CN101065635B

CN101065635B - Dimensionally-optimised device for the exchange of heat and method for optimisation of the dimensions of devices for the exchange of heat

Info

Publication number: CN101065635B
Application number: CN2005800400520A
Authority: CN
Inventors: 穆拉德·本-萨哈; 戈特弗里德·迪尔; 米夏埃尔·克拉尼希; 沃尔夫冈·泽瓦尔德; 卡尔-海因茨·斯塔法; 克里斯托夫·瓦尔特
Original assignee: Behr GmbH and Co KG
Current assignee: Mahle Behr GmbH and Co KG
Priority date: 2004-11-23
Filing date: 2005-11-17
Publication date: 2010-10-13
Anticipated expiration: 2025-11-17
Also published as: CN101065635A; WO2006056360A1; JP2008520489A; DE102004056557A1; EP1831632A1; BRPI0518471A2; US20080029242A1

Abstract

A method and apparatus for code multiplexing one or more control signals onto a shared control channel. According to the present invention, a control signal for transmission from a base station to a mobile station terminal is repeated in each slot of a predetermined time interval. The control signal in each slot is spread using a bit-level spreading sequence, where the bit-level spreading sequence varies from slot to slot according to a predefined sequence-hopping pattern. The spread control signals generated for transmission to each mobile station terminal are then combined and spread using a common channelization code.

Description

Heat exchanger device with optimized dimensions and method for optimizing dimensions of a heat exchanger device

Technical Field

The present invention relates to a heat exchange device. Such devices are particularly relevant for air conditioning systems in motor vehicles. It must be noted, however, that the device according to the invention can also be used in other air-conditioning plants or refrigeration cycles.

Background

In the prior art, it is known to use a refrigerant R134a for air conditioning or heat exchange equipment to achieve cooling. Further, there is known an air conditioner in which the refrigerant R134a is replaced with the refrigerant R744, where the refrigerant R744 is carbon dioxide (CO)₂). Using CO in comparison with the conventional refrigerants₂The environment can be better protected because such a refrigerant does not aggravate the greenhouse effect.

However, in the prior art, CO is used as compared with conventional refrigerants₂This locally leads to an increase in costs, since the refrigerant is under a significantly higher pressure in the device than in the case of R134 a. For example, if a refrigeration cycle of the same geometry or dimensions as those used with conventional refrigerants is used, the weight and cost of such devices are high, making the manufacture of such devices uneconomical. The invention aims to make the size of each heat exchange device and CO₂The utilization of the device is matched, so that the device with lower cost and light weight is manufactured.

Numerous studies have shown that weight and cost can be saved by changing the evaporator. A slight reduction in power is also permissible here, since numerous studies have concluded that this has little effect on cooling in a motor vehicle.

Object of the Invention

The invention aims to use CO in the device through matching with a certain size₂As a refrigerant, the device is improved, thereby improving manufacturing costs, power, weight, and the like.

Another object is to improve the apparatus using R134a as refrigerant.

According to the invention, this object is achieved by: although the specific cooling capacity of the evaporator as a component drops, its adverse effect on the refrigeration cycle of the vehicle cabin is still acceptable. More precisely, in designing the evaporator, its weight and manufacturing costs bring the refrigeration efficiency to a comparable level when compared to conventional refrigerants.

According to the invention, the critical geometry of the evaporator is optimized so that the cost/utility ratio of the overall system is as optimal as possible.

The object of the present invention is achieved by a heat exchange device as described below. Other preferred embodiments and further modifications are also included.

The heat exchanger device according to the invention has a plurality of flow tubes for conveying a fluid, wherein the device has a predetermined depth, hereinafter referred to as installation depth, and the flow tubes are at least partially at a predetermined distance from one another. According to the invention, the ratio of the depth to the predetermined distance is less than 7. The depth of the heat exchange means is substantially produced by the depth of the draught tubes, as described in detail in the accompanying drawings.

As shown in the drawings, the tube pitch between the draft tubes refers to the distance between the side faces of the draft tubes facing each other. This tube spacing also determines the height at which the fins are preferably disposed between the tubes. Therefore, the pitch is also referred to as fin height hereinafter.

Here, the pitch refers to the shortest geometric distance between the draft tubes. By at least partially predetermined spacing is meant that the tubes do not necessarily have to be maintained at the same spacing throughout their length.

The first set of tubes may be spaced apart from one another by a first distance and the second set of tubes may be spaced apart from one another by a second distance. This is illustrated in detail in the accompanying drawings.

In another preferred embodiment, the ratio V is less than 6.5, preferably less than 6.3, and more preferably less than 5.9. Research and analysis show that the proportion relation is expressed by CO₂Particularly good cost/utility relationships are obtained for the case of refrigerants, wherein the criteria for evaluating the cost/utility relationship include a specific refrigeration capacity, pressure drop on the air side and the refrigerant side, and manufacturing cost and weight.

In a further preferred embodiment, the draft tubes are at least partially parallel to one another. This ensures that the spacing between the draft tubes remains substantially constant.

The draft tubes are preferably parallel to each other along substantially their entire length, such that they have a constant, predetermined first spacing substantially throughout their length.

In a further preferred embodiment, the draft tube has a flat tubular cross section. By flattened tubular cross-section is meant that one side is substantially longer than the other side, for example an elongated rectangle, an elongated rectangle with rounded corners or an ellipse with a first radius substantially larger than a second radius.

In another preferred embodiment, the fluid is a refrigerant, preferably R744 (CO)₂)。

In a further preferred embodiment, the first plurality of flow ducts have at least partially a predetermined first distance from one another and the second plurality of flow ducts have at least partially a substantially predetermined second distance from one another, wherein the ratio V between the depth and at least one of the predetermined distances is less than 7.

This illustrates that some tubes have a different spacing between them than others. In this case, the respective spacings in the draft tubes which are substantially parallel to one another can be varied. In addition, when the preset first distance and the preset second distance are determined, the proportional relationship between the depth and the two preset distances may be respectively smaller than 7.

Preferably, in the heat exchange device, the fluid flows in one direction in the first plurality of draft tubes and the fluid flows in the other direction in the second plurality of draft tubes, and different preset tube pitches are respectively selected for such heat exchange device. In this way, a low-cost design can be achieved, taking into account the heat exchange efficiency achieved.

In a further preferred embodiment, the first plurality of flow ducts and the second plurality of flow ducts are laterally offset from one another. Here, the respective predetermined pitches of the plurality of first and second flow-through tubes may be selected to be the same or different. The predetermined spacing may also vary among the same plurality of draft tubes.

In a further preferred embodiment, heat dissipating fins are arranged between the draft tubes. These fins serve to improve the heat exchange with the surrounding air. Here, as described above, the height of these heat dissipating fins is substantially determined by the predetermined distance between the draft tubes.

In a preferred embodiment, the wall thickness of the individual cooling fins is between 0.04 and 0.2mm, preferably between 0.05 and 0.12mm, particularly preferably between 0.06 and 0.1 mm. The density of the fins is from 40 to 90 sheets/dm, preferably from 50 to 80 sheets/dm, particularly preferably from 60 to 70 sheets/dm.

In a further preferred embodiment, the depth of the device is from 10mm to 60mm, preferably from 20mm to 50mm, particularly preferably from 25 to 45 mm. These different depths have different uses, that is, depending on whether they are for small or medium or high-grade vehicles.

In a further preferred embodiment, the predetermined distance between the draft tubes is 4mm to 12mm, preferably 4.5mm to 10 mm. These spacings also have different applications.

In a further preferred embodiment, the predetermined distance of 5mm to 12mm, preferably 5.5mm to 10mm, corresponds to a depth of 30mm to 50mm, preferably 35mm to 45 mm. In this embodiment, a heat exchanger device of larger dimensions is involved, which is used in particular, but not exclusively, for air conditioning systems in medium-or high-class vehicles. The dimensions selected here basically ensure that the ratio is less than 7.

In a further preferred embodiment, the predetermined distance of 3mm to 10mm, preferably 4mm to 8.5mm, corresponds to a depth of 15mm to 40mm, preferably 20mm to 35 mm. These dimensions are used in particular for air conditioning in small and medium-sized vehicles.

At these dimensions, the proportionality is substantially guaranteed to be less than 7. Here, a proportional relationship of substantially 7 also means a proportional relationship slightly exceeding 7.

In a further preferred embodiment, the width of the draft tube is 1mm to 3mm, preferably 1.5mm to 2mm, particularly preferably 1.7mm to 1.9 mm. The wall thickness of the draft tube is 0.1mm to 0.6mm, preferably 0.2mm to 0.4mm, particularly preferably about 0.3 mm. Particularly good heat exchange with the surrounding air can be achieved by these dimensions.

The device according to the invention is preferably an evaporator as part of a refrigeration cycle of a motor vehicle air conditioning system.

The invention further relates to a motor vehicle air conditioning system having at least one heat exchanger device according to the invention.

The invention also relates to a method for dimensioning a heat exchanger, wherein a first step is to determine a first dimension of the device, a next step is to determine a second dimension of the device, in a subsequent step at least two first target parameters of the device are determined, subsequently at least one dimension is changed, two second target parameters of the device are retrieved from the changed dimension, and finally a preferred target parameter is selected by comparing the first and second target parameters.

The first and second dimensions are preferably selected from a group of dimensions including depth, height of the fins, pitch of the draft tubes, and the like.

Furthermore, dimensions may also refer to quantities such as fin density per dm and the like.

The target parameter is preferably selected from the group consisting of structural space depth, refrigeration capacity, air side pressure drop, weight and manufacturing cost. As previously mentioned, the effectiveness or value of the heat exchange device with respect to the different refrigerants, where R is the refrigerant, can ultimately be determined from these parameters

134a and R744 (CO)₂). The method according to the invention makes it possible to vary the important dimensions of the heat exchanger and to determine therefrom the relevant above-mentioned output values, so that a satisfactory and sufficient refrigeration capacity can be achieved with acceptable manufacturing costs and acceptable weight of the device using these dimensions.

In this approach, it is considered that even small modifications to one or the other dimension can result in large changes in the output value or target parameter.

The target parameters are preferably measured several times at different dimensions, and the best parameter set is selected from the several target parameters thus calculated. The efficiency or target parameter to be achieved of the heat exchanger can be evaluated very precisely by measuring and calculating the target parameter several times. When evaluating the optimal target parameter set, the target parameters are preferably weighted according to a predetermined criterion. For example, for devices used on premium cars, the weight and manufacturing costs of the target parameters are weighted less than for devices used on smaller cars.

Drawings

Other advantages and embodiments of the device and method of the invention are shown in the drawings. Wherein,

FIG.1 is a partial top view of the apparatus of the present invention;

FIG.2 is a side view of the apparatus of the present invention shown in FIG. 1;

FIG.3 is a schematic illustration of another embodiment;

FIG.4 is a schematic illustration of yet another embodiment;

FIG.5 is a schematic view of yet another embodiment;

FIG.6 is a schematic view for explaining the tube pitch;

FIG.7 is a graph illustrating the degree of cooling achieved;

FIG.8 is an analysis diagram of the elements;

FIG.9a is a graph of the relationship between cooling power and weight for the apparatus of the present invention;

FIG.9b is a table graph of air side pressure drop;

FIG.10 is a power map as a function of installation depth;

FIG.11 is a graph of the power to weight ratio as a function of installation depth;

FIG.12 is a graph of the power versus cost ratio with respect to installation depth;

FIG.13 is a power diagram relating installation depth to fin height;

FIG.14 is a graph of the power to weight ratio relating the relationship between installation depth and fin height;

FIG.15 is a graph of the power to cost ratio associated with the relationship between installation depth and fin height.

Detailed Description

Fig.1 is a partial top view of a heat exchange device 1 of the present invention. The device has a plurality of first draft tubes 3, a plurality of second draft tubes 5. In a preferred embodiment, the refrigerant flows in one direction in a plurality of first draught tubes 3, i.e. in a direction out of the plane of the drawing, and in another direction in a plurality of second draught tubes 5, i.e. in a direction out into the plane of the drawing.

Reference numeral 7 denotes a case of the draft tube. The draft tube is preferably divided into a plurality of tanks or channels.

Here, the first and

second draft tubes

3, 5 are separated from each other by a gap 8. The gap 8 is used for thermal insulation, since the temperature of the refrigerant in the

draught tubes

3 and 5 will be different, and no heat transfer between the two should take place. However, instead of the gaps, the draft tubes may be arranged continuously along the depth T, i.e., only a plurality of flat tubes may be provided. In this case, the tank or channel 7 is closed, i.e. no refrigerant flows into this channel.

Reference numeral 4 denotes a fin arranged between the

draft tubes

3 and 5 shown in plan view here. The dimension H is the fin height and is determined substantially by the spacing between the

draft tubes

3 or 5, and more precisely by the spacing between the mutually facing sides of the

draft tubes

3 and 5.

The reference T refers to the installation depth, which, as mentioned above, is the critical geometry of the device. The fins 4 extend substantially along the entire depth T and are preferably not received in the gapsAnd (7) breaking. The aforementioned proportional relationship V depends on the installation depth T and the fin height H_riThe proportional relationship between them.

FIG.2 is a side view of the partial heat exchange device shown in FIG. 1. Here, b means the width of each draft tube. In the heat exchange device using R134a as a refrigerant, the width of the tube is between 2 and 4mm, preferably 2.5 to 3 mm.

In the presence of CO₂The width of a tube in a heat exchange device for refrigerant, as described above, is preferably 1.2 to 2 mm. The overall width of the device is 120 to 400mm, preferably 215 to 350mm, particularly preferably 250 to 315 mm. Also advantageous is a width of 120 to 315 mm. The height of the device according to the invention is from 140 to 300mm, preferably from 200 to 300mm, particularly preferably from 220 to 250 mm. The height is likewise advantageously 140 to 270 mm. In a preferred embodiment, the device is made substantially of aluminum or a material containing aluminum.

Reference character a refers to the so-called transverse pitch, i.e. the distance between the geometric centres of the respective flow elements. Taking into account the width b of the tubes, the fin height H can be obtained from the transverse pitch A_riI.e. the fin height is directly related to the transverse pitch. If, due to the cross section of the

draft tubes

3, 5, a geometrically defined, constant fin height or draft tube pitch cannot be provided, for example if the pitch of the draft tubes shown in fig.2 changes in a direction perpendicular to the plane of the drawing (as would be the case with draft tubes having a circular contour), the transverse pitch can be used as a measure for the fin height. In this case, the proportional relationship between depth and tube pitch according to the invention can be replaced by a proportional relationship between depth and transverse pitch.

Fig.3 shows a further embodiment of the device according to the invention. Here,

reference numerals

3 and 5 respectively refer to the draft tubes in plan view. In contrast to the embodiment shown in fig.1, the

draft tubes

3 and 5 are laterally offset from one another. This means that the distance between the draught tubes can be determined for the

draught tubes

3 and 5, respectively. In the embodiment shown in FIG.3, through-flow is providedThe distance Hri between the tubes 3 and the distance H between the draft tubes 5_riAre identical.

Fig.4 is a schematic view of another embodiment of the device of the present invention. The distance H between the draft tubes 3 is here_riIs larger than the distance H between the draft tubes 5_ri2. Wherein two pitches H are selected_ri1Or H_ri2At least one of (a) here is at least the spacing H_ri1Preferably, the depth T and the pitch H are made_ri1The proportional relationship between them is less than 7. However, it is also possible to select both spacings such that the respective proportionality is less than 7.

Fig.5 shows a further embodiment of the device according to the invention. In this embodiment, the distance between the individual draught tubes varies only in the draught tube 3. However, it is also possible for the distance between the individual draught tubes to vary only in the draught tube 5 or both in the draught tube 3 and in the draught tube 5. In this embodiment too, it must be ensured that the distance H_riSatisfies the requirement that the proportional relationship between depth and this spacing is less than 7.

Other different spacings between the tubes or a plurality of different spacings, for example the spacing H, may also be provided_ri1、H_ri2、H_ri3And the like. The spacing H must be guaranteed anyway_riOne of which satisfies the above proportional relationship of less than 7.

FIG.6 is a diagram illustrating the distance H_riSchematic diagram of the definition. While the draft tubes in fig.3 to 5 each have straight sides, which at the same time directly define the distance, the draft tubes in the embodiment shown in fig.6 have an oval cross section. The spacing between the draught tubes is defined in this case as the spacing between two tangent lines T, each tangent to the draught tube 3.

However, as already mentioned, the spacing of the tubes may also be determined not by the spacing of the sides facing one another, but by the spacing between the geometric centerlines of the tubes, which is referred to above as the transverse pitch. As previously mentioned, this applies above all to draft tubes having a different geometry than shown here, for example concave or convex.

The chart in fig.7 is a simulation of the cooling curve for a premium vehicle. Here, the comparable cooling curves for refrigerant R134a (here represented by curves 11 and 12) and R744 (here represented by curves 14 and 15), respectively, are plotted at an idle-one operating point.

The

upper curves

12 and 14 represent the temperature variation in the vehicle cabin, and the

lower curves

11 and 15 represent the temperature variation of the evaporator itself.

Furthermore, the simulation was started from the fact that the installation depth of the R134a evaporator was 65mm, whereas the installation depth of the R744 evaporator was 25mm less, i.e. 40 mm.

The ordinate is time in minutes and the abscissa is temperature in degrees celsius. The simulation is divided into a number of time periods I to IV, wherein driving in time period I is gear 3 and speed is 32km/h, driving in time period II is gear 4 and speed is 64km/h, idling driving in time period III, driving in time period IV is gear 2 and speed is 64 km/h.

It can be seen that in gear 3 (I), the cooling achieved by the R744 evaporator is more rapid and uniform than the R134a evaporator. In zones II to IV, the evaporators reach substantially the same value respectively.

In fig.8, the power of different types of evaporators is compared at a typical operating point. Here, this operating point is defined so that the comparison is not affected by the refrigeration cycle.

It is to be noted that the method described below or the results obtained apply equally to the R134a evaporator and to R744 (CO)₂) Improvement of an evaporator.

In the diagram shown here, the following conditions are assumed: the air flow GLV is 8kg/min, the air flow inlet temperature tLVe is 40 ℃, and the relative humidityThe content was 40%.

In the graph, the diamonds are represented as refrigerant R744 (CO)₂) The measured value; the ellipse is represented as the value measured for R134 a.

The fin density was 70 fins/dm for the evaporator using R744 as the refrigerant and 60 fins/dm for the evaporator using R134a as the refrigerant.

The ordinate is the installation depth in mm and the abscissa is the total power in kW. Each pair of values or points 31 to 39 filled in is the temperature T, the fin height H_riDensity of fins z_riAnd a function of the so-called transverse pitch sq. The transverse pitch refers to the spacing between the centers of the draft tubes. Here, a range is formed by each pair of values or points 31 to 39, which covers different levels of the power level of the refrigeration cycle of the vehicle. The upper curve 22 corresponds to a premium vehicle or lorry and the lower limit curve 23 shows the power demand of a small vehicle.

For installation depths of less than 40mm, i.e. from the measuring points 31 to 35, the value relating to the refrigerant R744 is filled in. For the area of the installation depth Σ 40mm, the value relating to the refrigerant R134a is filled. As described above, for the measurement points 31 to 35, a uniform fin density of 70 pieces/dm was selected, and for the measurement points 36 to 39, a uniform fin density of 60 pieces/dm was selected.

The transverse pitch is smaller for measurement points 31 and 32 and larger for measurement points 33 to 35. Resulting from the smaller cross-pitch is the same smaller fin height, which is indicated by line 28. Also, resulting from the larger cross-pitch is a larger fin height, which is indicated by line 27.

For measurement points 36 and 37, the selected cross-pitch is small, resulting in a fin height H_RiAnd is also smaller as shown by line 25. For measurement points 38 and 39, the cross-pitch is selected to be larger, thereby making the fin height larger as well, as shown by line 26.

As can be seen from the graph, in the case of using R744And the power level represented by the coordinates remains unchanged, the installation depth becomes significantly smaller. That is, the installation depth T and the fin height H_RiThe corresponding or proportional relationship of (a) is shifted.

In the case of R134a, a depth of 65mm corresponds to a fin height of 7 to 10mm and a depth of 40mm corresponds to a fin height of 4 to 6mm, whereas in the case of R744, a depth of 40mm corresponds to a fin height of 7 to 10mm and a depth of 27mm corresponds to a fin height of 5 to 8 mm.

In the former type of construction, for refrigerant R744, the correspondence or size of R134a was employed. This results in a significant increase in power compared to R134a, but increases weight and cost due to the significantly higher pressures required when using R744. The significantly increased power values are here represented by, for example, points 41 and 42. The power represented by

points

41 and 42 is more than 15% higher than the required maximum power.

It is thus shown that, contrary to the industry's idea, also cost-reducing, weight-reducing modifications can be made in dimensioning, without at the same time compromising the cooling power.

The reason why the potential of R744 is significantly higher is that in the R744 cycle, the pressure drop can be achieved faster in the low pressure part due to the particularly high delivery capacity of the R744 compressor. This achieves higher dynamic performance and a higher driving temperature difference between air and refrigerant at the evaporator.

The pressure drop across the refrigerant side in the evaporator is on a comparable magnitude, with a pressure drop of 1bar causing a temperature change of about 9K when R134a is used and only 1K when R744 is used. Typically over the length of the flow in the evaporator, this results in a significantly higher, driving temperature difference between the air and the refrigerant (R744 evaporators generally have a significantly lower surface temperature).

As previously mentioned, the cost/utility optimum is a function of the values of installation depth, cooling power, air side pressure drop, weight and cost. Here, as previously described, the depth T, the fin height Hri, and the tube pitch or other values derived from the values, such as the lateral pitch, are variables.

According to considerations and studies so far, a mounting depth of 65mm is too large for the existing power levels; the preferred design is 55mm, as evaluated, which also reaches a power level of 65mm depth. Of course, such an embodiment can also lead to increased costs, which affect the pressure drop on the air side. In terms of power, the preferred depth for refrigerant R134a is 40 mm; but in this case there are disadvantages in terms of cost and air-side pressure drop. The above considerations show that the relationships between the various aspects are interleaved and extremely complex when evaluating and analyzing the evaporator to be manufactured.

A particularly suitable construction depth for an evaporator using refrigerant R744 is between 25 and 45 mm.

The graph in fig.9 illustrates several advantages of the present invention. Therein, in the sub-diagram labeled fig.9a, the relationship between the weight of the evaporator and the achievable cooling capacity is shown. The physical boundary conditions, such as the air flow GLV, are the same as those that are the basis for the description of fig. 8. Also, the size of the evaporator is the same.

Comparable cooling capacities can be achieved by a geometric fit as shown by the measuring points 44 and 45 for the small and medium-sized cars, with measuring point 44 for refrigerant R744 and measuring point 45 for refrigerant R134 a. For the measurement point 45, it is based on the average installation depth and the fin density of 60 pieces/dm. Whereas for the measurement point 44 a depth smaller than point 45, a smaller cross-pitch and a greater fin density are chosen.

The two

measuring points

46 and 47 relating to the devices on the higher-class vehicle show that the weight of the R744 evaporator is significantly less with the same refrigeration capacity. For the measuring point 46, a greater installation depth T, a predetermined fin density and a greater transverse pitch s are selected_q. At the measuring pointAt 47, the depth T of the R744 evaporator is less than at point 46, the fin density is the same as at point 46, and the cross-pitch is correspondingly the same. Thus, since the installation depth is small, the weight is remarkably reduced with the same lateral pitch, and there is an advantage in weight even compared with the R134a evaporator of the same power. Due to the fact that the installation depth is reduced, material consumption is correspondingly reduced, and therefore cost is reduced.

Furthermore, the installation depth can be reduced from 65 to 45mm for evaporators in premium vehicles and from 40 to 25mm for small vehicles. This also has the additional advantage that less space is occupied in the vehicle.

The air side pressure drop shown in the coordinates may also be reduced as shown in the graph of fig.9 b. Blocks 51 through 53 relate to refrigerant 134a and blocks 54 through 55 relate to refrigerant R744. It can be seen from the figure that the pressure drop on the air side is significantly reduced by about 50% when R744 is used. This increases the amount of air used for air conditioning of the vehicle, reduces power consumption in the blower, and provides the possibility of reducing the noise level of the air conditioning apparatus.

In fig.10, the power values of the respective evaporators are filled in the ordinate, and the installation depth is taken as the abscissa. Here, it is either CO₂The evaporator is also an R134a evaporator, where the evaporators with the same fin height are each in a straight line. Reference numeral 63 identifies a straight line corresponding to a higher fin height, herein referred to as a first fin height, reference numeral 62 identifies a straight line corresponding to a lower second fin height (hereinafter referred to as a second fin height), and reference numeral 61 identifies a straight line corresponding to a fin height less than the second fin height (hereinafter referred to as a third fin height).

As shown in fig.10, the individual lines 61 to 63 have a relatively similar upward trend, from which it is concluded that the power and the installation depth are proportionally dependent on one another with the same structural form or fin height. It can also be seen that the evaporator with smaller fin height, although of the same size, has a higher power due to the increased heat transfer surface.

The shaded areas 60 and 70 form boundaries for a desired or meaningful power value. The limit value for the power is obtained by simulation of the cooling of the vehicle cabin. In the upper region 60, the further increase in power does not bring any further advantages, whereas below the lower boundary value in the region 70 the cooling of the cabin is unacceptable. Reference numerals 65 to 68 refer to measured values lying within the required power range. They represent devices of different structural forms.

Reference numeral 67 denotes an R134a evaporator having a large installation depth and having the first fin height described. Reference numeral 65 designates an R134a evaporator having a small installation depth and having the third fin height described.

Reference numeral 66 denotes an R134a evaporator having a second fin height and an average installation depth.

Reference numeral 68 refers to an R134a evaporator having a first fin height and an average mounting depth. Reference numerals 71 to 74 refer to measured values of the evaporator which are not within the allowable range 75 between the regions 60 and 70. Wherein reference numeral 71 denotes an evaporator having a small installation depth and a first fin height, reference numeral 72 denotes an R744 evaporator having a third fin height and a small installation depth, and reference numeral 73 denotes a CO having a small installation depth and a third fin height₂Evaporator, reference numeral 74 refers to CO with a large installation depth and a first fin height₂An evaporator.

As can be seen, at a given installation depth and fin height, CO₂The power rating of the evaporator is significantly higher than that of the R134a evaporator. As also shown in FIG.10, the CO, for example, shown by line 76, has a smaller installation depth and a second fin height₂The evaporator has advantages in application. The ellipses 140, 141 represent the range within which preferred dimensions are located.

In fig.11, the power is proportional to the weight as a function of the installation depth. The quantities involved, such as power/weight, are evaluated weighted again against one another in order to evaluate the different meanings of the quantities correctly. In a preferred variant of the method, power and cost are taken as equivalent quantities, and weight and fin height play secondary roles.

The weighted evaluation in the graphs shown in fig.11 to 15 is such that: the power to cost ratio is 50: 50, the power to weight ratio is 80: 20, and the installation depth to fin height ratio is 70: 30. The triangle refers to CO₂Evaporator, and circular refers to the R134a evaporator. After the power/weight ratio is filled into the coordinates, a higher value, i.e. a ratio that moves in the power direction, is considered to be better.

It can be seen that the evaporator 81 having the average installation depth and the second fin height is good for the R134a evaporator, as is the evaporator 83 having the smaller installation depth and the third fin height.

The evaporator 84 with the first fin height, although also good in terms of power to weight ratio, is not acceptable for cooling small vehicles in absolute terms. It is conceivable to use this type of evaporator in the rear device. The evaporator with the second fin height can likewise be used as an alternative for small and/or medium-sized vehicles.

For refrigerant CO₂Preferred are evaporators 86 and 87 which are small in depth and large in fin height and an evaporator 88 which is small in depth and has a third fin height. The evaporator 89, which is of a small depth, is relatively good, but is at a limit in terms of power.

The evaporator 91 has significant disadvantages compared directly to evaporators having the second fin height. Furthermore, this evaporator already exceeds the upper power limit currently required.

The evaporator, designated by reference numeral 92, results in poor power to weight ratio at very low power due to the high density of the tubes and fins.

Reference numerals

95 and 96 refer to trend lines determined from the measured values. From the trend lines it can be determined or estimated which evaporator sizes can be used to achieve a preferred design, such as the preferred power/weight ratio relationship shown here.

For each, trend line 95 refers to CO₂Evaporator, trend line 96 refers to the R134a evaporator.

Fig.12 shows the proportional relationship between power and manufacturing cost in relation to the installation depth. Here too, the power to cost ratio is based on the ratio or weighted evaluation described above.

It can be seen that of the R134a evaporators represented by circles, the evaporator 101 having the average mounting depth and the first fin height has the best power/cost ratio relationship. However, the output of such an evaporator is low and is therefore not considered in formulating trend line 115.

Trend line 115 for R134a evaporator and for CO as before₂The trend lines 116 of the evaporator respectively indicate in which geometries particularly advantageous results can be obtained for the evaporator. Although the evaporator 102 having the third fin height is significantly inferior, it must be considered to have an advantage of a small installation depth when compared with the evaporators 104 to 106.

In examining CO represented by a circle₂In the case of evaporators, it was found that the

evaporators

107 and 108 having the first fin height or a slightly smaller fin height had a good power/cost ratio relationship, and the evaporator 110 having the first fin height also had a good power/cost ratio relationship.

The evaporator 111 having the third fin height is somewhat inferior as required due to the high arrangement density, which represents a negative influence in terms of cost. And the evaporator with the second fin height is logically located between the evaporator with the third fin height and the evaporator with the first fin height as a preferred alternative.

The above-described proportional relationship is also more disadvantageous for the evaporator 112 having a larger installation depth and the third fin height and the evaporator 113 having a smaller installation depth.

On the former evaporator, the cost becomes high due to the smaller fin height (or high packing density), while on the latter evaporator, although not costly, the power is lower. The evaporator 114 is the same as the evaporator 93 in fig.11, but is not considered for the reasons described above.

In general, CO₂The evaporator level is lower than the evaporator of the R134a configuration. It can be seen here that it has certain disadvantages in terms of cost, because of its strength or safety reasons (in the use of CO)₂In the case of (1), the operating pressure is significantly higher than the refrigerant) and a more stable structure is adopted, thus increasing the weight.

The graphs shown in fig.13 to 15 correlate with the graphs in fig.10 to 12. In the graphs of fig.13 to 15, however, the amount "mounting depth" filled in on the ordinate or abscissa is replaced by a weighted proportional relationship V' between the mounting depth and the fin height plus 10 mm.

As seen from the coordinate system formed by the weighted proportional relationship V' between the power of each evaporator and the installation depth and the fin height shown in fig.13, evaporators (R134a or CO) using the same refrigerant₂) Now in a constant straight line substantially independent of the fin height. This illustrates the weighting between the selected installation depth and the fin height, which is reflected in adding 10mm to the fin height. Here again, one can see CO₂The evaporator has an advantage in power compared to R134a with the same installation depth. The values here, as before, are also measured values or values obtained by simulation, which values allow confirmation of the measurement.

Substantially the same conclusions as above were drawn from the graph in fig.14 formed by the weight-dependent power and the proportional relationship between the weighted fin height and the mounting depth, compared to the absolute mounting depth (see fig. 11). In addition, the weight-dependent power of the R744 evaporator studied here reaches a maximum between V '1.3 and V' 2.8, and drops occur outside this range. Starting from V '1.5, the preferred value for the evaporator appears, and starting from V' 1.85, the better value for the evaporator appears. The weighted proportional relation V' of the evaporator with maximum power in relation to weight is 2.2 or 2.4. The maximum value exhibited by the trend line is approximately V' 2.1.

Similarly, in the graph shown in FIG.15, the power/cost ratio relationship fills in above the relevant installation depth (see FIGS. 12 and 15). Here, the priority is not changed. When the weighted proportional relationship V' is less than about 2.6, the cost-related power of the R744 evaporator exceeds that of the R134a evaporator.

It has been found that, by means of the method according to the invention, depending on the desired dimensions or parameters, such as installation depth and fin height, different target parameters, such as cost, power and weight, can be determined and evaluated against one another by means of different weights, which variables are embodied in the form of an optimum embodiment in terms of the final result. Thus, according to the method of the invention, R134a and CO are obtained in an efficient manner by using different filling methods (including locally also weighting)₂The optimal size of the evaporator. In this way, the optimum size for each evaporator can be selected in consideration of various criteria such as weight, power, etc.

A program can preferably be developed for the method, so that the user can input the index at will, and the target parameter at will, to meet the requirements for, for example, air conditioning of a motor vehicle. Experience gained through measurement and/or extensive thermodynamic studies is utilized or incorporated in writing such programs.

The invention therefore also relates to software which makes the method according to the invention available with the aid of a measuring and evaluation machine.

For CO₂The evaporator, preferably, has an installation depth of 20 to 45mm and a fin height of 4.0mm to 10.0 mm.

Particularly, when used in a high-class vehicle, it is preferable that the mounting depth is 35 to 45mm and the fin height is 5.5 to 10mm, and when used in a small-and medium-class vehicle, it is preferable that the mounting depth is 20 to 35mm and the fin height is 4 to 8.5 mm.

Claims

1. Heat exchange device for an air conditioning system of a motor vehicle, comprising a plurality of flow tubes for conveying a fluid, wherein the device has a predetermined depth (T) and a predetermined number of flow tubes (3, 5) are at least partially spaced apart from one another by a predetermined distance for arranging cooling fins; the depth-to-preset distance measuring device is characterized in that the proportional relation between the depth and the preset distance is smaller than 7, and/or the weighted proportional relation between the depth and the sum of the preset distance and 10mm is larger than 1.3 and smaller than 2.8.

2. The device of claim 1, wherein the predetermined spacing is less than or equal to 9 mm.

3. The device of claim 1, wherein the predetermined spacing is less than or equal to 8 mm.

4. The device of claim 1, wherein the predetermined spacing is less than or equal to 6 mm.

5. The apparatus of claim 1, wherein the proportional relationship is less than 6.8.

6. The apparatus of claim 1, wherein the proportional relationship is less than 6.6.

7. The apparatus of claim 1, wherein the proportional relationship is less than 6.3.

8. The apparatus of claim 1, wherein the proportional relationship is less than 6.1.

9. The apparatus of claim 1, wherein the proportional relationship is less than 5.9.

10. The apparatus of claim 1, wherein the proportional relationship is less than 5.1.

11. The apparatus of claim 1, wherein the weighted proportional relationship is at least 1.5.

12. The apparatus of claim 1, wherein the weighted proportional relationship is at least 1.85.

13. The apparatus of claim 1, wherein the weighted proportional relationship is at least 2.2.

14. The apparatus of claim 1, wherein the weighted proportional relationship is up to 2.6.

15. The apparatus of claim 1, wherein the weighted proportional relationship is up to 2.4.

16. The apparatus of claim 1, wherein the weighted proportional relationship is up to 2.25.

17. The apparatus of claim 1, wherein the draft tubes are at least partially parallel to each other.

18. The apparatus of claim 1 wherein the draft tubes have a constant predetermined first spacing therebetween.

19. The device of claim 1 wherein the draft tube has a flattened tubular cross section.

20. The apparatus of claim 1, wherein the draft tube is integrally formed.

21. The device of claim 1, wherein the draft tube is comprised of a sheet or extruded profile.

22. The device of claim 1, wherein the fracture pressure of the draft tube is greater than 90 bar.

23. The device of claim 1, wherein the fluid is R744.

24. Device according to claim 1, characterized in that the first plurality of through-flow ducts (3) have at least in sections a predetermined first distance from each other, the second plurality of through-flow ducts (5) have a predetermined second distance from each other, and the depth (V) to at least one predetermined distance has a proportionality (V) smaller than 7.

25. The device according to claim 1, characterized in that the first plurality of draught tubes (3) and the second plurality of draught tubes (5) are laterally offset from each other.

26. Device according to claim 1, characterized in that between the draught tubes heat-dissipating fins (4) are arranged.

27. The device of claim 1, wherein the device has a depth of 10mm to 60 mm.

28. The device of claim 1, wherein the device has a depth of 20mm to 50 mm.

29. The device of claim 1, wherein the device has a depth of 25mm to 45 mm.

30. The device of claim 1, wherein the predetermined spacing on the device is from 4mm to 12 mm.

31. The device of claim 1, wherein the predetermined spacing on the device is 4.5mm to 10 mm.

32. The device according to claim 1, wherein the preset spacing of 5mm to 12mm corresponds to a depth of 30mm to 50 mm.

33. The device of claim 1, wherein the predetermined spacing of 5.5mm to 10mm corresponds to a depth of 35mm to 45 mm.

34. The device according to claim 1, wherein the preset spacing of 3mm to 10mm corresponds to a depth of 20mm to 35 mm.

35. The device of claim 1, wherein the predetermined spacing of 4mm to 8mm corresponds to a depth of 25mm to 30 mm.

36. The apparatus of claim 1, wherein the draft tube has a width of 1mm to 3 mm.

37. The apparatus of claim 1, wherein the draft tube has a width of 1.3mm to 2 mm.

38. The apparatus of claim 1, wherein the draft tube has a width of 1.4mm to 1.9 mm.

39. The device of claim 1, wherein the draft tube has a wall thickness of 0.1mm to 0.6 mm.

40. The device of claim 1, wherein the draft tube has a wall thickness of 0.2mm to 0.4 mm.

41. The device of claim 1, wherein the draft tube has a wall thickness of 0.25mm to 0.3 mm.

42. The device of claim 1, wherein the device is an evaporator.

43. Air conditioning system for a motor vehicle, characterized in that it has at least one heat exchanger according to one of claims 1 to 42.