Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
  • F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
  • F24F13/081—Air-flow control members, e.g. louvres, grilles, flaps or guide plates for guiding air around a curve
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
  • F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
  • F28F9/02—Header boxes; End plates
  • F28F9/026—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits
  • F28F9/0265—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits by using guiding means or impingement means inside the header box
  • F28F9/0268—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits by using guiding means or impingement means inside the header box in the form of multiple deflectors for channeling the heat exchange medium

Definitions

• the object of the present invention are means for improving a heat exchanger between air and another means, where its air-side inlet front is flat.
• such a heat exchanger is an exchanger of a heat pump.
• such a heat exchanger is the evaporator of an air-water or air-air heat pump where, therefore, the heat source is air that crosses an evaporator, provided with a conveyor for air to be sent to the evaporator and where, but only preferably, said heat pump, if it is of the air-water type:
• - is intended to be installed in indoor environments, such as, generally, technical rooms, basements or utility rooms;
• the conduits used in air-water heat pumps are normally with a circular section with an increasing diameter for increasing operating flow rates.
• the diameters commercially used are 100, 125, 150, 160, 200 mm and anyway suggested by the manufacturer. Rectangular sections are only used for low flow applications.
• the figures included in the description show circular conduits without minimising the generality of the invention.
• the location of the heat pump is, wherever possible, a basement, implies that preferably the air inlet to the machine is made high, so as to be able to engage a conduit trunk descending vertically at least from the ground level, jointed with an elbow to a previous stretch of horizontal conduit connected to the air inlet on an outer wall of the building.
• the evaporator of the heat pump is arranged with vertical setup, at least for an easy expulsion, downstream, of the air that therefore has to cross it with horizontal direction of the flow.
• a conveyor that deflects the direction of the air flow by 90° from vertical to horizontal is provided at the air inlet.
• the conveyor has an inlet whereon a vertical conduit engages that substantially is almost always preceded, as said, by at least one further deviation by 90° in an elbow.
• the machine and the feeding conduits must be designed to be as little bulky as possible and therefore there is not the possibility to have gentle connecting curves at every change of direction thereof.
• document US 2014000841 A 1 describes a cooling apparatus for compressed gases provided with a heat exchanger that cools said gases.
• the inlet section is provided with a rectilinear conveyor with internal divider elements arranged regularly, that uniformly divide the passage section, creating "passage channels" with geometries substantially equal to each other.
• the conveyor has the purpose of reducing or eliminating the flow vortices with a direction parallel to the direction of the forward speed.
• the invention does not provide means that uniform the forward speed, but takes into account the rotational component that the flow has while exiting from the compressor, and acts on it in order to keep the pressure drops reduced.
• An object of the present invention is to significantly reduce air turbulence in the feeding conduits and in the conveyor upstream of the evaporator.
• a further object of the present invention is to reduce the air noise in the same conduits and conveyor.
• a further object is to significantly improve the uniformity of distribution of the air flow at the evaporator inlet.
• a further object of at least some variants of the present invention is to significantly improve the efficiency of the heal pump.
• a further object of at least some variants of the present invention is to significantly improve the cooling capacity of the heat pump.
• Fig. 1 shows the upper part of a heat pump suitable for using the teachings of the present invention and comprising air feeding and expulsion conduits;
• Fig. 2 in the details from (a) to (e), shows, in charts consisting in profiles and mappings, possible distributions of the air speeds in the various stretches of a conduit from a first stretch upstream in a straight indefinitely long zone (a) to a subsequent stretch in correspondence of an elbow (b) up to further rectilinear stretches (c), (d) and (e) downstream of the elbow and at increasing distances from the same; the profiles indicate speed patterns on the plane of symmetry of the conduit and the mappings, with different light and dark intensities speed patterns on the plane orthogonal to the axis of the conduit;
• FIG. 3 schematically shows a possible conveyor according to the prior art, viewed in section along a vertical plane of symmetry;
• Fig. 4 schematically shows a form of conveyor according to the invention viewed in section according to a vertical plane of symmetry
• Fig. 5 schematically shows a conveyor according to a preferred embodiment of the invention, always viewed in section according to a vertical plane of symmetry;
• Figures 6. a and 6.b show a possible distribution of the average speeds of the air at the inlet of the conveyor, via a mapping on a plane orthogonal to the direction of the same speeds and via a tracking of their profile according to a plane parallel to the same speeds, respectively;
• Fig. 6. a also shows details of means according to the invention;
• Figure 7 shows a detail of Fig. 5;
• Figure 8 shows axonometrically the same conveyor of Fig. 5;
• Figure 9 shows, in section according to the plane of symmetry of the feeding conduit of Fig. 1 , possible air baffles according to the invention placed in a curve present in the same conduit;
• Fig. 10 schematically shows a second form of conveyor according to the invention, in section according to its vertical plane of symmetry
• Fig. 1 1 schematically shows, with more details, the same conveyor of Fig.
• top/bottom possibly used hereinafter refers to the position taken by the elements that shall be described in operating conditions while terms of relative position such as “upstream downstream”, “preceded/followed” refer to the order according to which the described elements are encountered by the air sent to the evaporator in operating conditions.
• All aiTOws indicate the travelling direction of the air intended for the evaporator.
• the invention shall now be described with reference to a preferred application thereof usable in correspondence of the evaporator of a heat pump regardless of the air-air or air-water type.
• Fig. 1 shows the upper part 1 (or head 1) of a heat pump HP (regardless of the air-air or air-water type) installed in a compartment V.
• a feeding conduit 2 guides the air drawn from the outside environment E to the heat pump HP.
• An expulsion conduit 3 draws air from the heat pump HP, after it has crossed the evaporator and carries it back to the outside environment E.
• Figs. 3, 4 and 5 of the head 1 schematically show some of the main elements of the heat pump HP, that is enclosure 101 , evaporator 102, evaporator front 106, substantially flat, from which the air enters the evaporator, fan 103, conveyor 104, air inlet 105 in the conveyor 104.
• the conveyor 104 may be defined as a connecting chamber between air inlet 105 and evaporator 102 having the purpose of distributing the air flow as uniformly as possible on the evaporator front 106, which is rectangular.
• Such vorticity is generated only in part by the change of direction and section inside the conveyor 104 because it also depends on the presence or not of the feeding conduit 2 and on its shape as well as on the presence or not, inside such conduit 2, of suitable means for guiding the air provided by the invention to reduce the vorticity. Therefore, for the purposes of the invention, even the feeding conduit 2, at least starting from the last elbow 202 before the conveyor, must be considered, when present, as an essential part of the heat pump HP for the effects, changeable according to the invention, that it produces downstream.
• a curve 202 (Fig. 2.b) due to the presence of an elbow 202 perturbs the flow; in the case of a 90° curve, the fluid streamlines are accelerated in the extrados of the curve and decelerate in the intrados generating at the exit of the curve 202 an average profile of the speeds as shown.
• At distance L0 0 from the curve 202 there is a decentralised speed peak from the axis of the piping and a low speed zone in addition to marked vortices 204.
• the corresponding mapping shows that the acceleration in the extrados of the curve 202 creates a "horseshoe" shaped redistribution with the concavity towards the intrados. This effect is more marked for increasing flows rates and decreasing diameters.
• Non-uniformities of the flow density and formation of vortices originate, as already said, also inside the conveyor 104 regardless of the distribution of the flow density at the entrance of the same not only for the deviation substantially by 90° underwent by the air when this enters vertically from above but also for the variation of the shape of the passage section almost always circular in correspondence of the air inlet 105 and rectangular on the evaporator front 106 and always divergent from air inlet 105 to evaporator front 106.
• the problem of non-uniformity of flow density or at least of the air vorticity is partially solved by adopting a tapered shape for the conveyor 104 which, as shown in Figs. 4, 5, 7, 8 and 10, passes continuously and gradually from the air inlet 105 section, circular, to the outlet section in correspondence of the evaporator 102, rectangular.
• At least the possible elbow 202 immediately upstream of the air inlet 105 to the conveyor 104 is provided with a baffle 206 comprising fins 207 aimed at reducing the vorticity of the air inside and downstream of the same elbow 202.
• Such fins 207 are sheets
• the air speeds profile that is obtained at the air inlet 105 is substantially that devoid of vortices shown in Fig. 2.e.
• a reduction of the vortices inside the conveyor 104 is obtained, with reference to Figs. 5, 6, 7, 8 and 10, by providing the same conveyor 104 with a plurality of flow guides 107 adapted to form channels 108 that guide the air flow from the air inlet 105, where they have an inlet section of area Ai, towards the evaporator front 106 where they have an outlet section of area Si.
• such flow guides 107 the outermost thereof may be two opposed walls 109 of the channelled conveyor 104 are sheets of thin thickness that:
• each channel 108 and the corresponding area Aci vary from upstream to downstream along the flow guides 107 from said inlet Ai and outlet Si values but very preferably gradually, without discontinuity.
• each channel 108 is extended in a cross direction; in other words, preferably and wherever possible the average distance Di between two consecutive flow guides 107 is less than its width Li. This is clearly in order to limit the formation of vortices.
• the means shown so far according to the invention are adapted to eliminate the vorticity of the air in a more and more effective way, whether severally or jointly used.
• At least some of the flow guides 107 can stop at a distance from the evaporator front 106 sufficient for forming plenums (not shown in the figures) between outlet edges 1 13 and evaporator front 106 in which the various speeds have the possibility to uniform while giving rise to some swirling motion.
• the flow guides 107 end substantially in contact with the evaporator front 106 with sections of the channels 108, at the outlet edges 1 13, of such an outlet area Si that in correspondence, the air flow density is substantially equal for each channel and, consequently, there is a feeding at the same flow density in each zone of the , evaporator front 106. This is obviously equivalent to say that the air must exit at the same speed from all channels 108.
• each inlet area Ai substantially depends on the appropriate choice of each corresponding average distance Di in correspondence of the connecting edges 1 12. Having established the size of each inlet area Ai, and thus the air flow rate that enters it, the condition that in correspondence of the outlet edges 1 13 there is substantially uniform flow density for all the channels 108, determines the corresponding outlet areas Si being it understood, as said, that then the variation of section of each channel 108 from inlet to outlet is very appropriate to be gradual.
• Fig. 6 shows a simple way to meet such condition. It shows a vertical stretch 203 of a feeding conduit 2 at a distance LI from a preceding elbow 202, and thus with marked differences in speed. At a distance just over LI, the vertical stretch 203 engages in the air inlet 105.
• the sections of the channels 108 have, at the connecting edges 1 12, the shape of circle sectors comprised among successive parallel cords apart from each other of Di.
• the areas Al , A2,..., Ai,.., A6 of the sections are variable according to the speed of the inlet air, so that each channel 108 intercepts an equal air flow.
• the outlet areas Si are all equal to each other to feed the evaporator 102 uniformly.
• the all equal outlet areas are obtained, in turn, by simply placing the widths Li all equal to the width of the evaporator front 106 to the outlet edge and so the distances Di all equal as well.
• each ratio Ai/A may be provided to assign to each ratio Ai/A a value always equal or, preferably, different for one or more channels 108 to obtain channels 108 the section areas whereof are a greater fraction than that chosen for other channels; this way channels 108 of greater passage section may be obtained where it is deemed less necessary to guide the air (because of lower speed and/or subject to less sudden changes of direction).
• Fig. 7 which indicates on a scale a concrete possible distribution of the flow guides 107 according to to the invention, shows a solution where the distances Di between two subsequent guide walls 109 are, despite the previous example, markedly different also in the proximity of the evaporator 102 and, therefore, the outlet areas Si are equally different and this according to a non-intuitive sequence of distances Di but that actually takes into account a plurality of geometric and fluid dynamic factors that a man skilled in the art knows well such as, by way of a non limiting example:
• Fig. 7 the setup of Fig. 7 has been found by using the following well- known software: Ansys Meshing, ANSYS CFX, ModeFRONTEER whose performance does not need to be detailed being it known to the experts in fluid dynamics.
• the quantification of the distribution of the air speeds in various points of a duct downstream of an elbow with or without baffle 206 and in correspondence of the air inlet 105 may be performed both experimentally and with the aid of fluid-dynamic simulators.
• the design of the baffle 206 may also use the above software.
• the indispensable condition placed to determine the shape of the channels 108 is that air at variable flow density from zone to zone exits form all of them towards the evaporator 102 within predetermined margins deemed acceptable where such margins substantially depend on the expected or acceptable range of variability of the air speed at the air inlet 105.
• the said expected or acceptable range of variability of the distribution of the air speed at the air inlet 105 is equivalent to placing an expected or acceptable range of variability of the distance L of said elbow 202 from said air inlet 105.
• the channelled conveyor 104 may be provided in multiple versions each optimised for a particular range of variability of the said distance L.
• Such a unique version of channelled conveyor 104 may also be usable in the event that the entering air at the air inlet 105 does not come from a feeding conduit 2 but from the heat pump installation compartment V.
• the invention naturally applies to conveyors 104 with any relative position between air inlet 105 and evaporator front 106; in particular, the invention, as described, applies to the case where air enters horizontally into the conveyor 104, as in the case of Fig. 10.
• heat exchanger 102 may be the evaporator or the condenser of a heat pump.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

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• 2016
  • 2016-02-23 ES ES201790012U patent/ES1214854Y/es active Active
  • 2016-02-23 DE DE212016000060.8U patent/DE212016000060U1/de active Active
  • 2016-02-23 EP EP16715602.5A patent/EP3265727A1/de not_active Ceased
  • 2016-02-23 WO PCT/IB2016/000190 patent/WO2016142760A1/en active Application Filing

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