Heat exchanger group for a heat pump and heat pump

Abstract

The invention relates to a heat pump and a heat exchanger group for a heat pump, comprising a fan (10), a first heat exchanger (20) for guiding outside air along an outer circuit (21) of the first heat exchanger (20), and a second heat exchanger (30) with an inner circuit (31) which is thermally coupled to the first heat exchanger (20) for the transfer of heat energy extracted from the environment (U) or ambient air, wherein the inner circuit (31) is a heat transfer section sealed off from the environment (U) and carrying dehumidified air or a dehumidified gaseous medium.

Description

The invention relates to a heat exchanger group for a heat pump, a heat pump having such a heat exchanger group and a method for operating this heat exchanger group or heat pump.Heat pumps draw energy from the environment and transport it to the location where it is needed. There are many ways to do this. The term air heat pump summarizes, for example, the air-air heat pump and the air-water heat pump. Both forms recover heat from the ambient air.In contrast to the air-water heat pump, air-air heat pumps transfer the heat obtained, however, not by means of a heating water circuit, but rather by means of the air as transfer medium.A multiplicity of heat pumps is known from the prior art, which use a heat exchanger for energy transmission.One type of heat exchanger in the air heat pumps is the evaporator.In air / water heat pumps, for example, lamellar heat exchangers are used. These heat exchangers have a large surface area on the primary side. Heat pumps use a repetitive process to recover heat from environmental sources of energy. This process is based on refrigerant which evaporates and condenses in the plant. The former passes through the evaporator mentioned. Here, the refrigerant of an air heat pump impinges on the outside air sucked by a fan. It absorbs energy and changes from the liquid to the gaseous aggregate state. This process cools the outside air, so that this colder air can carry less moisture overall. Water condenses on the fins of the heat exchanger. If this is very cold, the heat pump is icy.At temperatures in the vicinity of the freezing point and below, the water vapor contained in the air thus freezes at the fins of the heat exchanger. Although the icing of the evaporator is delayed due to wide blade spacings, it can never be entirely prevented. Frozen heat exchangers increase the operating noises and the power consumption of the fan, and they must therefore be defrosted at regular intervals. This is indeed done as required and automatically in modern air heat pumps via defrosting programs. However, the less defrosting energy has to be used, the more efficient the heat pump works. In this respect, it is desirable to avoid or at least reduce this problem in order on the one hand to avoid undesired noise generation and on the other hand to improve the efficiency of the heat pump.In the prior art, partially encapsulated compressors are already used in order to improve the noise behavior of the heat pump. The main source of noise, however, is the fan, whose noise is also adversely affected in the event of the heat exchanger being icing up.The object of the invention is therefore to overcome the aforementioned disadvantages and to provide a heat pump with low noise behavior and low losses or good efficiency.This object is achieved by the combination of features according to claim 1.A basic idea of the invention provides, on the one hand, the air- and noise-tight encapsulation of the fan and optionally of the compressor and, on the other hand, the division into two (in particular serially linked) heat exchanger circuits. The approach according to the invention is the division of the central heat exchanger function of the conventional evaporator of a heat pump into an (outer) heat exchanger, in particular an outer heat exchanger and a second heat exchanger, designed as a sealed, in particular encapsulated inner circuit, in order to significantly reduce or almost completely prevent the topic of radiated noise and icing.Conceptually, this is preferably realized as follows. A first heat exchanger forms locally opposite a fan delivering the outside air an outer circuit which is designed to remove heat from the ambient air.The outer circuit is thermally coupled to a separate (e.g. closed or hermetically encapsulated) inner circuit of a second heat exchanger for heat transfer in order to transfer the heat extracted from the outside air to the medium guided in the second heat exchanger. The medium of the inner circuit for the heat transfer of the second heat exchanger is preferably dehumidified air.According to the invention, a heat exchanger group for a heat pump is therefore proposed, comprising a first heat exchanger / heat exchanger in order to guide outside air along this first heat exchanger and a second heat exchanger, which is thermally coupled to the first heat exchanger for transferring the heat from the ambient air and forms an inner circuit in which a fan is arranged, wherein the inner circuit represents an air which is closed off from the environment and the outer circuit and which is dehumidified or a dehumidified gaseous medium or a fluid-carrying heat transfer section.In a preferred embodiment of the invention, it is provided that the first heat exchanger is arranged at least partially around the inner circle. In other words, it is an advantageous configuration if the fan is arranged centrally within the inner circle.A solution is further advantageous in which the thermal coupling and consequently the heat transfer between the first heat exchanger and the second heat exchanger takes place directly via one or more chamber walls arranged therebetween. Due to the design, this can be achieved, for example, by arranging the second, and indeed encapsulated, heat exchanger spatially within the first heat exchanger and the heat transfer takes place indirectly via the adjoining walls between the two heat exchangers.The sealed inner circuit, which is preferably filled with dehumidified air, prevents icing since there is no or very little moisture in the air which could condense. The use of a different medium compared to air would likewise be conceivable in order to improve the heat transfer.In a preferred embodiment, the air guided in the inner circuit is dry, i.e. completely dehumidified. Alternatively, partially dehumidified air can also be used which has a significantly reduced moisture content compared to conventional ambient air. In the context of the present invention, therefore, "dehumidified" means that the relative air humidity of the air or of the medium within the inner circle is less than 15%, preferably less than 10%, further preferably less than 1%. In order to completely avoid the problems with icing, a completely dehumidified, i.e. dry air would be advantageous.In a further preferred embodiment of the invention, it is provided that the first heat exchanger is at least partially designed as a casing of the inner circuit with the fan arranged therein.A design is further preferred in which at least the first heat exchanger has a base surface which is circular when viewed in cross section and in the center of which the fan is arranged and the enclosure is preferably designed in the shape of a pot.A further advantageous embodiment provides that the inner circle of the second heat exchanger is arranged within the enclosure of the first heat exchanger, in particular is formed partially circular, helical, concentric or quasi-concentric within the latter.A further optimization of the solution according to the invention provides that the waste heat of power electronics present in the system is used and for this purpose a bypass duct is provided between the power electronics and the inner circuit in such a way that the heat generated by the power electronics of the fan can pass through the bypass to the outer heat exchanger. If the outer heat exchanger is rotationally movable with respect to the inner circuit, the respectively warm medium in the inner circuit flows through the bypass duct through the corresponding wall regions at the heat transfer to the outer heat exchanger in accordance with the rotated position and thus circumferentially an icing can also be prevented in the outer heat exchanger.In a further preferred embodiment of the invention, provision is made for a heat transfer means to be provided, which can transport the waste heat of a compressor used in the heat pump to the inner circuit.By encapsulating the inner circle, this encapsulated region can be made sound-insulated. Accordingly, when the air or medium is thus supplied from the fan in the inner circuit in a closed circuit, the fan losses can be fully utilized. All the energy to be applied remains in the heat generation system. The additional losses due to the flow through the 2nd heat exchanger are actually not losses, since these are converted by friction into heat which is used in the process for heat generation; furthermore, the losses of the overflow of the conventionally provided blow-out protection grids on the heat pump are dispensed with.In addition to the described device, a further aspect of the present invention also relates to a method for utilizing the ambient heat in a heat pump having a heat circuit, having the following steps: a) removing heat from the ambient air by the first (outer) heat exchanger in order to transfer this heat energy to the inner circuit with the second heat exchanger; b) supplying heat energy thus obtained from the inner circuit (or the air heated in the inner circuit) of the second heat exchanger to the heat circuit of the heat pump.Optionally, in the method waste heat from a heat source in the system can also be supplied indirectly or directly to the internal circuit (e.g. compressor or power modules).The features disclosed above can be combined as desired, provided that this is technically possible and they do not conflict with one another.Other advantageous developments of the invention are characterized in the dependent claims or are illustrated in more detail below together with the description of the preferred embodiment of the invention on the basis of the figures.The following are shown: FIG. 1 shows a schematic overview of the concept according to the invention; FIG. 2 is a partial perspective view of an embodiment of a heat exchanger group; FIG. 3 is a sectional view through the heat exchanger group according to FIG. 2, and FIG. 4 shows a further sectional view in the region of the bypass through the heat exchanger group according to FIG. 2.The figures are schematic by way of example. Like reference numerals in the figures indicate like functional and / or structural features.FIG. 1 is a schematic diagram for explaining the concept according to the invention.The first heat exchanger 20 is configured to transfer thermal energy from the ambient air to the interior circuit of the second heat exchanger 30. The fan 10 is located in the inner circuit; this fan 10 guides the medium in the inner circuit via the second heat exchanger 30 in a flow circuit (see exemplary arrows in FIG. 3 which are intended to indicate the flow circuit).The inner circuit 31 is encapsulated and filled with dehumidified air. Therefore, defrosting of the indoor circuit is not required. In addition, power electronics and compressor of the heat pump are schematically illustrated and coupled to the heat exchanger 30 for transferring the thermal energy.The heat from the inner circuit 31 is supplied to the heat circuit of the heat pump for heating.FIGS. 2 to 4 show different views of an embodiment of a heat exchanger group 1, the heat exchanger group 1 comprising a fan 10, a first heat exchanger 20 for guiding outside air along the outer circuit 21 of this heat exchanger 20. Furthermore, air guidance channels 22 are formed, in which ribs or lamellae 23 are arranged. Between the outer circuit 21 and the inner circuit 31, a partition wall T is provided as a heat exchanger.In the sectional view of FIG. 3, it can be clearly seen that the fan 10 is provided in the center of the arrangement in encapsulated form in the inner circuit 31 and the first heat exchanger 20 simultaneously also forms an enclosure for the inner circuit 31.Inside the first heat exchanger 20, radially offset in the direction of the fan 10, is the second heat exchanger 30, which is integrated in the encapsulated inner circle 31. The inner circuit 31 has a bypass duct 40 for supplying the waste heat of the power electronics of the fan 10 to the outer heat exchanger 20, which can likewise be seen well in FIG. 3.The inner circuit 31 with the second heat exchanger 30 is thermally coupled to the first heat exchanger 20 by a directly adjacent arrangement for the transmission of the thermal energy extracted from the environment or ambient air.The inner circuit 31 is a heat transfer portion sealed and encapsulated from the environment.The first heat exchanger 20 further has a defrosting area 23 in order to initiate a defrosting process in the area of the first heat exchanger in the event of a possibly still occurring frosting.The embodiment of the invention is not restricted to the preferred exemplary embodiments given above. Rather, a number of variants are conceivable which make use of the solution shown even in fundamentally different embodiments.

Claims

Heat exchanger group (1) for a heat pump, comprising a first heat exchanger (20) for guiding outside air along an outer circuit (21) of the first heat exchanger (20) and a second heat exchanger (30) in an inner circuit (31) which is thermally coupled to the first heat exchanger (20) for the transmission of a thermal energy extracted from the environment (U) or ambient air, wherein the inner circuit (31) represents an encapsulated heat transmission section which is closed off and dehumidified with respect to the environment (U) or a dehumidified gaseous medium, in which a fan (10) for conveying the medium is arranged.Heat exchanger group (1) according to claim 1, characterised in that the first heat exchanger (20) is arranged at least partially around the inner circle (31).Heat exchanger group (1) according to claim 1 or 2, characterized in that the thermal coupling and consequently the heat transfer between the first heat exchanger (20) and the medium in the inner circuit (31) takes place directly via one or more chamber walls (T) arranged therebetween.Heat exchanger group (1) according to one of the preceding claims, characterized in that the relative air humidity of the air or of the medium within the inner circuit (31) is less than 15%, preferably less than 10%, further preferably less than 1%, or the air is almost completely to completely dehumidified.Heat exchanger group (1) according to one of the preceding claims, characterized in that at least the first heat exchanger (20) is designed as a housing of the inner circuit (31).Heat exchanger group (1) according to one of the preceding claims, characterized in that at least the first heat exchanger (20) has a base surface which is circular when viewed in cross section and in the centre of which the fan (10) is arranged and the enclosure is preferably pot-shaped.Heat exchanger group (1) according to one of the preceding claims, characterized in that the inner circle (31) with the second heat exchanger (30) is arranged within the enclosure of the first heat exchanger (20), in particular is formed partially circular, helical, concentric or quasi-concentric within the latter.Heat exchanger group (1) according to one of the preceding claims, characterized in that power electronics are provided for driving the fan, and a bypass duct (40) is arranged between the power electronics and the first heat exchanger (20) in such a way that the heat generated by the power electronics can be supplied to the outer heat exchanger (20).Heat exchanger group (1) according to one of the preceding claims, characterized in that a heat transfer means is furthermore provided, which can transport the waste heat of a compressor used in a heat pump to the inner circuit.Heat exchanger group (1) according to one of the preceding claims, characterized in that the first heat exchanger (20) is designed to be rotatable with respect to the inner circuit (31) and / or the bypass.Method for utilizing the ambient heat in a heat pump having a heat circuit by means of a heat exchanger group (1) according to one of the preceding claims, having the following steps: c) removing heat energy from the ambient air by means of the first (outer) heat exchanger (20) in order to remove this heat energy and to transfer it to the inner circuit (31) of the second heat exchanger (30); d) supplying heat energy thus obtained from the inner circuit (31) of the second heat exchanger to the heat circuit of the heat pump.Method according to Claim 11, wherein waste heat is supplied indirectly or directly to the inner circuit (31) from power electronics of the fan (10), a compressor and / or a power component of the heat pump.Heat pump comprising a heat exchanger group (1) according to one of the preceding claims 1 to 10.

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