FR3064733A1 - EVAPORATOR FOR AIR CONDITIONING INSTALLATION - Google Patents

Abstract

The invention relates to an evaporator in which the fin overflow ratio (2 * EL) / TS is preferably comprised, in percentage, between 10% and 25% for an evaporator whose dimension (CS) of the fins measured according to the invention. alignment axis (X) is between 16 mm and 38 mm.

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number:

(to be used only for reproduction orders)

©) National registration number

064 733

52844

COURBEVOIE © Int Cl ⁸ : F28 F1 / 20 (2017.01)

PATENT INVENTION APPLICATION

A1

©) Date of filing: 03.04.17. © Applicant (s): VALEO THERMAL SYSTEMS (30) Priority: Simplified joint stock company - FR. @ Inventor (s): DE PELSEMAEKER GEORGES, RAGONDET DAMIEN, LEBLAY PATRICK and CHEVAL- (43) Date of public availability of the BIND CHRISTOPHE. request: 05.10.18 Bulletin 18/40. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): VALEO THERMAL SYSTEMS related: Joint stock company. ©) Extension request (s): © Agent (s): VALEO THERMAL SYSTEMS.

(34) EVAPORATOR FOR AIR CONDITIONING INSTALLATION.

The invention relates to an evaporator in which the fin overflow ratio (2 * EL) / TS is preferably comprised, in percentage, between 10% and 25% for an evaporator whose dimension (CS) of the fins measured along the alignment axis (X) is between 16 mm and 38 mm.

FR 3 064 733 - A1

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Evaporator for air conditioning system

The invention relates to an evaporator for a motor vehicle air conditioning installation.

US Pat. No. 4,998,580 discloses a condenser with tubes and fins.

The CO2 refrigerant, or also called R744, requires working at high pressure and with intense transport and heat transfer.

The present invention aims to provide an evaporator which is optimal for a refrigerant of this type, such as that R744.

The subject of the invention is therefore an evaporator for a motor vehicle air conditioning installation, this evaporator comprising:

- A plurality of tubes forming channels in which circulates a cooling fluid, these channels being aligned along an axis of alignment of the channels (X), these tubes being perpendicular to a transverse direction (D), o each channel having a height (Tr) measured along this transverse direction (D), o each tube having a height (Th) measured along this transverse direction, o each channel being separated from an external face of the tube by a thickness (Td) measured along this transverse direction , o the neighboring tubes are separated from each other by a pitch (Tp) measured in the transverse direction, the tube or tubes in a row along the alignment axis (X) extending over a distance (TS) measured according to this axis (X),

- at least one fin arranged in an air passage formed between two neighboring tubes, the fin projecting on either side of the row of tube (s) over a non-zero distance (EL) measured along the axis d alignment (X), evaporator in which the fin overflow ratio (2 * EL) / TS is preferably comprised, in percentage, between 10% and 25% for an evaporator whose dimension (CS) of the fins measured according to the alignment axis (X) is between 16 mm and 38 mm.

According to the invention, a coolant in the supercritical state, such as CO2 in particular, requires working under mechanical stresses at high pressures and taking into account high heat transfer properties. In this context, thanks to the invention, the tubes have smaller dimensions and the fins can be wider than the tube or tubes to improve the balance of heat transfer between the air and the refrigerant.

The invention also makes it possible to improve the protection against splashing water by forming drainage passages between the fins due to their overflow.

Thanks to calculations, it is shown that the parameter Power (in kW) per unit of mass (in kg) of the evaporator according to the invention is maximum, in the case of CO2 as refrigerant, when the total dimension added of the tubes and the inter-tube space is 26 mm, and the fin is 32 mm, all these dimensions being measured in the same direction.

According to an example of the invention, the fin overflow ratio (2 * EL) / TS is comprised, in percentage, between 12.5% and 25%.

According to an example of the invention, the fin overflow ratio (2 * EL) / TS is substantially equal to 22%.

According to an example of the invention, the pitch (Fp) of fins is between 1.2 and 1.5 mm, in particular 1.3 mm.

According to an example of the invention, the fins have a thickness of between 50 and 80 micrometers, in particular substantially equal to 70 micrometers.

According to an example of the invention, the tube height (Th) is between 1.25 and 1.65 mm, in particular substantially equal to 1.44 mm.

According to one aspect of the invention, the distance between the two manifolds is between 150 and 250 mm, in particular is substantially 190 mm.

According to one aspect of the invention, the distance H between the two manifolds is between 150 mm and 250 mm, being in particular 190 mm.

According to one aspect of the invention, the thickness of the fins is between 28 and 38 mm.

According to one aspect of the invention, the distance L between the two beam ends, measured parallel to the manifolds, is between 230 mm and 560 mm.

The number and dimensions of the tubes and channels are preferably a balance between the constraints of the extrusion process, the limitation of the pressure drop of the refrigerant flow and the mechanical strength.

According to one aspect of the invention, the tubes being made of a material with an anisotropy in particular greater than 0.6, the tubes being in particular produced by extrusion and brazed, each of the channels having in particular a cross section of elongated shape.

According to one aspect of the invention, the evaporator is arranged to be arranged on a low pressure line of an air conditioning system or installation.

The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of nonlimiting example with reference to the appended drawing in which:

- Figure 1 illustrates, schematically and partially, an evaporator according to an exemplary embodiment of the invention,

FIG. 2 illustrates, diagrammatically and partially, in section, a bundle of channels of the evaporator of FIG. 1,

- Figure 3 is a sectional view along the plane P of the tubes and fins of the evaporator of Figures 1 and 2,

FIG. 4 is a graph which diagrammatically illustrates the correlation between TS and the overflow parameter (2 * EL) / TS of the evaporator in FIG. 1,

- Figure 5 is a graph which schematically illustrates the correlation between the Power to mass ratio, and the depth of the fin.

FIG. 1 shows an evaporator 1 of an air conditioning installation with a transcritical operating cycle, which comprises a rotary compressor (not shown) driven, via a clutch, by a rotating element of the vehicle engine.

The coolant or coolant is a coolant in the supercritical state, such as CO2 in particular.

The evaporator 1 has two manifolds 2 arranged opposite. Between the manifolds 2 is disposed a bundle of heat exchange channels 4 intended to contain the refrigerant, and arranged parallel to each other. These channels 4 are formed in tubes 5.

Cooling fins 6 are arranged between the tubes 5.

Figure 2 is a cross-sectional view along the plane P of Figure 1, of channels 4 parallel to each other. The plane P is perpendicular to the tubes 5. The channels 4 of the tubes 5 are aligned along an axis X. This axis is in the plane P.

The tubes 5 are made of a material with an anisotropy in particular greater than 0.6.

The tubes 5 are produced by extrusion and brazed.

As shown in Figures 1 and 2, the evaporator 1 comprises:

- The plurality of flat tubes 5 forming the channels 4 in which the coolant circulates, these tubes 5 being perpendicular to a transverse direction D, o each channel 4 having a height Tr measured in this transverse direction D, o each flat tube 5 having a height Th measured in this transverse direction D, where each channel 4 is separated from an outer face 8 of the tube by a thickness Td measured in this transverse direction D, where the neighboring tubes 5 are separated from each other by a pitch Tp measured according to the transverse direction D,

- the fins 6 arranged in air passages formed between two neighboring tubes 5.

The tubes of a row along the alignment axis X extend over a distance TS measured along this axis X.

Each fin disposed in an air passage formed between two neighboring tubes, the fin projecting on either side of the row of tubes over a non-zero distance EL measured along the alignment axis X, as visible on the figure 3.

The fin overflow ratio (2 * EL) / TS is, in percentage, between 10% and 25% for an evaporator whose dimension CS of the fins measured along the alignment axis X is between 16 mm and 38 mm, as can be seen materialized by the large rectangle in Figure 4.

Thanks to calculations, the results of which are visible in FIG. 5, it is shown that the parameter (data on the ordinate) Power (in kW) per unit of mass (in kg) of the evaporator according to the invention is maximum, in the case of CO2 as a refrigerant, when the total added dimension of the tubes and the inter-tube space is 26 mm, and the fin is 32 mm (data on the abscissa), all these dimensions being measured according to the same direction.

In the example illustrated, the fin overflow ratio (2 * EL) / TS is substantially equal to 22%.

The pitch (Fp) of fins is between 1.2 and 1.5 mm, in particular 1.3 mm.

The fins have a thickness of between 50 and 80 micrometers, in particular substantially equal to 70 micrometers.

The tube height (Th) is between 1.25 and 1.65 mm, in particular substantially equal to 1.44 mm.

Claims (7)

1. Evaporator for a motor vehicle air conditioning installation, this evaporator comprising: - A plurality of tubes forming channels in which circulates a cooling fluid, these channels (4) being aligned along an axis of alignment of the channels (X), these tubes being perpendicular to a transverse direction (D), o each channel having a height (Tr) measured along this transverse direction (D), o each tube having a height (Th) measured along this transverse direction, o each channel being separated from an outer face of the tube by a thickness (Td) measured according to this transverse direction, where the neighboring tubes are separated from each other by a pitch (Tp) measured in the transverse direction, the tube or tubes of a row along the alignment axis (X) extending over a distance (TS ) measured along this axis (X), - at least one fin arranged in an air passage formed between two neighboring tubes, the fin projecting on either side of the row of tube (s) over a non-zero distance (EL) measured along the axis d alignment (X), evaporator in which the fin overflow ratio (2 * EL) / TS is preferably comprised, in percentage, between 10% and 25% for an evaporator whose dimension (CS) of the fins measured according to the alignment axis (X) is between 16 mm and 38 mm. 2. Evaporator according to the preceding claim, the fin overflow ratio (2 * EL) / TS being, in percentage, between 12.5% and 25%. 5 3. Evaporator according to claim 1 or 2, the fin overflow ratio (2 * EL) / TS being substantially equal to 22%. 4. Evaporator according to one of the preceding claims, the pitch (Fp) of fins being between 1.2 and 1.5 mm, in particular 1.3 mm. 5. Evaporator according to one of the preceding claims, the fins have a thickness between 50 and 80 micrometers, in particular substantially equal to 70 micrometers. 15 6. Evaporator according to one of the preceding claims, the tube height (Th) being between 1.25 and 1.65 mm, in particular substantially equal to 1.44 mm. 7. Evaporator according to one of the preceding claims, the 20 coolant is a coolant in the supercritical state, such as CO2 in particular. 1 /