Standards related to:

GB/T 34334-2017GB/T 34334-2017

GB

NATIONAL STANDARD OF THE

PEOPLE’S REPUBLIC OF CHINA

ICS 81.040.30

Q 34

Test method of mirror shape for solar collector

ISSUED ON. OCTOBER 14, 2017

IMPLEMENTED ON. SEPTEMBER 1, 2018

Issued by. General Administration of Quality Supervision, Inspection and

Quarantine;

Standardization Administration Committee.

Table of Contents

Foreword . 3

1 Scope .. 4

2 Terms and definitions .. 4

3 Symbols.. 5

4 Test principle .. 6

5 Instruments .. 6

6 Testing process .. 11

7 Parameter calculation .. 11

8 Test report .. 18

Foreword

This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This Standard was proposed by China Federation of Building Materials.

This Standard shall be under the jurisdiction of National Technical Committee

on Industrial Glass and Special Glass of Standardization Administration of

China (SAC/TC 447).

The drafting organizations of this Standard. Beijing Aobotai Technology Co.,

Ltd., China Building Materials Inspection & Certification Group Co., Ltd., China

Haiyang Energy Group Co., Ltd., China Guangdong Nuclear Power

Development Co., Ltd.

Main drafters of this Standard. Bo Cong, Wang Jingjing, Zhang Zhemin, Li

Menglei, Wang Shanshan, Lu Jun, Zhang Yuxia, Yuan Jing, Wang Dong, Qiu

Juan, Li Boye, Li Yang, Wang Lichuang, Yang Fan, Feng Tian, Fu Lu, Zhu

Xiaowei, Zhang Ji, Yang Hui, Qi Bin.

Test method of mirror shape for solar collector

1 Scope

This Standard specifies the terms and definitions, symbols, test principle,

instruments, test procedures, parameter calculation and test report of mirror

shape for solar collector based on stripe reflection principle.

This Standard is applicable to the tests of mirror shape for slot, dish, tower solar

collectors.

2 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

2.1 height deviation

height deviation in the reference direction between the actual mirror and the

ideal mirror

2.2 slope

the tangent of the angle between the tangent plane and the reference plane at

a point on the reflector

2.3 slope deviation

the angle between the actual mirror normal and the ideal mirror normal at a

point on the mirror

2.4 focus deviation

under use conditions, the distance from the reflected light to the mirror's ideal

focus or focal line

2.5 focus deviation distribution

the distribution of focus point deviation of the mirror on the reference plane

2.6 parallel ray intercept factor

parallel light rays evenly distributed along the ideal direction of incidence, the

ratio of the amount of light reflected by the mirror to the heat sink to the amount

of light incident on the mirror

2.7 sun intercept factor

the ratio of the amount of sunlight reflected in the ideal direction of incidence to

the heat sink by the mirror TO the amount of light incident on the mirror

2.8 intercept factor distribution

take the diameter of the heat-absorbing device as the abscissa, the actual

mirror-parallel light-cutting factor of the corresponding caliber as the ordinate,

form the distribution curve of the parallel light-cutting factor under different

caliber conditions

2.9 concentrating quality factor

the ratio of the area under the actual mirror parallel light cut-off factor

distribution curve TO the area under the ideal mirror parallel light cut-off factor

distribution curve with a use aperture of the heat-absorbing device as the

boundary condition of the parallel light cut-off factor distribution curve

3 Symbols

The following symbols apply to this document.

CQF. concentrating quality factor

FDx. mean square root of focus deviation in x-axis direction in the use

coordinate system (xyz)

fdx (X, Y). focus deviation distribution in X-axis direction in the measurement

coordinate system (XYZ)

FDy. mean square root of focus deviation in y-axis direction in the use

coordinate system (xyz)

fdy (X, Y). focus deviation distribution in Y-axis direction in the measurement

coordinate system (XYZ)

HD. mean square root of height deviation in the measurement coordinate

system (XYZ)

hd (X, Y). mirror height deviation distribution in the measurement coordinate

system (XYZ)

IC. parallel ray intercept factor

ICsun. sun intercept factor

RIC(φ). parallel ray intercept factor distribution of heat absorption device

g (X, Y) - the slope at some fixed point (X, Y) on the tested mirror; its modulus

value is calculated according to equation (4).

5.2.4 Obtain mirror shape parameters

5.2.4.1 According to the mirror shape obtained from the measurement

coordinate system, the following parameters can be calculated. height deviation

distribution hd(X, Y), mean square root of height deviation HD, slope deviation

distribution sdX(X, Y) in the X axis direction, slope deviation distribution sdY(X,

Y) in the Y axis direction, mean square root of slope deviation in X-axis direction

SDX, mean square root of slope deviation in Y-axis direction SDY, focus

deviation distribution in X-axis direction fdX (X, Y), focus deviation distribution

in X-axis direction fdY (X, Y).

5.2.4.2 Convert the slope distribution gx (X, Y), gy (X, Y) in the measurement

coordinate system XYZ to the slope distribution gx (x, y), gy (x, y) in the use

coordinate system xyz according to the use requirements. In the use coordinate

system xyz, the z-axis is the direction of the ideal incident light, the y-axis is the

mirror bus direction, and the x-axis is the vertical yoz plane direction. Use linear

interpolation or area projection weighing methods, in the use coordinate system

xyz plane, according to the parameter calculation requirements, form an equal

interval slope distribution. Combined with the sun divergence angle and the

diameter of the heat collector, the following parameters can be calculated.

mean square root of focus deviation in x-axis direction FDx, mean square root

of focus deviation in y-axis direction FDy, parallel ray intercept factor IC, sun

intercept factor ICsun, parallel ray intercept factor distribution of heat absorption

device RIC(φ), concentrating quality factor CQF.

5.3 Requirements

5.3.1 Sample bench

The sample bench shall satisfy the positioning installation of the tested sample.

The sample positioning accuracy shall be less than 1mm.

5.3.2 Graphic generator

The graphic generator can be implemented by a display or projection method

that can generate a dynamic pattern. The display area shall meet the complete

reflective mirror test of the tested sample.

sdX - the slope deviation of the surface test point of the test sample in the X-

axis direction, in milliradians (mrad);

β'X - the angle between the projection direction of the test point's measured

normal on the XOZ plane and the Z-axis, in milliradians (mrad);

βX - the angle between the projection direction of the test point's ideal normal

on the XOZ plane and the Z axis, in milliradians (mrad).

See equation (8) for the calculation of the mean square root of slope deviation

of the tested sample SDX in X-axis direction.

where,

SDX - the mean square root of slope deviation of the tested sample, in

milliradians (mrad);

sdxi - the slope deviation of a certain test point on the surface of the test sample

in the direction of the X-axis direction, in milliradians (mrad);

n - total number of test points.

The slope deviation distribution sdX (X, Y) in the X-axis direction is the

distribution of the slope deviation of each test point on the sample surface on

the XOY coordinate plane sdXi, represented in two-dimensional error map.

7.2.2 Mean square root of slope deviation in Y-axis direction SDY

In the measurement coordinate system, the slope deviation of the test point on

the tested sample surface in Y-axis direction sdY is equal to the angle between

the actual normal direction and the ideal normal direction of the test point on

the YOZ projection plane. See equation (9) for the calculation.

where,

sdY - the slope deviation of the test point on the tested sample surface in Y-axis

direction, in milliradians (mrad);

β'Y - the angle between the actual measured normal of test point on the

projection direction of YOZ and the Z-axis, in milliradians (mrad);

7.3.3 Mean square root of focus deviation in y-axis direction FDy

See equation (13) for the calculation of focus deviation fdY in the Y direction.

where,

fdY - the focus deviation of the test point on the tested sample surface along

with the Y direction, in millimeters (mm);

sdY - the slope deviation of the test point on the tested sample surface in the Y

direction, in milliradians (mrad);

L - the distance from the test point on the tested sample surface to the ideal

focus or focal line, in millimeters (mm).

Convert the measurement coordinate system to use coordinate system.

Interpolation and other methods can be used to achieve uniform light sampling

and obtain the focus deviation fdY in the use coordinate system. The mean

square root of focus deviation in y-axis direction FDy is calculated according to

equation (14).

where,

FDy - the mean square root of focus deviation of tested sample in the y-axis

direction;

fdYi - the focus deviation of a test point on the tested sample surface along with

the Y direction;

m - total number of data points.

Use XOY plane as reference plane. The focus deviation distribution on the Y-

axis direction fdY (X, Y) is the distribution of the focus deviation of each test

point on the sample surface on the XOY coordinate plane fdYi, represented in

two-dimensional error map.

7.4 Intercept factor calculation

7.4.1 Calculation principle

The intercept factor can be calculated by ray tracing simulation, and the number

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