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DE-102015209380-B4 - Air conditioning device for a motor vehicle

DE102015209380B4DE 102015209380 B4DE102015209380 B4DE 102015209380B4DE-102015209380-B4

Abstract

Air conditioning device for a motor vehicle, comprising an evaporator (10) designed as an air/refrigerant heat exchanger, which is internally permeable with refrigerant and externally with an airflow (14) of a predetermined airflow rate, comprising two evaporator sections (11, 12) arranged adjacent to one another and sequentially permeable by the same airflow (14), each having a plurality of horizontally extending, parallel fins (24, 26) around which the airflow can flow and which are arranged at a distance (Δ) from one another which, measured in the direction of the airflow, is 10 mm to 30 mm, preferably 10 mm to 20 mm, particularly preferably 12 mm to 17 mm, wherein in the free space (16) resulting from the distance (Δ) between the evaporator sections (11, 12) a frame-shaped or partial frame-shaped element connecting the evaporator sections (11, 12) at their edges is located. An insulating layer (18) made of a metal foam with a thermal conductivity of less than 200 W/(m*K) is arranged.

Inventors

  • Jan-Christoph Albrecht
  • Cartsten Wachsmuth

Assignees

  • VOLKSWAGEN AKTIENGESELLSCHAFT

Dates

Publication Date
20260513
Application Date
20150521

Claims (10)

  1. Air conditioning device for a motor vehicle, comprising an evaporator (10) designed as an air/refrigerant heat exchanger, which is internally permeable with refrigerant and externally with an airflow (14) of a predetermined airflow rate, comprising two evaporator sections (11, 12) arranged adjacent to one another and sequentially permeable by the same airflow (14), each having a plurality of horizontally extending, parallel fins (24, 26) around which the airflow can flow and which are arranged at a distance (Δ) from one another which, measured in the direction of the airflow, is 10 mm to 30 mm, preferably 10 mm to 20 mm, particularly preferably 12 mm to 17 mm, wherein in the free space (16) resulting from the distance (Δ) between the evaporator sections (11, 12) a frame-shaped or partial frame-shaped element connecting the evaporator sections (11, 12) at their edges is located. An insulating layer (18) made of a metal foam with a thermal conductivity of less than 200 W/(m*K) is arranged.
  2. Air conditioning device according to one of the preceding claims, characterized in that in the free space (16) resulting from the distance (Δ) between the evaporator sections (11, 12) the evaporator sections (11, 12) are arranged ribs (20) connecting them at points.
  3. air conditioning device according to Claim 2 , characterized in that the webs (20) are made of a rigid plastic material with a thermal conductivity of less than 200 W/(m*K).
  4. Air conditioning device according to one of the preceding claims, characterized in that a grid or mesh (22) is arranged in the free space (16) between the evaporator sections (11, 12) resulting from the distance (Δ).
  5. Air conditioning device according to one of the preceding claims, characterized in that the louvers (24) of the airflow inlet-side evaporator section (11) each have a first louver section (241) aligned parallel to the airflow direction and arranged on the airflow inlet side and a second louver section (242) angled downwards and arranged on the airflow outlet side.
  6. Air conditioning device according to one of the preceding claims, characterized in that the fins of at least one evaporator section in their horizontal extent The tung runs parallel to the respective evaporator section in a sinusoidal wave pattern.
  7. Air conditioning device according to one of the preceding claims, characterized in that the distance between the fins (24) of the airflow inlet side evaporator section (11) is smaller than the distance between the fins (26) of the airflow outlet side evaporator section (12).
  8. Air conditioning device according to one of the preceding claims, characterized in that the louvers (24) of at least one evaporator section (11) have vertical openings (243) with air guide vanes (244) inclined to the respective louver plane.
  9. air conditioning device according to Claim 8 , characterized in that the air guide vanes (244) have an angle of attack of 20° to 40°, preferably 25° to 35°, particularly preferably 28° to 32°.
  10. Air conditioning device according to one of the preceding claims, characterized in that the evaporator sections (11, 12) are connected in series in terms of refrigerant technology.

Description

The invention relates to an air conditioning device for a motor vehicle. Central subject of the DE 10 2014 207 278 A1 This is an air conditioning device for motor vehicles with a two-part evaporator. The two-part evaporator has two evaporator sections connected in series on the air side. This means that both evaporator sections are successively traversed by the same airflow, which is thereby cooled and dehumidified before being blown into the passenger compartment of the vehicle as the air conditioning airflow. The special feature of the air conditioning device disclosed in the aforementioned publication is that the evaporator section on the airflow outlet side operates at temperatures below 0°C, while the evaporator section on the airflow inlet side operates at temperatures above 0°C. As a result, the airflow undergoes pre-cooling as it passes through the airflow inlet-side evaporator section, hereinafter referred to as the first evaporator section, which is associated with significant dehumidification. As the airflow passes through the evaporator section on the outlet side, referred to below as the second evaporator section, it experiences a further, significant cooling below the freezing point of water. However, the risk of ice formation on the second evaporator section is considerably reduced by the dehumidification that occurred previously in the first evaporator section. This leads to a considerable delay in the inevitable clogging of the second evaporator section with ice. Consequently, the number and frequency of so-called defrosting intervals, during which the second evaporator section is operated at temperatures above 0°C, resulting in temporary discomfort in the passenger compartment, can be significantly reduced compared to air conditioning systems with only one evaporator section. Especially at high humidity, dehumidification in the first evaporator section is associated with the formation of considerable amounts of condensation. If this liquid water were to come into contact with the surface of the second evaporator section, which has cooled below 0°C, it would freeze there, quickly leading to clogging of the second evaporator section. Three pathways for water transport from the first to the second evaporator section are of practical importance: firstly, large droplets running down the back of the first evaporator section can contact the front of the second evaporator section. Secondly, it is conceivable that running water could accumulate in an open channel or tray between the two evaporator sections. Finally, there is a risk that water droplets on the first evaporator section will be carried by the airflow to the second evaporator section. This can, of course, be prevented by establishing a significant distance between the first and second evaporator sections. This approach is used, for example, in the DE 697 29 836 T2 This has been implemented. However, given the notoriously critical space constraints in automotive engineering, this is not a suitable solution. The WO 2007/ 037 670 A1 and the US 2014/ 0 262 181 A1 The air-side heat exchanger sections are connected in series and are mechanically and thermally linked by common fins extending from the air-inlet front surface of the first heat exchanger section to the air-outlet rear surface of the second heat exchanger section. This thermal coupling prevents the effective implementation of the pre-dehumidification and subsequent extreme cooling concept described above, even if such a heat exchanger were used as an evaporator. Furthermore, the transport of condensate from the first to the second heat exchanger section is not prevented, as the water can flow across the fins from one section to the other. A similar situation exists with the... DE 600 31 932 T2 . From the DE 10 2007 056 473 A1 A known evaporator is one connected to a thermal storage unit and designed as an air/refrigerant heat exchanger. A similar aspect is found in the DE 10 2006 011 327 A1 addressed. The US 2012/ 0 103 582 A1 The diagram reveals a heat exchanger with two vertical tubes, between which horizontal transverse tubes extend, between which in turn microstructured fins are arranged to optimize heat transfer between a fluid flowing in the transverse tubes and air flowing perpendicularly through the heat exchanger. A similar concept, which includes different microstructures, is found in the US 2009/ 0 308 585 A1 revealed. From the US 2014/ 0 144 605 A1 A heat exchanger is known which is arranged in a housing and sealed by means of a specially shaped gasket. Similar aspects are found in the DE 102 42 899 A1 addressed. The DE 690 19 633 T2 Disclosing a condenser for use in a motor vehicle air conditioning system, the condenser comprises two condenser sections arranged one behind the other in the direction of airflow and sequentially traversed by the same airflow, spaced approximately 10 mm apart in the direction of airflow. The icing problem described above does not occur wi