CN103684236B - A kind of disc type solar energy concentrator and method for designing thereof - Google Patents

Abstract

A kind of disc type solar energy concentrator, dish is provided with circular open bottom face, and dish face is surface of revolution, and the bus of surface of revolution is based on specific First-Order Nonlinear Differential Equation curve.A method for designing for disc type solar energy concentrator, according to uniform light principle of reflection and related optical geometric knowledge, draws the specific First-Order Nonlinear Differential Equation bus equation of the surface of revolution in dish face through calculating to derive.Provided by the invention there is dish face bottom opening, disc type solar energy concentrator and method for designing thereof that the surface of revolution bus in dish face is specific First-Order Nonlinear Differential Equation curve, this disc type solar energy concentrator can form very uniform heat flux distribution on the receiver, significantly improve energy conversion efficiency and other combination property of concentrator, be specially adapted to the concentration photovoltaic solar energy device of large scale receiver.

Description

A kind of disc type solar energy concentrator and method for designing thereof

Technical field

The present invention relates to a kind of disc type solar energy concentrator and method for designing thereof, belong to solar concentrator technical field.

Background technology

Solar energy, as a kind of cleanliness without any pollution, inexhaustible regenerative resource, becomes the study hotspot of current energy field day by day.Particularly concentration photovoltaic solar energy technology develops rapidly in recent years, does not reduce total system cost gradually, and effectively improves energy conversion efficiency and produce electricity, thus obtain applying more and more widely by means of only minimizing photovoltaic cell raw material.Concentration photovoltaic solar energy device adopts dish-style concentrator, and the reflector of dish-style concentrator is the paraboloid of revolution, has good condenser performance and solar collecting performance.

But, also there is intrinsic defect in existing disc type solar energy concentrator: namely the geometrical property of the paraboloid of revolution structure in reflection dish face itself is make light to focus, therefore, the light formed after the reflection of dish face is heterogeneous naturally, and the hot-fluid thus formed on the receiver is also heterogeneous.The hot-fluid on receiver surface is uneven, and both reduced the light gathering efficiency of concentrator, too high hot-fluid easily causes again the damage of element, equipment, has had a strong impact on the combination property of solar concentrator, also prevents the development of solar concentrator maximization, scale.In addition, make the middle part of dish-style concentrator there is no light because receiver blocks, the reflective structure thus in the middle part of dish-style concentrator is unactual to be used, and there is structure waste.The more important thing is, define shadow region, middle part due to blocking of receiver on the receiver, receiver heat flux distribution defines medial recess, exacerbates the problem that receiver heat flux distribution is uneven.

See shade defect schematic diagram in the middle part of the optically focused of the existing dish-style concentrator of Fig. 1, incident ray from receiver edge is after the reflection of dish-style concentrator, disperse after re-shooting receiver after burnt stream interface focuses on, a fritter shadow region is formed at the middle part of receiver, can learn according to optics geometric knowledge, without any light in this fritter shadow region, thus the hot-fluid in this region is very little, and this phenomenon is called burnt stream interface medial recess phenomenon.See the receiver heat flux distribution schematic diagram of the existing dish-style concentrator of Fig. 2, focussing force due to the paraboloid of revolution makes the heat flow at receiver edge be less than middle part, and burnt stream interface medial recess phenomenon causes middle part hot-fluid depression, thus define the curve distribution of dual hump formula in the heat flux distribution of whole receiver, heat flux distribution is extremely uneven.

Receiver surface heat flow uneven phenomenon has had a strong impact on the application of disc type solar energy concentrator, mainly can cause hot spot effect, and then have a negative impact to solar cell on the impact of photovoltaic cell.Along with the development of photovoltaic generating system, the physical dimension of dish-style concentrator constantly increases, this phenomenon of blocking the heat flux distribution inequality of formation due to receiver is even more serious, in addition large-scale concentrator itself more easily produce making, alignment error, the factors such as ray trace trueness error, exacerbate the degree that focal beam spot is large, heat flux distribution is uneven of receiver especially, thus, the technical problem of receiver surface heat flow inequality has seriously perplexed further genralrlization and the development of disc type solar energy concentrator.

Summary of the invention

What object of the present invention was intended to exist for existing disc type solar energy concentrator blocks due to receiver, the receiver heat flux distribution that the factors such as paraboloid of revolution geometry cause is uneven, affect condenser performance, reduce the shortcomings and deficiencies such as energy conversion efficiency, one is provided to have dish face bottom opening, the surface of revolution bus in dish face is disc type solar energy concentrator and the method for designing thereof of special curve, this disc type solar energy concentrator can form comparatively uniform heat flux distribution on the receiver, improve energy conversion efficiency and other combination property of concentrator, be specially adapted to the concentration photovoltaic solar energy device of large scale receiver.

The present invention is the technical scheme that actualizing technology object adopts: a kind of disc type solar energy concentrator, comprise dish face and receiver, described dish face is surface of revolution, and be provided with the circular open that diameter is more than or equal to the diameter of receiver bottom dish face, the bus of the surface of revolution in described dish face is the curve described based on following First-Order Nonlinear Differential Equation Y1 or Y2, and the surface of revolution bus in described dish face to be blocked symmetrically by the line segment that length equals dish face bottom opening diameter be two sections of curves:

$Y^{\′}=\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{{4Y}^2-{d_0}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{{4Y}^2-{d_0}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}---\left(Y1\right)$

Or

$Y^{\′}=\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{{1-4Y}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{1-{4Y}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}---\left(Y2\right)$

In above formula: a is the diameter of receiver, and D is dish face diameter, a ₀represent the dimensionless diameter of receiver;

d is dish face bottom opening diameter, and D is dish face diameter, d ₀represent dish face bottom opening dimensionless diameter;

l is the distance to receiver bottom dish face, L ₀represent the dimensionless distance to receiver bottom dish face;

Y represents the ordinate of any point on dish face, and Y ' represents the derivative value of point (X, Y) on dish face;

Y (0)=d0/2 represents the starting point of bus, is the initial condition of this differential equation.

A method for designing for disc type solar energy concentrator, comprises the following steps:

(1) basic parameter setting described disc type solar energy concentrator is: dish face diameter is D, and dish face bottom opening diameter is d, and be L to the distance of receiver bottom dish face, the diameter of receiver is a;

Assuming that the incidence point coordinate of an incident ray on dish face is (x, y), the distance of the incidence point of incident ray on dish face and symmetry axis is L ₁, the distance of incident ray incidence point on the receiver and symmetry axis is L _2,, for making the hot spot in receiver plane be uniformly distributed parallel input light, from geometric knowledge, then this light is at circular area (the π * L of receiver plane ₁^2) the dish face annulus area in described incident ray incidence range and the ratio of the total annulus area in dish face should be equaled with the ratio of whole theoretical facula area (1/4* π * a^2), obtain following equation a1 thus:

$\frac{\mathrm{\π}{L_2}^2}{\mathrm{\π}\frac{1}{4}{a}^2}=\frac{\mathrm{\π}({L_1}^2-\frac{1}{4}{d}^2)}{\frac{1}{4}\mathrm{\π}(D^2-d^2)}(\frac{d}{2}\≤L_1\≤\frac{D}{2},0\≤a\≤d)---\left(a1\right)$

(2) following dimensionless group is introduced further:

$\begin{array}{ccccc}{a}_0=\frac{a}{D}& d_0=\frac{d}{D}& L_0=\frac{L}{D}& X=\frac{x}{D}& Y=\frac{y}{D}\end{array}$

In formula: a ₀represent the dimensionless diameter of receiver;

D ₀represent dish face bottom opening dimensionless diameter;

L ₀represent the dimensionless distance to receiver bottom dish face;

X represents the dimensionless abscissa of the incidence point of incident ray on dish face;

Y represents the dimensionless ordinate of the incidence point of incident ray on dish face;

(3) following equations b1, c1, d1 can be obtained by geometrical relationship:

$Y^{\′}=\tan (\frac{\mathrm{\π}}{2}-\frac{\mathrm{\θ}}{2})---\left(b1\right)$

$Y-(L_0-X)\tan \mathrm{\θ}=\frac{L_2}{D}---\left(c1\right)$

$Y=\frac{L_1}{D}---\left(d1\right)$

In above-mentioned equation, Y ' represents the derivative at (X, Y) some place, and θ represents the incident light of incident ray on dish face and the angle of reverberation;

(4) by equation b1 and c1 simultaneous solution cancellation angle θ, and obtained equation is substituted into equation a1 together with equation d1, calculates and after arranging, obtain the First-Order Nonlinear Differential Equation Y1 describing dish face surface of revolution bus:

$Y^{\′}=\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{{4Y}^2-{d_0}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{{4Y}^2-{d_0}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}$

A method for designing for disc type solar energy concentrator, comprises the following steps:

(1) basic parameter of described disc type solar energy concentrator is: dish face opening diameter is D, and bottom surface, dish face opening diameter is d, and be L to the distance of receiver bottom dish face, the diameter of receiver is a;

Assuming that the incidence point coordinate of an incident ray on dish face is (x, y), the distance of the incidence point of incident ray on dish face and symmetry axis is L ₁, incidence point on the receiver and the distance of symmetry axis are L ₂, for making the hot spot in receiver plane be uniformly distributed parallel input light, from geometric knowledge, then this light is at circular area (the π * L of receiver plane ₁dish face annulus area and the ratio of the total annulus area in dish face in the incidence range that ^2) should equal described incident ray with the ratio of whole theoretical facula area (1/4* π * a^2), obtain following equation (a2) thus:

$\frac{\mathrm{\π}{L_2}^2}{\mathrm{\π}\frac{1}{4}{a}^2}=\frac{\mathrm{\π}(\frac{1}{4}{D}^2-{L_1}^2)}{\frac{1}{4}\mathrm{\π}(D^2-d^2)}(\frac{d}{2}\≤L_1\≤\frac{D}{2},0\≤a\≤d)---\left(a2\right)$

(2) following dimensionless group is introduced further:

$\begin{array}{ccccc}{a}_0=\frac{a}{D}& d_0=\frac{d}{D}& L_0=\frac{L}{D}& X=\frac{x}{D}& Y=\frac{y}{D}\end{array}$

In formula: a ₀represent the dimensionless diameter of receiver;

D ₀represent dish face bottom opening dimensionless diameter;

L ₀represent the dimensionless distance to receiver bottom dish face;

X represents the dimensionless abscissa of the incidence point of incident ray on dish face;

Y represents the dimensionless ordinate of the incidence point of incident ray on dish face;

(3) following equations b2, c2, d2 can be obtained by geometrical relationship:

$Y^{\′}=\tan (\frac{\mathrm{\π}}{2}-\frac{\mathrm{\θ}}{2})---\left(b2\right)$

$(L_0-X)\tan \mathrm{\θ}-Y=\frac{L_2}{D}---\left(c2\right)$

$Y=\frac{L_1}{D}---\left(d2\right)$

In above-mentioned equation, Y ' represents the derivative at (X, Y) some place, and θ represents the incident light of the incidence point of incident ray on dish face and the angle of reverberation;

(4) by equation b2 and c2 simultaneous solution cancellation angle θ, and obtained equation is substituted into equation a2 together with equation (d2), calculates and after arranging, obtain the First-Order Nonlinear Differential Equation Y2 describing dish face surface of revolution bus:

$Y^{\′}=\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{{1-4Y}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{1-{4Y}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}$

Compared with prior art, beneficial effect of the present invention is:

1., for opening designs bottom the dish face of dish-style concentrator of the present invention, saved the reflective structure not having actual use in the middle part of dish-style concentrator because receiver blocks, reduced infrastructure cost.

2. the bus of the surface of revolution in the dish face of dish-style concentrator of the present invention is based on specific First-Order Nonlinear Differential Equation curve, this curvilinear equation is according to uniform light principle of reflection and related optical geometric knowledge, draw through calculating derivation, thus make the receiver surface heat flow of dish-style concentrator of the present invention distribute and be tending towards even, significantly improve condenser performance and the energy conversion efficiency of concentrator, and other combination property.

3. the method for designing of dish-style concentrator of the present invention, use uniform light principle of reflection and related optical geometric knowledge, the First-Order Nonlinear Differential Equation of dish face surface of revolution bus is drawn through calculating to derive, the receiver surface heat flow of the dish-style concentrator of design is distributed and is tending towards even, significantly improve condenser performance and the energy conversion efficiency of concentrator, and other combination property.

Accompanying drawing explanation

Fig. 1 is the middle part shade defect schematic diagram of existing dish-style concentrator.

Fig. 2 is the receiver heat flux distribution schematic diagram of existing dish-style concentrator.

Fig. 3 is first embodiment of the present invention A-type dish face and concentrating light principles schematic diagram.

Fig. 4 is second embodiment of the present invention B-type dish face and concentrating light principles schematic diagram.

Fig. 5 is the stereogram in the dish face of dish-style concentrator of the present invention.

Fig. 6 is the receiver heat flux distribution schematic diagram in first embodiment of the present invention A-type dish face.

Fig. 7 is the receiver heat flux distribution schematic diagram in second embodiment of the present invention B-type dish face.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

Disc type solar energy concentrator provided by the invention, comprises dish face and receiver, and wherein, dish is provided with circular open bottom face, and the diameter d of circular open is more than or equal to receiver diameter.Consider according to the situation being generally directional light incidence, due to blocking of receiver, the circular portion being less than receiver diameter bottom dish face there is no light, and therefore its reflective structure can omit, therefore bottom dish face, arrange the circular open being more than or equal to receiver diameter.

See Fig. 3, first embodiment A-type dish face of disc type solar energy concentrator of the present invention and concentrating light principles schematic diagram, dish face is surface of revolution, the bus of the surface of revolution in dish face is the curve described based on following First-Order Nonlinear Differential Equation Y1, and the surface of revolution bus in dish face to be blocked symmetrically by the line segment that length equals dish face bottom opening diameter be two sections of curves:

$Y^{\′}=\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{{4Y}^2-{d_0}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{{4Y}^2-{d_0}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}$

In above formula: l ₀represent the dimensionless distance to PV receiver bottom ground;

a is the diameter of receiver, and D is dish face diameter, a ₀represent the dimensionless diameter of receiver;

d is dish face bottom opening diameter, and D is dish face diameter, d ₀represent dish face bottom opening dimensionless diameter;

Y represents the ordinate of any point on dish face, and Y ' represents the derivative value of point (X, Y) on dish face;

Y (0)=d ₀the starting point of/2 expression buses is the initial condition of this differential equation.

First embodiment A-type dish face of disc type solar energy concentrator of the present invention obtains based on following methods design:

(1) basic parameter setting described disc type solar energy concentrator is: dish face diameter is D, and dish face bottom opening diameter is d, and be L to the distance of receiver bottom dish face, the diameter of receiver is a;

Assuming that the distance of incidence point on dish face of incident ray and symmetry axis is L ₁, incidence point on the receiver and the distance of symmetry axis are L ₂, for making the hot spot in receiver plane be uniformly distributed parallel input light, from geometric knowledge, then this light is at circular area (the π * L of receiver plane ₁^2) the dish face annulus area in described incident ray incidence range and the ratio of the total annulus area in dish face should be equaled with the ratio of whole theoretical facula area (1/4* π * a^2), be equivalent to a ring surface to project to the geometrical condition that a circular face must meet.

Obtain following equation a1 thus:

$\frac{\mathrm{\π}{L_2}^2}{\mathrm{\π}\frac{1}{4}{a}^2}=\frac{\mathrm{\π}({L_1}^2-\frac{1}{4}{d}^2)}{\frac{1}{4}\mathrm{\π}(D^2-d^2)}(\frac{d}{2}\≤L_1\≤\frac{D}{2},0\≤a\≤d)---\left(a1\right)$

(2) following dimensionless group is introduced further:

$\begin{array}{ccccc}{a}_0=\frac{a}{D}& d_0=\frac{d}{D}& L_0=\frac{L}{D}& X=\frac{x}{D}& Y=\frac{y}{D}\end{array}$

In formula: a ₀represent the dimensionless diameter of receiver;

D ₀represent dish face bottom opening dimensionless diameter;

L ₀represent the dimensionless distance to receiver bottom dish face;

X represents the dimensionless abscissa of the incidence point of incident ray on dish face;

Y represents the dimensionless ordinate of the incidence point of incident ray on dish face;

(3) following equations b1, c1, d1 can be obtained by geometrical relationship:

$Y^{\′}=\tan (\frac{\mathrm{\π}}{2}-\frac{\mathrm{\θ}}{2})---\left(b1\right)$

$Y-(L_0-X)\tan \mathrm{\θ}=\frac{L_2}{D}---\left(c1\right)$

$Y=\frac{L_1}{D}---\left(d1\right)$

In above-mentioned equation, Y ' represents the derivative at (X, Y) some place, and θ represents the angle of dish face M point reflection light and incident light, and Y represents dimensionless ordinate;

(4) by equation b1 and c1 simultaneous solution cancellation angle θ, and obtained equation is substituted into equation a1 together with equation d1, calculates and after arranging, obtain the First-Order Nonlinear Differential Equation Y1 of following description dish face surface of revolution bus:

$Y^{\′}=\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{{4Y}^2-{d_0}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{{4Y}^2-{d_0}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}$

See Fig. 4, second Embodiment B-type dish face of disc type solar energy concentrator of the present invention and concentrating light principles schematic diagram, dish face is surface of revolution, the bus of the surface of revolution in dish face is the curve described based on following First-Order Nonlinear Differential Equation, and the surface of revolution bus in dish face to be blocked symmetrically by the line segment that length equals dish face bottom opening diameter be two sections of curves:

$Y^{\′}=\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{{1-4Y}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{1-{4Y}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}$

In above formula: l ₀represent the dimensionless distance to PV receiver bottom ground;

a is the diameter of receiver, and D is dish face diameter, a ₀represent the dimensionless diameter of receiver;

d is bottom surface, dish face opening diameter, and D is dish face diameter, d ₀represent dish face bottom opening dimensionless diameter;

Y represents the ordinate of any point on dish face, and Y ' represents the derivative value of point (X, Y) on dish face;

Y (0)=d ₀the starting point of/2 expression buses is the initial condition of this differential equation.

Second Embodiment B-type dish face of disc type solar energy concentrator of the present invention obtains based on following method for designing:

(1) basic parameter of described disc type solar energy concentrator is: dish face opening diameter is D, and bottom surface, dish face opening diameter is d, and be L to the distance of receiver bottom dish face, the diameter of receiver is a;

Assuming that the distance of incidence point on dish face of incident ray and symmetry axis is L ₁, incidence point on the receiver and the distance of symmetry axis are L ₂, for making the hot spot in receiver plane be uniformly distributed parallel input light, from geometric knowledge, then this light is at circular area (the π * L of receiver plane ₁dish face annulus area and the ratio of the total annulus area in dish face in the incidence range that ^2) should equal described incident ray with the ratio of whole theoretical facula area (1/4* π * a^2), obtain following equation a2 thus:

$\frac{\mathrm{\π}{L_2}^2}{\mathrm{\π}\frac{1}{4}{a}^2}=\frac{\mathrm{\π}(\frac{1}{4}{D}^2-{L_1}^2)}{\frac{1}{4}\mathrm{\π}(D^2-d^2)}(\frac{d}{2}\≤L_1\≤\frac{D}{2},0\≤a\≤d)---\left(a2\right)$

(2) following dimensionless group is introduced further:

$\begin{array}{ccccc}{a}_0=\frac{a}{D}& d_0=\frac{d}{D}& L_0=\frac{L}{D}& X=\frac{x}{D}& Y=\frac{y}{D}\end{array}$

In formula: a ₀represent the dimensionless diameter of receiver;

D ₀represent dish face bottom opening dimensionless diameter;

L ₀represent the dimensionless distance to receiver bottom dish face;

X represents the dimensionless abscissa of the incidence point of incident ray on dish face;

Y represents the dimensionless ordinate of the incidence point of incident ray on dish face;

(3) following equations b2, c2, d2 can be obtained by geometrical relationship:

$Y^{\′}=\tan (\frac{\mathrm{\π}}{2}-\frac{\mathrm{\θ}}{2})---\left(b2\right)$

$(L_0-X)\tan \mathrm{\θ}-Y=\frac{L_2}{D}---\left(c2\right)$

$Y=\frac{L_1}{D}---\left(d2\right)$

In above-mentioned equation, Y ' represents the derivative at (X, Y) some place, and θ represents the angle of dish face M point reflection light and incident light, and Y represents dimensionless ordinate;

(4) by equation b2 and c2 simultaneous solution cancellation angle θ, and obtained equation is substituted into equation a2 together with equation d2, calculates and after arranging, obtain the First-Order Nonlinear Differential Equation Y2 of following description dish face surface of revolution bus:

$Y^{\′}=\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{{1-4Y}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{1-{4Y}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}$

First embodiment A-type dish face of disc type solar energy concentrator provided by the invention and the method for designing in the second Embodiment B-type dish face, carry out calculating owing to having used light reflection principle and relevant geometric knowledge to derive, obtain the special dish face that specific first order nonlinear curve rotates the ring-type surface of revolution formed, make to reflect through special dish face the light formed on the receiver and be tending towards even, thus equally distributed hot-fluid is formed on the receiver, considerably improve condenser performance and the energy conversion efficiency of solar concentrator, also be conducive to protecting relevant device, extend the useful life of solar concentrator.

For verifying that disc type solar energy concentrator of the present invention has more excellent condenser performance, first embodiment of the present invention A-type dish face and two kinds of concentrators in the second Embodiment B-type dish face and the concentrator in common paraboloid of revolution dish face have been carried out contrast experiment, namely under identical focusing ratio, relatively three kinds, the paraboloid of revolution dish face concentrator of A-type dish face, B-type dish face, prior art reflects different CSR(circumsolarratio) sun light beam of value, the heat flux distribution that receiver is formed on the surface, experimental result is see shown in Fig. 6, Fig. 7 and Fig. 2.

As can be seen from accompanying drawing 6, A-type dish face concentrator all forms quite uniform heat flux distribution on receiver surface, wherein, uniform condensing region area about 0.048, account for 80% of PV receiving area area 0.06, and in uniform condensing region, heat flux distribution is very even, does not almost have obvious peak value or concave point.As can be seen from accompanying drawing 7, B-type dish face concentrator also form quite uniform heat flux distribution on receiver surface, wherein, uniform condensing region area about 0.044, account for 73% of PV receiving area area 0.06, only have at middle part an area be 0.01 central protrusion region, account for 16.7% of PV receiving area area.And as can be seen from accompanying drawing 2, the paraboloid of revolution dish face concentrator of prior art, the heat flux distribution on receiver surface is the curve with two outstanding crest, substantially uniform condensing region is not had, hot-fluid peak 340 differs more than twice with minimum 100, thus receiver no matter focal plane or the heat flux distribution at rearmounted place all undesirable.In sum, two kinds of concentrators in the first embodiment A-type dish face provided by the invention and the second Embodiment B-type dish face, very uniform heat flux distribution all can be formed on receiver surface, energy conversion efficiency and other combination property of concentrator can be significantly improved, be specially adapted to the concentration photovoltaic solar energy device of large scale receiver.

Those skilled in the art will readily understand; the foregoing is only better enforcement example of the present invention; not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (3)

1. a disc type solar energy concentrator, comprise dish face and receiver, it is characterized in that: described dish face is surface of revolution, and be provided with the circular open that diameter is more than or equal to receiver diameter bottom dish face, the bus of the surface of revolution in described dish face is the curve described based on following First-Order Nonlinear Differential Equation Y1 or Y2, and the surface of revolution bus in described dish face to be blocked symmetrically by the line segment that length equals dish face bottom opening diameter be two sections of curves:

$Y^{\′}=\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{4Y^2-{d_0}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{4Y^2-{d_0}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}---\left(Y1\right)$

Or

$Y^{\′}=\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{1-4Y^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{1-4Y^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}---\left(Y2\right)$

In above formula: a is the diameter of receiver, and D is dish face opening diameter, a ₀represent the dimensionless diameter of receiver;

d is dish face bottom opening diameter, d ₀represent dish face bottom opening dimensionless diameter;

l is the distance to receiver bottom dish face, L ₀represent the dimensionless distance to receiver bottom dish face;

Y represent incidence point on dish face dimensionless ordinate, Y ' represents the derivative value of point (X, Y) on dish face, and wherein X represents the dimensionless abscissa of the incidence point of incident ray on dish face;

Y (0)=d ₀the starting point of/2 expression buses is the initial condition of this differential equation.

2. a method for designing for disc type solar energy concentrator according to claim 1, is characterized in that comprising the following steps:

(1) basic parameter setting described disc type solar energy concentrator is: dish face diameter is D, and dish face bottom opening diameter is d, and be L to the distance of receiver bottom dish face, the diameter of receiver is a;

Assuming that the incidence point coordinate of an incident ray on dish face is (x, y), the distance of the incidence point of incident ray on dish face and symmetry axis is L ₁, the distance of incident ray incidence point on the receiver and symmetry axis is L ₂, for making the hot spot in receiver plane be uniformly distributed parallel input light, from geometric knowledge, then this light is at circular area (the π * L of receiver plane ₁^2) the dish face annulus area in described incident ray incidence range and the ratio of the total annulus area in dish face should be equaled with the ratio of whole theoretical facula area (1/4* π * a^2), obtain following equation a1 thus:

$\frac{{{\mathrm{\πL}}_2}^2}{\mathrm{\π}\frac{1}{4}{a}^2}=\frac{\mathrm{\π}\left({L_1}^2-\frac{1}{4}{d}^2\right)}{\frac{1}{4}\mathrm{\π}\left(D^2-d^2\right)}\left(\frac{d}{2}\≤L_1\≤\frac{D}{2},0\≤a\≤d\right)---\left(a1\right)$

(2) following dimensionless group is introduced further:

$\begin{array}{ccccc}{a}_0=\frac{a}{D}& d_0=\frac{d}{D}& L_0=\frac{L}{D}& X=\frac{x}{D}& Y=\frac{y}{D}\end{array}$

In formula: a ₀represent the dimensionless diameter of receiver;

D ₀represent dish face bottom opening dimensionless diameter;

L ₀represent the dimensionless distance to receiver bottom dish face;

X represents the abscissa of the incidence point of incident ray on dish face;

Y represents the ordinate of the incidence point of incident ray on dish face;

(3) following equations b1, c1, d1 can be obtained by geometrical relationship:

$Y^{\′}=tan(\frac{\mathrm{\π}}{2}-\frac{\mathrm{\θ}}{2})---\left(b1\right)$

$Y-(L_0-X)tan\mathrm{\θ}=\frac{L_2}{D}---\left(c1\right)$

$Y=\frac{L_1}{D}---\left(d1\right)$

In above-mentioned equation: Y ' represents the derivative at (X, Y) some place, and θ represents the incident light of incident ray on dish face and the angle of reverberation;

(4) by equation b1 and c1 simultaneous solution cancellation angle θ, and obtained equation is substituted into equation a1 together with equation d1, calculates and after arranging, obtain the First-Order Nonlinear Differential Equation Y1 describing dish face surface of revolution bus:

$Y^{\′}=\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{4Y^2-{d_0}^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y-\frac{a_0}{2}\sqrt{\frac{4Y^2-{d_0}^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}---\left(Y1\right).$

3. a method for designing for disc type solar energy concentrator according to claim 1, is characterized in that comprising the following steps:

(1) basic parameter of described disc type solar energy concentrator is: dish face opening diameter is D, and bottom surface, dish face opening diameter is d, and be L to the distance of receiver bottom dish face, the diameter of receiver is a;

Assuming that the incidence point coordinate of an incident ray on dish face is (x, y), the distance of the incidence point of incident ray on dish face and symmetry axis is L ₁, incidence point on the receiver and the distance of symmetry axis are L ₂, for making the hot spot in receiver plane be uniformly distributed parallel input light, from geometric knowledge, then this light is at circular area (the π * L of receiver plane ₁dish face annulus area and the ratio of the total annulus area in dish face in the incidence range that ^2) should equal described incident ray with the ratio of whole theoretical facula area (1/4* π * a^2), obtain following equation a2 thus:

$\frac{{{\mathrm{\πL}}_2}^2}{\mathrm{\π}\frac{1}{4}{a}^2}=\frac{\mathrm{\π}(\frac{1}{4}{D}^2-{L_1}^2)}{\frac{1}{4}\mathrm{\π}(D^2-d^2)}(\frac{d}{2}\≤L_1\≤\frac{D}{2},0\≤a\≤d)---\left(a2\right)$

(2) following dimensionless group is introduced further:

$\begin{array}{ccccc}{a}_0=\frac{a}{D}& d_0=\frac{d}{D}& L_0=\frac{L}{D}& X=\frac{x}{D}& Y=\frac{y}{D}\end{array}$

In formula: a ₀represent the dimensionless diameter of receiver;

D ₀represent dish face bottom opening dimensionless diameter;

L ₀represent the dimensionless distance to receiver bottom dish face;

X represents the abscissa of the incidence point of incident ray on dish face;

Y represents the ordinate of the incidence point of incident ray on dish face;

(3) following equations b2, c2, d2 can be obtained by geometrical relationship:

$Y^{\′}=tan(\frac{\mathrm{\π}}{2}-\frac{\mathrm{\θ}}{2})---\left(b2\right)$

$(L_0-X)tan\mathrm{\θ}-Y=\frac{L_2}{D}---\left(c2\right)$

$Y=\frac{L_1}{D}---\left(d2\right)$

In above-mentioned equation, Y ' represents the derivative at (X, Y) some place, and θ represents the incident light of the incidence point of incident ray on dish face and the angle of reverberation;

(4) by equation b2 and c2 simultaneous solution cancellation angle θ, and obtained equation is substituted into equation a2 together with equation d2, calculates and after arranging, obtain the First-Order Nonlinear Differential Equation Y2 of following description dish face surface of revolution bus:

$Y^{\′}=\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{1-4Y^2}{1-{d_0}^2}}}+\sqrt{{\left(\frac{L_0-X}{Y+\frac{a_0}{2}\sqrt{\frac{1-4Y^2}{1-{d_0}^2}}}\right)}^2+1},Y\left(0\right)=\frac{d_0}{2}---\left(Y2\right).$