Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D7/08—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being otherwise bent, e.g. in a serpentine or zig-zag
  • F28D7/082—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being otherwise bent, e.g. in a serpentine or zig-zag with serpentine or zig-zag configuration
  • F28D7/085—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being otherwise bent, e.g. in a serpentine or zig-zag with serpentine or zig-zag configuration in the form of parallel conduits coupled by bent portions
  • F28D7/087—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being otherwise bent, e.g. in a serpentine or zig-zag with serpentine or zig-zag configuration in the form of parallel conduits coupled by bent portions assembled in arrays, each array being arranged in the same plane
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D7/16—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation
  • F28D7/163—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation with conduit assemblies having a particular shape, e.g. square or annular; with assemblies of conduits having different geometrical features; with multiple groups of conduits connected in series or parallel and arranged inside common casing
  • F28D7/1638—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation with conduit assemblies having a particular shape, e.g. square or annular; with assemblies of conduits having different geometrical features; with multiple groups of conduits connected in series or parallel and arranged inside common casing with particular pattern of flow or the heat exchange medium flowing inside the conduits assemblies, e.g. change of flow direction from one conduit assembly to another one
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
  • G01M9/02—Wind tunnels
  • G01M9/04—Details

Definitions

• the present invention relates to a system for heat exchange with the airflow inside a wind tunnel, as well as a method for regulating the temperature of the airflow inside a wind tunnel and for designing said exchanger. It is necessary to cool the airflow and control the temperature of the said airflow inside a wind tunnel.
• Heat exchangers are used in both horizontal and vertical wind tunnels for cooling the airflow, which increases the temperature thereof due to friction between the said airflow and the internal walls of the duct of the wind tunnel.
• heat exchangers inside the duct for cooling the airflow similar to water radiators used to cool an automobile engine, are known. These devices introduce high pressure losses in the airflow as the heat transfer area increases.
• Aerodynamic profiles installed in bends or corners of the wind tunnel which allow obtaining a better flow profile with the corresponding introduction of certain pressure loss, are also used.
• this system requires including inside said profiles a system designed to act like a heat exchanger .
• there are also options for cooling the inside of the wind tunnel by means of spraying water or non-deep geothermal energy which does not allow for the optimal regulation of the temperature profile of the airflow and cannot be applied in all types of systems, furthermore being able to have unwanted negative effects such as the excessive increase of relative humidity in the air inside the tunnel.
• the present invention proposes a solution to the preceding problems by means of a heat exchanger according to claim 1, a wind tunnel according to claim 14, a method for regulating the temperature of the airflow inside a wind tunnel according to claim 15 and a design method for designing an exchanger according to claim 16.
• the dependent claims define preferred embodiments of the invention.
• a first inventive aspect provides a heat exchanger for wind tunnels, comprising:
• each wall comprising at least a first edge, a second edge, a third edge and a fourth edge
• T ijk a total number (N) of tubes (T ijk ) adapted for containing a working fluid, at least a plurality of said tubes (T ijk ) making up at least one series (S j ) , the total number of series (S j ) being n s ,
• At least one working fluid inlet manifold connected to a first end of at least one tube (T ijk ) , and
• At least one working fluid outlet manifold connected to a second end of at least one tube (T ijk ) ,
• each series (S j ) form a plurality (n Fj ) of rows (F j ) and a plurality (n cjf ) of columns (C j ) distributed according to rows (F j ) , and wherein:
• the parameterization relative to the rows (F j ) mainly optimizes pressure loss of the heat exchanger
• the parameterization relative to the columns (C j ) mainly optimizes the total effective heat transfer area of the heat exchanger .
• the heat exchanger is comprised between at least two walls, between which the total number (N) of tubes (T ijk ) of the heat exchanger are comprised. Said exchanger is partially limited in volume by means of these walls, such that the volume defined by said walls is preferably the volume also defined by the dimensions of the wind tunnel. Airflow thereby completely strikes the total number (N) of tubes (T ijk ) of the heat exchanger.
• the section of the wind tunnel is taken up entirely by tubes (T ijk ) of the heat exchanger, such that there is an increased area for heat transfer with the airflow without any obstacles in the path of said airflow except the tubes (T ijk ) themselves.
• Said tubes (T ijk ) of the heat exchanger contain a working fluid, preferably a coolant, circulating through the tubes (Ti jk: ) r allowing the heat transfer between said tubes (T ijk ) and the airflow outside these tubes (T ijk ) .
• the working fluid can be either gaseous or liquid or solid.
• said working fluid allows both cooling and heating the airflow, or any other fluid, circulating outside the tubes (T ijk ) of said heat exchanger.
• a series (S j ) is an assembly of tubes (T ijk ) in turn forming a number of rows (F j ) and columns (C j ) which can be both variable and constant between the different series.
• the distribution of the tubes (T ijk ) in rows (F j ) and columns (C j ) in the heat exchanger following a distribution established by means of parameters DT jf , DLl jf , DL2 jf and DG j , allows thermal power exchange in the heat exchanger with minimal pressure loss.
• distances DT jf and DG j are considered to be transverse distances, whereas DLl jf i and DL2 jf are longitudinal distances.
• Determining the parameters allows optimal heat transfer in the heat exchanger, given that an excessively low value of parameter DT jf causes high separation of the airflow striking the tubes (Ti jk: ) , such that a large portion of effective heat transfer area is lost, whereas if the value of said parameter is excessively high, there is a high pressure loss in the heat exchanger .
• determining the parameter DL2 jf allows reducing the separation of the airflow, allowing said airflow to flow between the different rows (F j ) of each series (S j ) .
• an excessively low value of the parameter DLl jf i causes a reduction of the heat transfer area of the heat exchanger .
• determining the parameter DG j allows optimal maintenance of the total number (N) of tubes (T ijk ) of the heat exchanger .
• the value of the parameter DG j between consecutive series (S j ) allows a maintenance operator or unit to access each of the tubes (T ijk ) .
• determining each of the different parameters allows improving the features of the heat exchanger. Additionally, the design of these parameters combined in the heat exchanger allows optimal heat exchange with the airflow.
• Correct parameterization relative to the rows (F j ) additionally allows optimizing mainly the velocity profile of the airflow at the outlet of the heat exchanger, whereas correct parameterization relative to the columns (C j ) additionally allows optimizing mainly the temperature profile of said airflow, also at the outlet of the heat exchanger.
• the heat exchanger comprises at least two tubes (T ijk ) in fluid communication making up at least one coil ( Ri ) .
• Coil ( Ri ) is understood as an attachment of tubes (T ijk ) through which the working fluid can circulate continuously.
• the heat exchanger comprises a plurality ( ni ) of coils ( Ri ) , wherein:
• each coil ( RJ comprises a plurality (g) of groups (G j ), and
• each group (G j ) comprises a plurality (n g ) of tubes (T ijk ) , wherein each series (S j ) is formed by the same group (G j ) of each coil ( Ri ) , and wherein:
• This distribution of tubes (T ijk ) in the heat exchanger advantageously allows a preferably correlative attachment of tubes (T ijk ) , such that the temperature profile of the working fluid allows homogenous heat transfer with the airflow.
• the number (n g ) of tubes (T ijk ) of each group (G j ) is two or three tubes (T ijk ) .
• At least one tube (T ijk ) does not allow circulation of the working fluid.
• At least one coil ( Ri ) does not allow circulation of the working fluid.
• the total number (N) of tubes (T ijk ) of the heat exchanger satisfies the following expression:
• the number of tubes (T ijk ) is thereby obtained according to an expression which depends on the number of rows (F j ), the number of columns (C j ) and the number of series (n s ) of the heat exchanger, taking into account each of the series (S j ), which thereby allows obtaining a heat exchanger with more uniform velocity and temperature profiles at the outlet thereof, with lower pressure loss.
• the total number (N) of tubes (T ijk ) of the heat exchanger satisfies the following expression:
• N g.n n g
• the number of tubes (T ijk ) is thereby obtained according to an expression which depends on both the number of rows (F j ) and the number of columns (C j ) of the heat exchanger, taking into account each of the series (S j ) .
• Said number of tubes, arranged according to groups with the same amount of tubes in equal coils, allows obtaining a velocity profile and temperature profile that are more uniform at the outlet of the heat exchanger, with lower pressure losses.
• the total number (N) of tubes (T ijk ) of the heat exchanger is obtained from the following expression :
• A being the total effective heat transfer area of the heat exchanger
• F m being a heat transfer factor which allows taking into account that the airflow of the tunnel does not completely wet the total area of each tube due to the actual separation of said flow
• a tubem being the total heat transfer area of a tube (T ijk ) .
• the total effective heat transfer area of the exchanger according to the number of tubes obtained therefore has a value equal to or greater than the total effective transfer area value required for the design of said heat exchanger.
• the heat exchanger comprises a distance DL3 jn , which is the distance from the third edge or fourth edge to the closest tube (T ijk ) of each series (S j ), this distance preferably being the minimum distance established by construction of the heat exchanger.
• This minimum distance is established according to manufacturability criteria of the heat exchanger.
• introducing the parameter DL3 jn allows a correct manufacturing, transport and/or installation of the heat exchanger, such that the tubes (T ijk ) cannot be damaged during the process and the space available for installing said tubes (T ijk ) in the heat exchanger is maximum.
• DT jf , DLl jf i, DL2 jf , DL3 jn and DG j of the heat exchanger satisfy the following expressions according to the width (B) and the length (L) of the heat exchanger:
• the maximum value out of the values obtained in each case for the parameter Ljf corresponding to each of the rows (F j ) of one and the same series (S j ), for each of the series (S j ), is taken for sizing the heat exchanger.
• Said maximum value advantageously allows considering the maximum value of the sum of different values of the parameters DLl jfl and DL2jf from among those obtained for all the rows (F j ) of one and the same series (S j ), and for each of the series (S j ) .
• these ratios allow obtaining a heat exchanger having minimum pressure loss and maximum heat transfer .
• At least one of the parameterized distances DT jf , DLl jf i, DL2 jf , DL3 jn and DG j of the heat exchanger maintains a constant value.
• all the parameterized distances DT jf are equal, all the parameterized distances DG j between tubes (Ti jk: ) are equal and the number (n Fj ) of rows (F j ) of each series (S j ) is equal in the heat exchanger, and the following expression is satisfied:
• this allows a more uniform distribution of the tubes (T ijk ) in the heat exchanger and an easier manufacture thereof .
• all the parameterized distances DLl jf i are equal, all the parameterized distances DL3 jn are equal, the number (n Fj ) of rows (F j ) of each series (S j ) is equal and the number (n cjf ) of columns (C j ) of each series (S j ) is equal, and the following expression is satisfied:
• this allows a more uniform distribution of the tubes (T ijk ) in the heat exchanger and a simpler and less expensive manufacture thereof.
• the heat exchanger comprises two inlet manifolds and two outlet manifolds, wherein each of the coils (Ri) is alternately connected to a different inlet manifold and a different outlet manifold, such that the path of the working fluid has an alternating direction in each coil (Ri) ⁇
• Each adjacent coil (Ri) is thereby alternating as regards the circulation direction of the working fluid.
• the closure means allow the closure of at least one tube (T ijk ) , allowing the closure of said tube for maintenance work, or in the event of heat transfer needs that are less than the maximum heat transfer achievable with the exchanger.
• each tube (Ti jk: ) is a circular tube (T ijk ) with the same outer diameter (0) .
• the cross section of the tube (T ijk ) is determined by the allowable range of velocities of the working fluid.
• the determination of the inner diameter of said tube (T ijk ) is therefore also determined by the allowable range of velocities of the working fluid when this tube (T ijk ) is circular.
• the outer diameter of said tube (T ijk ) is determined by criteria of maximum pressure that said tube (T ijk ) must withstand or other structural or manufacturability criteria of the heat exchanger.
• the heat exchanger is manufactured with commercial elements, preferably circular tubes, which allows reducing the manufacturing cost.
• the total effective heat transfer area of the heat exchanger, all the tubes (T ijk ) being circular is the following:
• F being an average heat transfer factor for all the tubes (T ijk ) .
• the invention provides a wind tunnel comprising at least one heat exchanger like the one of the first inventive aspect.
• the invention provides a method for regulating the temperature of the airflow inside a wind tunnel comprising the following steps:
• Said modifiable conditions of the working fluid can be the temperature, composition or physical state of said fluid.
• Regulation by means of modifying parameterized distances comprises both modifying the distances during the design of the system and physically modifying the arrangement of at least one tube (Ti jk: ) once all the tubes (T ijk ) are installed.
• the step of regulating the temperature of the airflow is performed by modifying the parameterized distances DT jf , DLl j f i , DL2 jf , DL3 jn and DG j .
• the invention provides a design method for designing a heat exchanger according to the first inventive aspect for a wind tunnel comprising the following steps:
• the total heat transfer area (A tube m ) of a tube (T ijk ) is defined depending on the section of each tube as well as the total number (N) of tubes (T ijk ) .
• determining the parameters DT jf , DLl jf i, DL2 jf , DL3 jn , DG j , n s , n Fj and nc jf allows for the design of a heat exchanger having optimal heat transfer with the airflow inside the wind tunnel and low pressure loss.
• the design method further comprises the step of determining the total number (ni) of coils (Ri) , the number (g) of groups (G j ) and the number (n g ) of tubes (Ti jk: ) in each group (G j ), prior to the step of determining the different parameters DT jf , DLl jf i, DL2 jf , DL3 jn and DG j .
• Figure 1 shows a perspective view of an embodiment of the heat exchanger.
• Figure 2A shows a front view of an embodiment of the heat exchanger .
• Figure 2B shows a plan view of section A-A of Figure 2A.
• Figure 2C shows a detail view of Figure 2B.
• Figure 3 shows a front view of an embodiment of the heat exchanger .
• Figure 4 shows a diagram of the layout of an embodiment of the heat exchanger inside the wind tunnel.
• Figures 5A and 5B show the comparison for the temperature profile contours of the fluid in the tested heat exchangers.
• Figures 6A and 6B show the comparison for the velocity profile contours of the fluid in the tested heat exchangers.
• Figure 1 shows a heat exchanger (1) according to a particular embodiment of the invention, envisaged for being installed in a wind tunnel (2) .
• Said heat exchanger (1) comprises a first wall (3) as a lower wall and a second wall (4) as an upper wall.
• the airflow to be cooled coming from the wind tunnel (2) enters the heat exchanger (1) according to the direction depicted in Figure 1, i.e., from the edge (9) of the heat exchanger (1) towards the edge (10) of the heat exchanger (1) .
• the number (ni) of coils (Ri) is 55, each of said coils (Ri) comprising a total (g) of 6 groups (G j ), and each of these groups (G j ) comprising a number (n g ) of 3 tubes (T ijk ) .
• Said arrangement of tubes (T ijk ) makes up a total of 6 series (S j ), each of said series (S j ) comprising a total (n Fj ) of 3 rows (F j ), the number of rows (F j ) being the number (n g ) of tubes (Ti jk: ) of each group (G j ), and also comprising a total (n cjf ) of 55 columns (C j ), said number of columns (C j ) being the number (ni) of coils (Ri) .
• the total number (N) of tubes (T ijk ) in this particular example is 990 tubes, according to the described arrangement.
• N The value of the parameters N, n Fj , n g , n cjf , F j , S j , G j , C j , ni are always integer values.
• Said tubes (T ijk ) all have a cylindrical section, with an outer diameter of 28 mm in this particular example.
• the heat exchanger (1) also comprises two inlet manifolds (5) and two outlet manifolds (6) which are alternately connected to each of the coils (Ri) .
• the odd-numbered coils (Ri) are thereby connected to the inlet manifold (5) located on the left side of Figure 1 and to the outlet manifold (6) located on the right side of Figure 1, whereas the even-numbered coils (Ri) are connected to the remaining inlet manifold (5) and outlet manifold ( 6 ) .
• the working fluid circulates through the inside of the coils (Ri) and accesses said coil (Ri) through the inlet manifold (5) and exits the coil ( Ri ) through the outlet manifold (6) .
• Figure 2A shows a front view of an embodiment of a heat exchanger (1) limited by means of a first wall (3) as a lower wall and a second wall (4) as an upper wall, said walls (3, 4) defining the height (H) of the heat exchanger (1) .
• said height (H) has a value of 3 m.
• This drawing shows the first coil ( Ri ) of the heat exchanger (1) formed by tubes (T ijk ) attached to one another by means of elbows. Said elbows allow the fluid communication both between tubes (T ijk ) of the same group ( G j ) and between groups
• elbows are outside the airflow, being located outside the walls (3, 4) of the heat exchanger. This also occurs with the inlet manifolds (5) and outlet manifolds (6) . This allows the airflow to find no obstacles during its passage with the exception of the tubes (T ijk ) , such that pressure loss is minimized.
• Figure 2B shows a plan view of section A-A made on the front view of Figure 2A.
• Said plan view shows the remaining dimensions of the heat exchanger (1), i.e., its width (B) and length (L) .
• the width (B) has a value of 6 m and the length (L) has a value of 3.5 m.
• Figure 2B also shows the arrangement of the 55 coils ( Ri ) and the 6 series (S j ) they form.
• the different groups (G j ) making up the series (S j ) are also observed in each of the series (S j ) .
• a series (S j ) is the cluster of the same group (G j ) of each coil ( RJ .
• series ( Si ) is the assembly of group ( Gi ) of the 55 coils making up the heat exchanger (1) .
• Figure 2C shows a detail (C) taken from the plan view of the section of Figure 2B.
• This particular embodiment shows the different parameters defining the distribution of the tubes (T ijk ) in the heat exchanger .
• Each series (S j ) is formed by 3 rows (F j ) and in them a maximum of 10 columns (C j ) are shown.
• the dimensioned parameters in this particular embodiment are DT jf , DLl jf i, DL2 jf and DG j , all of them being constant between different series (S j ), with the exception of the values of DL2 jf in each series (S j ) , which takes a value of zero for the odd- numbered rows (Fi and F 3 ) of each series and a constant value for the even-numbered rows (F 2 ) .
• DT jf defines the distance existing between two rows
• said distance has a value of 112 mm, such that it allows a machine or operator access to carry out the maintenance of each of the tubes (T ijk ) of the even-numbered rows (F 2 ) of each series (S j ) .
• This distance also allows forming a longitudinal duct, i.e., in the airflow passage direction, for passage of said airflow .
• the distance DLl jf i defines the distance existing between two tubes (Ti jk: ) of one and the same row (F j ), said two tubes (Ti jk: ) of one and the same row (F j ) always being perfectly aligned.
• the value of the distance DLl jf i is 59 mm in this particular embodiment.
• This distance allows the airflow impacting both tubes (T ijk ) to follow a path suitable for making better use of the heat transfer area of the tube (T ijk ) located behind the previous one.
• the distance DL2 jf defines the distance existing between two tubes (T ijk ) of two different rows (F j ) and the same column (C j ) , said column (C j ) being the closest to the third edge (9) with respect to the tube (T ijk ) of the same series (S j ) closest to said third edge (9) .
• the columns (C j ) are shifted in Figure 2C, they match up to one another one-by- one.
• Figure 2B shows the arrangement of a column, i.e., a coil (Ri) .
• the value of the distance DL2 jf is 0 mm for the odd- numbered rows (Fi and F 3 ) and 84 mm for the even-numbered rows (F 2 ) in this particular embodiment.
• This distance allows the airflow to strike a larger surface of tubes (Ti jk: ) r reducing separation of the flow, such that heat transfer increases and pressure loss of the exchanger (1) decreases .
• the distance DG j defines the distance which exists between the two closest tubes (T ijk ) of two consecutive series (S j ) .
• the distance DG j also defines the distance existing between the tubes (Ti jk: ) of the rows (F j ) located at the ends of the distribution of the total number (N) of tubes (T ijk ) and the edges (7, 8) of the exchanger (1), located on the left and right sides of Figures 2B and 2C.
• the value of the distance DG j is 665 mm in this particular embodiment.
• This distance allows a machine or operator to access the tubes (T ijk ) and to move freely for the maintenance of each of the tubes (T ijk ) of the odd-numbered rows (F x and F 3 ) of each series (S j ) .
• This distance also allows forming a longitudinal duct, i.e., in the airflow passage direction, for passage of said airflow.
• the parameter DL3 jn is also dimensioned in a particular embodiment .
• Said distance DL3 jn defines the distance between the edges
• This drawing shows the situation of the upper and lower walls (3, 4) as well as one of the coils ( Ri ) connected to the inlet manifold (5) and to the outlet manifold (6) .
• Said drawing also shows the connection between the different tubes (T ijk ) making up the coil, by means of elbows, and the parameterization related with the ducts which allow passage of airflow as well as maintenance of each tube (T ijk ) by both an operator and/or by a machine adapted for this purpose.
• Figure 4 shows a diagram of a wind tunnel (2) through which airflow circulates. A heat exchanger (1) already installed in said wind tunnel (2) is depicted.
• the heat exchanger (1) has fluidic connections between tubes (T ijk ) and the inlet manifolds (5) and outlet manifolds (6) located outside the actual duct of the wind tunnel (2) through which airflow circulates .
• the first heat exchanger (HE1) is the one disclosed in the preferred embodiment already described, with the given parameters values
• the second heat exchanger (HE2) corresponds to a known heat exchanger with a classical distribution of tubes, wherein said tubes are arranged as an aligned tube bank, having equal longitudinal and equal transverse distances between tubes.
• the values of the parameters of both heat exchangers are as follows:
• Figures 5a, 5b, 6a and 6b Two different comparisons have been tested, and are shown in Figures 5a, 5b, 6a and 6b.
• the airflow enters the heat exchanger from the top of the figures, and exits said heat exchanger from the bottom of said figures.
• Figures 5A and 5B show the temperature profile contours of the fluid in the tested heat exchangers. Results of the temperature evolution of the fluid of HE1 can be observed in Figure 5A, wherein there is a wake of cooled fluid on the outlet of the heat exchanger, stronger than the one observed for HE2 in Figure 5B, lowering the average outlet temperature. Consequently, the heat transfer is higher for HE1, which proves that the parameters conditions given in the preferred embodiment improve the performance of the known heat exchanger HE2.
• Figures 6A and 6B show the velocity profile contours of the fluid in the same tested heat exchangers. Results of the velocity distribution of the fluid of HE1 can be observed in Figure 6A, wherein the wake of the flow for each of the two sets of tubes is slightly wider than the one shown for each of the six sets of tubes of HE2, which can be observed in Figure 6B, suggesting a higher pressure loss for this area in the distribution with two sets of tubes (HE1) . These two sets of tubes can potentially yield higher local pressure losses than the equally spaced tubes in the distribution of HE2. However, due to the parameterization performed in HE1, related to the values of DG, DT and DL2, the local pressure losses in the passages wherein DG is measured will be considerably lower for HE1.
• HE1 i.e. the heat exchanger of the preferred embodiment, has lower pressure losses while improving its temperature drop, thus improving its heat exchanger performance .
• the parameterization of a heat exchanger according to the first inventive aspect provides a heat exchanger wherein the heat exchange with the fluid is higher, while resulting in lower pressure losses.
• a heat exchanger (1) for wind tunnels (2) comprising:
• each wall (3, 4) comprising at least a first edge (7), a second edge (8), a third edge (9) and a fourth edge (10),
• T ijk a total number (N) of tubes (T ijk ) adapted for containing a working fluid, at least a plurality of said tubes (T ijk ) making up at least one series (S j ), the total number of series (S j ) being (n s ) ,
• At least one working fluid inlet manifold (5) connected to a first end of at least one tube (T ijk ) , and
• At least one working fluid outlet manifold (6) connected to a second end of at least one tube (T ijk ) ,
• each series (S j ) form a plurality ( n ⁇ j ) of rows (F j ) and a plurality (n Cjf ) of columns (C j ) distributed according to rows (F j ), and wherein:
• the parameterization relative to the rows (F j ) mainly optimizes pressure loss of the heat exchanger (1)
• the parameterization relative to the columns (C j ) mainly optimizes the total effective heat transfer area of the heat exchanger (1) .
• each coil (RJ comprises a plurality (g) of groups (G j ), and
• each group (G j ) comprises a plurality (n g ) of tubes (T ijk ) , wherein each series (S j ) is formed by the same group (G j ) of each coil (Ri) , and wherein:
• the number (n Fj ) of rows (F j ) of each series (S j ) is the number of tubes (T ijk ) comprised in each group (G j ), and the number (n cjf ) of columns (C j ) of each series (S j ) is the number of coils (Ri) .
• N g.n n g
• A being the total effective heat transfer area of the heat exchanger (1), F m a heat transfer factor and A tubem the total heat transfer area of a tube (T ijk ) .
• each of the coils ( Ri ) is alternately connected to a different inlet manifold (5) and a different outlet manifold (6), such that the path of the working fluid has an alternating direction in each coil ( Ri ) .
• each tube (T ijk ) is a circular tube with the same outer diameter ( ⁇ ) ⁇
• a wind tunnel (2) comprising at least one heat exchanger (1) according to any of [1-13] .
• a method for regulating the temperature of airflow inside a wind tunnel (2) comprising the following steps:
• a design method for designing a heat exchanger (1) for a wind tunnel (2) according to any of [7-13] comprising the following steps:

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• Geometry (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Aerodynamic Tests, Hydrodynamic Tests, Wind Tunnels, And Water Tanks (AREA)

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• 2016
  • 2016-04-29 ES ES201790043A patent/ES2652517B1/es active Active
  • 2016-04-29 WO PCT/EP2016/059622 patent/WO2016174209A1/en active Application Filing

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