CN108826713A - A kind of non-porous heat absorption flat plate type solar energy air heat collector - Google Patents
A kind of non-porous heat absorption flat plate type solar energy air heat collector Download PDFInfo
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- CN108826713A CN108826713A CN201810427378.8A CN201810427378A CN108826713A CN 108826713 A CN108826713 A CN 108826713A CN 201810427378 A CN201810427378 A CN 201810427378A CN 108826713 A CN108826713 A CN 108826713A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S10/00—Solar heat collectors using working fluids
- F24S10/50—Solar heat collectors using working fluids the working fluids being conveyed between plates
- F24S10/55—Solar heat collectors using working fluids the working fluids being conveyed between plates with enlarged surfaces, e.g. with protrusions or corrugations
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S80/00—Details, accessories or component parts of solar heat collectors not provided for in groups F24S10/00-F24S70/00
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S80/00—Details, accessories or component parts of solar heat collectors not provided for in groups F24S10/00-F24S70/00
- F24S2080/03—Arrangements for heat transfer optimization
- F24S2080/05—Flow guiding means; Inserts inside conduits
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
- Y02E10/44—Heat exchange systems
Abstract
The invention discloses a kind of non-porous heat absorption flat plate type solar energy air heat collectors.By carrying out structure optimization to the multiple V-shaped fin as enhanced heat transfer component being set on absorber plate, the optimal aperture width for constituting the single chevron of the multi-v fin, w=C are provided0+35×(H/H0‑1)‑12×(e/e0‑1)+2×(P/P0‑1)+9×(α/α0- 1) (formula I).The opening width of the best single chevron of the available synthesis exchange capability of heat that can be improved non-porous heat absorption flat plate type solar energy air heat collector based on different air ducts and fin height, fin pitch and the fin angle of attack according to the present invention, to reduce the heat loss to environment, collecting efficiency is improved.
Description
Technical field
The invention belongs to solar energy utilization technique fields, and in particular to a kind of non-porous heat absorption flat plate type solar air collection
The optimization of the rib structure of hot device.
Background technique
Solar energy is inexhaustible clean energy resource.Solar energy air heat collector is with air for collection hot working fluid
The device that the radiation energy of the sun is converted to thermal energy, in terms of being chiefly used in solar heating and solar energy drying.Non-porous heat absorption flat plate
Type solar energy air heat collector is made of the part such as shell, transparent cover plate, absorber plate and thermal insulation layer.Air is in absorber plate and bottom plate
Between rectangular channel in flowing.Since the heat-transfer capability of air is lower, so that the temperature of absorber plate is higher, cause to environment
Heat loss is larger.
It, can be in air duct side in order to reduce heat absorption plate temperature to improve the collecting efficiency of solar energy air heat collector
Fin is arranged in plate surface of absorbing heat, this can not only increase heat transfer area, can also improve convection current because of the enhancing of air agitation and change
Hot coefficient.The fin form used in non-porous heat absorption flat plate type solar energy air heat collector has cross rib piece, diagonal rib piece, V-arrangement fin
(fin of only one chevron on channel width direction) (multiple chevrons connect on channel width direction with multiple V-shaped fin
Made of fin) etc., wherein the heat conduction reinforced effect of multiple V-shaped fin is best.Multiple V-shaped fin can generate more in channel
A spiral shape longitudinal direction vortex promotes mutual blending of the absorber plate nearby between hot fluid and main flow area cold fluid, while also in phase
Secondary vortex is generated in space between adjacent fin, further promotes the blending of fluid near absorber plate.
Although the augmentation of heat transfer effect of multiple V-shaped fin is better than single V-arrangement fin, the V-arrangement of channel width direction
Part number is not The more the better.When the chevron number of channel width direction increases, grow up again between adjacent fin
The length of thermal boundary layer can become smaller, this is advantageous heat transfer；But when channel width direction chevron number increases, vortex
Intensity can decline, this is unfavorable to heat transfer.Under these advantageous and collective effects of unfavorable factor, it may appear that one makes thermal-arrest
The heat transfer property of device reaches the chevron number of highest channel width direction, i.e., best chevron number, and with this best V
The corresponding best single chevron width of shape part number.Therefore, it when strengthening the heat transfer of heat collector using multiple V-shaped fin, removes
It to select outside the parameters such as suitable fin height, pitch, the angle of attack, also to select the V-arrangement of an optimal channel width direction
Part number, or best single chevron width.But the best single chevron width provided in current document is all definite value, cannot
Meet the optimal design requirement of heat collector.
Summary of the invention
In view of above-mentioned problems of the prior art, the present invention provides a kind of non-porous heat absorption flat plate type solar air collection
Hot device improves thermal-arrest by carrying out structure optimization to the multiple V-shaped fin as enhanced heat transfer component being set on absorber plate
The synthesis exchange capability of heat of device improves collecting efficiency to reduce the heat loss to environment.
Technical scheme is as follows：
A kind of non-porous heat absorption flat plate type solar energy air heat collector, including ontology and transparent cover plate, the ontology are hollow
Without top formula frame structure, the transparent cover plate is arranged in the top of ontology, and absorber plate, the absorber plate are arranged in the ontology
Ontology is divided into the first cavity and the second cavity, one end of second cavity is provided with air inlet, and the other end is provided with out
Air port is fixedly installed multiple fins arranged in parallel between each other on the lower surface of the absorber plate in certain intervals, makees
Air for collection thermal medium is contacted with fin and is flowed along the length direction of heat collector, and the fin is by multiple chevrons with head
The mode that tail connects extends along the width direction interconnection of heat collector,
The opening width w of the chevron is as shown in formula I：
W=C0+35×(H/H0-1)-12×(e/e0-1)+2×(P/P0-1)+9×(α/α0- 1) (mm) (formula I)
In formula I, H is the distance between absorber plate lower surface and the second well floor inner wall, and e is chevron height, and P is rib
Piece pitch, α are the angle of attack；H=20~30mm, e=1~3mm, P/e=8~12, α=30~45 °, C0=30~37.5, H0=
25mm, e0=2mm, P0=20mm, α0=45 °.
In the above-mentioned technical solutions, in formula (I), H=25mm, e=2mm, P/e=10, α=30 °.
In the above-mentioned technical solutions, the α is 1/2 of the angle between two branches of chevron.
In above-mentioned all technical solutions, first cavity and the second cavity are mutually independent space.
In above-mentioned all technical solutions, the material of the chevron is thermal conductive metallic material.
In above-mentioned all technical solutions, the chevron is equilateral V-type, the side that identical multiple chevrons are connected with head and the tail
Formula is connected with each other along the width direction of heat collector to be extended and forms a fin, and all chevrons in each fin are same
The opening endpoint of all chevrons in plane, and in each fin is on same straight line, the straight line and heat collector side wall
Vertically.
Beneficial effects of the present invention：
The present invention provide it is a kind of with multiple V-shaped fin plate type solar air collector design in, can
The design scheme of the fin of the comprehensive heat transfer effect of higher heat collector is obtained, can be obtained corresponding to different heat collectors according to the program
The opening of the best single chevron of structure (different air duct specification etc.) and fin height, fin pitch and the fin angle of attack
Width, overcoming the best single chevron width that current document provides all is definite value, does not account for fin and channel other
Influence of the geometric parameter to it, be not able to satisfy heat collector optimal design require the shortcomings that.It is available according to the present invention to be based on
Different air ducts and fin height, fin pitch and the fin angle of attack can be improved non-porous heat absorption flat plate type solar air collection
The opening width of the best single chevron of the synthesis exchange capability of heat of hot device improves collection thermal effect to reduce the heat loss to environment
Rate.
Detailed description of the invention
Fig. 1 is the main view cross section structure schematic diagram of solar energy air heat collector of the invention；
Fig. 2 is the side cross-sectional structural schematic diagram of solar energy air heat collector of the invention；
Fig. 3 looks up cross section structure schematic diagram for solar energy air heat collector of the invention；
Fig. 4 is the computation model of solar energy air heat collector of the invention；
Fig. 5 is the partial enlarged view of the heat absorption plate surface of solar energy air heat collector of the invention；
Fig. 6 is the grid independence inspection result for average nusselt number and friction factor；
Fig. 7 is nusselt number cloud charts during grid independence is examined；
Fig. 8 is chevron width and influence of the fin angle of attack to average nusselt number；
Fig. 9 is chevron width and influence of the fin angle of attack to friction factor；
Figure 10 is chevron width and influence of the fin angle of attack to thermal-hydraulic performance factor；
Figure 11 is H=25mm, e/Dh=0.043, P/e=10 and when α=45 °, nusselt number cloud charts；
Figure 12 is H=25mm, e/Dh=0.043, P/e=10 and when α=45 °, different chevron width is to nusselt number
The influence of distribution；
Streamline when Figure 13 is different chevron width, wherein Figure 13 (a), (b) and (c) channel width (w) be respectively
60.0mm, 33.3mm and 23.1mm；
Figure 14 is the influence that the different fin angles of attack are distributed nusselt number；
Figure 15 is influence of the different fin pitches to thermal-hydraulic performance factor；
Figure 16 is H=25mm, e=2mm, α=45 °, when w=37.5mm, influence of the fin pitch to main vortex pitch,
Middle Figure 16 (a) and (b) fin pitch are respectively 20mm and 40mm；
Figure 17 is influence of the fin height to thermal-hydraulic performance factor；
Figure 18 is H=25mm, P=20mm, α=45 °, when w=37.5mm, influence of the fin height to main vortex pitch,
Wherein, the fin height of Figure 18 (a) and (b) are respectively 2mm and 4mm；
Figure 19 is influence of the channel height to thermal-hydraulic performance factor；
Figure 20 is P=20mm, e=2mm, α=45 °, when w=37.5mm, influence of the channel height to main vortex pitch,
In, the channel height of Figure 20 (a) and (b) are respectively 20mm and 25mm；
Symbol mark：1, ontology, 2, transparent cover plate, 3, absorber plate, the 4, first cavity, the 5, second cavity, 6, air inlet, 7,
Air outlet, 8, fin, 9, chevron.
Specific embodiment
Following non-limiting embodiments can with a person of ordinary skill in the art will more fully understand the present invention, but not with
Any mode limits the present invention.
Embodiment 1
As shown in Fig. 1~2, a kind of non-porous heat absorption flat plate type solar energy air heat collector includes ontology and transparent cover plate, institute
Stating ontology is hollow without top formula frame structure, and the top of ontology is arranged in the transparent cover plate, setting heat absorption in the ontology
Ontology is divided into the first cavity and the second cavity by plate, the absorber plate, and one end of second cavity is provided with air inlet, separately
One end is provided with air outlet, is fixedly installed in certain intervals on the lower surface of the absorber plate along the length direction of heat collector
There are multiple fins arranged in parallel between each other, the air as collection thermal medium contacts with fin and along the length side of heat collector
To flowing, the fin by multiple chevrons with end to end mode along heat collector width direction be connected with each other extend and
At.
The insulation with a thickness of 35~50mm need to be arranged in outer layer of the solar thermal collector other than transparent cover plate
Layer (not shown), to reduce heat loss.
Metal production, such as copper, aluminium, stainless steel can be used in the absorber plate.The upper surface of absorber plate can pass through chemistry, electricity
The techniques such as plating are fabricated to solar selective surface.Heat collector is divided into mutually independent two cavitys by absorber plate, i.e., and
One cavity and the second cavity.It is stamped transparent cover plate on first cavity, closed is made of transparent cover plate, side plate and absorber plate
One cavity, the surface of side plate are smooth.Second cavity includes absorber plate, side plate and bottom plate, by the side plate, bottom plate and absorber plate
To constitute the second cavity.Absorber plate absorption penetrates the solar radiant energy that transparent cover plate shines in and converts it to thermal energy, passes
Pass the air flowed through thereunder.Air enters the second cavity by air inlet, flows along the length direction of heat collector, simultaneously
It is heated by absorber plate lower surface, the air being heated up is flowed out by air outlet.The fin of absorber plate lower surface setting is to air
It is disturbed, improve the turbulivity of flowing and causes vortex, promote the blending of inner fluid passage, thus augmentation of heat transfer.
In non-porous heat absorption flat plate type solar energy air heat collector, multiple fins on the length direction of heat collector, to each other
It is fixed on the lower surface of heating plate in parallel to each other, it is preferred that the spacing between the multiple fin is identical.Institute
It states fin and is extended in end to end mode along the width direction connection of heat collector by multiple chevrons.Herein, in order to
It conceptually integrates with the prior art, the above-mentioned fin of the present invention is referred to as multiple V-shaped fin below.Preferably, described
The length of multiple V-shaped fin and heating plate it is of same size, the multiple V-shaped fin is fixedly connected on the lower surface of absorber plate
On.The chevron is equilateral V-type, identical multiple chevrons phase in the width direction in such a way that head and the tail connect along heat collector
It connects extension and forms a fin, all chevrons in each fin are in the same plane, and all in each fin
The opening endpoint of chevron is all on same straight line, and the straight line is vertical with the second cavity side plate inner wall, in other words, each
The opening of all chevrons in fin is is same direction, and each chevron vertex (angle point) is on the same straight line, and
The straight line is vertical with the second cavity side plate inner wall.Wherein, identical multiple chevrons refer to, the shape of the chevron and
The specification of each section is all the same.Preferably, the cross section of the chevron is rectangle or circle, can use silk strip, piece
The heat-conducting metal pieces of shape make to obtain.The solar energy air heat collector, wherein the opening width w such as formula of the chevron
Shown in I：
W=C0+35×(H/H0-1)-12×(e/e0-1)+2×(P/P0-1)+9×(α/α0- 1) (mm) (formula I)
In formula I, H is the distance between absorber plate lower surface and the second well floor inner wall (height in channel), and e is V-arrangement
Part height, P are fin pitch, and α is the angle of attack；H=20~30mm, e=1~3mm, P/e=8~12, α=30~45 °,
C0=30~37.5, H0=25mm, e0=2mm, P0=20mm, α0=45 °.
As shown in Figure 1, fin pitch P described in formula I refers to the distance between corresponding points on two adjacent fin profiles；
The α is 1/2 of the angle between two branches of chevron.
Preferably, in formula (I), H=25mm, e=2mm, P/e=10, α=30 °.
Embodiment 2
The present invention obtains non-porous heat absorption flat plate type solar air collection as shown in Figures 1 to 3 by numerical simulation and analysis
In hot device, the optimized dimensions of multiple V-shaped fin.Numerical simulation uses computational fluid dynamics special-purpose software ANSYS FLUENT.
Fig. 4~5 are the physical model schematic diagrames of calculating.The case where for the ease of observing multiple V-shaped fin, in schematic diagram
It is middle that heat collector has been done 180 ° of overturnings up and down, so that absorber plate is in the bottom surface of channel (i.e. the second cavity).Calculating channel is by three
Part forms, respectively entrance, active section and outlet section.Active section is equivalent to actual air collector channel, in calculating
Take that the length is 1000mm.Upstream extend 500mm as entrance from active section entrance, guarantees that the flowing of active section entrance is abundant
Development；Downstream extend 500mm as outlet section from active section outlet, guarantees outlet without reflux.The width W in channel and fin
Thickness t takes definite value in calculating:W=300mm and t=1mm.
Parameter definition：
(1) Reynolds number：Re=UDh/ ν (formula II)
In formula (II), U is the air average speed in main flow direction (direction x in Fig. 4), m/s；DhIt is straight for the equivalent in channel
Diameter, m；ν is the kinematic viscosity of air, m2/s。
(2) local convective heat transfer coefficient hloc：hloc=q/ (Tw-Tb,x) (formula III)
In formula (III), Tb,x=Ti+x(To-Ti)/L, q are local heat flux density, W/m2；TwFor local wall temperature, K；Tb,x
For the local average temperatures of air, K；TiAnd ToThe respectively average temperature of air of active section inlet and exit, K；Based on x
Flow the coordinate in direction, m；L is the length of active section, m；
(3) local nusselt number Nuloc：Nuloc=hlocDh/ k (formula IV)
In formula (IV), k is the thermal coefficient of air, W/ (mK).
Average nusselt number Nu：Usable floor area weighted average function passes through to Nu in FLUENTlocIt is averaged and acquires.
(4) friction factor f：F=(Δ p/L) Dh/(2ρU2) (formula V)
In formula (V), Δ p is pressure drop when air flows through active section, Pa；ρ is the density of air, kg/m3。
(5) thermal-hydraulic performance factor η：
The factor of two aspects of heat transfer and flow resistance, overall merit fin are integrated using thermal-hydraulic performance factor η
Heat transfer property.
η=(Nu/Nus)/(f/fs)1/3(formula VI)
In formula (VI), NusAnd fsThe respectively average nusselt number and friction factor of smooth passage.Thermal-hydraulic performance because
Subrepresentation is：Under identical blower power consumption, there is the ratio in the channel of fin and the heat convection ability of smooth passage.If η>
1, then it is beneficial using fin.η is bigger, and the getable reinforcing of conductivity of heat is more.
Turbulent flow preference pattern：
Flowing in solar energy air heat collector channel belongs to turbulent flow, needs to be calculated using turbulence model.RNG
K- ε model can most accurately simulate flowing and heat transfer in the channel with multiple V-shaped fin, and RNG is selected in this calculating
K- ε model, while near wall region is using enhancing casing treatment.
Boundary condition and physical properties of fluids：
In order to reduce number of grid, symmetrical boundary condition, mould are used at the median plane y=W/2 of channel width direction
The channel of quasi- a half width (y=0~0.5W).Entry condition uses speed entrance, and temperature is the air of 300K from entrance
Entrance flows into, and entrance velocity can convert according to given Reynolds number and obtain；Exit condition selects pressure export, and outlet gauge pressure is set as
0Pa.The import and export turbulence intensity of air takes 5%.Wall surface is using no slip boundary condition.Apply in heat absorption plate surface
1000W/m2Uniform Heat density analog solar radiation, other all wall surfaces in each section of channel and fin surface are set as adiabatic wall
Face.
Reference pressure is set as 1atm.Temperature change when passing through heat collector in view of air is little, it is assumed that the physical property of air
For definite value, and use the dry air physics value under inlet temperature and reference pressure.
Method for solving：
Assuming that flowing is stable state, irrotationality, and ignore radiation heat transfer and viscous dissipation.The separate type based on pressure is selected to solve
Device solves governing equation.Pressure x velocity coupled modes select SIMPLE algorithm.Pressure in governing equation using reference format into
Row is discrete, and remaining variables are carried out discrete using Second-order Up-wind format.It owes relaxation factor and uses default value.
Grid generates and independence is examined：
Grid is generated using ANSYS ICEM CFD software.The three-dimentional structured mesh of generation is in channel and the wall surface of fin
Place carry out mesh refinement, with guarantee first layer grid mass center to wall surface dimensionless distance y+It is approximately 1.0.For H=25mm,
The case where e=2mm, P=20mm, α=45 °, W/w=6 and Re=10000 using 5 nested grid numbers is respectively 4,480,000,6,570,000,
9970000,14,020,000 and 20,560,000 grid carries out the inspection of grid independence.Fig. 6 gives average nusselt number and friction factor
With the variation of grid number, Fig. 7 then gives the influence that grid number is distributed local nusselt number.When with maximum mesh number 20,560,000
The case where compare, when grid number is 14,020,000, the deviation of average nusselt number and friction factor is only 0.40% and 0.14% (to scheme
6), local nusselt number is distributed also almost the same (Fig. 7).Therefore, it in order to guarantee the accuracy calculated and reduce calculation amount, selects
The grid that grid number is 14,020,000.The case where for other geometric parameters, has selected grid having the same most using with front
The grid of small adherent size of mesh opening and grid growth rate and similar maximum mesh size.
Results and discussion：
In the case where channel width (W=300mm), fin thickness (t=1mm) and Reynolds number (Re=10000) are certain,
The opening width for studying channel height H, fin pitch P, fin height e, fin angle of attack α and single chevron passes heat collector
The optimal aperture width w of the single chevron in multiple V-shaped fin is analyzed in the influence of hot propertyoptChanging rule.
Fig. 8 gives in channel height H, opposing fins height e/DhWith opposing fins pitch P/e it is certain in the case where,
That is, logical H=25mm, e/DhWhen=0.043, P/e=10, average nusselt number Nu is with single chevron width w and fin angle of attack α
Situation of change.It can be seen that, with the increase of single chevron width, average nusselt number first increases when one timing of the fin angle of attack
After subtract, there are a maximum values.Increase of the maximum value of this average nusselt number with the fin angle of attack, first increases and then decreases,
Occurs maximum average nusselt number maximum value when α=45 °.Single V-arrangement corresponding with the maximum value of average nusselt number
Part width then increases with the increase of the fin angle of attack.That is, when the fin angle of attack is 30 °, 45 ° and 60 °, with average nusselt number
The corresponding chevron width of maximum value is respectively 27.2mm, 30.0mm and 42.9mm.
Fig. 9 and Figure 10 gives under the same conditions, friction factor f and thermal-hydraulic performance factor η are with single with Fig. 8
The situation of change of chevron width w and fin angle of attack α, they with the average nusselt number in the variation tendency and Fig. 8 of w variation
Trend is similar.As shown in Figure 10, the maximum value of thermal-hydraulic performance factor is reduced with the increase of the fin angle of attack.In addition, comparing
Fig. 8 and Figure 10 it is found that the maximum value of average nusselt number and the maximum value of thermal-hydraulic performance factor not always in identical list
Occur under a chevron width value.
It is existing in view of thermal-hydraulic performance factor can more reflect than average nusselt number the complex heat transfer performance of fin comprehensively
Geometric parameter when there is maximum value using thermal-hydraulic performance factor is as optimal geometrical parameter.As shown in Figure 10, when α=30 °
When, maximum thermal technology's hydraulic performance factor ηmaxIt is 2.3, best single chevron width w correspondinglyoptFor 30.0mm；When α=
At 45 °, ηmax=2.2, wopt=33.3mm；And when α=60 °, ηmax=2.0, wopt=42.9mm.
(the Solar Energy 2010 of document disclosed in Hans VS etc.；84:898-911) in, with the average Nu Saier of maximum
Corresponding number is w=50mm (W/w=6 at this time), this is a fixed value in the document, not with the variation of other geometric parameters
And change.Since the document is not involved with the concept of thermal-hydraulic performance factor, this is the best single V-arrangement that the document provides
Part width.In addition, the optimum rib angle of attack in the document is 60 °, this is also a fixed value.And in this calculating, scheming
Under the conditions of 10 fin height and pitch, the optimum value of both parameters is w=30.0mm and α=30 ° respectively.Therefore, from Fig. 8
With Figure 10 it is found that compared with provided using document [3] optimal parameter when as a result, if under the conditions of the fin height and pitch
Select the optimal geometrical parameter of this calculating, average nusselt number and thermal-hydraulic performance factor that can will be higher by 4.2% He respectively
15.0%.
Figure 11~12 are H=25mm, e/Dh=0.043, P/e=10 and when α=45 °, the cloud charts of nusselt number.By
Figure 11 can be seen that the width direction in channel, and local nusselt number shows periodic variation characteristic, and the period is single
The width w of chevron.The local peaking of length direction in channel, nusselt number first gradually increases with the increase of x, reaches maximum
It is gradually reduced again after value, about since at x=2/3L, the nusselt number between two adjacent fins does periodic variation.In V
Nearby there is the high nusselt number region in part in the front end of shape part, and then there is the low nusselt number in part near the rear end of chevron
Region.Figure 12 indicates the influence that is distributed to nusselt number of chevron width, by Figure 12 it can be seen that, when w is reduced to from 60.0mm
When 33.3mm, the area change in high nusselt number region is little near chevron front end, but the region is whole between two adjacent fins
Shared area specific gravity but increases in a region, and therefore, average nusselt number will increase.When w continues to be reduced to from 33.3mm
When 23.1mm, the peak-fall of local nusselt number is obvious, and high nusselt number region disappears substantially, this will lead to average Nu Saier
Several decline.Therefore, as shown in figure 8, average nusselt number can with the reduction of single chevron width occur first increase, after subtract
Small variation tendency.
Figure 13 is H=25mm, e/Dh=0.043, P/e=10 and motion pattern when α=45 °, under different chevron width.
For simplicity, the streamline in a chevron width range of channel center face y=W/2 is only gived in figure.Figure
In (I), (II), (III) and (IV) be respectively main view, the enlarged drawing of dotted box portion in main view, dotted line frame portion in main view
The top perspective view and right view divided.As seen from Figure 13, every a line chevron along channel-length direction arrangement can all induce
Generate the opposite spiral shape longitudinal direction vortex in a pair of of direction of rotation.Therefore, n weight V-arrangement fin can induce generation 2n longitudinal vortex, this
Flowing is divided into 2n mutually independent Secondary Flow units in the width direction in channel by a little vortexs, in adjacent Secondary Flow unit
The direction of rotation of these vortexs is opposite.When w reduces (or n increases), the streamline beam of vortex gradually dissipates, in a z-direction to master
The perturbation distance in stream area also gradually becomes smaller, these phenomenons are more obvious at w hours, meanwhile, the pitch of vortex also gradually becomes smaller.When
When longitudinal vortex (main vortex) fluid flows through the region between two adjacent fins, secondary vortex (figure can be also generated in the area
Streamline 1 in 13).Moreover, when fluid skims over fin, all close to that portion of chevron front end only on the direction z and the direction y
Shunting body could be formed secondary vortex (streamline 1), and remaining fluid (streamline 2,3,4) is just fallen into after then crossing over this secondary vortex
Region between fin, so as to cause the separation of flowing.
Fluid is rotating under the action of main vortex and rushes at absorber plate, flows between two adjacent fins from chevron front end
Space, the region between inswept fin, then flows out near chevron rear end.The cold fluid of main vortex bring main flow area is in V-arrangement
Part front end area washes away absorber plate, reduces the temperature of absorber plate at this, to improve the local nusselt number at this.Another party
Face is heated when being flowed through the region between fin due to fluid by absorber plate, has higher temperature when reaching chevron back-end region,
This can improve the temperature of absorber plate at this, reduce the local nusselt number at this.Therefore, as shown in figure 11, local nusselt number
Can occur violent variation in y-direction.In addition, secondary vortex can further promote local blending of falling liquid film, make nusselt number
It is generated in secondary vortex and reaches local peaking near point.
In four wall surfaces in channel, wall surface only with ribbing could induce the generation of vortex.Pledge love in channel height H mono-
Under condition, as w is reduced, the cross-sectional width of each Secondary Flow unit also becomes smaller, and side length with ribbing is in Secondary Flow cell cross-section
Perimeter in shared specific gravity reduce, therefore, the driving force for generating main vortex becomes smaller, the weakened of main vortex, so that streamline
Misconvergence of beams and becoming smaller to the range of disturbance of main flow area, this can weaken the blending of the neighbouring hot fluid of main flow area cold fluid and absorber plate,
To reduce nusselt number and flow resistance.At the same time, when w is reduced, the side length of chevron shortens, so that in adjacent fin
Between the length of thermal boundary layer that grows up again also shorten therewith, this will increase average nusselt number.In addition, when w is reduced,
Need to consume more energy to generate more mutually independent Secondary Flow units, to increase flow resistance.It is previously noted that
When w is reduced, the pitch of main vortex is gradually become smaller, this meeting is so that main flow area cold fluid and the blending of hot fluid near absorber plate are secondary
Number increases, to increase nusselt number and flow resistance.
Therefore, the factors collective effect such as length of thermal boundary layer between the intensity, pitch of main vortex, adjacent fin makes average
There is a maximum value (such as Fig. 8) with the variation of w in nusselt number.Meanwhile friction factor also can the quantity of main vortex, intensity,
Under the combined influence of the factors such as pitch, there is a maximum value (such as Fig. 9) with the variation of w.
It is less that number is blended when w is larger (w=60.0mm), between cold fluid and hot fluid, and thermal boundary layer between adjacent fin
Length it is also larger, therefore average nusselt number is lower.But the temperature difference at this time between cold fluid and hot fluid is larger, the intensity of main vortex
It is relatively strong, therefore washed away at chevron front end by compared with the stronger of cold fluid, so the local nusselt number peak value at this is larger.With
The reduction of w (w=33.3mm), due to cold fluid and hot fluid blending number increase and adjacent fin between thermal boundary layer length become
Short, average nusselt number rises, but weakened due to main vortex and the cold fluid and hot fluid temperature difference become smaller, rushing at chevron front end
It brush intensity and is but gradually died down by the low temperature bring cooling effect of incoming fluid, therefore, phase the case where with when w=60.0mm
Than local nusselt number peak value can keep being basically unchanged.But it is further reduced (w=23.1mm) with w, due to main vortex
Intensity quickly die down, cause average nusselt number to begin to decline, in addition scouring intensity at chevron front end and by incoming fluid
Low temperature bring cooling effect also continue to decline, therefore the local nusselt number peak value at chevron front end will be also decreased obviously
(such as Figure 12).
Figure 14 is H=25mm, e/Dh=0.043, part when P/e=10 and w=42.9mm, under different fin angle of attack α
The cloud charts of nusselt number, from left to right the fin angle of attack is respectively 60 °, 45 ° and 30 °.Single chevron width value at this time is
Optimum value when α=60 °.As can be seen that with the reduction of the fin angle of attack, the high nusselt number region institute in whole region in part
The area specific gravity accounted for reduces.This is because single one timing of chevron width, with the reduction of the fin angle of attack, the side length of chevron
Elongated, correspondingly, the length of the thermal boundary layer between adjacent fin is also elongated, thus the reason for increasing low nusselt number region.
Fin for the angle of attack in Figure 14 less than 60 °, from the point of view of improving average nusselt number, current single chevron width is also
It has a margin, area specific gravity shared by low nusselt number region can be reduced by reducing single chevron width.Therefore, with rib
The reduction of the piece angle of attack, woptAlso it can reduce (such as Figure 10).
Figure 15 gives in channel height H, opposing fins height e/DhWith one timing of fin angle of attack α, that is, H=25mm, e/
DhWhen=0.043, α=45 °, thermal-hydraulic performance factor η with single chevron width w and opposing fins pitch P/e variation feelings
Condition.It can be found that when P/e increases to 10 from 6, woptIt is basically unchanged, and when P/e continues to increase to 20 from 10, woptIt can increase
Greatly.
When fin pitch increases, the fin quantity on main flow direction will tail off, this can weaken the driving force of main vortex, from
And reduce the intensity of main vortex.Meanwhile with the increase of fin pitch, along the length of the thermal boundary layer of main flow direction between adjacent fin
Degree also will correspondingly increase.In addition, Figure 16 gives H=25mm, e=2mm, α=45 °, when w=37.5mm, fin pitch pair
The influence situation of main vortex pitch, as shown in Figure 16, the pitch of main vortex can increase with the increase of fin pitch.Front mentions
Arrive, between the number of main vortex, intensity, pitch and adjacent fin length of thermal boundary layer etc. these influence thermal-hydraulic performances because
The factor of son can be influenced by single chevron width, thus there are one corresponding to the best of maximum thermal technology's hydraulic performance factor
The wide w of single chevronopt.The variation of the influence factor of this variation bring thermal-hydraulic performance factor by fin pitch, meeting
Lead to the variation (such as Figure 15) of best single chevron width.
Figure 17 gives in channel height H, opposing fins pitch P/e and one timing of fin angle of attack α, that is, H=25mm, P/e
When=10, α=45 °, thermal-hydraulic performance factor η is with single chevron width w and opposing fins height e/DhSituation of change.
It can be found that working as e/DhWhen increasing to 0.043 from 0.022, woptIt can reduce, but work as e/Dh0.087 is continued to increase to from 0.043
When, woptIt is basically unchanged.
When fin height increases, the flow area in channel becomes smaller, and fin enhances the disturbance of fluid, this will increase main rotation
The driving force in whirlpool, to increase the intensity of main vortex.Figure 18 gives H=25mm, P=20mm, α=45 °, when w=37.5mm,
Fin height is to the influence situation of main vortex pitch, and as shown in Figure 18, with the increase of fin height, the pitch of main vortex becomes
It is small.In addition, fin pitch will also increase, at this time main rotation when in the case where opposing fins pitch P/e is certain, fin height increases
The length of thermal boundary layer will also be influenced by fin pitch is increased between vortices breakdown, pitch and adjacent fin.Therefore, opposing fins are high
Spend e/DhVariation can cause to influence heat between the main vortex intensity, main vortex pitch and adjacent fin of best single chevron width
The variation of the factors such as boundary layer length, to change best single chevron width woptValue (such as Figure 17).
Figure 19 gives in opposing fins height e/Dh, opposing fins pitch P/e and the timing of fin angle of attack α one, that is, e/Dh
=0.043, P/e=10, when α=45 °, the influence of single chevron width w and channel height H to thermal-hydraulic performance factor.It can
With discovery, woptIt can increase with the increase of channel height.
When channel height increases, the height of Secondary Flow unit increases, this makes side length with ribbing in Secondary Flow unit
Shared specific gravity reduces in section girth, therefore, generates the driving force decline of main vortex, main vortex intensity weakens.Figure 20 gives
Go out P=20mm, e=2mm, α=45 °, when w=37.5mm, influence of the channel height to main vortex pitch, as shown in Figure 20,
With the increase of channel height, the pitch of main vortex will become larger.In addition, in opposing fins height e/DhWith opposing fins pitch P/
When channel height increases in the case that e is certain, the height of fin also will correspondingly increase with pitch, to further influence main rotation
The length of thermal boundary layer between vortices breakdown, pitch and adjacent fin.Therefore, the variation of channel height will lead to best single chevron
Width woptVariation (such as Figure 19).
Claims (6)
1. a kind of non-porous heat absorption flat plate type solar energy air heat collector, including ontology and transparent cover plate, the ontology is hollow
Without top formula frame structure, the top of ontology is arranged in the transparent cover plate, and absorber plate is arranged in the ontology, and the absorber plate will
Ontology is divided into the first cavity and the second cavity, and one end of second cavity is provided with air inlet, and the other end is provided with outlet air
Mouthful, which is characterized in that it is fixedly installed in certain intervals on the lower surface of the absorber plate arranged in parallel more between each other
A fin, the air as collection thermal medium are contacted with fin and are flowed along the length direction of heat collector, and the fin is by multiple V
Shape part is extended in end to end mode along the width direction interconnection of heat collector,
The opening width w of the chevron is as shown in formula I：
W=C0+35×(H/H0-1)-12×(e/e0-1)+2×(P/P0-1)+9×(α/α0- 1) (mm) (formula I)
In formula I, H is the distance between absorber plate lower surface and the second well floor inner wall, and e is chevron height, and P is fin section
Away from α is the angle of attack；H=20~30mm, e=1~3mm, P/e=8~12, α=30~45 °, C0=30~37.5, H0=25mm,
e0=2mm, P0=20mm, α0=45 °.
2. solar energy air heat collector according to claim 1, which is characterized in that in formula (I), H=25mm, e=
2mm, P/e=10, α=30 °.
3. solar energy air heat collector according to claim 1, which is characterized in that the α is between two branches of chevron
Angle 1/2.
4. solar energy air heat collector according to claim 1, which is characterized in that first cavity and the second cavity are
Mutually independent space.
5. solar energy air heat collector according to claim 1, which is characterized in that the material of the chevron is thermally conductive gold
Belong to material.
6. solar energy air heat collector according to claim 1, which is characterized in that the chevron is equilateral V-type, identical
Multiple chevrons be connected with each other in width direction along heat collector in such a way that head and the tail connect and extend and form a fin,
In the same plane, and the opening endpoint of all chevrons in each fin is same for all chevrons in each fin
On straight line, the straight line is vertical with heat collector side wall.
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| CN201810427378.8A CN108826713B (en) | 2018-05-07 | 2018-05-07 | A kind of non-porous heat absorption flat plate type solar energy air heat collector |
| KR1020180121066A KR102169394B1 (en) | 2018-05-07 | 2018-10-11 | A solar air heater with an imperforated flat absorber plate |
| JP2018215143A JP6672434B2 (en) | 2018-05-07 | 2018-11-16 | Non-porous heat-absorbing flat panel solar air collector |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH034934A (en) * | 1989-05-31 | 1991-01-10 | Shinwa Sangyo Kk | Packing plate for gas-liquid contact |
| DE29620248U1 (en) * | 1996-11-21 | 1997-02-13 | Kuhr Thomas | Counterflow heat exchanger made of profile plates |
| JP2002071289A (en) * | 2000-08-30 | 2002-03-08 | Toshiba Kyaria Kk | Heat exchanger for air conditioner |
| CN200996736Y (en) * | 2006-12-29 | 2007-12-26 | 苏文佳 | Solar V-shaped plated double-range air heat collecter with cellular structure |
| CN102706016A (en) * | 2012-06-07 | 2012-10-03 | 西藏自治区能源研究示范中心 | Absorber plate core for flat plate solar thermal collector and solar thermal collector |
| CN202947523U (en) * | 2012-11-30 | 2013-05-22 | 艾普尔换热器(苏州)有限公司 | Fin of heat exchanger |
| CN206755620U (en) * | 2017-03-17 | 2017-12-15 | 浙江理工大学 | A kind of V-type thermal-arrest orifice plate resistance balancing type solar energy air heat collector |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20160011724A (en) * | 2014-07-22 | 2016-02-02 | 주식회사 탑솔 | Hybrid plain to complex use of air heat and solar thermal |
| KR101623351B1 (en) * | 2015-01-12 | 2016-05-23 | 공주대학교 산학협력단 | Air Type Photohvoltaic-thermal Hybrid System |
-
2018
- 2018-05-07 CN CN201810427378.8A patent/CN108826713B/en active Active
- 2018-10-11 KR KR1020180121066A patent/KR102169394B1/en active IP Right Grant
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Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH034934A (en) * | 1989-05-31 | 1991-01-10 | Shinwa Sangyo Kk | Packing plate for gas-liquid contact |
| DE29620248U1 (en) * | 1996-11-21 | 1997-02-13 | Kuhr Thomas | Counterflow heat exchanger made of profile plates |
| JP2002071289A (en) * | 2000-08-30 | 2002-03-08 | Toshiba Kyaria Kk | Heat exchanger for air conditioner |
| CN200996736Y (en) * | 2006-12-29 | 2007-12-26 | 苏文佳 | Solar V-shaped plated double-range air heat collecter with cellular structure |
| CN102706016A (en) * | 2012-06-07 | 2012-10-03 | 西藏自治区能源研究示范中心 | Absorber plate core for flat plate solar thermal collector and solar thermal collector |
| CN202947523U (en) * | 2012-11-30 | 2013-05-22 | 艾普尔换热器(苏州)有限公司 | Fin of heat exchanger |
| CN206755620U (en) * | 2017-03-17 | 2017-12-15 | 浙江理工大学 | A kind of V-type thermal-arrest orifice plate resistance balancing type solar energy air heat collector |
Also Published As
| Publication number | Publication date |
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| JP2019196897A (en) | 2019-11-14 |
| KR20190128105A (en) | 2019-11-15 |
| JP6672434B2 (en) | 2020-03-25 |
| CN108826713B (en) | 2019-11-26 |
| KR102169394B1 (en) | 2020-10-26 |
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