HEAT EXCHANGER, IN PARTICULAR A HEATING ELEMENT FOR MOTOR VEHICLES
A heat exchanger, in particular a heating element for motor vehicles, is provided that includes a block that has flat tubes and corrugated fins and a collecting tank on the inlet side and on the outlet side, wherein the flat tubes comprise flat sides having embossed vortex generators, and a coolant can flow through the flat tubes. The flat tubes can have an inner diameter in the range of 0.9 to 1.2 mm, preferably of 1.0 mm, and the corrugated fins can have a height in the range of 6.3 to 8.0 mm, preferably of 8.3 mm.
This nonprovisional application is a continuation of International Application No. PCT/EP2010/051232, which was filed on Feb. 2, 2010, and which claims priority to German Patent Application No. DE 10 2009 007 619, which was filed in Germany on Feb. 5, 2009, and which are both herein incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The invention relates to a heat exchanger, in particular a heater core for motor vehicles.
2. Description of the Background Art
Document EP 0 710 811 B1, which corresponds to U.S. Pat. No. 5,564,497, made known a heat exchanger that is used as a heater core of an air conditioning system for motor vehicles. The known heater core comprises a block formed of flat tubes and corrugated fins, and a collecting tank on the inlet side and on the outlet side for the inflow and outflow of coolant of a cooling circuit of an internal combustion engine. Coolant flows through the flat tubes of the heater core in only one direction. The coolant is therefore not redirected along the width or the depth. The heater core is optimized such that the same amount of heat is output, to the greatest extent possible, when coolant throughput through the heater core is low, e.g. when the internal combustion engine idles, and when coolant throughput rates are higher. The flat tubes of the heater core block have an inner diameter of 0.6 to 1.2 mm, and the corrugated fins between the flat tubes have a height of 3 to 6 mm; this corresponds to a ratio of corrugated fin height to inner tube diameter of 5.0.
Document DE 101 27 084 A1, which corresponds to U.S. Pat. No. 6,892,806, and which is incorporated herein by reference discloses a single-row flat tube and a heat exchanger comprising corrugated fins for motor vehicles, wherein a coolant of a cooling circuit of an internal combustion engine flows through the flat tubes. To increase the heat transfer on the coolant side, longitudinal vortex generators arranged in the shape of a “V” are formed in the flat sides of the flat tubes. The vortex generators are arranged in rows transverse to the flow direction of the coolant, and are inclined at an angle of approximately 20° relative to the flow direction. The vortex generators have a height which extends into the flow cross-section of the flat tubes and is in the range of 5 to 40% of the width of the flat tubes.
The known heat exchangers often have a low output/weight ratio, i.e. the weight of the heat exchanger is relatively high compared to the output thereof. This is due to the fact that greater output is obtained using more weight: For example, if the number of tubes of the heat exchanger is increased (reduction of lateral distribution), greater output is obtained since the heat-dissipating surface is greater, but the heat exchanger becomes heavier. Increasing the depth of the heat exchanger also has an unfavorable effect on the output/weight ratio.
SUMMARY OF THE INVENTIONIt is therefore an objection of the present invention to provide a heat exchanger that has the highest possible output/weight ratio, i.e. a high ratio of output of the heat exchanger to the weight thereof. A further problem addressed by the invention is that of ensuring that the heat exchanger has a low pressure drop on the air side and on the coolant side, in particular a favorable ratio of air-side pressure drop to coolant-side pressure drop. Finally, it should be possible to manufacture the heat exchanger at low cost and using a reliable process. The problem addressed by the invention is therefore also that of reducing the fuel consumption of the motor vehicle (reducing the blower and coolant pump output that is taken up).
According to an embodiment of the invention, the flat tube has an inner diameter L in the range of 0.9 to 1.2 mm, preferably 1.0 mm, and the corrugated fins have a height H in the range of 6.3 to 8.0 mm, preferably 6.3 mm. Preferably, the ratio of corrugated fin height H to inner diameter L is in a range of 5 to 9, in particular in a range of 6.3 to 7.2. The advantage of a high output/weight ratio is therefore obtained, in combination with a low pressure drop of the heat exchanger on the air side and on the coolant side. Due to the high output/weight ratio, material for the heat exchanger is saved, thereby making it possible to lower the manufacturing costs.
According to an embodiment, the flat tubes comprise vortex generators which extend inwardly into the flow cross-section of the flat tubes, are longitudinal, and are arranged in the shape of a “V” in rows transversely to the flow direction of the coolant. The vortex generators have been optimized in respect of their dimensions (length, width, depth), their number, and their inclination angle relative to the coolant flow in respect to the coolant-side pressure drop and heat transfer. Due to the vortex generators which have been dimensioned according to the invention, the output can therefore be increased while maintaining a justifiable coolant-side pressure drop.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:
According to an embodiment, vortex generators 7, 8 have the following dimensions: depth W (see
In an embodiment, vortex generators 7, 8 can have the following dimensions: W1=2.5 mm; W2=1.25 mm; W=0.25 mm; α=20°; WA=6.
Dimensions of the flat tube can be: L=1.0 mm and T=26 mm.
With consideration for the two ratios Q100/(dp1·dp2) and Q100/dp2 (see
The aforementioned diagrams and the associated explanations show that the heater core according to the invention has a high output/weight ratio, thereby combining low material usage and low material costs. The heater core according to the invention is also highly efficient. The low air-side pressure drop results in low blower output and, therefore, lower current uptake, thereby reducing fuel costs. The low coolant-side pressure drop results in a lower current uptake of the coolant pump in the cooling circuit and, therefore, higher output of the internal combustion engine.
Further dimensions of a preferred embodiment are: Fin density, i.e. the number of fins per dm (decimeter=10 cm), is in a range of 85 to 105 fins/dm. The material thickness of the flat tubes is in a range of stube0.15 to 0.3 mm, in particular 0.20 mm. The material thickness of the corrugated fins is in a range of sfin=0.06 to 0.10 mm, in particular in a range of 0.07 to 0.08 mm.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.
Claims
1. A heat exchanger comprising:
- a block having flat tubes and corrugated fins;
- a collecting tank arranged on an inlet side and on an outlet side,
- wherein the flat tubes comprise flat sides having embossed vortex generators, the flat tubes being configured such that a coolant flows there through, and
- wherein the flat tubes have an inner diameter in a range of 0.9 to 1.2 mm, and the corrugated fins have a height in a range of 6.3 to 8.0 mm.
2. The heat exchanger according to claim 1, wherein the ratio of the corrugated fin height to inner diameter of the flat tubes is in a range of 5 to 9 or in a range of 6.3 to 7.2 mm.
3. The heat exchanger according to claim 1, wherein the flat tube is configured as a folded tube having two chambers partitioned off by a fold.
4. The heat exchanger according to claim 1, wherein the flat tube has a depth in a range of 15 to 35 mm, preferably 26 mm.
5. The heat exchanger according to claim 1, wherein the vortex generators are longitudinal and have a length in a range of 1.5 to 4.0 mm, preferably 2.5 mm.
6. The heat exchanger according to claim 1, wherein the vortex generators have a width in a range of 1.0 to 2.5 mm, in particular 1.25 mm.
7. The heat exchanger according to claim 1, wherein the vortex generators have a depth in a range of 0.15 to 0.35 mm, in particular 0.25 mm.
8. The heat exchanger according to claim 1, wherein the vortex generators have a longitudinal axis, and the longitudinal axis forms an inclination angle with the flow direction in the flat tube in a range of 15 to 25°, in particular 20°.
9. The heat exchanger according to claim 1, wherein the vortex generators are arranged in rows transversely to the flow direction in the flat tube, and wherein a plurality of vortex generators in the range of 4 to 10, in particular 6 vortex generators are provided in one row of the flat tube.
10. The heat exchanger according to claim 1, wherein a density of the corrugated fins is in a range of 85 to 105 fins/dm.
11. The heat exchanger according to claim 1, wherein a material thickness of the flat tubes is in a range of 0.15 to 0.3 mm, in particular 0.20 mm.
12. The heat exchanger according to claim 1, wherein a material thickness of the corrugated fins is in a range of 0.06 to 0.10 mm, in particular in a range of 0.07 to 0.08 mm.
13. The heat exchanger according to claim 1, wherein the heat exchanger is a heater core for a motor vehicle.
14. The heat exchanger according to claim 1, wherein the inner diameter of the flat tubes is 1.0 mm, and wherein the height of the corrugated fins is 6.3 mm.
Type: Application
Filed: Aug 5, 2011
Publication Date: Feb 2, 2012
Inventors: Michael KOHL (Bietigheim), Ying Fu (Stuttgart)
Application Number: 13/204,100
International Classification: F28F 9/02 (20060101);