according to an embodiment, an internal heat exchanger 50 and a four-way switching valve 60.

[0040] The gaseous refrigerant is compressed by the compressor 10 and delivered to the heat exchanger 32 of the condenser 30, where the refrigerant is cooled and liquefied.

[0041] Subsequently, according to Figure 1b and 1c The liquefied refrigerant is depressurized at pressure reducing element 20. Figure 1a and 1d In the process, supercooling first occurs in the internal heat exchanger 50.

[0042] The refrigerant is then guided through the heat exchanger 42 of the evaporator 40, where it is evaporated and superheated so that it can be subsequently delivered back to the compressor 10. Figure 1b and 1c ).

[0043] exist Figure 1a and 1d In the process, after evaporation in evaporator 40, further evaporation and overheating may occur in the internal heat exchanger 50.

[0044] according to Figure 1c and 1d The refrigeration circuit 100 also has a four-way switching valve 60.

[0045] As in Figure 1a and 1d As shown, the internal heat exchanger 50 is integrated into the refrigerant circuit 100.

[0046] The four-way switching valve 60 can also be used to defrost the heat exchanger 42 of the evaporator 40. For this purpose, the four-way switching valve 60 is switched to provide a direct connection extending in the refrigerant flow direction between the compressor 10 and the heat exchanger 42 of the evaporator 40, and another connection between the heat exchanger 32 of the condenser 30 and the internal heat exchanger 50. Thus, while maintaining the refrigerant flow direction through the compressor 10, the flow direction of the refrigerant through the remaining components of the refrigerant circuit 100 is reversed. Here, the compressed and heated gaseous refrigerant flows from the compressor 10 through the heat exchanger 42 of the condenser 40, so as to defrost the heat exchanger 42 of the evaporator 40, for example, in the event of icing. Alternatively, the heat pump can also provide air conditioning facilities with the aid of this switching action of the four-way switching valve 60. Figure 2a A schematic enlarged cross-sectional view of a symmetrical plate heat exchanger is shown. This type of plate heat exchanger consists of multiple plates P n The plate P is composed of n This pressing section creates a volume V of the same size between adjacent plates. M V K The channel through which fluid can flow.

[0047] Depending on the depth and shape of the pressing section, in a single plate P n The channels generated on both sides can have the same or different volumes V M V K If the passage is as follows Figure 2a If the dimensions are the same, then it involves a symmetrical plate heat exchanger. This means that the volume V of refrigerant contained in the plate heat exchanger... K and the volume V of the medium M That is, the volume of the fluid that absorbs heat from the refrigerant or dissipates heat to the refrigerant is the same size, such as in... Figure 2a As shown in the figure.

[0048] On the contrary, in Figure 2b The asymmetric plate heat exchanger shown in the figure has two adjacent plates P n The pressing sections are different, resulting in channels with different volumes V on both sides of a single plate. K and V M The volume V of the mediumM Greater than the volume V of the refrigerant K .

[0049] The refrigerant circuit 100 of the heat pump according to the present invention includes a condenser 30 and an evaporator 40, wherein the condenser and evaporator respectively include heat exchangers 32 and 42, wherein at least the heat exchanger 32 of the condenser 30 can be constructed in the form of an asymmetric plate heat exchanger (see FIG. 1). Here, the asymmetry is at least 10%, that is, the volume V of the refrigerant. K Specific volume V M At least 10% smaller.

[0050] With the aid of a hydraulic rectifier assembly 70 formed by a one-way valve 71, the "Gretz bridge" known in electrical engineering is... "Transferred to the hydraulic system, the refrigerant in heating, cooling and defrosting operation is always guided in the same direction R through the expansion device and advantageously also through the internal heat exchanger 50."

[0051] Figure 2c and 2d Showing plate P n .

[0052] For example, in Figure 3a and 3b The arrow-shaped pressing part shown in the figure or as in Figure 4 The grooved pressing part visible in the middle is used as the pressing part.

[0053] In the case of arrowhead-type or herringbone-type pressing sections, the sweep angle or pressing angle β determines the magnitude of the pressure loss between the inlet and outlet sides of the plate heat exchanger. For example, in... Figure 3b As can be seen, a compression angle of β > 45° causes a high pressure loss, while... Figure 3a The diagram shows a low pressure loss at a compression angle of β < 45°.

[0054] As in Figure 4 As can be seen, the grooved pressing section, in addition to the low pressure loss of the heat exchanger, can also reduce the amount of refrigerant.

[0055] exist Figure 5 and Figure 6 The finned tube heat exchanger 42 is shown partially and schematically, as exemplified by its design according to... Figure 5 The refrigerant circuit 100, as used in the evaporator 40, includes multiple evaporator tubes 44, a collection tube 46, and a distributor 48.

[0056] Preferably, a plurality of capillary tubes 49 having an inner diameter preferably from 0.5 mm to 3 mm extend from the distributor 48 to the evaporator tube 44, as shown in Figure 6 As shown in the figure.

[0057] To improve the power coefficient of the finned tube heat exchanger 42 and reduce the required refrigerant charge, the inner diameter of the tube 44 of the finned tube heat exchanger 42 is 3 mm to 7 mm, and its outer diameter is 3.5 mm to 7.5 mm. Additionally, fins can be provided on the inner side of the tube 44 of the finned tube heat exchanger 42 to further improve heat transfer between the refrigerant and the fluid.

[0058] The components of the refrigerant circuit are interconnected via corresponding piping. To further reduce the amount of refrigerant, the piping should be configured with the smallest possible inner diameter.

[0059] Furthermore, for acoustic reasons, the flow velocity in the refrigerant piping should not exceed 3.5 m / s, and should not fall below 0.5 m / s at the maximum power of the heat pump or the maximum speed of the compressor, in the sense of refrigerant reduction. The following formula applies to the design of the pipe's inner diameter:

[0060]

[0061] according to Figure 1a , 1b The condenser 30 and heat exchanger 32 of the refrigeration circuit 100 of 1c or 1d are configured as an asymmetrical plate heat exchanger, such as in combination with Figure 2b This is particularly true in the case of brine-water heat pumps, water-water heat pumps, or air-water heat pumps.

[0062] The heat exchanger 42 of the evaporator 40 is a finned tube heat exchanger, such as in... Figure 5 As described in [the text]. Of course, the heat exchanger 42 of the evaporator 40 can also be configured as an asymmetrical plate heat exchanger (…). Figure 2b This is especially true in the case of brine-water heat pumps or water-water heat pumps.

[0063] The internal heat exchanger 50 is also configured as a plate heat exchanger and has the following characteristics: Figure 4 The plate heat exchanger has a grooved pressing section. However, it is also possible for the plate heat exchanger to have an arrow-shaped pressing section. The plate heat exchanger 50 can be a symmetrical or asymmetrical plate heat exchanger.

Claims

1. A heat pump having a refrigerant circuit (100), the refrigerant circuit comprising: a compressor (10), an expansion mechanism (20), a condenser (30), and an evaporator (40) connected to a refrigerant line; and a refrigerant contained in the refrigerant circuit (100), the refrigerant being circulated in the refrigerant circuit (100) by means of the compressor (10), and The condenser (30) and the evaporator (40) include heat exchangers (32, 42) having a refrigerant side and a medium side, wherein the heat exchanger (32) of the condenser (30) is a plate heat exchanger, and the heat exchanger (42) of the evaporator (40) is a plate heat exchanger or a finned tube heat exchanger. Its features are, The heat exchangers (32, 42) of the condenser (30) and / or evaporator (40) are asymmetrically designed between the refrigerant side and the medium side, such that the volume of the refrigerant side is reduced by at least 10% compared to the volume of the medium side, wherein the heat pump also includes a regulator connected to the compressor and the expansion mechanism. The regulator is configured to control the compressor and the expansion mechanism such that the flow velocity in the liquid line at the operating point is at least 0.05 m / s and at most 3.5 m / s.

2. The heat pump according to claim 1, wherein the plates of the heat exchangers (32, 42) of the condenser (30) and / or the evaporator (40) have arrow-shaped pressed portions having a sweep angle of at least 45°.

3. The heat pump according to claim 1 or 2, wherein a finned tube heat exchanger is used as the heat exchanger (42) of the evaporator (40), The inner diameter of the tubes in the finned tube heat exchanger is 3 mm to 7 mm, and the outer diameter is 3.5 mm to 7.5 mm.

4. The heat pump according to claim 3, wherein the inner side of the tube of the finned tube heat exchanger is provided with fins.

5. The heat pump according to claim 1 or 2 further includes an internal heat exchanger (50), said internal heat exchanger being configured as a plate heat exchanger.

6. The heat pump according to claim 5, wherein the plate of the heat exchanger (50) has an arrow-shaped pressing portion having a sweep angle of less than 45°.

7. The heat pump according to claim 5, wherein the plate of the internal heat exchanger (50) has a grooved pressing portion.

8. The heat pump according to claim 5, wherein the heat exchanger (50) is constructed asymmetrically.

9. The heat pump according to claim 1 or 2, wherein, To comply with acoustic requirements at the operating point and reduce the refrigerant charge of the heat pump, the inner diameter of the liquid piping is designed according to the following formula:

10. The heat pump according to claim 1 or 2, wherein the liquid line is the refrigerant line.

11. The heat pump according to claim 9, wherein, The liquid pipeline is a refrigerant pipeline.

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