U.S. patent application number 14/403696 was filed with the patent office on 2015-04-09 for spacer for a heat exchanger and associated heat exchanger.
The applicant listed for this patent is Valeo Systemes Thermiques. Invention is credited to Badr Alouane, Isabelle Citti, Christian Riondet.
Application Number | 20150096726 14/403696 |
Document ID | / |
Family ID | 48483064 |
Filed Date | 2015-04-09 |
United States Patent
Application |
20150096726 |
Kind Code |
A1 |
Citti; Isabelle ; et
al. |
April 9, 2015 |
Spacer For A Heat Exchanger And Associated Heat Exchanger
Abstract
A spacer (7) for an air heater comprises a predefined number of
planar walls (13; 113) that are substantially parallel and are
connected two-by-two by folds (15). The planar walls (13; 113)
include a plurality of louvers (17.sub.1, 17.sub.2) that are
substantially inclined relative to the general plane (P) defined by
the planar wall (13; 113). The planar wall (13; 113) further
includes at least one strap (19; 119.sub.1, 119.sub.2, 119.sub.3,
119.sub.4) having longitudinal sides (21) that extend parallel to
the planar wall (13; 113) and lateral sides (23) that are linked to
the planar wall (13; 113) by means of at least one connecting rail
(24). An air heater comprises a heat exchange bundle comprising a
stack of parallel tubes (5) for the circulation of the fluid, the
tubes having the width (l.sub.1) of a tube, and a plurality of such
spacers (7) disposed respectively between two tubes (5).
Inventors: |
Citti; Isabelle; (Rosnay,
FR) ; Riondet; Christian; (Bourgogne, FR) ;
Alouane; Badr; (Reims, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Valeo Systemes Thermiques |
Le Mesnil Saint Denis |
|
FR |
|
|
Family ID: |
48483064 |
Appl. No.: |
14/403696 |
Filed: |
May 21, 2013 |
PCT Filed: |
May 21, 2013 |
PCT NO: |
PCT/EP2013/060359 |
371 Date: |
November 25, 2014 |
Current U.S.
Class: |
165/151 |
Current CPC
Class: |
F28F 1/128 20130101;
F28F 1/12 20130101; F28D 1/0233 20130101; F28D 1/053 20130101 |
Class at
Publication: |
165/151 |
International
Class: |
F28D 1/02 20060101
F28D001/02; F28D 1/053 20060101 F28D001/053; F28F 1/12 20060101
F28F001/12 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2012 |
FR |
1254852 |
Claims
1. A spacer for an air heater, the spacer comprising a predefined
number of planar walls that are substantially parallel and are
connected two-by-two by folds, the planar walls including a
plurality of louvers that are substantially inclined relative to
the general plane (P) defined by a planar wall, wherein at least
one of the planar walls further includes at least one strap having
longitudinal sides that extend parallel to the planar wall and
lateral sides that are linked to the planar wall by means of at
least one connecting rail.
2. The spacer as claimed in claim 1, in which one planar wall has a
substantially rectangular general form and the longitudinal sides
of one strap extend in the direction of the height (h') of the
planar wall.
3. The spacer as claimed in claim 2, in which one strap extends for
a distance in the order of at least 75% of the height (h') of the
planar wall.
4. The spacer as claimed in claim 1, in which one strap has a
substantially strip-shaped general form defining a plane
substantially parallel to the plane (P) defined by the planar
wall.
5. The spacer as claimed in claim 1, in which at least one strap is
arranged at one extremity of the planar wall intended to be
oriented facing towards the inlet of a gas stream (F) in the air
heater.
6. The spacer as claimed in claim 1, in which one planar wall
includes at least two straps facing in two opposite directions.
7. The spacer as claimed in claim 1, in which one planar wall
includes at least two straps arranged in a symmetrical manner on
two opposite extremities of the planar wall.
8. The spacer as claimed in claim 1, in which the louvers are
arranged on a substantially central part of a planar wall.
9. The spacer as claimed in claim 1, formed from a metallic
material and in which one strap is produced by cutting and folding
of the metallic material.
10. The spacer as claimed in claim 1, in which the planar walls
respectively include at least two groups of louvers having a
respective orientation, the louvers of one group being
substantially identical.
11. The spacer as claimed in claim 1, having a substantially
corrugated general form, the planar walls being connected
two-by-two by folds in such a way as to form alternate
corrugations.
12. An air heater in which there circulates a fluid for a thermal
exchange with a gas stream (F), the heater comprising a heat
exchange bundle having substantially parallelepipedic general form
and comprising: a stack of parallel tubes for the circulation of
the fluid, the tubes having the width (l.sub.1) of a tube, and a
plurality of spacers disposed respectively between two tubes so as
to be traversed by the gas stream (F), such that the spacers have a
width of a spacer (l.sub.2) greater than the width of a tube
(l.sub.1) in such a way as to extend beyond the tubes, and
respectively comprise a predefined number of planar walls connected
two-by-two by folds, the planar walls including a plurality of
louvers substantially inclined relative to the plane (P) defined by
the planar walls, wherein at least one of the planar walls further
includes at least one strap: having longitudinal sides that extend
parallel to the planar wall and lateral sides linked to the planar
wall by means of at least one connecting rail, and arranged on the
upstream extremity of the planar wall that is oriented facing
towards the inlet of the gas stream (F).
Description
[0001] The invention belongs to the field of ventilation, heating
and/or air conditioning systems for an electric or hybrid
automobile.
[0002] The invention has as its object a spacer for an air heater
interacting with such an installation and an associated air
heater.
[0003] An electric or hybrid automobile, of which the propulsion is
provided at least partially by an electric motor, is commonly
equipped with a system of ventilation, heating and/or air
conditioning for the purpose of modifying the aerothermic
parameters of the air in the interior of the passenger compartment
of the vehicle by delivering a flow of conditioned air to the
interior of the passenger compartment.
[0004] Such a conditioning system may be used, for example, during
the summer in order to meet a need for cooling of the passenger
compartment, but also during the winter, for example, in order to
meet a need for heating of the passenger compartment.
[0005] Generally, the conditioning system includes at least one air
heater that is capable of operating in condenser mode or in
evaporator mode, depending on the needs.
[0006] The air heater generally includes a bundle of, for example,
corrugated tubes and spacers, also referred to as corrugated fins,
arranged between the tubes of the bundle and attached to these
tubes, usually by brazing, by their respective folds.
[0007] The bundle of tubes is usually swept by a gas stream such as
a flow of air which will exchange heat with another fluid, usually
a heat transfer medium, that is circulating inside the tubes of the
bundle.
[0008] The corrugated spacers are generally formed from a metal
strip and comprise an assembly of planar walls, connected
two-by-two by folds in order to form alternate corrugations.
[0009] Already familiar are spacers in which each of the planar
walls is equipped with a plurality of inclined louvers that are
produced by cutting and forming the strip. The principal function
of the louvers that are included in the corrugated spacers is to
improve the thermal exchange by the active, thorough mixing of the
flow of air which sweeps the bundle, by so doing forcing a flow of
air through the louvers.
[0010] Furthermore, such an air heater may be capable of operating
in evaporator or condenser mode and is arranged, for example, at
the level of the front surface of the vehicle for a thermal
exchange between the fluid and a flow of outside air to the
vehicle.
[0011] In particular, in order to meet the needs for heating, a
known solution is to use the conditioning system in heat pump
mode.
[0012] In this case, the external air heater operates in evaporator
mode.
[0013] The disadvantage of such a solution when it is implemented
in winter conditions is the risk of icing of the external air
heater when operating in evaporator mode as a result of the
condensation of the water vapor in the air and its cooling in
contact with the walls. In particular, the spacers in the interior
of the air heater may become iced up.
[0014] This has the effect of reducing significantly the thermal
exchanges within this air heater, and, as a consequence, the output
and the efficiency of the conditioning system.
[0015] Already familiar from the prior art is a solution which
involves the use of the air heater in condenser mode. In order to
do this, the conditioning system is generally used in air
conditioning mode. The air heater in condenser mode is accordingly
traversed by hot gases, which permits the deicing.
[0016] However, this solution also does nothing in terms of
suppressing the retention of water in the spacers, so that, on each
occasion when the buckle is used in heat pump mode air/air, the
phenomenon may recur more frequently and more rapidly.
[0017] A spacer that is capable of being wider than the tubes and
of which the upstream part, that is to say the part oriented
towards the flow of air, lacks louvers, has been proposed according
to a solution that is familiar from the prior art. Conversely, the
downstream part of the spacer, that is to say the opposite part
relative to the air inlet, has louvers. This makes it possible to
limit the exchange with the air on the upstream part of the spacer
due to the absence of a louver and, therefore, to control the
icing.
[0018] The disadvantage of such a solution is to reduce the thermal
exchange due to the absence of louvers over a large width of the
spacer, resulting in a reduction in the efficiency.
[0019] According to another known solution, the spacer is likewise
wider than the tube and has an assembly of small louvers, rather
than a single full louver, over the entire height of the spacer on
the upstream and downstream parts of the spacer.
[0020] A major disadvantage is that the water formed during the
first deicing may stagnate between two folds in the upstream part
of the spacer and increases the risk of accumulation of ice
upstream of the exchanger.
[0021] The object of the invention is therefore to overcome at
least partially these disadvantages of the prior art by proposing a
spacer making it easier to control the formation of ice and to
facilitate the flow of the condensate during deicing.
[0022] To this effect, the object of the invention is a spacer for
an air heater, said spacer comprising a predefined number of planar
walls that are substantially parallel and are connected two-by-two
by folds, the planar walls including a plurality of louvers that
are substantially inclined relative to the general plane defined by
a planar wall, characterized in that a planar wall further includes
at least one strap having longitudinal sides that extend parallel
to the planar wall and lateral sides that are linked to the planar
wall by means of at least one connecting rail.
[0023] With such a strap, the retention of water is reduced and the
condensates flow more freely during deicing.
[0024] Said spacer may further include one or a plurality of the
following characterizing features, either individually or in
combination: [0025] one planar wall has a substantially rectangular
general form, and the longitudinal sides of one strap extend in the
direction of the height of the planar wall, [0026] one strap
extends for a distance in the order of at least 75% of the height
of the planar wall, [0027] one strap has a substantially
strip-shaped general form defining a plane substantially parallel
to the plane defined by the planar wall, [0028] at least one strap
is arranged at one extremity of the planar wall intended to be
oriented facing towards the inlet of a gas stream in the air
heater, [0029] one planar wall includes at least two straps facing
in two opposite directions, [0030] one planar wall includes at
least two straps arranged in a symmetrical manner on two opposite
extremities of the planar wall, [0031] said louvers are arranged on
a substantially central part of a planar wall, [0032] said spacer
is formed from a metallic material and one strap is produced by
cutting and folding of the metallic material, [0033] the planar
walls respectively include at least two groups of louvers having a
respective orientation, the louvers of one group being
substantially identical, [0034] said spacer has a substantially
corrugated general form, the planar walls being connected
two-by-two by folds in such a way as to form alternate
corrugations.
[0035] The invention likewise relates to an air heater in which
there circulates a fluid for a thermal exchange with a gas stream,
said heater comprising a heat exchange bundle having a
substantially parallelepipedic general form and comprising: [0036]
a stack of parallel tubes for the circulation of the fluid, the
tubes having the width of a tube, and [0037] a plurality of spacers
disposed respectively between two tubes so as to be traversed by
the gas stream, such that the spacers have a width of a spacer
greater than the width of a tube, in such a way as to extend beyond
the tubes, and respectively comprise a predefined number of planar
walls connected two-by-two by folds, the planar walls including a
plurality of louvers that are substantially inclined relative to
the plane defined by the planar walls, characterized in that a
planar wall further includes at least one strap having longitudinal
sides that extend parallel to the planar wall and lateral sides
linked to the planar wall by means of at least one connecting rail,
and arranged on the upstream extremity of the planar wall that is
oriented facing towards the inlet of the gas stream.
[0038] Other characterizing features and advantages of the
invention will emerge more clearly from a perusal of the following
description, which is provided by way of illustrative and
non-restrictive example, and of the accompanying drawings, in
which:
[0039] FIG. 1 is a frontal view of an air heater in particular for
an automobile,
[0040] FIG. 2a is a perspective view of a part of a spacer and of
two adjacent tubes of the air heater in FIG. 1 according to a first
variant,
[0041] FIG. 2b is a partial side view of the spacer and of the two
adjacent tubes in FIG. 2a,
[0042] FIG. 2c is a sectional view of the spacer in FIGS. 2a and
2b,
[0043] FIG. 3 depicts a graph illustrating the results of tests on
a spacer with or without a strap, showing the retention of water
over time during a first phase A of immersion of a sample of a
spacer in water, and the evolution of the flow of the water during
a second phase B of removal of the sample from the water,
[0044] FIG. 4a is a partial side view of a spacer and of two
adjacent tubes of the air heater according to a second variant,
[0045] FIG. 4b is a sectional view of adjacent spacers in FIG.
4a,
[0046] FIG. 5a is a partial side view of a spacer and of two
adjacent tubes of the air heater according to a third variant,
and
[0047] FIG. 5b is a sectional view of adjacent spacers in FIG.
5a.
[0048] In these figures, the substantially identical elements bear
the same references.
[0049] An air heater 1, in particular for an automobile, is
depicted in a schematic manner in FIG. 1. In particular, such a
heater may be intended for use in a hybrid and/or electric
vehicle.
[0050] For example, this can be an external air heater of a
conditioning system for heating or cooling the passenger
compartment of the vehicle.
[0051] Such an external air heater is able to permit an exchange of
calories between a fluid, in particular a heat transfer medium, and
a gas stream as a flow of outside air.
[0052] The heat transfer medium is by way of example a refrigerant,
such as tetrafluoroethane, known as R134a, carbon dioxide CO.sub.2,
or even tetrafluoropropene, known as HFO-1234yf.
[0053] Generally, an external air heater is installed on the front
surface of the vehicle in such a way as to benefit from a dynamic
air flow, in the form of a flow of outside air, when the vehicle is
in motion.
[0054] The external air heater is capable of functioning as a
condenser or as an evaporator, according to various modes of
operation of the conditioning system.
[0055] In particular the external air heater may be used as a
condenser in an air conditioning mode in order to cool the
passenger compartment of the vehicle, and in evaporator in a heat
pump mode in order to heat the passenger compartment. In evaporator
mode, the external air heater makes it possible to extract calories
in the form of heat from the flow of outside air. In condenser
mode, the fluid releases heat to the flow of outside air passing
through the external air heater.
[0056] Provision may also be made to operate the external air
heater in condenser mode in an air conditioning mode in order to
permit deicing of this external air heater.
[0057] In fact, when the external air heater has a temperature that
is lower than that of the outdoor air, or even negative, the
humidity of the outdoor air condenses and freezes on this external
air heater. This is the case in particular when the external air
heater is used as an evaporator when the conditioning system is
being operated in heat pump mode.
[0058] The air heater 1 includes a heat exchange bundle 3.
[0059] The bundle 3 has a substantially parallelepipedic general
form with a length L, a height h, and a width in the perpendicular
direction in FIG. 1.
[0060] The bundle 3 comprises:
[0061] a stack of parallel tubes 5 and spacers 7 disposed between
two tubes 5, and
[0062] two collector boxes 9, 11 for the fluid, namely one inlet
box 9 and one outlet box 11.
[0063] The tubes 5 respectively have at least one channel for
circulation of the fluid.
[0064] The tubes 5 are, for example, substantially longitudinal
flat tubes, of which the length extends parallel to the length L of
the bundle 3 (see FIG. 1).
[0065] Moreover, the tubes 5 discharge respectively via their
opposite longitudinal extremities into the collector boxes 9 and
11. This permits the introduction of the fluid into the bundle 3
via the inlet box 9 and the removal of the fluid via the outlet box
11. These inlet collector boxes 9 and outlet collector boxes 11 are
associated with a circuit for the fluid in which the heater 1 is
installed.
[0066] The tubes 5 have a tube width or initial width l.sub.1 (see
FIGS. 2a, 2b) parallel to the direction of the width of the bundle
3.
[0067] The tubes 5 and the spacers 7 are metallic, for example. By
way of example, provision may be made for tubes 5 and spacers 7
that are made from an aluminum alloy.
[0068] In particular, the spacers 7 may be formed from a metal
strip, for example, from an aluminum alloy.
[0069] The tubes 5 and the spacers 7 may be brazed together.
[0070] The spacers 7 are interposed between the tubes 5 for
circulation of the fluid in order to improve the thermal exchange
between the gas stream F (see FIG. 2b), such as the flow of outside
air, and the fluid.
[0071] In fact, these spacers 7 disrupt the flow of the gas stream
F and increase the thermal exchange surface between the fluid and
the gas stream F.
[0072] The spacers 7 have a length extending parallel to the length
L of the bundle 3.
[0073] The spacers 7 also have the width of a spacer or a second
width l.sub.2 parallel to the width l.sub.2 of the tubes 5 and to
the width of the bundle 3. This second width l.sub.2 is greater
than the first width l.sub.2, so that the spacers 7 extend beyond
the tubes 5.
[0074] In addition, the spacers 7 have a height h' which defines
the distance between two adjacent tubes 5.
[0075] The spacers 7 have, for example, a substantially corrugated
general form. These are also referred to as spacers 7 folded in a
concertina-like manner.
[0076] With reference to FIGS. 1 and 2a, a spacer 7 comprises a
predefined number of planar walls 13.
[0077] The planar walls 13 are substantially rectangular with a
height h' corresponding to the height h' of the spacer 7.
[0078] These planar walls 13 are substantially parallel and are
connected two-by-two by folds 15.
[0079] In the case of a corrugated spacer 7, as in the example
illustrated here, the folds 15 are substantially rounded and the
planar walls 13 are connected two-by-two by folds 15 in such a way
as to form alternate corrugations.
[0080] The spacers 7 may be secured to the tubes 5 by their
respective folds, for example by brazing.
[0081] In addition, the planar walls 13 include a plurality of
louvers 17.sub.1, 17.sub.2 that are substantially inclined relative
to the general plane P defined by the planar walls 13 (see FIGS. 2a
and 2b).
[0082] These louvers 17.sub.1, 17.sub.2 respectively have a
substantially blade-shaped general form.
[0083] The louvers 17.sub.1, 17.sub.2 may be produced by cutting
and folding the metallic material of the spacer 7.
[0084] These louvers 17.sub.1, 17.sub.2 are, for example, arranged
on a substantially central part of the planar wall 13. The louvers
17.sub.1, 17.sub.2 may also be disposed at right angles to the tube
5.
[0085] Provision may be made for two groups of louvers: a first
group of louvers 17.sub.1 and a second group of louvers 17.sub.2.
The louvers of the same group may be substantially identical.
[0086] Each group of louvers 17.sub.1, 17.sub.2 may have its own
respective orientation. According to the example illustrated here,
the louvers 17.sub.1 of the first group are oriented, for example,
towards the upstream part of the planar wall 13, whereas the
louvers 17.sub.2 of the second group are oriented towards the
downstream part of the planar wall 13.
[0087] According to the embodiment described here, once the spacer
7 has been assembled in the air heater 1, the upstream part of the
plane 13 is oriented facing towards the inlet for the gas stream F,
and the downstream part of the planar wall 13 is thus opposite the
inlet for the gas stream F.
[0088] Moreover, these louvers 17.sub.1, 17.sub.2 may extend for
the entire height h' of the planar wall 13.
[0089] The louvers 17.sub.1, 17.sub.2 therefore define openings
according to a given angle of opening, through which the gas stream
F passes, which increases the thermal exchange surface.
[0090] Furthermore, in addition to these louvers 17.sub.1,
17.sub.2, a planar wall 13 further includes at least one strap
19.
[0091] Such a strap 19 is produced, for example, by cutting and
folding the metallic material of the spacer 7.
[0092] Once formed, for example, the strap 19 is offset relative to
the plane P defined by the planar wall 13.
[0093] Such an offset d, or "offset" in English, is more clearly
visible in FIG. 2c. A sinking of material forming the strap 19
relative to the general plane P defined by the planar wall 13 can
be noted, in fact. According to the example illustrated here, this
sinking takes place in a manner perpendicular to the general plane
P defined by the planar wall 13.
[0094] This offset d may be at least in the order of 0.1 mm. By way
of example, provision may be made for an offset d in the order of
0.4 to 0.5 mm.
[0095] This strap 19 is arranged, for example, on at least one
extremity of the planar wall 13. According to the example
illustrated here, the planar wall 13 is substantially rectangular
and the strap 19 is produced on one longitudinal extremity of the
planar wall 13.
[0096] More precisely, the strap 19 is produced on one upstream
extremity of the planar wall 13 intended to be oriented facing
towards the inlet for the gas stream F during assembly of the air
heater 1.
[0097] This arrangement of the strap 19 at the level of the inlet
for the gas stream F into the air heater 1 is particularly
advantageous since, in the case of icing, for example due to the
use of the air heater 1 in evaporator mode, the accumulation of ice
initially occurs upstream of the air heater 1. As will be described
later, the strap 19 also makes it possible to reduce the formation
of ice because the strap 19 is less prone to the retention of
water, for example, relative to a louver 17.sub.1, 17.sub.2. The
strap 19 thus helps to trap the moisture upstream.
[0098] As a variant or in addition, provision may be made for the
spacer 7 to have at least one strap 19 on a downstream extremity,
being intended specifically to be opposite the inlet for the gas
stream in the air heater 1.
[0099] Furthermore, the strap 19 has, for example, a substantially
strip-like general form. This strip defines a plane substantially
parallel to the general plane P defined by the planar wall 13. For
this reason, the planar wall 13 including such a strap 19 thus has
a substantially rectangular hollow form.
[0100] By way of example, the width of this strap 19 may be in the
order of at least 0.5 mm. Provision may be made, for example, for a
width in the order of 2 mm.
[0101] The strap 19 has parallel and opposite longitudinal sides
21, and parallel and opposite lateral sides 23, so that the strap
19 is of substantially rectangular form.
[0102] The longitudinal sides 21 extend parallel to the planar wall
13 in the direction of the height h' of the planar wall 13. This
strap 19 may extend longitudinally for a distance of at least 75%
of the height h' of the planar wall 13, or for a distance
corresponding to the full height h' of the planar wall 13.
[0103] At least one of the longitudinal sides 21 of the strap 19 is
intended to extend substantially at right angles to the gas stream
F.
[0104] The lateral sides 23, for their part, are linked to the
planar wall 13 by means of at least one connecting rail 24.
[0105] This strap 19 is therefore substantially parallel to the
flow of the gas stream F, such as the flow of air; this makes it
possible to reduce the loss of charge.
[0106] The presence of such a strap 19 makes it possible to control
the formation of ice more effectively, especially in winter
conditions when the air heater 1 is being operated as an evaporator
in a heat pump mode. The reduction in the quantity of ice permits
the exchange surface between the gas stream and the refrigerant to
be increased, which makes it possible to improve the performance of
the air heater 1. In addition, the strap 19 being planar, the
condensates will flow more freely during deicing.
[0107] This is represented in a schematic manner in FIG. 3
illustrating the results of tests with the help of a sample of a
spacer 7 equipped with straps 19 and a sample of a spacer without
straps 19.
[0108] On the graph in FIG. 3, the first curve C1, identified with
the help of diamonds, corresponds to a spacer 7 equipped with
straps 19, and the second C2, identified with the help of
triangles, corresponds to a spacer without straps 19; this latter
spacer only has louvers 17.sub.1, 17.sub.2.
[0109] This graph illustrates: [0110] a first phase A of immersion
of a sample of a spacer 7 in the water, so as to illustrate in a
schematic manner the retention of water in the spacer 7, and [0111]
a second phase B of removal of the sample of a spacer 7 from the
water, so as to illustrate schematically the flow of the water that
is retained over time.
[0112] By way of example, according to the test carried out, the
first phase A of immersion is for a period in the order of 120 s.
The second phase B commences at 120 s.
[0113] The graph 3 shows the time in seconds (s) on the horizontal
axis and the weight of the water in the spacer in grams (g) on the
vertical axis.
[0114] During the first phase A, it can be noted that the retention
of water is greater in the spacer equipped with louvers 17.sub.1,
17.sub.2, but without straps 19. This is illustrated by the second
curve C2, which increases more rapidly during this first phase
A.
[0115] Conversely, the first curve C1 increases more slowly than
the second curve C2. The retention of water is therefore less
significant in the spacer 7 equipped with straps 19 than in the
spacer without straps 19.
[0116] Therefore, the ice adheres less to a strap 19 than to a
louver 17.sub.1, 17.sub.2.
[0117] Moreover, the Applicant has noted that the ice attaches
less, the greater the offset d of the strap 19 relative to the
general plane P defined by the planar wall 13.
[0118] Subsequently, when the sample is removed from the water, the
flow is stronger in the spacer 7 equipped with straps 19 (see curve
C1) due to the lower retention of water relative to the spacer
without straps 19 (curve C2).
[0119] It will be appreciated, therefore, that the strap 19 makes
it possible to reduce the formation of ice upstream of the spacer
7, and to improve the drainage of the condensates during the stage
of deicing by operating the air heater 1 in condenser mode. In
fact, the strap 19 is substantially parallel to the flow of the gas
stream F passing through the air heater 1, which facilitates the
flow of the condensates.
[0120] Spacers 7 having one strap 19 on the upstream extremities of
the planar walls 13 have been described previously.
[0121] Provision may be made, as a variant, for more than one strap
on an extremity of a planar wall 113, as illustrated in FIGS. 4a
and 4b.
[0122] Provision may be made, for example, for two straps 119.sub.1
and 119.sub.2 on one upstream extremity of a planar wall 113.
[0123] The straps 119.sub.1 and 119.sub.2 are, for example,
substantially identical in form to the strap 19 previously
described with reference to FIGS. 2a to 2c, with longitudinal sides
21 and lateral sides 23 linked to the planar wall 113 by means of
at least one connecting rail 24.
[0124] These two straps 119.sub.1 and 119.sub.2 may, for example,
be produced in an opposing manner. This opposition of the two
straps 119.sub.1 and 119.sub.2 is more clearly visible in FIG. 4b.
In order to do this, provision may be made for one of the straps
119.sub.1 to be produced by sinking in a first direction indicated
schematically by the arrow S.sub.1 in FIG. 4b, and the other strap
119.sub.2 by sinking in a second direction S.sub.2 opposite the
first direction S.sub.1. Thus, the sinking of the two straps
119.sub.1 and 119.sub.2 may take place in the direction
perpendicular to the general plane P defined by the planar wall 13,
but in two opposite directions S.sub.1 and S.sub.2. The two straps
119.sub.1 and 119.sub.2 thus formed are therefore oriented in two
opposite directions S.sub.1 and S.sub.2.
[0125] The offset d or "offset" of the two straps 119.sub.1 and
119.sub.2 relative to the general plane P defined by the planar
wall 113 may be substantially identical.
[0126] Finally, provision may likewise be made for one planar wall
113 to include at least one strap 119.sub.1, 119.sub.2, 119.sub.3,
119.sub.4 on the two opposite extremities of the planar wall (see
FIGS. 5a and 5b). This design makes the production process for the
spacer 7 easier.
[0127] In particular, provision may be made for at least two straps
119.sub.1, 119.sub.2, 119.sub.3, 119.sub.4 to be arranged in a
symmetrical manner relative to the width l.sub.2 of a spacer.
[0128] As previously stated, the planar wall 113 has a
substantially rectangular general form, for example, and the two
straps 119.sub.1, 119.sub.2, 119.sub.3, 119.sub.4 are supported,
for example, by the two opposite longitudinal extremities of the
planar wall 113.
[0129] In particular, a planar wall 113 may have at least two
straps 119.sub.1, 119.sub.2, 119.sub.3, 119.sub.4 arranged
respectively on the upstream extremity of the planar wall 113 that
is intended to be oriented facing towards the inlet for the gas
stream F in the assembled air heater 1, and on the downstream
extremity of the planar wall 113 that is intended to be opposite
this inlet for the gas stream F.
[0130] Provision may be made for the straps 119.sub.1, 119.sub.2,
119.sub.3, 119.sub.4 to be opposite two-by-two. More precisely, the
two straps 119.sub.1 and 119.sub.2 on the upstream extremity of the
planar wall 113 are oriented respectively in two opposite
directions S.sub.1 and S.sub.2. Likewise, the two straps 119.sub.4
and 119.sub.3 on the downstream extremity are oriented respectively
in the two opposite directions S.sub.1 and S.sub.2.
[0131] Thus, by way of example, when the straps 119.sub.1,
119.sub.2, 119.sub.3, 119.sub.4 are produced in a symmetrical
manner, the two extreme straps 119.sub.1 and 119.sub.4 of the
planar wall 113 are oriented respectively in the first direction
S.sub.1, whereas the two intermediate straps 119.sub.2 and
119.sub.3 are oriented respectively in the second direction
S.sub.2.
[0132] In addition, according to this variant embodiment, the
louvers 17.sub.1 and 17.sub.2 are arranged, for example, on a
substantially central part of the planar wall 113, and the straps
119.sub.1, 119.sub.2, 119.sub.3, 119.sub.4 are arranged to either
side of these louvers 17.sub.1 and 17.sub.2.
[0133] It will be appreciated, therefore, that a spacer 7 for an
air heater 1, in particular an external air heater, that is
susceptible to becoming iced up, for example during the use of the
air heater 1 in evaporator mode under winter conditions, and
equipped with at least one strap 19, 119.sub.1, 119.sub.2,
119.sub.3, 119.sub.4, makes it possible to control the formation of
the ice more effectively and to improve the flow of the condensates
during switching of the function of the air heater 1 into condenser
mode.
[0134] Such an air heater may comprise an upstream extremity of a
planar wall 13 of a spacer provided with at least one strap 19,
119.sub.1, 119.sub.2 which projects beyond the tubes 5.
[0135] Such an air heater may also comprise a downstream extremity
of a planar wall 13 of a spacer provided with at least one strap
119.sub.3, 119.sub.4 which is situated at right angles to at least
one tube 5.
* * * * *