NATL INST. OF STAND & TECH

III 111 II II I REFERENCE

AlllOb t1Q37M

NBSIR 74-635

Method of Testing for Rating Solar

Collectors Based on Thermal

Performance

James E. Hill Tamami Kusuda

Thermal Engineering Systems Section

Center for Building Technology

National Bureau of Standards

Washington, D. C. 20234

December 1974

Interim Report

Prepared for National Science Foundation

"800 G Street

-QC -ashington, D. C. 20550

100

• U56

#74-635

1974

NBSIR 74-635

METHOD OF TESTING FOR RATING SOLAR

COLLECTORS BASE ON THERMAL

PERFORMANCE

James E. Hill Tamami Kusuda

Thermal Engineering Systems Section

Center for Building Technology

National Bureau of Standards

Washington, D. C. 20234

December 1974

Interim Report

Prepared for National Science Foundation

1800 G Street Washington, D.C. 20550

U. S. DEPARTMENT OF COMMERCE, Frederick B. Dent. Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director

Method of Testing for Rating Solar Collectors

Based on Thermal Performance

James E. Hill and Tamami Kusuda

Thermal Engineering Systems Section

Center for Building Technology

National Bureau of Standards

Washington, D. C. 20234

ABSTRACT

The National Bureau of Standards has made a study of the different

techniques that could be used for testing solar collectors and rating

them on the basis of thermal performance. This document outlines a

proposed standard test procedure based on that study. It is written in

the format of a standard of the American Society of Heating, Refrigerating,

and Air Conditioning Engineers and specifies the recommended apparatus,

instrumentation, and test procedure.

Key Words: Solar collector; standard test; thermal performance;

solar energy; standard; solar radiation.

i
TABLE OF CONTENTS

PACE

SECTION 1. PURPOSE 1

SECTION 2 . SCOPE 1

SECTION 3. DEFINITIONS 2

SECTION 4. CLASSIFICATIONS 4

SECTION 5. REQUIREMENTS 5

SECTION 6. INSTRUMENTATION 6

SECTION 7. APPARATUS AND METHOD OF TESTING 11

SECTION 8. TEST PROCEDURE AND CALCULATIONS 17

SECTION 9. DATA TO BE RECORDED AND TEST REPORT 25

SECTION 10. NOMENCLATURE 25

SECTION 11. REFERENCES 27

TABLES 30

FIGURES 46

ii
SECTION 1. PURPOSE

The purpose of this standard is to provide test methods for

determining the thermal performance of solar collectors which

heat fluids and are used in systems to provide the thermal requirements for heating, cooling, and the generation of domestic hot water

in buildings.

SECTION 2 . SCOPE

This standard applies to solar collectors in which a fluid enters

the device through a single inlet and leaves the device through a single outlet. The collector containing more than one inlet and/or

outlet can be tested according to this standard provided that the

external piping can be connected in such a way as to effectively

provide a single inlet and/or outlet for the determination of the

bulk properties of the fluid entering and leaving the collector.

The fluid can be either a gas or liquid but not a mixture of the

two. The collector can be a concentrating collector provided that

the aperture or interception area for the device can be determined.

The collector may have the capability of rotating so as to track

the sun.

This standard is not applicable to those configurations in which

the flow into the collector and out of the collector cannot be re- duced effectively to one inlet and one outlet. This standard is

not applicable to those collectors in which the thermal storage

unit is an integral part of the collector such that the collection

process and storage process cannot be separated for the purpose of

making measurements.

This standard does not address factors relating to cost or consideration of requirements for interfacing with a specific heating

and cooling system.

The present version of the standard provides test methods for determining the steady-state efficiency of solar collectors. The

transient response of solar collectors cannot be determined with

the test methods outlined herein.
SECTION 3. DEFINITIONS

3.1 AMBIENT AIR

Ambient air is the outdoor air in the vicinity of the solar collector being tested.

3 .2 ABSORBER

The absorber is that part of the solar collector that receives the

incident solar radiation and transforms it into thermal energy.

It is usually a solid surface through which energy is transferred

to the transfer fluid; however, the transfer fluid itself could

be the absorber in the case of a "black liquid".

3.3 APERTURE

The aperture is the opening or projected area of a solar collector

through which the unconcentrated solar energy is admitted and directed to the absorber.

3 .4 CONCENTRATING COLLECTOR

A concentrating collector is a solar collector that contains re- flectors, lenses, or other optical elements to concentrate the en- ergy falling on the aperture onto a heat exchanger of surface area

smaller than the aperture.

3.5 CONCENTRATOR

The concentrator is that part of a concentrating collector which

directs the incident solar radiation onto the absorber.

3.6 COVER PLATE

The cover plate designates the diathermanous material or materials

covering the aperture and most directly exposed to the solar

radiation. These materials are generally used to reduce the heat

loss from the absorber to the surroundings and to protect the

absorber

.

3.7 FLAT-PLATE COLLECTOR

A flat-plate collector is a solar collector in which the solid

surface absorbing the incident solar radiation is essentially

flat and employs no concentration.

2
3.8 GROSS CROSS-SECTIONAL AREA

Gross cross-sectional area is the overall or outside area of a flat-plate collector. It is usually slightly larger than the absorber area since it includes the framework required to hold the

absorber

.

3.9 INCIDENT ANGLE

The incident angle is the angle between the sun's rays and the outward drawn normal from the solar collector.

3.10 INSOLATION

Insolation is the rate of solar radiation received by a unit sur- face area in unit time (W/m2

, Btu/ (h • ft^)).

3.11 INSTANTANEOUS EFFICIENCY

The instantaneous efficiency of a solar collector is defined as the amount of energy removed by the transfer fluid per unit of

transparent frontal area over a given 15 minute period divided

by the total incident solar radiation onto the collector per unit

area for the 15 minute period.

3.12 INTEGRATED AVERAGE INSOLATION

The integrated average insolation is the total energy per unit area received by a surface for a specified time period divided by the

time period (W/m2

, Btu/(h • ft2 )).

3.13 PYRANOMETER

A pyranometer is a radiometer used to measure the total incident

solar energy per unit time per unit area upon a surface which includes the beam radiation from the sun, the diffuse radiation from

the sky, and the shortwave radiation reflected from the foreground.

3.14 PYRHELIOMETER

A pyrheliometer is a radiometer used to measure the direct or beam

radiation on a surface normal to the sun's rays.

3
3.15 QUASISTEADY

Quasisteady is the term used in this document to describe the state

of the solar collector test when the flow rate and temperature of

the fluid entering the collector is constant but the exit fluid

temperature changes "gradually" due to the normal change in insolation that occurs with time for clear sky conditions.

3 . 16 SOLAR COLLECTOR

A solar collector is a device designed to absorb incident solar

radiation and to transfer the energy to a fluid passing in contact

with it

.

3 . 17 TOTAL INCIDENT INSOLATION

Total incident insolation is the total energy received by a unit

surface area for a specified time period (j/rn^).

3.18 TRANSFER FLUID

The transfer fluid is the medium such as air, water, or other fluid

which passes through or in contact with the solar collector and

carries the thermal energy away from the collector.

3.19 TRANSPARENT FRONTAL AREA

The transparent frontal area is the area of the transparent frontal

surface for flat-plate collectors.

3.20 STANDARD AIR

3 3 Standard air is air weighing 1.2 kg/m (0.075 lb/ft ), and is

equivalent in density to dry air at a temperature of 21.1°C (70°F)

and a barometric pressure of 1.01 x 105 N/m^ (29.92 ia of Hg)

3.21 STANDARD BAROMETRIC PRESSURE

1.01 x 105 N/ m2 (29.92 in. of Hg)

SECTION 4. CLASSIFICATIONS

4.1 Solar collectors may be classified according to their collecting

characteristics, the way in which they are mounted, and the type

of transfer fluid they employ.

4
4.1.1 Collecting Characteristics . A non-concentrating or "flatplate" collector is one in which the absorbing surface for

solar radiation is essentially flat with no means for con- centrating the incoming solar radiation. A concentrating

or "focusing" collector is one which usually contains re- flectors or employs other optical means to concentrate the

energy falling on the aperture onto a heat exchanger of

surface area smaller than the aperture.

4.1.2 Mounting

.

A collector can be mounted to remain stationary,

be adjustable as to tilt angle (measured from the horizontal)

to follow the change in solar declination, or be designed

to track the sun. Tracking is done by employing either an equatorial mount or an altazimuth mounting, for the purpose

of increasing the absorption of the daily solar irradiation.

4.1.3 Type of Fluid . A collector will usually use either a liquid or a gas as the transfer fluid. The most common liquids are water or a water-ethy lene glycol solution. The

most common gas is air.

SECTION 5. REQUIREMENTS

5.1 Solar collectors shall be tested for rating in accordance with the

provisions set forth below and in Section 8.

5.1.1 The size of collector tested shall be large enough so that

the performance characteristics determined will be indicative of those that would occur when the collector is part

of an installed system. If the collector is modular and

the test is being done on one module, it should be mounted

and insulated in such a way that the back and edge losses

will be characteristic of those that will occur during operation on a structure.

5.1.2 The collector shall be mounted in a location such that there

will be no significant energy reflected or reradiated onto

the collector from surrounding buildings or any other sur- faces in the vicinity of the test stand for the duration

of the test(s). This will be satisfied if the ground and

immediately adjacent surfaces are diffuse with a reflectance of less than 0.20. If significent reflection will

occur, provision shall be made to shield the collector by

the use of a non-reflective shield. In addition, the test

stand shall be located so that a shadow will not be cast

onto the collector at any time during the test period.

5
5.1.3 The test(s) shall be conducted on days having weather con- ditions such that the 15 minute integrated average insolation measured in the plane of the collector or aperture,

reported, and used for the computation of instantaneous

efficiency values shall be a minimum of 630 W/m (199.8 Btu/(

h.ft^)). Specific values that can be expected for clear sky

conditions are shown in Tables Al through A6 taken from

reference [1] . More accurate estimates can be made using

the tables in conjunction with clearness numbers*.

5.1.4 The orientation of the collector shall be such that the incident angle (measured from the normal to the collector

surface or aperture) is less than 45° during the period in

which test data is being taken. Angles of incidence can be

estimated from Tables A7 through A12 taken from reference

[2] . More accurate estimates can be made using the procedures outlined in references [3] , p. 393 or [4] , pp. 283-

292.

5.1.5 The air velocity across the collector surface of a flatplate collector or aperture of a concentrating collector

during the test(s) shall be measured. The measurement shall

be made at a distance of approximately 1 m (3.3 ft) from the

collector along the direction it faces and at a height cor- responding to the center of the collector panel.

5.1.6 The range of ambient temperatures for all reported test

points comprising the "efficiency curve" shall be less than

30°C (54°F).

5.1.7 The transfer fluid used in the solar collector shall have

a known specific heat which varies by less than 0.5% over

the temperature range of the fluid during a particular 15

minute test period.

SECTION 6. INSTRUMENTATION

6.1 SOLAR RADIATION MEASUREMENT

6.1.1 A pyranometer shall be used to measure the total short-wave

radiation from both the sun and the sky. The instrument

shall have the following characteristics [5]

:

Reference [3], p. 394, Figure 4.

6
6.1.1.1 Change of Response Due to Variation in Ambient Temperature . The instrument shall either be equipped

with a built-in temperature compensation circuit

and have a temperature sensitivity of less than + 1 percent over the range of ambient temperature

encountered during the test(s) or have been tested

in a temperature-controlled chamber over the same temperature range so that its temperature coefficient has been determined in accordance with refer- ence [5] .

6.1.1.2 Variation in Spectral Response . Errors caused by

a departure from the required spectral response of

the sensor shall not exceed + 2 percent over the

range of interest*.

6.1.1.3 Nonlinearity of Response . Unless the pyranometer

was supplied with a calibration curve relating the

output to the insolation, its response shall be

within + 1 percent of being linear over the range

of insolation existing during the tests.

6.1.1.4 Time Response of Pyranometer . The time constant

of the pyranometer shall be less than 5 s. 6.1.1.5 Variation of Response With Attitude . The calibration factor of a pyranometer can change when the

instrument is used in other than the orientation

for which it was calibrated. The instruments'

calibration factor (including corrections) shall

change less than +0.5 percent compared with the

calibrated orientation when placed in the orientation used during the test(s).

6.1.1.6 Variation of Response With Angle of Incidence . Ideally the response of the receiver is proportional to the cosine of the zenith angle of the

solar beam and is constant at all azimuth angles.

The pyranometer 's deviation from a true cosine

response shall be less than + 1 percent for the

incident angles encountered during the test(s).

Pyranometer thermopiles which are "all black" and which are coated with

Parson's black or 3M 101C10 velvet black paint and which have selected

optical grade hemispheres usually satisfy this requirement [5]. Note:

Identification of commercial materials does not imply recommendation or endorsement by the National Bureau of Standards.

7
6.1.2 The pyranometer shall be calibrated within six months of

the collector test(s) against other pyranometers whose cal'

ibration uncertainty relative to recognized measurement

standards is known*.

6.2 TEMPERATURE MEASUREMENTS

6.2.1 Temperature measurements shall be made in accordance with

ASHRAE Standard 41-66, Part 1 [6].

6 .2 .2 Temperature Difference Measurements Across the Solar Collector . The temperature difference of the transfer fluid

across the solar collector shall be measured with:

a. Thermopile (air or water as the transfer fluid)

b. Calibrated resistance thermometers connected in

two arms of a bridge circuit (only when a liquid

is the transfer fluid)

6.2.3 The accuracy and precision of the instruments and their

associated readout devices shall be within the limits as

f ol lows :

Instrument Accuracy*-' Instrument Precision'

Temperature + 0.5°C (+ 0.9°F) + 0.2 °C (+ 0.4 °F)

Temperature + 0.1°C (+ 0.2 °F) + 0.1°C (+ 0.2 °F)

Difference

One nationally recognized calibration center is the Eppley Laboratory

in Newport, Rhode Island. The calibration data are commonly expressed

in cal/ (cm • min) or in langleys/min. In some meteorological services,

calibration data are supplied in milliwatt/ cm^ . The following equivalent units shall be used:

1 cal/(cm2. mm ) = 1 ly/min = .001434 W/m^

1 mW/cm2 =0.1 W/m2

The ability of the instrument to indicate the true value of the measured quantity.

Closeness of agreement among repeated measurements of the same physical quantity.

8
6.2.4 In no case should the smallest scale division of the instrument or instrument system exceed 2 1/2 times the specified

precision. For example, if the specified precision is +

0.1 (+ 0.2°F), the smallest scale division shall not exceed

0.25% 70.5°F).

6.2.5 The instruments shall be configured and used in accordance

with Section 7. of this standard.

6.2.6 When using thermopiles, they shall be constructed in accor- dance with ANSI Standard C96. 1-1964 (R 1969) [7].

6.3 LIQUID FLOW MEASUREMENTS

6.3.1 The accuracy of the liquid flow rate measurement using the

calibration, if furnished shall be equal to or better than + 1.0% of the measured value.

6.4 INTEGRATORS AND RECORDERS

6.4.1 Strip chart recorders used shall have an accuracy equal to or better than + 0.5% of the temperature difference and/or

voltage measured and have a time constant of 1 s or less.

6.4.2 Electronic integrators used shall have an accuracy equal

to or better than + 1.07o of the measured value.

6.5 AIR FLOW MEASUREMENTS

When air is used as the transfer fluid, air flow rate shall be determined as described in Section 7.

6.6 PRESSURE MEASUREMENTS

6.6.1 Nozzle Throat Pressure . The pressure measurement at the

nozzle throat shall be made with instruments which shall

permit measurements of pressure to within + 2.0% absolute

and whose smallest sca?le division shall not exceed 2 1/2

times the specified accuracy [11]

.

9
6.6.2 Air Flow Measurements . The static pressure across the nozzle and the velocity pressure at the nozzle throat shall be

measured with manometers which have been calibrated to have an accuracy to within + 1.0% of the reading. The smallest

manometer scale division shall not exceed 2.0% of the reading [11].

6.6.3 Pressure Drop Across Collector . The static pressure drop across the solar collector shall be measured with a manometer having an accuracy of 2.49 N/m2 (0.01 in. of water).

6.7 TIME AND MASS MEASUREMENTS

Time measurements and mass measurements shall be made to an ac- curacy of + 0.20% [11] .

6.8 WIND VELOCITY

The wind velocity shall be measured with an instrument and associated readout device that can determine the integrated average wind

velocity for each 15 minute test period to an accuracy of + 0.08

m/s (1.8 mph).

10
SECTION 7. APPARATUS AND METHOD OF TESTING

7 . 1 LIQUID AS THE TRANSFER FLUID

The test configuration for the solar collector employing liquid as the transfer fluid is shown in Figure Al*

.

7.1.1 Solar Collector . The solar collector should be mounted in

its rigid frame at the predetermined tilt angle (for stationary collectors) or movable frame (for movable collectors) and anchored rigidly enough to a foundation so that

the collector can hold its selected angular position against

a strong gust of wind.

7.1.2 Ambient Temperature . The ambient temperature sensor shall

be housed in a well-ventilated instrumentation shelter with

its bottom 1.25 m (4.1 ft) above the ground and with its

door facing north, so that the sun's direct beam cannot fall

upon the sensor when the door is opened. The instrument

shelter shall be painted white outside and shall not be

closer to any obstruction than twice the height of the obstruction itself (i.e., trees, fences, buildings, etc.)

[15] .

7.1.3 Pyranometer . The pyranometer shall be mounted on the surface parallel to the collector surface in such a manner that

it does not cast a shadow onto the collector plate. Precautions should be always taken to avoid subjecting the instrument to mechanical shocks or vibration during the installation. The pyranometer should be oriented so that the emerging leads or the connector are located north of the receiving surface (in the Northern Hemisphere) or are in some other

manner shaded. This minimizes heating of the electrical con- nections by the sun. Care should also be taken to minimize reflected and reradiated

energy from the solar collector onto the pyranometer. Some

pyranometers come supplied with shields. This should be

adjusted so that the highest point on the shield lies parallel to and just below the plane of the thermopile. Some

pyranometers not supplied with a shield may be susceptible

to error due to reflections by radiation that originates

below the plane of the thermopile. Precautions can be

taken by constructing a cylindrical shield, the top of which

should be coplaner with the thermopile [5].

The recommended apparatus consists of a closed loop configuration. An

open loop configuration is an acceptable alternative provided that the

test conditions specified herein can be satisfied.

11
7.1.4 Temperature Measurement Across the Solar Collector . The

temperature difference of the transfer fluid between entering and leaving the solar collector shall be measured using

either two calibrated resistance thermometers connected in

two arms of a bridge or a thermopile made from calibrated,

type T thermocouple wire all taken from a single spool. The

thermopile shall contain any even number of junctions con- structed according to the recommendations in reference [7].

Each resistance thermometer or each end of the thermopile

is to be inserted into a well [8] located as shown in Figure

Al. To insure good thermal contact, the wells shall be filled

with light oil. The wells should be located just downstream

of a right angle bend to insure proper mixing [6].

To minimize temperature measurement error, each probe should

be located as close as possible to the inlet or outlet of

the solar collector device. In addition, the piping between

the wells and the collector shall be insulated in such a manner that the calculated heat loss or gain from the ambient air would not cause a temperature change for any test

of more than 0.05°C (0.09°F) between each well and the collector .

7.1.5 Additional Temperature Measurements . The temperature of the

transfer fluid at the two positions cited above shall also

be measured by inserting appropriate sensors into the wells.

Reference [6] should be followed in making these measurements.

7.1.6 Pressure Drop Across the Solar Collector . The pressure drop across the solar collector shall be measured using static

pressure tap holes and a manometer. The edges of the holes

on the inside surface of the pipe should be free of burrs

and should be as small as practicable and not exceeding

1.6 mm (1/16 inch) diameter [12]. The thickness of the

pipe wall should be 2 1/2 times the hole diameter [12]

.

7.1.7 Reconditioning Apparatus . As shown in Figure Al, a heat

exchanger is used to cool the transfer fluid to simulate

the building load and an adjustable electric resistance

heater is used to control the inlet temperature to the

prescribed test value. This combination of equipment or equivalent shall control the temperature of the fluid entering the solar collector to within + 0.5°C (+ 0.9°F)

at all times during the tests.

7.1.8 Additional Equipment . A pressure gauge, a pump, and a means

of adjusting the flow rate of the transfer fluid shall be

provided at the relative locations shown in Figure Al. Depending upon the test apparatus design, an additional throttle valve may be required in the line just preceding the

solar collector for proper control. An expansion tank and

12
a pressure relief valve should be installed to allow the

transfer fluid to freely expand and contract in the apparatus*. In addition, filters should be installed within the

apparatus as well as a sight glass to insure that the transfer fluid passing through the collector is free of contaminants including air bubbles.

7 .2 AIR AS THE TRANSFER FLUID

The test configuration for the solar collector employing air as the

transfer fluid is shown in Figure A2**

.

7.2.1 Solar Collector . The solar collector should be mounted in

its rigid frame at the predetermined tilt angle (for stationary collectors) or movable frame (for movable collectors) and anchored rigidly enough to a foundation so that

the collector can hold its selected angular position against

a strong gust of wind.

7.2.2 Ambient Temperature . The ambient temperature sensor shall

be housed in a well-ventilated instrumentation shelter with

its bottom 1.25 m (4.1 ft) above the ground and with its

door facing north, so that the sun's direct beam cannot fall

upon the sensor when the door is opened. The instrument

shelter shall be painted white outside and shall not be

closer to any obstruction than twice the height of the obstruction itself (i.e., trees, fences, buildings, etc.)

[15] .

7.2.3 Pyranometer . The pyranometer shall be mounted on the sur- face parallel to the collector surface in such a manner

that it does not cast a shadow onto the collector plate.

Precautions should be always taken to avoid subjecting the

instrument to mechanical shocks or vibration during the installation. The pyranometer should be oriented so that the

emerging leads or the connector are located north of the

receiving surface (in the Northern Hemisphere) or are in some other manner shaded. This minimizes heating of the

electrical connections by the sun.

Figure Al should not be interpreted to mean that the relief valve and

expansion tank necessarily be located below the solar collector.

The recommended apparatus consists of a closed loop configuration. An

open loop configuration is an acceptable alternative provided that the

test conditions specified herein can be satisfied.

13
Care should also be taken to minimize reflected and reradiated

energy from the solar collector onto the pyranometer. Some

pyranometers come supplied with shields. This should be

adjusted to be parallel to and to lie just below the plane

of the thermopile. Some pyranometers not supplied with

a shield may be susceptible to error due to reflections by

radiation that originates below the plane of the thermopile.

Precautions can be taken by constructing a cylindrical shield,

the top of which should be coplaner with the thermopile [5].

7.2.4 Test Ducts. The air inlet duct, between the air flow measuring apparatus and the solar collector, shall have the same cross-sectional dimensions as the inlet manifold to

the solar collector. The air outlet duct, between the so- lar collector and the reconditioning apparatus, shall have

the same cross-sectional dimensions as the outlet manifold

from the solar collector*.

7.2.5 Temperature Measurement Across the Solar Collector. A thermopile shall be used to measure the difference between the

inlet air temperature and outlet air temperature of the so- lar collector. It shall be constructed from calibrated

type T thermocouple wire all taken from a single spool.

No extension wires are to be used in either its fabrication or installation. The wire diameter must be no larger than 0.51mm

(24 AWG) and the thermopile shall be fabricated as shown in

Figure A3. There shall be a minimum of six junctions in the

air inlet test duct and six junctions in the air outlet test

duct. These junctions shall be located at the center of

equal cross-sectional areas.

During all tests, the variation in temperature at a given

cross section of the air inlet and air outlet test ducts

shall be less than + 0.5°C (+ 0.9°F) at the location of the

thermopile junctions. The variation shall be checked prior

to testing utilizing instrumentation and procedures outlined

in reference [6]. If the variation exceeds the limits above,

mixing devices shall be installed to achieve this degree

of temperature uniformity. Reference [16] discusses the

positioning and performance of several types of air mixers.

The ends of the thermopile should be located as near as possible to the inlet and outlet of the solar collector. The

air inlet and air outlet ducts shall be insulated in such a manner that the calculated heat loss or gain to or from the

ambient air would not cause a temperature change for any test

The performance of air heaters is expected to be affected by the ductwork entering and leaving the solar collector considerably more so than

in the case of solar collectors using a liquid as the transfer fluid.

14
of more than 0.05°^ (0.09°F) between the temperature measuring locations and the collector.

7.2.6 Temperature Measurements . Sensors and read-out devices

meeting the accuracy requirements of Section 6. and giving

a continuous reading shall be used to measure the temperature at the locations in the air inlet and air outlet ducts

shown in Figure A2 . Reference [6] should be followed in

making these measurements

.

7.2.7 Duct Pressure Measurements . The static pressure drop across

the solar collector shall be measured using a manometer as shown in Figures A2 and A4 £11], Each side of the manometer

shall be connected to four externally manifolded pressure

taps on the air inlet and air outlet ducts. The pressure

taps should consist of 6.4 mm (1/4 inch) nipples soldered

to the duct and centered over 1 mm (0.040 inch) diameter holes.

The edges of these holes on the inside surfaces of the ducts

should be free of burrs and other surface irregularities [121.

7.2.8 Air Flow Measuring Apparatus . Where the air flow rate is

sufficiently large, it shall be measured with the nozzle

apparatus discussed in Section 7. of reference [11] . As

shown in Figure A5 , this apparatus consists basically of

a receiving chamber, a discharge chamber and an air flow

measuring nozzle. The distance from the center of the nozzle to the side walls shall not be less than 1 1/2 times

the nozzle throat diameter, and the diffusion baffles shall

be installed in the receiving chamber at least 1 1/2 nozzle

throat diameters upstream of the nozzle and 2 1/2 nozzle

throat diameters downstream of the nozzle. The apparatus

should be designed so that the nozzle can be easily changed

and the nozzle used on each test shall be selected so that

the throat velocity is between 15 m/s (2 960 fpm) and 35 m/s

(6900 fpm). When nozzles are constructed in accordance with

Figure A6 and installed in accordance with Section 7.2.9 of

this Standard, the discharge coefficient may be assumed to

be as fol lows

:

15
Reynolds

Number

,

Coefficient

of Discharge,

C

20,000

50,000

100,000

150,000

200,000

250,000

300,000

400,000

500,000

0.96

0.97

0.98

0.98

0.99

0.99

0.99

0.99

0.99

If the throat diameter of the nozzle is 0.13 m (5 in.) or larger, the discharge coefficient may be assumed to be 0.99.

For nozzles smaller than 0.05 m (2 in.) and where a more precise discharge coefficient than given above is desired, the

nozzle should be calibrated. The area of the nozzle shall

be determined by measuring its diameter to an accuracy of + 0.2 07=. in four places approximately 45 degrees apart around

the nozzle in each of two planes through the nozzle throat,

one at the outlet and the other in the straight section near

the radius [ 11]

.

Where the nozzle apparatus is used, an exhaust fan capable

of providing the desired flow rates through the solar collector shall be installed in the end wall of the discharge

chamber rather than separate from the air flow measuring

apparatus as shown in Figure A2 . The dry and wet bulb temperature of the air entering the nozzle shall be measured

in accordance with reference [6] . The velocity of the air

passing through the nozzle shall be determined by either

measuring the velocity head by means of a commercially

available pitot tube or by measuring the static pressure

drop across the nozzle with a manometer. If the latter

method is used, one end of the manometer shall be connected

to a static pressure tap located flush with the inner wall

of the discharge chamber, or preferably, several taps in

each chamber should be manifolded to a single manometer.

A means shall also be provided for measuring the absolute

pressure of the air in the nozzle throat.

Where the air flow rate is sufficiently small so that a nozzle constructed and installed in accordance with the re- quirements above would have a throat diameter of smaller

than 0.025 m (1 in.), the above configuration should not be

used and the air flow measuring apparatus as shown in Fig16
ure A2 should consist of a calibrated flow element* where

at least 10 pipe diameters of upstream and downstream pipe

section have been included in the calibration-Wc .

7.2.9 Air Leakage . Air leakage through the air flow measuring

apparatus, air inlet test duct, the solar collector and the

air outlet test duct shall not exceed + 1.0% of the measured

air flow.

7.2.10 Air Reconditioning Apparatus . The reconditioning apparatus

shall control the dry bulb temperature of the transfer medium entering the solar collector to within + 1.0°C (+ 1.8°F)

of the desired test values at all times during the tests.

Its heating and cooling capacity shall be selected so that

dry bulb temperature of the air entering the reconditioning

apparatus may be raised or lowered the required amount to

meet the applicable test conditions in Section 8.

SECTION 8. TEST PROCEDURE AND CALCULATIONS

8.1 GENERAL

The performance of the solar collector is determined by obtaining

values of instantaneous efficiency for a large combination of values of incident insolation, ambient temperature, and inlet fluid

temperature. This requires experimentally measuring the rate of

incident solar radiation onto the solar collector as well as the

rate of energy addition to the transfer fluid as it passes through

the collector, all under quasi-steady conditions.

8.2 INSTANTANEOUS EFFICIENCY

It has been shown and discussed by a number of investigators [17,

18, 19 and 20] that the performance of flat plate solar collector

operating under steady conditions can be successfully described

by the following relationship:

Usually an orifice, venturi, or flow nozzle.

For small flow elements, the discharge coefficients associated with

elements varies considerably from those associated with the larger

elements. In addition, for small pipe or duct sizes, the ratio of

pipe circumference to pipe area becomes large and the characteristics

of the upstream and downstream pipe sections affect the behavior of

the element itself.

17
J»

- I '(T.). - D

L

(t

p

- t a

) (1)

A very similar equation can be used to describe the performance

of concentrating collectors [21, 22 and 23]. Equation (1) be- comes modified as follows [21]

:

^ - I (T0 )e

p Y

- U

L f (t - t a

) (2) a a

To assist in obtaining detailed information about the performance

of collectors and to prevent the necessity of determining some average surface temperature, it has been convenient to introduce

a parameter F

1 where

, _ actual useful energy collected

useful energy collected if the

entire collector surface were

at the average fluid temperature

Introducing this factor into equation (1) results in

q—u _ „, T T , , TT (t r . + t r Y]

= F» i I ( TO ) - U

L (_f,l If^e _ t

) \ (3)

2 a'

If the solar collector efficiency can be defined as

_ actual useful energy collected

' _ solar energy incident upon or intercepted by the collector

or in equation form

q /A

Tl - "V (4)

then the efficiency of the flat-plate collector is given by:

18
+ t

t

/'

T] .= F a

1 (to) - F' U. 2 (5)

I

Equation (5) indicates that if the efficiency is plotted against

an appropriate a straight line will result where the slope is some function of and the y intercept is some function of (xa) • In reality Ul is not a constant but rather a function of the temperature of the collector and of the ambient weather conditions.

In addition, the product (xct) e varies with incident angle to the

col lector

.

The procedures outlined in this document have been developed in an attempt to control the test conditions so that a well defined

efficiency "curve" can be obtained with a minimum of scatter.

Figure A7 shows typical test results taken from reference [24]

for two flat-plate collectors using air as the transfer fluid.

The collector tests were conducted outside and the scatter about

the two lines in each figure indicates " ... apart from experimental errors, the order of variation on account of the variations

in heat loss coefficient U^, and the parameter F

1 due to variations in ambient wind speed and sky temperatures". Figure A10 was taken from reference [25] and is for a flat-plate collector using

water as the transfer fluid. There is less scatter due to the

fact that the tests were conducted indoors using a "solar simulaThe curves shown in Figures A7 and A10 are duplicates of those re- ported in references [24] and [25] , respectively. The abscissa in

the first, case is in metric units and in the second, english units.

The curves to be presented in the test report described herein

should be done so the abscissa is either in the SI units of (°C-m2VW

(as in Figures A8 and All) or as shown in Figures A9 and A12 . Here

the experimentally determined temperature difference has been divided by the difference in temperature between the boiling point

and freezing point on the respective scale (100°C, 180°F) and the

insolation has been divided by the solar constant, I gc

(1353 W/m ),

in appropriate units [26] . The result is an abscissa whose units

are dimensionless.

It is expected that a "straight- line" representation will suffice

for most conventional flat-plate collectors but that an attempt

to represent the performance of a concentrating collector on such

a plot will require the use of a "higher-order fit" due to the

larger variation in UL

and the product (xa) •

tor

19
8.3 TESTING PROCEDURE

The testing of the solar collector shall be conducted in such a way that an "efficiency curve" is determined for the collector under test conditions described in Section 5. and 8.3. At least four

different values of inlet fluid temperature shall be used to obtain

the values of At /I. Ideally the inlet fluid temperature should

correspond to 10, 30, 50, and 70°C (18, 54, 90, and 126°F) above

the ambient temperature ; however the values that can realistically

be used will depend upon the particular collector design and the

environmental conditions at the location and time of year when the

collector is being tested. Consequently, the four different inlet

fluid temperatures selected should be as close to the above values

as is feasible. At least four "data points" shall be taken for

each value of t^ ^

; two during the time period preceding solar noon

and two in the period following solar noon , the specific periods

being chosen so that the data points represent times symmetrical

to solar noon. This latter requirement is made so that any "transient effects" that may be present will not bias the test results

when they are used for design purposes. All test data shall be

reported in addition to the fitted curve (see Section 9.) so that

any difference in efficiency due solely to the operating temperature level of the collector can be discerned in the test report.

The curve shall be established by "data points" that represent 15

minute integrated efficiency values. In other words, the integrated value of incident solar energy will be divided into the integrated value of energy obtained from the collector to obtain the

efficiency value for that "instant". Care should be taken to in- sure that the incident solar energy is steady for each 15 minute

segment during which an efficiency value is calculated. Either

electronic integrators or continuous pen strip chart recorders may

be used to determine the integrated values of incident solar radiation and temperature rise across the collector. However, a strip

chart recorder with a recommended chart speed of 30 cm/hr must always be used to monitor the output of the pyranometer to insure

that the incident radiation has remained steady during the 15 minute segment. Figures A13 and A14 show a strip chart recording of

incident solar radiation on a horizontal surface at the National

Bureau of Standards site in Gaithersburg , Maryland. Whereas the

conditions of Figure A13 would be perfectly acceptable for obtaining efficiency values, those of Figure A14 would not be*.

One or two "blips" of 10 s or less occurring during the 15 minute period such as at 12:18 in Figure All is acceptable.

20
The surface of the collector cover plate (if present) as well as exposed envelope of the pyranometer should be wiped clean and dry

prior to the tests. If local pollution or sand has formed a deposit on the transparent surfaces, the wiping should be carried

out very gently, preferably after blowing off most of the loose * material or after wetting it a little, in order to prevent scratching of the surface. This is particularly important for the pyranometer since such abrasive action can appreciably alter the original transmission properties of the enclosing envelope.

The pyranometer shall be checked prior to testing to see if there

is any accumulation of water vapor enclosed within the glass cover. The use of "wet" pyranometers (where moisture is visible) shall not

be allowed.

In order to obtain sufficiently good "quasi-steady" conditions for

the solar collection process, the collector should stand in the sun under no flow conditions until the contained fluid heats up to a temperature equivalent to or slightly greater than the inlet fluid

temperature for the test. The transfer fluid should then be circulated through the collector at the appropriate temperature level

for at least 30 minutes* prior to the period in which data will be

taken to calculate the efficiency values. During this period, a check should be made to insure that the flow rate of the transfer

fluid does not vary by more than + 1% and that the incident solar

radiation is steady as described above.

The flow rate of transfer fluid through the collector shall be

standardized at one value for all data points. The recommended

value of flow rate per unit area (transparent frontal or aperture)

for tests are 0.02 kg/(s-m2) (14.7 lbm/ (h • ft 2 )) when a liquid is

the transfer fluid and 0.01 m3/(s«m2

) (1.96 cfm per ft 2

) of standard

are when the transfer fluid is air. It is recognized that in some cases the collector will have been designed for a flow rate much

different than specified above. In such cases, the design flow

rate should be used.

In order to determine and report the fraction of the incident solar radiation that is diffuse for each efficiency value, the sensing element of the pyranometer shall be shaded from the direct

beam of sun just prior and just following each 15 minute testing

30 minutes is felt to be sufficient for typical tube and sheet type

solar collectors using water as the transfer fluid. For those collectors having higher thermal capacity, a longer time period may be nec- essary .

21
period and the value of the incident radiation determined*. This

shall be accomplished by using a small disk attached to a slender

rod held on a direct line between the pyranometer and the sun. The disk should be just large enough to shade the sensing element

alone. In reference [5], this is accomplished by a disk 100 mm

in diameter and held at a distance of 1 m from the sensing element** .

8 . 4 CALCULATION OF INSTANTANEOUS EFFICIENCY

For each 15 minute segment for which an efficiency value is to be

determined, the value is calculated using the equation:

Fa c

T2

P

f (t. - t. . ) dT :/A

J f,e f,i £ T

l

T] = ±— (6)

T2

T

l

The quantities m and Cp have been taken out of the integration in

the numerator since they remain essentially constant during the

test. Note that the collector area used for the calculation is

not the absorbing surface area but rather the transparent frontal area or aperture area.

At least sixteen data points shall be obtained for the establishment of the "efficiency curve" and an equation for the curve shall

be obtained using the standard technique of a least -squares fit to a second-order polynomial***.

8.5 AN EXPERIMENTAL CHECK

As an independent check on the experimental results, the inlet tem

perature, tf,i> and the outlet temperature, tf >e , of the collector

shall be recorded on continuous pen strip chart recorders. The

A normal incidence pyrheliometer can be used in lieu of shading the

sensing element of the pyranometer.

**

This was when using a Moll-Gorszynski Pyranometer made by Kipp and

Zonen

.

***

One should consult any standard text discussing analysis of experimental data for a presentation of this technique (i.e., [27] and [28])

22
quantity f (t - t . ) cIt shall be approximated using these re-

-J r ,e r ,1

' 1 . cordings and compared with the identical quantity obtained by using the primary method which measures the temperature difference

direct ly

.

8 . 6 CALCULATION OF AIR FLOW RATE

The air flow rate through the nozzle is calculated by the following equations

:

Q . = 1.41 C A (P v' )°* 5 mi n v n

v * = 10.1 x 10 v /P (1 + W ) n n n n

(7)

(8)

The air flow rate of standard air is then;

Q = Q ./(1.2 v' ) s mi n

(9)

8.7 CALCULATION OF NOZZLE REYNOLDS NUMBER

The Reynolds number is calculated as follows

N = f V D

Re a

(10)

The temperature factor is as follows

Temperature ,°C Factor, f

-6.7

+4 .4 +15.6

+26.7

+37.8

+48.9

+60.0

+71.1

782 75

72 075

67425

62 775

58125

55025

5192 5 48825

23
8.8 CALCULATION OF THEORETICAL POWER REQUIREMENTS

In order to calculate the theoretical power required to move the

transfer fluid through the solar collector, the following equation

shall be used:

P

h

= m AP / p (11)

24
SECTION 9. DATA TO BE RECORDED AND TEST REPORT

9.1 TEST DATA

Table A13 lists the measurements which are to be made at the beginning of the testing day and during the individual tests to obtain an efficiency "data point".

9.2 TEST REPORT

Table A14 specifies the data and information that shall be reported

in testing the solar collector.

SECTION 10. NOMENCLATURE

A cross-sectional area, m^

A transparent frontal area for a flat-plate collector or aperture

for a concentrating collector, m£

A area of nozzle, m^ nA absorbing or receiving area of the concentrating solar collecr tor , m^

C nozzle coefficient of discharge

Cp specific heat of the transfer fluid, J/tkgPC)

D nozzle throat diameter, m

f temperature factor for the calculation of nozzle N„Re

F

1 solar collector efficiency factor

h outside surface heat transfer coefficient (includes radiation

and convection) for the solar collector, W/£tf\

0

C)

I total solar energy incident upon the plane of the solar collector per unit time per unit area, W/itf^

1^ diffuse solar energy incident upon the plane of the solar collector per unit time per unit area, W/rn^

2 I solar constant, 1353 W/m

sc

25
mass flow rate of the transfer fluid, kg/s

Reynolds number

absolute pressure at the nozzle throat, N/m^

theoretical power required to move the transfer fluid

through the solar collector, W

velocity pressure at the nozzle throat or the static pressure

difference across the nozzle, N/m^

pressure drop across the solar collector, N/rn^

measured air flow rate, m^/s

standard air flow rate, nP/s

rate of useful energy extraction from the solar collector, W

ambient air temperature ,°C

temperature of the boiling point on a temperature scale ,°C or°F

temperature of the fluid leaving the collector ,°C

temperature of the fluid entering the collector ,°C

temperature of freezing point on a temperature scale ,°C or°F

average temperature of the absorber surface of the solar collector, °C

average temperature of the absorber surface of the concentrating

solar collector, °G

temperature difference ,°C

2

heat transfer loss coefficient for the solar collector, W/<m ^C)

velocity of the air at the nozzle throat, m/s

specific volume of the air at dry and wet bulb temperature con- ditions existing at the nozzle but at standard barometric pressure, m^/kg dry air

3 specific volume of the air at the nozzle, m /kg dry air

humidity ratio at the nozzle, kg t^O/kg dry air

absorptance of the solar collector absorbing surface to solar

radiation

the fraction of specularly reflected radiation from the reflector

which is intercepted by the solar collector absorbing surface

26
solar collector efficiency, %

specular reflectance of the solar collector reflector, or density, kg/m 3

P

T time, s, or transmittance of the solar collector cover plate

(xa)

e effective transmission-absorptance factor for the solar collector

time at the beginning of a 15 minute test period, s

time at the end of a 15 minute test period, s

SECTION 11. REFERENCES

1. Morrison, C. A., and E. A. Farber , "Development and Use of Insolation

Data for South Facing Surfaces in Northern Latitudes", paper presented

at the ASHRAE Symposium, Solar Energy Applications, Montreal, Canada,

June 22 , 1974.

2o Personal communication with J. I. Yellott, Arizona State University,

Tempe , Arizona, data to be published in 1975 revised edition of the

ASHRAE publication, Low Temperature Engineering Application of Solar

Energy .

3. ASHRAE Handbook of Fundamentals , American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 345 East 47th Street,

New York, N. Y. 10017, 1972.

4. Threlkeld, J. L., Thermal Environmental Engineering , Prentice-Hall,

Englewood Cliffs, New Jersey, Second Edition, 1970.

5. Latimer, J. R. , "Radiation Measurement", International Field Year for

the Great Lakes, Technical Manual Series, No. 2 , The Secretariet,

Canadian National Committee for the International Hydrological Decade,

No. 8 Building, Car ling Avenue, Ottawa, Canada, 1971.

6. "Standard Measurements Guide: Section on Temperature Measurements",

ASHRAE Standard 41-66, Part 1 , American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 345 East 47th Street,

New York, N. Y. 10017, January, 1966.

7. "American Standard for Temperature Measurement Thermocouples C96 . 1- 1964" (R 1969), American National Standards Institute, 1969.

8. "Instruments and Apparatus, Part 3, Temperature Measurement", Supplement to the ASME Power Test Codes, American Society of Mechanical Engineers, 345 East 47th Street, New York, N. Y. 10017, March, 1961.

27
9. Davis, J. C, "Radiation Errors in Air Ducts Under Isothermal Conditions Using Thermocouples, Thermistors, and a Resistance Thermometer", NBS Building Science Series 26 , November, 1969. (Available

from the Superintendent of Documents, U. S. Government Printing Office, Washington, D. C. 20402 - order by SD Catalog No. C 13.29/2:26,

$0.25.)

10. Davis, J. C, Faison, T. K. , and P. R. Achenbach , "Errors in Temperature Measurement of Moving Air Under Isothermal Conditions Using

Thermocouples, Thermistors, and Thermometers, ASHRAE Transactions , Vol. 72 , Part 1, 1966.

11. "Methods of Testing for Rating Unitary Air Conditioning and Heat Pump

Equipment", ASHRAE Standard 37-69 , American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 345 East 47th Street,

New York, N. Y. 10017, April, 1969.

12. "Instruments and Apparatus, Part 2, Pressure Measurement", Supplement

to the ASME Power Test Codes, American Society of Mechanical Engineers,

345 East 47th Street, New York, N. Y. 10017, July, 1964.

13. "Instruments and Apparatus, Part 5, Measurement of Quantity of Materials, Chapter 4, Flow Measurement", Supplement to the ASME Power

Test Codes, American Society of Mechanical Engineers, 345 East 47th

Street, New York, N. Y. 10017, February, 1959.

14. "Fluid Meters, Their Theory and Application", 5th edition, American

Society of Mechanical Engineers, 345 East 47th Street, New York,

N. Y. 10017, 1959.

15. "Instructions for Climatological Observations, Circular B" , United

States Weather Bureau Service, 11th edition, January, 1962.

16. Faison, T. K., Davis, J. C, and P. R. Achenbach, "Performance of

Louvered Devices as Air Mixers, NBS Building Science Series 27 , March, 1970. (Available from the Superintendent of Documents,

U. S. Government Printing Office, Washington, D. C. 2 0402 - order

by SD Catalog No. C 13.29/2:27, $0.30.)

17. Hottel, H. C, and B. B. Woertz , "The Performance of Flat-Plate

Solar-Heat Collectors", ASME Transactions , Vol. 64, p. 91, 1942.

18. Hottel, H. C, and A. Whillier, "Evaluation of Flat-Plate Collector Performance" , Transactions of the Conference on the Use of

Solar Energy , Vol. 2, Part I, p. 74, University of Arizona Press,

1958.

19. Bliss, R. W., "The Derivation of Several 'Plate-Efficiency Factors'

Useful in the Design of Flat-Plate Solar Heat Collectors", Solar

Energy , Vol. 3, No. 4, p. 55, 1959.

28
2 0. Whillier, A., "Design Factors Influencing Collector Performance",

Low Temperature Engineering Application of Solar Energy , American

Society of Heating, Refrigerating and Air -Conditioning Engineers,

Inc., 345 East 47th Street, New York, N . Y. 10017, 1967.

21. Duffie, J. A., and W. A. Beckman, Solar Energy Thermal Processes , John Wiley and Sons, 1974.

22. Nevins, R. G., and P. E. McNall, "A High-Flux Low-Temperature Solar

Collector", ASHRAE Transactions , Vol. 64, pp. 69-82, 1958.

23. Lof, G. 0. G., Fester, D. A., and J. A. Duffie, "Energy Balance on

a Parabolic Cylinder Solar Reflector", ASME Transactions , Vol. 84A,

p. 24, 1962.

24. Gupta, C. L., and H. P. Garg, "Performance Studies on Solar Air

Heaters", Solar Energy , Vol. 11, No. 1, 1967.

25. Simon, F. F. , and P. Harlament, "Flat-Plate Collector Performance

Evaluation: The Case for a Solar Simulator Approach", NASA TM X7 142 7 , October, 1973.

26. Thekaekara, M. P., "Solar Energy Outside the Earth's Atmosphere",

Solar Energy , Vol. 14, No. 2, p. 109, 1973.

27. Holman, J. P., Experimental Methods for Engineers , McGraw-Hill,

Second Edition, 1971.

28. Bevington, P.R. , Data Reduction and Error Analysis for the Physical

Sciences, McGraw-Hill, 1969.

29
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35
table A7 LATITUDE 24°N, INCIDENT ANGLES FOR HORIZONTAL

AND SOUTH-FACING TILTED SURFACES

Dates: (Decl.)

Dec. 21 (-23.45)

Jan. 21 (-19.9)

Nov. 21 (-19.9)

Feb. 21 (-10.6)

Oct. 21 (-10.7)

Mar. 21 (0.0) Sep. 21 (0.0)

Horiz. L - 10 Lat. Lat. + 10 Lat. + 20 Vert.

7 5 86.8 80.5 76.

3

72 4 68.9 62.6

8 4 75.

1

67.5 (,1.1 58!& 55.4 56.6

9 3 64.5 55.3 49.6 44.9 41.8 51.1

10 2 55. 7 44.5 37.4 31 .6 28.0 46.6

11 1 49.

b

36.5 27.6 19.6 14.3 43.6

12 47.4 33.4 23.5 13.5 3.4 42.5

Horiz. I - 10 Lat. Lat. + 10 Lat. + 20 Vert.

7 5 85.2 79.6 75.9 72.6 69.8 65.7

8 4 73.1 66.2 62.0 58^5 56.0 59.8

9 3 62.

1

53.5 48.4 44.5 42.2 54.4

10 2 52.8 42.1 35.5 30 6 28.2 50.0

11 1 46.4 33.4 24 8 17 6 14.1 47.0

12

i

44.0 30.0 20.0 10.0 0.0 46.0

Horlz. L - 10 Lat. Lat. + 10 L3t. + 20 Vert.

7 5 80.7 77.2 75.2 73 7 72.6 74.8

8 4 • 67.7 62.9 60.5 59^0 58.5 69.0

9 3 55.6 49.0 45.9 44. 3 44.5 63.8

10 2 44.9 35.9 31.5 29.5 30.6 59.6

11 1 37.0 25.0 18.0 14.8 17.6 56.9

12 34.0 20.0 10.0 0.0 10.0 56.0

Horlz. L - 10 Lat. Lat. + 10 Lat. + 20 Vert.

7

' 7b.

3

75.2 75.0 75.2 75.9 84.0

8 4 62.8 60.5 60.0 60.5 62.0 78.3

9 3 49.8 45.9 45.0 45.9 48.4 73.3

10 2 ! 37.7 31.5 30.0 31 .5 35.5 69.4

11 1 28.1 18.0 15.0 18.0 24.8 66.9

12

i

| 24.0 10.0 0.0 10.0 20.0 66.0

Apr. 21 (+11.9)

Aug. 21 (+12.1)

Hay 21 (+20.3)

Jul 21 (+20.5)

Horlz. L - 10 Lat. Lat. + 10 Lat. + 20

r

-Vert.

6 6 85.3 88.0 90.0 92.0 93.9 100.6

7 5 71.7 73.5 75.3 77.6 80.2 94.6

8 4 58.0 58.9 60.7 63.4 67.0 89.1

9 3 44.4 44.2 46.2 49.7 54.4 84.4

10 2 31.0 29.5 32.0 36.8 43.2 80.7

11 18.9 14.8 18.9 26.2 34.9 78.4

12 12.4 1.6 11.6 21.6 31 .6 77.6

12

Horlz.

82.0

68.8 55.4

41.7 28.0

14.5

4.0

10

86.0

72.6

58.5 44.5

30.6

17.6

10.0

Lat.

90.0

75.9 62.0

48.4

35.5 24.8

20.0

Lat. + 10

93.4

79.6 66.2

53.5

42.1 33.4

30.0

Lat. + 20

96 7 108.2

83 6 102.3

71 1 97.0

59 5 92.4

49 6 88.9

42 6 86.7

40 0 86.0

Vert.

Jun. 21 (+23.45)

Horlz. L - 10 Lat. Lat. 10 — - Lat. + 20 Vert.

6 6 80.7 86.0 90.0 94.0 97.8 111.3

7 5 67.7 72.4 76.3 80.5 85.0 105.5

8 4 54.5 58.6 62.7 67.5 72.8 100.2

9 3 41.0 44.9 49.6 55.8 6'.7 95.7

10 2 27.4 31.6 37.4 44.5 52.4 92.3

11 1 13.7 19.7 27.6 36.5 45.9 90.2

12 0.6 13.4 23.4 33.4 43.4 89.4

36
table A8 LATITUDE 32°N, INCIDENT AN6LES FOR HORIZONTAL

AND SOUTH-FACING TILTED SURFACES

Horiz

L - 10 Lat Lot + 10 Lit. 20 P— " - Vert

Dates (Decl .

)

Doc. 21 (-23.45

e

910

11

4

32

1

79.7

70 2 62.4

57.3

67.5

55.3 44.5

36.5

62.7

49.6

37.4 27.6

58.6 44.9

31.6

19.6

55.4 41.8

28.0

14.3

54.5

47.1 40.7

36.2

12 55.4 33.4 23.4 13.5 3.5 34.5

Horlz. L - 10 Lat. Lat. 10 Lat 20

1 " V6r t

Jan. c \ i-i9.yj

Nov. 21 (-19.9)

78

9 10

11

5

4

32

1

88.6

77.5 67.5

59.4 53.9

79.6

66.2

53.5

42.1 33.4

75.9 62.0

48.4

35.5 24.8

72.6 58.5

44.5

30.6

17.6

69.8

30 . U 42.2

28.2

14.1

65.2

50.0

43.8

39.6

12 52.0 30.0 20.0 10.0 0.0 38.0

.- . -1

Horlz. L - 10 Lat. Lat. + 10 Lat. 20 r

Vert

Feb. 21 (-10.6)

Oct. 21 (-10.7)

78

910

11

54

32

1

82.9

71.0

60.1 50.9 44.4

77.2 62.9

49.0

35.9 25.0

75.2 60.5 45.9

31.5

18.0

73.7 59.0 44.3

29.5

14.8

72.6

58.5 44.5

30.6 17.6

73.6 65.9

58.9

53.2

49.4

48.0

1Z 42.0 20.0 10.0 0.0 10.0

Horlz. L - 10 Lat. Lat. + 10 Lat. 20 Vert.

Mar. 21 (0.0)

Sep. 21 (0.0)

78

910

11

54

3

2

1

77.3

64.9

53.2 42.7

35.0

75.2 60.5 45.9

31.5 18.0

75.0 60.0

45.0

30.0

15.0

75.2 60.5

45.9

31.5 18.0

75.9 62.0

48.4

35.5 24.8

82.1 74.6 68.0

62.7

59.2'

12 32.0 10.0 0.0 10.0 20.0 58.0

Apr.

Aug,

2121 ;+11.9) 12.1

Horlz. L - 10 Lat. Lat. 10 Lat. + 20 Vert.

6 6 83.9 88.0 90.0 92.0 93.9 99.8

7 5 71.2 73.5 75.3 77.6 80.2 92.1

8 4 58.5 58.9 60.7 63.4 67.0 84.9

9 3 46.1 44.2 46.2 49.7 54.4 78.7

10 2 34.3 29.5 32.0 36.8 43.2 .3.8

11 1 24.6 14.8 18.9 26.2 34.9 70.7

12 20.4 1.6 11.6 21.6 31.6 69.6

Hay 21 (+20.3)

Jul. 21 (+20.5)

Horlz. L - 10 Lat. Lat. + 10 Lat. 20

1 Vert.

6 6 79.6 86.6 90.0 93.4 96.7 106.9

7 5 67.2 72.6 75.9 79.6 83.6 99.3

8 4 54.6 58.5 62.0 66.2 71.1 92.4

9 3 41.9 44.5 48.4 53.5 59.5 86.4

10 2 29.4 30.6 35.5 • 42.1 49.6 81.9

11 1 18.0 17.6 24.8 33.4 42.6 79.0

12 12.0 10.0 20.0 30.0 40.0 78.0

Horlz. L - 10 Lat. Lat. 10 Lat. + 20

1 Vert.

6 6 77.8 86.0 90.0 94.0 97.8 109.7

7 5 65.7 72.4 76.3 80.5 85.0 102.2

8 4 53.1 58.6 62.7 67.5 72.8 95.4

9 3 40.4 44.9 49.6 55.3 61.7 89.6

10 2 27.8 31.6 37.4 44.5 52.4 65.2

11 1 15.8 19.6 27.6 36.5 45.8 82.4

12 8.6 13.4 23.4 33.4 43.4 81.4

37
table A9 LATITUDE 40°N. INCIDENT ANGLES FOR HORIZONTAL

AND SOUTH-FACING TILTED SURFACES

Horlz. L - 10 tat. Lat. + 10 Lat. + 20 Vert.

8 4 84.5 67.5 62.7 58.6 55.4 53.2

Date: (Decl.

)

9 3 76.0 55.3 49.6 44.9 41.8 43.8

Dec. 21 (-23.45) 10 2 69.3 44.5 37.4 31.6 28.0 35.4

11 1 65.0 36.5 27.6 19.6 14.3 29.0

12 63.4 33.4 23.4 13.5 3.5 26.6

Horlz. I - 10 Lat. Lat. + 10 Lat. + 20 Vert.

Jan. 21 (-19.9) 8 4 81 .9 66.2 62.0 58.5 56.0 55.7

9 3 73.2 53.5 48.4 44.5 42.2 46.4

Nov. 21 (-19.9) 10 2 66.2 42.1 35.5 30.6 28.2 38.3

11 1 61 .6 33.4 24.8 17.6 14.1 32.3

12 60.0 30.0 —20.0

;

10.0 0.0 30.0 r— — , |, , . .

Horlz. L - 10 Lat. Lat. + 10 Lat. + 20

r Vert.

7 5 85.2 77.2 75.2 73.7 72.6 72.7

Feb. 21 (-10.6) 8 4 74.6 62.9 60.5 59.0 58.5 63.3

Oct. 21 (-10.7) 9 3 65.0 49.0 45.9 44.3 44.5 59.5

10 2 57.2 35.9 31.5 29.5 30.6 47.1

11 1 51.9 .25.0 18.0 14.8 17.6 41.9

12

1

50.0 20.0 10.0 0.0 10.0 40.0

•

Mar. 21 (0.0)

Sep. 21 (0.0)

78

910

11 12

Horlz.

78.6

67.5

57.2 48.4

42.3 40.0

- 10 Lat. Lat. + 10 Lat. 20

1 Vert.

75.2 75.0 75.2 75.9 80.4

60.5 60.0 60.5 62.0 71.3 45.9 45.0 45.9 48.4 63.0

31.5 30.0 31.5 35.5 56.2

18.0 15.0 18.0 24.8 51.6

10.0 0.0 10.0 20.0 50.0

Horlz. L - 10 Lat. Lat. + 10 Lat. 20 Vert.

6 6 82.6 88.0 90.0 92.0 93.9 98.9

7 5 71.1 73.5 75.3 77.6 80.2 89.5

8 4 59.7 58.9 60.7 63.4 67.0 80.7

9 3 48.7 44.2 46.2 49.7 54.4 73.1 10 2 38.8 29.5 32.0 36.8 43.2 67.0

11 1 31.3 14.8 18.9 26.2 34.9 63.0

12 28.4 1.6 11.6 21.6 31.6 61.6

May 21 (+20.3) Jul. 21 (+20.5)

t—

Horlz. L - 10 Lat. Lat. + 10

1 Lat. + 20

' Vert.

5 2 88.1 100.4 104.1 107.4 110.2 114.7

6 6 77.3 86.6 90.0 93.4 96.7 105.2

7 5 66.0 72.6 75.9 79.6 83.6 96.1 8 4 54.6 58.5 62.0 66.2 71.1 87.7

9 3 43.2 44.5 48.4 53.5 59.5 80.5

10 2 32.5 30.6 35.5 42.1 49.6 74.9

11 1 23.8 17.6 24.8 33.4 42.6 71.2

12

i i 20.0 10.0 20.0 30.0 40.0 70.0

Jun. 21 (+23.45)

Horlz. L - 10 Lat. Lat. 10

1 Lat. + 20 Vert.

5 7 85.8 99.5 103.7 107.6 111.1 117.2

6 6 75.2 86.0 90.0 94.0 97.8 107.7

7 5 64.0 72.4 76.3 80.5 85.0 98.8

8 4 52.6 58.6 62.7 67.5 72.8 90.6

9 3 41.2 44.9 49.6 55.3 61.7 83.6

10 2 30.2 31.6 37.4 44.5 52.4 78.1

11 1 20.8 19.6 27.6 36.5 45.8 74.6

12 16.6 13.4 23.4 33.4 43.4 73.4

38
table aio LATITUDE WN. INCIDENT ANGLES FOR HORIZONTAL

AND SOUTH-FACING TILTED SURFACES

Horii. L

- 10 Ut. Ut. 10 Ut. 20 Vert

9 3 82.0 55 3 49.6 44.9 41.8 41.6

10 2 76.4 44 5 37.4 31.6 28.0 31.1

11 1 72.7 36 S 27.6 19.6 14.3 22.4

12 71.4 33 4 23.4 13.5 3.5 18.5

Jan. 21 (-19.9)

Nov. 21 (-19.9)

Horn. I

- 10 Ut. Lit. * 10 Ut. 20 Vert.

8 4 86.5 66 2 62.0 58.5 56.0 54.7

9 3 79.0 53 5 43.4 44.5 42.2 43.7

10 2 73.42 1 35.5 30.6 28.2 33.5

11 1 69.3 33 4 24.8 17.6 14.1 25.4

1 I 68.0 30 0 20.0 10.0 0.0 22.0

Horti. I - 10 Ut. Ut. * 10 Ut. 20 Vert,

7 5 87.6 77.2 75.2 73.7 72.6 72.2

8 41 78.4 62.9 60.5 59.0 58.5 61.2

9 3 70.3 49.0 45.9 44.3 44 .5 50.7

10 2 63.8 36.9 31.5 29.5 30.6 41.4

11 1 59.5 25.0 18.0 14.8 17.6 34.6

12 58.0 20.0 10.0 0.0 10.0 32.0

1

Horll. Ut. Lit. * 10 lit. 20

Mar. 21 (0.0)

Sep. 21 (0.0)

80.0

70.5 61.8

54.6

49.7

75.2 60.5 45.9

31.5

18.0

75.0 60.0 4S.0

30.0

15.0

73.2 60.5

45.9

31.5 18.0

75.9 62.0

48.4

35.5 24.8

78.9 68.2

58.3 49.9

44.1

48.0 10.0 0.0 10.0 20.0 42.0

Horlz. I - 10 Ut. Lit. * 10 Ut. 20 Vert.

6 6 81.4 88 0 90.0 92.0 93.9 97.7

7 5 71.4 73 5 7S.3 77.6 80.2 86.9

8 4 61.5 58 9 60.7 63.4 67.0 76.7

9 3 52.2 44 2 46.2 49.7 54.4 67.7

10 2 44.2 29 5 32.0 36.8 43.2 60.3

11 1 38.5 14 8 18.9 26.2 34.9 SS.3

12

1

36.4 1 6 11.6 21.6 31.6 53.6

Hiy 21 (*20.3)

Jul. 21 f»20.5)

Horll. I - 10 Lit. Ut. « to Ut. » Vert.

5 7 8L8 100.4 104.1 107.4 110.2 114.2

6 6 75.3 B6.6 90.0 93.4 96.7 101.2

7 5 65.4 72.6 75.9 79.6 83.6 92.8

8 4 55.4 58.5 62.0 66.2 71.1 83.1

9 3 45.7 44.5 48.4 53.5 59.5 74.6

10 2 37.0 30.6 35.5 42.1 49.6 67.9

11 1 30.5 17.6 24.8 33.4 42.6 63.5

12 28.0 10.0 20.0 30.0 40.0 62.0

Jun. 21 (»23.45)

Horli. I - 10 Ut. Ut. 10 Ut. 20 Vert.

5 82.1 99.5 103.7 107.6 111.1 116.3 C 72.8 86.0 90.0 94.0 97.

105.4

7 63.0 72.4 76.3 80.5 85.0 95.2

8 52.9 58.6 62.7 67.5 72.1 85.7

9 43.1 44.9 49.6 55.3 61.2 77.5

10 34.2 31.6 37.4 44.5 52.4 71.1

11 1 27.3 19.6 27.6 36.5 45.8 66.9

24.6 13 4 23 4 11.4 43 3 (5.4

39
table All LATITUDE 56°N. INCIDENT ANGLES FOR HORIZONTAL

AND SOUTH-FACING TILTED SURFACES

Hon i. I - 10 Lit. Lit. » 10 lit. 70 Vert.

9 } 83.

1

55.3 49.6 44.9 41.8 40.5

10 2 U3.4 44.5 37.4 31.6 28.0 28.2 H 1 80.5 36.5 27.6 19.6 14.3 16.8

12

1

79.4 33.4 23.4 13.5 3.4 10.5

J«n. 21 (-19.9)

Nov. 21 (-19.9)

HorU. L - 10 Lit. lit. 10

9 3 85.0 53.5 48.4 44.5

10 2 80.1 42.1 35.5 30.6

11 1 77.1 33.4 24.8 17.6

1? 76.0 30.0 20.0 10.0

L«t. 20

42.2

28.2

14.1

0.0

(-10.6)

i-10.7)

Hortz. I - 10 lit

.

Lit. * 10 lit. • 20 Vert.

B 4 82.5 62.9 60.5 59.0 58.5 59.6

9 3 75.8 49.0 45.9 44.3 44.5 47.6

10 2 70.6 35.9 31.5 29.5 30.6 36.5

11 1 67.2 25.0 18.0 14.8 17.6 27.7

1 ! 66.0 20.0 10.0 0.0 10.0 24.0

Horiz. I - 10 Lat. Lit. 10

i —

Lit. 20 r

Vert. !

7 81 . 7 75.2 75.0 75.2 75.9 77.6

8 73.9 60.5 60.0 60.5 62.0 65.0

9 66.7 45.9 45.0 45.9 48.4 54.1

10 61.0 31.5 30.0 31.5 35.5 44.1

11 57.3 18.0 15.0 18.0 24.8 36.8

12 56.0 10.0 0.0 10.0 20.0 34.0

Apr. 21 (11.9)

Aug. 21 (12.1)

Horu. L - 10 Lit. Lit. 10 Lit. 20 Vert.

5 7 83.6 102.4 104.7 106.5 107.9 108.8

6 6 80.4 83.0 90.0 92.0 93.9 96.5

7 5 72.0 73.5 75.3 77.6 80.2 84.4

8 4 63.9 58.9 60.7 63.4 67.0 72.9

9 3 56.4 44.2 46.2 49.7 54.4 62.5

10 2 50.1 29.5 32.0 36.8 43.2 S3.

8

11 1 45.9 14.8 18.9 26.2 34.9 47.8

12 44.4 1.6 11.6 21.6 31.6 45.6

Hi/ 21 1*20.3)

Jul. 21 (*20.5)

Hor i i

.

L - 10 Lit. Lit. 10 Lit. • li> Vert.

4 B C8.8 113.8 118.0 121.5 124.0 125.5

6 7 81.5 100.4 104.1 107.4 1 10? 113.1

6 6 73.5 86.6 90.0 93.4 96.7 101.0

7 65.2 72.6 75.9 79.6 83.6 89.4

8 56.9 58.5 62.0 66.2 71.1 78.

6

9 49.1 44.5 48.4 53.5 59.5 68.9

10 42.4 30.6 35.5 42.1 49.6 61.1

11 37.7 17.6 24.8 33.4 42.6 55.9

1 7 is n in (i TM « in n UUL. .

HorU. L - 10 lit. Lit. • 10 Lit. 20 Vert.

4 8 85.8 112.5 117.3 121.4 124.6 127.1

5 7 78.6 99.5 103.7 IC7.6 111.1 1H.8

6 6

' 70.7 86.0 90.0 94.0 97.8 102.9

7 5 62.4 72.4 76.3 80.5 85.0 91.5

8 54.1 58.6 62.7 67.5 72.8 80.9

9 46.2 44.9 49.6 55.3 61.7 71.6

10 39.3 31.6 37.4 41.5 52.4 64.1

11 34.4 19.6 27.6 36.

5

45.8 59.2

12 32.6 13.4 23.4 33.4 43.4 57.4 40
table A12 LATITUDE INCIDENT ANGLES FOR HORIZONTAL

AND SOU I H-FAC IiMG TILTED SURFACES

Dec. 21 (-2J.4S)

Jtn. Nov.

1-19.9)

1-19.9)

(lord. I - 10 Lit. Lit. 10 Ut. 20 Vert.

11 1 68.2 36. $ 27.6 19.6 14.3 13.9

12 87.4 33.4 23.4 13.5 3.4 2.$

•

Horu. I - 10 Lit, Lit. • 10 Ut. 20 Vert.

10

11 2

1 87.2 81.8

42.1 33.4 35.5 24.8

30.6

17.6 28.2

14.1 28.2 15.0

1 " 1 1

2

1

1

C4.0 30.0 20.0 10.0 0.0 • 6.0

Feb. 21 Oct. 21 -10.6) -10.7)

tor. 21 (0.0)

Sep. 21 (0.0)

Mori I

L - 10 Lit. Ut. 10 Lit. • 20 Vert.

80.6 62.9 60.5 59.0 58.5 58.8

81 .4 49.0 45.9 44.3 44.6 45.4

77.4 15.9 31.5 29.5 30.6 32.6

74.9 2S.0 18.0 14.8 17.6 21.4

74.0 20.0 10.0 0.0 10.0 16.0

Horll L - 10 Lit. L»t. » 10 lit. » 20 Vert.

7 83.5 75.2 75.0 75.2 75.9 76.5

8 77.3 60.5 60.0 60.5 62.0 63.3

9 71.9 45.9 45.0 45.9 48.4 50.5

10 67.7 31.

30.0 31.5 35.5 38.9

11 64.9 18.0 15.0 18.0 24.8 29.6

12

1

64.0 10.0 0.0 10.0 20.0 26.0

Apr. 21 (11.9)

Aug. 21 («12.1)

tUv 21 (»20.3)

Jul. 21 (»20.5)

Horil. L - 10 Lit. Lit. 10 Lit. 20 Vert .

s 86.0 102.4 104.7 106.5 107.9 ion.

6 79.6 88.0 90.0 92.0 93.9 95.1

7 73.0 73.5 75.3 77.6 80.2 82.0

8 66.7 58.9 60.7 63.4 67.0 69.4

9 61.0 44.2 46.2 49.7 54.4 57.7

10 56.5 29.5 32.0 36.8 43.2 47.6

11 53.5 14.8 18.9 26.2 34.9 40.3

12 52.4 1.6 11.6 21.6 31.6 37.6

Horll. I - 10 Lit. Lit. » 10 Lit. 20 Vert.

4 6 84.2 113.8 118.0 121.5 124.0 124.9

s 78.4 100.4 104.107.4 110.2 111.6

6 72. 1 86.6 90.0 93.4 96.7 98.6

7 65.5 72.6 75.9 79.6 83.6 86.1

8 59.1 58.5 62.0 66.2 71.1 74.2

9 53.2 44.5 48.4 53.5 59.5 63.4

10 48.4 30.6 35.5 42.1 49.6 54.4

11 45.1 17.6 24.8 33.4 42.6 48.3 «-0 ., 10.0 20.0 30.0 40.0 46.0

Jun. 21 (»23.45)

Horll. L - 10 Lit. Lit. 10 Lit. '20 Vert

3 9 85 8 124.7 130.4 135.1 138.2 139.2

4 8 81.0 112.5 117.3 121.4 124.6 l?6.9

5 75.3 99.5 103.7 107.6 111.1 1 12.8

6 69.0 86.0 90.0 94.0 97.6 100.0

; 62.5 72.4 76.3 80.5 86.0 87.8

a 56.0 58.6 62.7 67.5 72.8 76.2

9 50.1 44.9 49.6 55.6 61 .7 65.9

10 45.1 31.6 37.4 44.5 52.4 57.3

11 41.7 19.6 27.6 36.5 45.8 51. S

1* 40.6 1},} »«. U.1

4.3.4.

41
Table A13 Test Data to be Recorded

i

Item

03 u C

•r-l cd <

u Tr

do 01 t»0 e M—

1

C

fl 03 •rl X! > c > u 1—

1

ct3 i—

1

o rl o CO X) > H > ca •rl c e 3

1-1 01 M r-l X! *o •rl fa U 4J •H 4J s

cn 3 (0 tr S-i 01 03 rH 0) •r-l <u H fa H »4-l

Date X X

Observer (s) X X

Equipment name plate data X X

Collector tilt angle X X

Collector azimuth angle (as a function of time if

movable) X X

Collector aperture area or frontal transparent

area X X

Local standard time, at the beginning of collector

warm-up and at the beginning and end of each 15

minute test period X X

Barometric pressure X

Ambient air temperature (at the beginning and end

of each 15 minute test period) X X

At = tf - | across solar collector (either as

a continuous ' function of time or as a 15 minute

integrated quantity) X X

Inlet temperature, tf ^ (as a continuous function

of time ' X X

Outlet temperature, t

f

• (as a continuous function

of time ,e XX

42
Table A13 - continued

i

Item

co u c

td <

l-t

CO Tr

too <U toO c M-< c CU H CO •r-( x: > C > 4-1 r-H cti O O (A -a > H > •i-i c c 3 M 0) H X) —

-C X) •H

4-1 4-1 •H 4J 3

CO 3 CO cr M

01 co i—i CD CU H H 1-3

Liquid flow rate X

Gauge pressure at solar collector inlet X

Gauge pressure at nozzle throat X

Nozzle throat diameter X

Velocity pressure at nozzle throat or static pressure difference across nozzle X

Dry bulb temperature at nozzle throat X

Wet bulb temperature at nozzle throat X

Pressure drop across solar collector X X

Height of the collector outlet above the collector

inlet X X

Wind velocity near the collector surface or aperture (15 minute average) X X

I, the incident solar radiation onto the collector (as a continuous function of time and as a

15 minute integrated quantity if desired) X X

1^, the diffuse component of the solar radiation

onto the collector (at the beginning of the 15

minute period and after the completion of the

15 minute period) X X

43
Table A14 Data to be Reported

General Information

Manufacturer or Project Name „ . Collector Model No

Construction details of the collector

gross dimensions and area

area of absorbing surface

cover plate", dimensions, materials, optical properties (if known) . . reflector*, dimensions and shape, materials, optical properties (if

known ) absorber plate, dimensional layout and configuration of flow path,

absorptivity to short wave radiation (if known), emissivity for

long wave radiation (if known), description of coating (including

maximum allowable temperature if known)

air space (s)*, thickness and description of contained gas or con- struction

insulation* , material, thickness, thermal properties

Transfer fluid used and its properties

2 Weight of collector per m of gross cross-sectional area

2 Volumetric capacity of the collector per m of gross cross-sectional

area if designed to operate with a liquid as the transfer fluid . . .

Normal operating temperature range

Minimum transfer fluid flow rate

Maximum transfer fluid flow rate

Maximum operating pressure

Description of apparatus, including flow configuration and instrumentation used in testing (include photographs)

Description of the mounting of the collector for testing . . .

Location of tests (longitude, latitude, and elevation above see level)

Efficiency Tests

A plot of the efficiency versus

if applicable

44
An equation for the efficiency curve

For each "data point ii

m

c

P

(t

f,e

- t f ,i

) dT

I dT

pressure drop across the solar collector

collector tilt angle

collector azimuth angle (as a function of time if movable)

incident angle

inlet fluid temperature, tf ^ percentage of incident radiation that is diffuse

wind speed near the collector surface or aperture . . . .

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58

NBS-'I 14A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLIC ATI ON OK REPORT NO. NBSIR 74-635

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITI.lv AND SUBTITI.lv Method of Testing for Rating Solar Collectors Based on Thermal Performance

5. Publication Date December 1974

6. Performing Or ££in l Zdt ion C ode

7 A irrn e <

,\ /- A U 1 MUK (

)

James E. Hill and Tamami Kusuda

8. Performing Or^an. Report No. NBSIR 74-635

9. PKK FOR MING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project /Task/Work Unit No. 4624417

11. Contract/Grant No. AG493

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

National Science Foundation

1800 G. Street

Washington, D.C. 20550

13. Type of Report & Period

ov e r g d Interim Report

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRAC 1 (A 200-word or less [actual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) The National Bureau of Standards has made a study of the different techniques

that could be used for testing solar collectors and rating them on the basis of

thermal performance. This document outlines a standard test procedure based on

that study. It is written in the format of a standard of the American Society

of Heating, Refrigerating, and Air Conditioning Engineers and specifies the

recommended apparatus, instrumentation, and test procedure.

17. KEY WORDS fs;x to (welve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

)

Solar collector; standard test; thermal performance; solar energy; standard;

solar radiation.

18. AVAILABILITY §C Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

7 Eor Official Distribution. Do Not Release to NTIS

UNCLASSIFIED 63

Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CM

20. SECURITY CLASS

(THIS PAGE)

22. Price

Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151 UNCLASSIFIED $4.25

U5COMM.DC 29042-P74