Micro-channel heat exchanger

Abstract

Heat exchanger (100) with an inlet line (102), an outlet line and a plurality of parallel microchannel profiles (110), wherein the microchannel profiles (110) each have a plurality of channels (112) arranged parallel to one another, wherein a Venturi distributor (104) is arranged between the inlet line (102) and the plurality of parallel microchannel profiles (110) and / or the outlet line (103) and the plurality of parallel microchannel profiles (110), and capillary lines (106) leading from the Venturi distributor (104) to the individual microchannel profiles (110) are arranged, and a connection section (111) is arranged between the respective capillary lines (106) and a respective microchannel profile (110),wherein the connecting section (111) is formed with a cross-sectional widening and an extended connecting cross-section (Aa) of the connecting section (111) opens into the entirety of the individual channels (112) of the respective microchannel profile (110).

Description

[0001] The invention relates to a heat exchanger with microchannel profiles, in particular for use as an evaporator and / or condenser of a heat pump.

[0002] So-called microchannel profiles are increasingly being used in heat exchangers. The individual microchannel profiles feature several, for example, seven or a different number of parallel channels with a small cross-section through which the heat transfer fluid flows. Due to the small cross-section (diameter approximately 1 mm) of the channels in the microchannel profiles, high pressure resistance can be achieved even with thin walls. Microchannel heat exchangers are particularly well suited as evaporators or condensers (condensers) in refrigerant circuits.

[0003] The background of the invention is that the heat transfer fluid should flow evenly through the microchannel heat exchanger in all areas in order to ensure good heat transfer with a small temperature spread between the primary side and the secondary side of the heat exchanger.

[0004] It is known from the state of the art that Venturi distributors are used to distribute the heat transfer medium flow in finned tube evaporators.

[0005] The starting point of the invention is a heat exchanger, in particular an (evaporator or condenser) heat exchanger, which is designed with several microchannel profiles arranged in parallel and through which flow takes place. The heat transfer medium is fed to the microchannel heat exchanger via an inlet line and discharged from the microchannel heat exchanger via an outlet line. The individual microchannel profiles each have several channels arranged parallel to one another.

[0006] Against this background, it was an object of the present invention to provide a heat exchanger formed with microchannel profiles, wherein both all microchannel profiles and the respective channels of the individual microchannel profiles are flowed through by the heat transfer medium with as equal a throughput as possible.

[0007] According to the invention, a Venturi distributor is used upstream of the inlet line to ensure even distribution of the heat transfer medium to the individual microchannel profiles. The outlet connections of the Venturi distributor are connected to the individual microchannel profiles via capillary lines.

[0008] A Venturi distributor comprises a centrally located inlet connection and outlet connections, particularly in a star-shaped configuration, extending from the inlet connection. Due to the centrally located outlet connections, all outlet connections have the same pressure drop, so that all outlet connections are flowed through at the same rate. A collector similar to the Venturi distributor, but with opposite flow, is advantageously arranged downstream of the heat exchanger.

[0009] Accordingly, the Venturi distributors advantageously ensure a uniform distribution of the heat transfer medium flow to the individual microchannel profiles.

[0010] Furthermore, a uniform mixing of gaseous and liquid refrigerant is advantageous.

[0011] Furthermore, the invention provides that, for the uniform distribution of the heat transfer medium to the individual channels of the respective microchannel profiles, a connecting section with a cross-sectional expansion is arranged directly at the connection of the capillary lines to the individual channels. The expanded connection cross-section of the connecting section opens into the entirety of the individual channels of the respective microchannel profile.

[0012] The cross-sectional expansion of the connecting section can be achieved in one or two dimensions. The cross-sectional expansion is preferably carried out in the direction of the width of the microchannel profiles. This cross-sectional expansion therefore acts as a diffuser and will be referred to as such from now on.

[0013] By expanding the cross-section of the connection section or diffuser, the flow velocity is reduced to such an extent that the individual channels of the microchannel profiles are each flowed through with the same amount of heat transfer medium.

[0014] Thus, the heat exchanger according to the invention advantageously has a uniform flow according to the task. As a result, the heat exchanger can be advantageously operated with a small temperature difference between the primary and secondary sides. This advantageously enables optimal operation of the heat exchanger, as intended by the invention.

[0015] With an evaporator heat exchanger of a heat pump designed as an air-to-refrigerant heat exchanger according to the invention, the refrigerant is optimally evaporated and superheated, thus ensuring the best possible utilization of the heat supplied by the air on the primary side. A heat exchanger designed according to the invention can also be efficiently operated as a condenser in a heat pump.

[0016] As a result, a heat pump equipped with an evaporator heat exchanger designed according to the invention can advantageously be operated with high efficiency.

[0017] Features of advantageous embodiments of the invention are defined in particular in the subclaims, wherein further advantageous features, embodiments and configurations can also be inferred by the person skilled in the art from the above explanations and the following discussion.

[0018] According to a preferred embodiment of the heat exchanger, the expanded connection cross-section of the connection section—correspondingly, on the microchannel profile side—is approximately 2 to 10 times the size of the capillary line connection cross-section. The capillary line connection cross-section is the cross-section at the connection section in the area where the capillary lines are connected. This cross-sectional expansion ensures an even distribution of the heat transfer medium across all channels of the microchannel profile.

[0019] According to a further preferred embodiment of the heat exchanger, the length of the cross-sectional expansion of the connection section is 2 to 15 times the diameter of the capillary line connection cross-section. This diameter-to-length ratio of the cross-sectional expansion ensures a uniform distribution of the heat transfer medium across all channels of the respective microchannel profile.

[0020] According to a further preferred embodiment of the heat exchanger, objects influencing the heat transfer medium flow are arranged in the cross-sectional expansion in the connection section. These objects prevent a main flow in continuation of the capillary line to the centrally arranged channels of the microchannel profile by slowing and swirling the heat transfer medium flow, thus ensuring a uniform distribution of the heat transfer medium across all channels.

[0021] Suitable and therefore preferred objects for improving the distribution of the heat transfer medium among the individual channels of the microchannel profile are cylindrical objects, conical objects, spherical objects, pyramidal objects, or metal wool / wool-like / fibrous structures. Accordingly, the length of the connection sections with cross-sectional expansion can be advantageously reduced. The invention thus provides a compact and thus space-saving heat exchanger.

[0022] The present invention is further illustrated and explained below with reference to exemplary embodiments shown in the figures. Fig. 1 in a partial view from above a basic representation of the invention with an inlet line (injection channel), a venturi distributor, a capillary line and a connection section to a microchannel profile as well as a section of the microchannel profile, Fig. 2 in a partial view the structure of a heat exchanger according to the invention designed as an evaporator of a heat pump, Fig. 3 in a partial view an exemplary microchannel profile, Fig. 4 a sectional view through a heat exchanger and Fig. 5 in a partial view the arrangement of diffuser and venturi distributor.

[0023] In the accompanying drawings and the explanations to these drawings, corresponding or related elements are marked with corresponding reference symbols where appropriate.

[0024] The Fig. 1shows a schematic diagram of a microchannel heat exchanger 100 according to the invention, which is intended as an evaporator of a heat pump. A refrigerant is supplied as a heat transfer medium via an inlet line 102 to an inlet connection 120 of a Venturi distributor 104.

[0025] A capillary line 106 is connected to each outlet connection 122 of the Venturi distributor 104, which leads to a connection section 111 of a microchannel profile 110, shown in detail. The air-refrigerant heat exchanger 100 formed by the parallel microchannel profiles 110, through which air flows, serves, for example, as an evaporator of an air-water heat pump (not shown). The outlet line of the air-refrigerant heat exchanger 100 is not shown.

[0026] In Fig. 2The structure of the heat exchanger 100, designed as an evaporator 100, is shown. It can be seen that a plurality of microchannel profiles 110 arranged parallel in the heat exchanger 100 form the actual heat exchanger 100. Between the microchannel profiles 110, connected sheet metal fins 130 are arranged, which improve the transfer of heat from the air flowing through the sheet metal fins 130 to the microchannel profiles 110.

[0027] Each of the microchannel profiles 110 is connected by means of a connection section 111 and a capillary line 106 to a drain connection 122 of the venturi distributor 104 (see Fig. 1 ) tied together.

[0028] The liquid refrigerant flows from the capillary line 106 into the connection section 111 to the microchannel profile 110. The connection section 111 is formed with a cross-sectional widening.

[0029] The cross section of the connecting section 111 expands in the dimension of the width of the microchannel profile 110, so that at an expanded cross section Aa of the connecting section 111, all channels 112 of the respective microchannel profile 110 are encompassed by the latter.

[0030] Thus, the flow velocity of the still liquid refrigerant in the widening connection section 111 is reduced considerably, which ultimately leads to the fact that, according to the invention, all channels 112 of the microchannel profile 110 are flowed through by the refrigerant to the same extent.

[0031] Due to the fact that the refrigerant flows equally through the channels 112 of the microchannel profile 110 and through the individual microchannel profiles 110, the heat exchanger 100 can advantageously be operated with a small temperature spread between the primary side and the secondary side. This advantageously enables optimal operation of the heat exchanger 100, as intended by the invention. Accordingly, a heat pump equipped with a heat exchanger designed according to the invention can advantageously be operated with high efficiency.

[0032] However, reducing the flow velocity of the refrigerant requires a relatively large length of the widening connection section 111 to the microchannel profile 110, since a main flow to the middle channels 112 would be established.

[0033] Preferably, therefore, the length L of the connection section 111 is advantageously 2 to 15 times the diameter De of the capillary line connection cross-section Ae. The capillary line connection cross-section Ae is the cross-section of the connection section 111 at the point of connection to the capillary line 106.

[0034] The effect of distributing the refrigerant flow can be improved according to the invention if objects, such as spheres 116, are arranged in the connecting section 111, which disrupt the main flow between the capillary line 106 and the central channels 112 and thus even out the inflow to the individual channels 112. Accordingly, the length L of the connecting section 111 can be reduced to, for example, 60%.

[0035] Fig. 3shows a partial view of an exemplary microchannel profile 110 with seven channels 112. The channels 112 are not round, but are created by subdividing the essentially rectangular microchannel profile 110, with the corners being rounded. This means that the five central channels 112 in this example are essentially rectangular, and the side channels 112 are essentially D-shaped. Other configurations of channels 112 are also possible; for example, all channels 112 can be round in cross-section. Fig. 3 The structure shown is characterized by its particular simplicity.

[0036] Fig. 4shows a schematic and exemplary sectional view through a heat exchanger 100. The example shows three levels of microchannel profiles 110, between which finned plates 130 are arranged as heat conducting plates. The supply and discharge lines of the refrigerant to the microchannel profiles 110 are arranged in a manifold 140 formed on both sides of the heat exchanger 100.

[0037] Fig. 5 shows schematically and exemplarily in a partial view the arrangement of diffuser 111 and venturi distributor 104 of a microchannel heat exchanger 100 according to the invention, in a view perpendicular to the view in Fig. 1 . The view will therefore be adjusted accordingly Fig. 4 shown in which the microchannel profile 110 is adjacent to the slatted sheets 130. List of reference symbols

[0038] 100Heat exchanger, evaporator 102Inlet line, injection channel 104Venturi distributor 106Capillary line 110Microchannel profile 111Connection section to the microchannel profile; diffuser 112Channels of the microchannel profile 116Objects in the connection section of the microchannel profile 120Inlet connection of the Venturi distributor 122Outlet connection of the Venturi distributor 130Lamellar plates 140Collector AaExtended connection cross-section of the connection section to the microchannel profile AeCapillary line connection cross-section to the connection section to the microchannel profile DeDiameter of the capillary line connection cross-section LLength of the cross-sectional extension or connection section

Claims

1. Heat exchanger (100) with an inlet line (102), an outlet line and a plurality of parallel microchannel profiles (110), wherein the microchannel profiles (110) each have a plurality of channels (112) arranged parallel to one another, wherein a Venturi distributor (104) is arranged between the inlet line (102) and the plurality of parallel microchannel profiles (110) and / or the outlet line (103) and the plurality of parallel microchannel profiles (110), and capillary lines (106) leading from the Venturi distributor (104) to the individual microchannel profiles (110) are arranged, and wherein a connection section (111) is arranged between the respective capillary lines (106) and a respective microchannel profile (110),wherein the connecting section (111) is formed with a cross-sectional widening and an extended connecting cross-section (Aa) of the connecting section (111) opens into the entirety of the individual channels (112) of the respective microchannel profile (110).

2. Heat exchanger (100) according to claim 1, wherein the cross-sectional expansion of the connection section (111) from a capillary line connection cross-section (Ae) to the expanded connection cross-section (Aa) is 2 to 10 times the capillary line connection cross-section (Ae).

3. Heat exchanger (100) according to one of the preceding claims, wherein the length (L) of the cross-sectional extension of the connection section (111) is 2 to 15 times the diameter (De) of the capillary line connection cross-section (Ae).

4. Heat exchanger (100) according to one of the preceding claims, wherein objects (116) are arranged in the connection section (111).

5. Heat exchanger (100) according to claim 4, wherein the objects (116) are cylindrical objects, conical objects, spherical objects (116), pyramidal objects or metal wool / wool-shaped / fibrous structures.

6. Heat exchanger (100) according to one of the preceding claims, wherein the heat exchanger (100) is designed as an evaporator or condenser in a heat pump system.

7. Heat pump, in particular air / water heat pump or air / air heat pump, with a heat exchanger (100) according to one of the preceding claims.

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