Direct Heat-Flux Measurement System (MDF) for Solar Central ...

Informes Técnicos Ciemat 961Abril,2001

Direct Heat-Flux MeasurementSystem (MDF)for Solar CentralReceiver Evaluation

J. Ballestrín

Plataforma Solar de Almería

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publicados por el Office of Scientific and Technical Information del Departamento de Energía

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publicación.

Depósito Legal: M-14226-1995ISSN: 1135-9420ÑIPO: 402-01-008-3

Editorial CIEMAT

CLASIFICACIÓN DOE Y DESCRIPTORES

S14

HEAT FLUX; MEASURING METHODS; SOLAR THERMAL CONVERSIÓN; SOLAR

THERMAL POWER PLANTS; SOLAR RECEIVERS; SOLAR FLUX

Direct Heat-Flux Measurement System (MDF)for Solar Central Receiver Evaluation

Ballestrín, J.44 pp. 18 fig. 18refs.

Abstract:

A direct flux measurement system, MDF, has been designed, constructed and mounted on top of the SSPS-CRS tower at the Plataforma Solar de Almería (PSA) in addition to an indirect flux measurement systembased on a CCD camera. It's one of the main future objectives to compare systematically both measurementsof the concentrated solar power, increasing in this way the confidence in the estímate of this quantity. Todayeverything is prepared to perforan the direct flux measurement on the apernare of solar receivers: calorimeterarray, data acquisition system and software. The geometry of the receiver determines the operation andanalysis procedures to obtain the incident power onto the defined área.

The study of previous experienees with direct flux measurement systems has been useful to define a new,simpler and more aecurate system. A description of each component of the MDF system is included,focusing on the heat-flux sensors or calorimeters, which enables these measurements to be done in a fewseconds without water-cooling.

The incident solar power and the spatial flux distribution on the aperture of the volumetric receiver Hitrec IIare supplied by the above-mentioned MDF system. The first results obtained during the evaluation of thissolar receiver are presented including a sunrise-sunset test. AU these measurements have been concentratedin one coeffícient that describes the global behavior of the Solar Power Plant.

Sistema de Medida Directa de Flujo de Calor (MDF)para Evaluación de Receptores Solares Centrales

Ballestrín, J.44 pp. 18 fig. 18refs.

Resumen:

Un sistema de medida directa de flujo, MDF, ha sido diseñado, construido y montado en la parte alta de latorre SSPS-CRS en la Plataforma Solar de Almería (PSA) junto a un sistema de medida indirecta de flujobasado en una cámara CCD. Uno de los futuros objetivos es llegar a comparar sistemáticamente las medi-das que de la potencia solar concentrada hagan los dos sistemas, aumentando de este modo la confianza enla estimación de esta magnitud. Actualmente todo está a punto para llevar a cabo la medida directa de flujoen la apertura de receptores solares: grupo de calorímetros, sistema de adquisición de datos y software. Lageometría del receptor determina los procedimientos de operación y análisis para obtener la potencia inci-dente sobre el área definida.

El estudio de experiencias previas con sistemas de medida directa de flujo ha sido de gran ayuda para definirun nuevo sistema más sencillo y exacto. La descripción de cada componente del sistema MDF es presen-tada, haciendo énfasis en los calorímetros, los cuales permiten que estas medidas sean llevadas a cabo enunos pocos segundos evitando la refrigeración con agua.

La potencia solar incidente y la distribución espacial de flujo en la apertura del receptor volumétrico HitrecII son obtenidas por el sistema MDF. Los primeros resultados obtenidos durante la evaluación de estereceptor solar son presentados, incluyendo un test de orto a ocaso. Todas estas medidas han sido concentra-das en un coeficiente que describe el comportamiento global de la Planta Solar.

ACKNOWLEDGMENTS:

This work is included in the evaluation of the HITREC II volumetric receiver, which is taking

place during this year at the Platafonna Solar de Almería (PSA). Thanks to the responsible of

the Solar Central Receiver Technology project, M. Romero, who encouraged these ideas from

the beginning. Thanks to the responsible of the Instrumentation Department, G. García, for

the technical support. Special mention to my colleagues: R. Monterreal, A. Valverde, J.

Fernández, I. Borretzen, R. Maillard and J. A. García. I'd like to thank everybody who helped

this research with his participation or advice. Thanks to all the kind people of Operation and

Maintenance.

Direct heat-flux measurement system (MDF) for solar receiver evaluation

CONTENTS:

1 INTRODUCTION 1

2 HITREC II RECEIVER 2

3 FLUX MEASUREMENT 4

4 THE MDF SYSTEM (MEDIDA DIRECTA DE FLUJO) 5

4.1 HEAT FLUX MICROSENSOR (HFM) 6

4.2 DATA ACQUISITION SYSTEM 8

4.3 OPERATION PROCEDURE AND ALGORITHMS FOR THE ANALYSIS 10

5 RESULTS 18

6 SUMMARY 23

7 RELATED LITERATURE 23

BOOKS 23REPORTS 24

APPENDIX 1: CALIBRATION SHEETS 25

J. Ballestrin


FIGURES:

FIGURE 1: LATERAL VIEW OF THE RECEIVER 2

FIGURE 2: HITREC I RECEIVER APERTURE 3

FIGURE 3: HITREC II RECEIVER APERTURE 4

FIGURE 4: HEAT FLUX MICROSENSOR (HFM) 7

FIGURE 5: HEAT FLUX MICROSENSOR 8

FIGURE 6: MDF DIAGRAM 9

FIGURE 7: DASYLAB WORKSHEET 9

FIGURE 8: LAYOUT OF THE HFM CALORIMETERS IN THE BAR 10

FIGURE 9: MDF AND CCD BAR 11

FIGURE 10: SIGNAL OF THE REFERENCE CALORIMETER 12

FIGURE 11: GEOMETRY BAR-RECEIVER APERTURE 12

FIGURE 12: BAR-RECEIVER APERTURE 13

FIGURE 13: RECEIVER APERTURE RECORDS 14

FIGURE 14: SPATIAL FLUX DISTRIBUTION IN THE RECEIVER APERTURE 15

FIGURE 15: FLUX DISTRIBUTION 2D 17

FIGURE 16: FLUX DISTRIBUTION 3D 18

FIGURE 17: SUNRISE-SUNSETOF 13-2-2001 21

FIGURE 18: MDF EXCEL TOOL 22

J. Ballestrín


1 INTRODUCTION

A direct flux measurement system, MDF, has been designed, constructed and mounted on top

of the SSPS-CRS tower at the Plataforma Solar de Almería (PSA) in addition to an indirect

flux measurement system based on a CCD camera. It's one of the main future objectives to

compare systematically both measurements of the concentrated solar power, increasing in this

way the confidence in the estímate of this quantity. Today everything is prepared to perform

the direct flux measurement on the aperture of solar receivers: calorimeter array, data

acquisition system and software. The geometry of the receiver determines the operation and

analysis procedures to obtain the incident power onto the defined área.

The study of previous experiences with direct flux measurement systems has been useful to

define a new, simpler and more accurate system. The Germán HFD (Heat Flux Distribution)

system was mounted in 1981 at the top of the SSPS-CRS tower to evalúate solar receivers.

The mstrumentation consists of ten calorimeters "Hycal Engineering" which were mounted in

the traversing bar. This bar could be hidden behind a protecting píate if no measurements

were taken and it was moved in horizontal direction in front of the receiver aperture when

measurements were taken. The calorimeters were designed to receive heat on 16-mm

diameter front face. This face and the cooled heat sink were connected to copper-constantan

thermocouples. The thermal voltages and the differences were proportional to the incoming

heat flux. The temperature could go up to slightly more than 200°C without changing the

calibration curve. Because the response time of this sensor is around 0.5 seconds, it was

necessary to spend 80 seconds to drive the total measurement sequence and the driving time

for the return-run carne to 70 seconds. For this reason, the bar was water-cooled with

incoming flow of 14 bars and the calorimeters too with a sepárate cooling system at a pressure

level of 7 bars. This complicated cooling procedure and the big áreas scanned were the main

negative points of this system.

The Spanish MFV (Medida de Flujo receptores Volumétricos) system was mounted in 1988

at the top of the SSPS-CRS tower to evalúate volumetric receivers. This system was

composed of the following elements:

• A measuring cross with 13 calorimeters "HYCAL Engineering" used to make

the measurements. These calorimeters cooled with water at a constant flow of

1.4 liters per minute allow ±3% accuracy, ±0.5% repetitivity and

±3%linearity.

• Positioning device to place the cross in the measurement positions pivoting in

a fíx point and stand by. This device includes a motor, reduce and switch

limits.

J. Ballestrín 1


® Control boards to centralize all the digital signáis of the system and

responsible for any movements of the cross.

« Acquisition cards to receive analog and digital signáis and transfer them

through the net Une of the computer.

The cross was moved by the positioning device and remained in front of the receiver aperture

for fíve seconds. During this time, it performed the necessary measurements after which it

was retrieved immediately to allow it to be cooled. This system represented a forward step

because the resolution in the flux measurements increased and the operation procedure for the

moving bar was simpler.

A description of each component of the new MDF system is included, focusing on the heat-

flux sensors or calorimeters, which enables these measurements to be done in a few seconds

without water-cooling.

The incident solar power and the spatial flux distribution on the aperture of the volumetric

receiver Hitrec II are supplied by the above-mentioned MDF system. The fírst results

obtained during the evaluation of this solar receiver are presented including a sunrise-sunset

test. All these measurements have been concentrated in one coeffícient that describes the

global behavior of the Solar Power Plant.

The volumetric receiver under evaluation is the Hitrec II, which has been installed at the 43

meters level of the CRS tower at the PSA.

Figure 1: Lateral view of the receiver

J. Bailestrín


T h e Hitrec I receiver was evaluated at the P S A in 1997/98 achieving 200 k W ; during these

tests, problems on the thermal stractural stability of the supporting steel membrane were

observed. This is one of the reasons for the design o f the n e w Hitrec II. However , the circular

apernare o f 880 ± 1 m m of diameter and the hexagonal absorber cups o f the Hitrec I receiver

are going to b e the same.

•¿Sai

Figure 2: Hitrec I receiver aperture

Several results obtained in the past test campaign of the Hitrec I receiver were:

« Efficiency 68% at 980 °C

« Flux Average 400-500 kW/m2

• Flux Peak 600 kW/m2

• Incoming power on the receiver aperture 200 kW

J. Ballestón


. - y *•-•

y

Figure 3: Hitrec II receiver aperture

In this context, from the point of view of the flux measurement the effective área of the

receiver to be considered is the área covered by hexagonal cups including the gaps between

them. Therefore, the data acquisition is defíned to obtain the flux distribution and the incident

power in this área.

Flux measurement is essential to obtain the efficiency of the receiver, T|R, because the flux

distribution on the receiver aperture supplies the radiant power P¡ incident on the receiver

aperture. The receiver efficiency is:

IR =Pi

(1)

Where Po is the outgoing power through the coolant that is represented by the expression:

(2)Po = m cp AT

where:

© m is the coolant mass flow rate.

9 cp specific heat capacity.

J. Ballestrín


» AT temperature difference between the incoming temperature and the

outgoing temperature of the coolant.

The measurement of the radiant power, which is refiected by the heliostat field, presents more

diffículties. There are two methods for the measurement of this quantity:

> The first one is a direct method based on a moving bar with a calorimeter array passing in

a parallel fíat in front of the receiver aperture. The signáis from these calorimeters supply

the flux distribution on the receiver and the integration of this map over the interesting

área provides the incoming power on the receiver aperture. The main disadvantages of

this method are:

o Data are obtained only in specifíc positions of the total área.

• Less accuracy during transients.

© The longer recording data time the less accurate measurement.

However, the main advantages of this method are the simplicity and the fact that it is a direct

method.

> The second method is indirect. A lambertian píate passes in front of the receiver aperture

isotropically reflecting the concentrated radiation. A CCD camera records a set of images

from a moving píate. Using a calorimeter located in the surroundings of the receiver

aperture does the calibration of the CCD camera. The processing of the recorded images

allows the flux distribution on the receiver and the integration of this map over the

interesting área provides the incident power onto the receiver aperture. This method

presents several advantages compared with the direct philosophy:

• A better spatial resolution.

® A smaller data acquisition time.

It's one of the main objectives in the future to compare systematically both measurements

increasing the confidence in the estímate of the incident power and the flux distribution on the

aperture of the volumetric receiver.

4 THE MDF SYSTEM (MEDIDA DIRECTA DE FLUJO)

The next system improves the technical deficiencies of the previous direct flux measurement

systems. A new kind of calorimeters with response times of microseconds allows thinking in

an instantaneous direct flux measurement. Based in this principie a moving bar with several

of these sensors has been built. The moving bar passes in front of the receiver aperture in a

parallel plañe pivoting in a fix point placed under the receiver aperture, in the vertical line of

J. Ballestón 5


the center. Using a fast acquisition system for these calorimeters and a convenient moving bar

speed allow measuring instantaneously the flux distribution without cooling.

The bar with calorimeters and the lambertian plates used in the indirect method with CCD

camera are mounted together. Working in the same plañe with both methods is a good chance

to compare the results.

In 1997, the United States Navy successfully measured the heat flux pro file across a solid

rocket motor exhaust plume. One of these sensors was swept through the exhaust plume of the

solid rocket motor immediately downstream of the nozzle exit plañe. The results of these tests

represented a signifícant milestone in flux measurement history due to the extreme conditions

of the tests. During this year The National Aerospace Laboratories in Kakuda (Japan) has

used a similar system with an array of these calorimeters to investígate the rocket engines. An

aerospike nozzle rocket engine has a curved jet attachment surface in the hot gas stream

produced by a linear array of cell combustors. This arrangement produces a controlled

expansión of the hot gases that can be optimized for a range of altitudes. The attachment

surface of the aerospike nozzle is subjected to a high heat load, however. An array of these

sensors was employed to measure the distribution of this heat load.

These previous experiences in the aerospace field allow thinking in a successful direct flux

measurement system in the solar thermal field.

4.1 Heat Flux Microsensor (HFM)

Vatell's Heat Flux Microsensors are made using thin film processes. Thin film construction

gives the sensors many unique advantages:

o The Industry's fastest response: 2-6 microseconds

• Minimal effects on measured variables.

• Operates in temperatures up to 850°C (300°C in our case) without

external cooling.

• Measures both heat flux and temperature at the face of the sensor.

• Measures heat flux in all three modes.

o Low electrical noise.

• Sensitivity: 15 ^V/kW/m2

© Front face of 6.32 mm diameter.

© Accuracy: ± 3%

J. Ballestrín


Figure 4: Heat Flux Microsensor (HFM)

Two measurements are made with the HFM:

> The first is a temperature measurement obtained from a resistance temperature

sensing element (Resistance Temperature Sensor, RTS) which consists of a puré

platinum thin film deposited in a loop pattern around the outer edge of the sensor face.

> The second is a heat flux measurement obtained from a thermopile heat flux

sensor (HFS) that occupies most of the surface.

The RTS measurement is critical to proper heat flux measurement, because the HFS is

temperature dependent. The RTS relies on the fact that the film resistance changes as a

function of temperature. This function is cióse to linear for most temperature of interest,

although strictly speaking it is better described by a cubic polynomial:

T = aRi +b R2 +cR + d (3)where:

• T is the temperarme (in °C).

• a, b, c, d are the coefficients of the polynomial, which are given on the

calibration data sheet supplied with each sensor by Vatell (Appendix 1).

• R is the eléctrica! resistance of the RTS (in ohms).

The resistance of the RTS is related to the voltage by:

R = ̂ - + Ro (4)

where:

J. Ballestrin


0 VRTS is the voltage output of the RTS amplifier channel (in volts), which may

be positive or negative.

is the excitation current (in amperes) through the RTS used to genérate

S, equal to 0.001 amperes in our case.

HFM

RTS Temperature

HFS Flux

Figure 5: Heat Flux Microsensor

Once the temperature, T, is known, the heat flux can be computed by:

v,HFS

Signal 1

Signal 2

(5)gT + h

where:

© q" is the heat flux in W/cm2.

• VHFS is the instantaneous voltage signal in uV from the HFS.

• g, h are the coefficients for the relationship between sensitivity and

temperature, which are given on the calibration data sheet supplied with each sensor by Vatell

(Appendix 1).

4.2 Data Acquisition System

The MDF system is mainly a data acquisition system with three main components (Figure 6):

• Moving bar with eight HFM calorimeters.

• Acquisition card with 32 differential channels of 3 ¡aV of highest

resolution which represents a flux resolution of 0.2 kW/m2 and a power

resolutionof 0.006 W.

© Software for the data acquisition (Dasylab) and for the analysis (Matlab).

The signáis from the calorimeters are acquired by the acquisition card of the 6031E family,

which is integrated in a PXI/CPCI (National Instruments) placed in a rack at the top of the

J. Ballestrín


CRS tower. The transmission of the data to the PC in the operation room is performed by

optical fíber, which is a guarantee of the good quality of the recorded data.

Movina bar + 8 calorimeters

Acquisition card

Optical fiber

PC + Software

Figure 6: MDF diagram

The easy to use Dasylab software helps to solve complex data acquisition scenarios easily and

quickly by working with a flowchart directly on the screen (Figure 7). Module icons are

placed on the screen and connected with wires in a schematic diagram, which represents the

fiow of data through the system.

File £dit Modylss Ejípenment J¿isw J3ptíons X^indow

^í'H'l'al D|GS|B1 % N | i l AI Nal ¿\ -M-M 1-AJD

*Í5í

ISWBfA/D

-fl-12'

-rs-re-i?*

I—-n- F 2

LLJ.IT 3:53:54"^

; i Dibujo ~ fe Qj Autoformas ^

l'fég. 16 Sec. 4 " 18/26 1'A~ ~ !.¡n._ _ Col. ¡'SP.B ÍBCA' |S;T ¡IJOJÍ J Español (ES;^a'stait||-:| ^ c g g g ^ »|;j :^JExplorando ...I BjCopy of inlo,..|lg|,PASYLab...: EgMATLAB C... [ 3:59

Figure 7: Dasylab worksheet

J. Ballestrín

Direct heat-flux measurement system (MDF) for solar receivers evaluation

Dasylab allows fast sampling rates under Windows. Given the proper hardware, data can be

acquired at rates of more than 800 kHz and can continuously be displayed on Une at more

than 100 kHz.

4.3 Operation procedure and algorüthms for the analysis

The new system improves the technical deñciencies of the previous direct flux measurement

systems. A new kind of calorimeters with response times of microseconds allows an almost

instantaneous direct flux measurement. Based on this principie a moving bar with eight of

these sensors has been built with a sheet of carbón steel:

® After this campaign of tests, it has been proved that aluminum would have been a

better choice because the máximum temperature achieved in the bar was 200 °C and it

would have been lighter.

• The two extremes calorimeters were positioned nearer to the edge to avoid the

problem of extrapolation.

• During the ñrst tests with the moving bar the fifth calorimeter (522-mm) was

damaged. The lack of confídence in this sensor forced the analyst to make the

decisión to reject this information.

The eight HFM calorimeters are placed in the bar in order to obtain an optimal resolution of

the área of interest (Figure 8).

40 mn15 mm

1045 mm

6..32 mm

872 mm

722 mm

622 mm

522 mm472 mm422 mm

322 mm

172 mm

0 mm

Figure 8: Layout of the HFM calorimeters in the bar

J. Ballestrín 10


The moving bar passes in front of the receiver aperture at a distance of 25 cm in a parallel

plañe pivoting in a fix point, P (0, -D), placed under the receiver aperture, in the vertical line

of the center O (0,0). Using an acquisition rate of 40 data/s for these calorimeters and a

moving bar speed of approximately 0.21 rad/s allow the flux distribution to be measured

almost instantaneously without cooling. Of course, this is not a fix recipe and could be

different depending on many factors.


camera are mounted together. Working in the same plañe with both methods is a good chance

to compare the results.

1030 mm

MDF o

©

o535 mm

CCD

Figure 9: MDF and CCD bar

The moving bar pivots in a fix point placed under the receiver aperture, in the vertical line of

the receiver aperture center. Two small sticks made of carbón steel ("hot fingers") are the

references to estimate the needed time by the moving bar to sean the receiver aperture

(Figures 10,11,12). These sticks cover one of the fast calorimeters in two positions of the

receiver aperture. In this way, the angular speed of the moving bar in the interesting área is

obtained. In the next figure, it is presented the recorded signal from the reference calorimeter

during the movement of the bar from the parking position to the receiver aperture and return.

J. Ballestrín 11


700

Figure 10: Signal of the reference calorimeter

Hot fíngers

Aperture

MDF

Reference calorimeter

Figure 11: Geometry bar-receiver aperture

J. Ballestrín 12



camera are mounted together. Working in the same flat with both methods is a good chance to

compare the results. On the other hand, the calorimeter bar is placed at a z distance from the

rotational axis (Figure 9); this fact has been considered in the data analysis.

Figure 12: Bar-receiver aperture

When the moving bar and the eight calorimeters pass in front of the receiver aperture a set of

N flux measurements, F¡j, are obtained in the positions \Xy,yy). These positional variables

are the Cartesians coordinates referred to the center 0(0,0) of the receiver aperture:

(6)

where:

« Lj represents the distance of each calorimeter from the pivoting point.

© D is the distance between the center of the receiver aperture and the pivoting

point.

J. Ballestrín 13


A matrix M(N, 15) is obtained:

® The first column represents the time.

« Two columns per each HFM calorimeter; the row i represent the same

angle and the column j the same sensor.

Two relevant angles have to be considered to estímate the angle supported by the two hot

fingers and the axis bar:

. .R + z.a - -are sm( )

P = are sin( - )

where R is radio of the circular aperture.

5.5 6.0 6.5 7.0

Time ( s )

(7)

E

IXDU_

i uu -

600-

500-

400-

300-

200-

100-

Hot finger t•

1 "o1 nI Q

" o0" T * '

1 1

Eg * T- • -T7

.i"

1

(O5*? "na

-4" - i *

1 1 '

o . v

o » ... Vo ". ^

0 ^ 0 " 7

3 °O *4¿4-; ° ' 7

" a "1 • ""* 0 ^

Bm "' ° Q V

a ^g

Q *

n B

a

fHot finger

7.5 8.0

Figure 13: Receiver aperture records

When the MDF bar pass behind the two hot fingers the reference calorimeter is covered

twice, the times TI and T2 are estimated and the time needed to sean the receiver aperture

with the MDF bar is obtained by:

The angular speed of the bar is:(8)

co =AT

(9)

J. Ballestrín 14


So, the angles 8¡ for the times t¡ can be obtained by:

(10)

The radiant power incident on the aperture is obtained by integrating the flux distribution over

the aperture área. Previously it was needed to obtain the flux distribution with a higher

resolution in the different bar directions. So it is possible to interpólate in every temporal

array of data, t¡, with a minimal error due to the flux distribution has a soft shape. After

interpolating with a gap of 10 mm a set of m data is obtamed. It could be possible to

interpólate with a smaller gap but there is not any significant change in the incident power

obtained in the posterior integration and, on the contrary, the calculation time increases.

To obtain only the n (n~3000) data in the interesting área, n<m, a set of conditions are

applied.

Receiver aperture

-0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4

Figure 14: Spatial flux distribution on the receiver aperture

To obtain the incident power onto the receiver aperture the integration of the flux distribution

over the interesting área, A, is done by:

(11)

where F¡ is each of the flux data in the área.

J. Ballestrín 15


To obtain the error of the incident power, three main errors have to be considered:

® The integration error from the equation 11, AP i.

® The interpolaron error, AP2.

® And the error due to the movement of the bar, the positioning of the

sensors in the moving bar... AP3

The integration error is obtained by:

AP - d-̂ v- KA , V ^" " AF -¿Al 1 — ¿X/i ~t~ / LXV • — . . . .

1 dA tt dF¡(12)

n i=\

The estimate of the área is A = 0.414 ± 0.005 m2 and AF¡/F¡= ± 3%, the error AP, is ± 4.3 %.

The dispersión of results when different methods of interpolation are used is almost

neglected, AP2=±0.1%, due to the soft shape of the flux distribution.

The positioning of the sensors in the bar and the movement of the bar also affect the final error.

Probably the bar speed isn't completely constant and the plañe scanned by it isn't parallel

completely to the receiver aperture. Nevertheless, it is quite realistic to consider AP3 « ± 1%.

Therefore, it is possible to obtain an estimation of the global error:

AP¡n =APl+AP2+APi<± 6% (13)

A Matlab program for the analysis of data has been prepared to obtain the flux distribution

onto the receiver aperture. Several interesting quantities as the total incident power, the valué

of the flux peak and its positioning referred to the center of the aperture are also obtained. In

the next pages an example of measurement analysis is presented.

J. Ballestrín 16


Total Power = 198.2 kW kW/m2

-0.4 -0.3 -0.2 -0.1 0 0.1 0.2

560

540

520

500

480

460

,440

i 420

i 400

380

360

Figure 15: Flux disíribution 2D

Last figure is a synthetic image obtained from a group of analog signáis such as been

described before; it represents the 2D-flux distribution onto the receiver aperture by 20

heliostats. The convolution of the contributions of all heliostats supplies the reproduction of

the solar disk as expected. Several relevant quantities associated to this image are:

® Flux peak = 564.7 kW/m2

o xmax =-0.001 m

» ymax = 0.053 m

o Total Power = 198.2 kW

a Power Error = ± 10.7 kW

• Power Error = ±5 .4%

« Flux Average = 478.8 kW/rn2

«• Energy = 0.09 kWli

o Scanning Time = 1.58 s

J. Ballestrín 17


In the next figure, the associated 3D-flux distribution is presented.

Flux distribution (kW/rn2) kW/m2

600-.

550.

500.

450.

400.

350 s

-

-

-

-

-

-

-

-

-

560

540

520

500

480

460

440

420

400

380

360

Figure 16: Flux distribution 3B


receiver Hitrec II are supplied by the above-mentioned MDF system. The first results

obtained during the evaluation of this solar receiver are presented including a sunrise-sunset

test.

DATE: 08/01/2001

GMT (hh:mm:ss)

10:41:2311:11:5611:22:1811:42:11

N° of heiiostats

10152025

Insolation (W/m2)

940957962960

Flux average (kW/m2)

303360479621

Flux peak (kW/m2)

362434565724

Incident power (kW)

126 + 7149 + 8198 ±11257 ±14

J. Ballestrín 18

Direct heat-flux measurement system (MDF) for solar receivers evaluation

DATE: 15/01/2001

GMT (hh:mm:ss)

9:56:1810:13:2610:27:4610:56:0511:09:0111:35:2011:47:1412:10:2512:39:4412:51:5513:04:0014:00:1514:21:1614:31:05

N° of heliostats

1015202525252525252525252727

Insoiation (W/m2)

850867890896907919911904820777762880780828


217345421530549581594567606580596553491546

Flux peak (kW/m2)

257426493635669696703656702684700641581656

Incident power (kW)

90 ±5143 ±8174 ±9

220 + 12227 ± 12241 ±13246 ±13235 ±13251 ± 14240 ±13247 ±13229 ±12203 ±11226 ±12

DATE: 17/01/2001

GMT (hh:mm:ss)

11:05:0311:18:4511:24:0911:33:5911:42:0811:49:1611:56:0712:22:2012:29:2112:59:2713:04:4713:16:0713:42:2514:10:5614:28:4614:40:44

N° of heliostats

25252525252525252525252525252825

Insoiation (Wlm2)

935940941945945950952959955942945944933908887887


560616621608640626650655659619632636635578609591

Flux peak (kW/m2)

715774785771807780813777806746746807759697731717

Incident power (kW)

232 ±13255 ± 14257 ± 14252 ± 14265 ± 14259 ±14269 ±15271 ±15273 + 15256 ± 14262 ± 14263 ± 14263 ±14239 ±13252 ± 14245 ±13

DATE: 23/01/2001

GMT (hh:mm:ss)

11:55:3112:00:5012:08:3312:16:0712:38:18

N° of heliostats

510202528

Insoiation (W/m2)

890300500650850


135161303526641

Flux peak (kW/m2)

158190374662814

Incident power (kW)

56 ±367 ±4125 ±7

218 ±12265 ± 14

DATE: 09/02/2001

GMT (hh:mm:ss)

10:51:2911:17:0111:42:3811:51:5812:55:2013:24:1913:34:5514:26:32

N° of heliostats

2525252524252525

Insoiation (W/m2)

960980989991990980967913


556595615627584576545535

Flux peak (kW/m2)

705701706737677702681661

incident power (kW)

230 ± 12246 ±13255 ± 14259 ± 14242 ±13239 ±13226 ±12221 ± 12

J. Ballestrín 19


DATE: 01/02/2001

GMT (hh:mm:ss)

9:20:519:26:129:30:509:34:569:40:1910:56:0611:07:2811:19:3711:31:4812:29:2612:40:2712:50:5213:04:5813:34:0313:53:4414:30:5214:52:08

N° of heliostats

510152025232323232323232324262626

Insolation (W/m2)

855865875880885945946946968964960956961943935913898


94227330402480541570562564584570576548553555556494

Flux peak (kW/m2)

131272390470560655676669674697672685661702711735644

Incident power (kW)

39 ±294 ±5137 ±7166 ±9199 ±11224 ±12236 ±13233 ±13233 ±13242 ±13236 ±13238 ±13227 ±12229 ±12230 ±12230 ±12205 ±11

DATE:02/02/2001

GMT (hh:mm:ss)

10:36:4110:42:1810:45:3110:53:2611:39:1811:52:4412:17:4412:33:0112:42:5913:09:09

N° of heliostats

6121824252525252525

Insolation (W/m2)

922925930935953964960965958947


154336442585579607603599590565

Flux peak (kW/m2)

178413514685675719705720703665

Incident power (kW)

64 ±3139 ±8183 ±10242 + 13240 ±13252 ±14250 + 14248 ±13244 ±13234 ±13

DATE:05/02/2001

GMT {hh:mm:ss)

9:42:159:47:529:51:5510:58:4311:10:4911:23:1411:38:2911:46:0412:16:4712:36:1812:54:1013:32:3413:49:14

N° of hellostats

8182528282727272627272930

Insolation (W/m2)

840850860916922927921919928935932914907


191385527626642629612631615621625585615

Flux peak (kW/m2)

228449620771743769725759729738734716740

Incident power (kW)

79 ±4159 ±9

218± 12259 ±14266 ± 14260 ±14253 ± 14261 ± 14255 ±14257 ±14259 ±14242 ±13255 ±14

DATE: 08/02/2001

GMT(hh:mm:ss)

10:59:3811:06:3911:25:12

N° of heliostats

262626

Insolation (W/m2)

881873875


565563559

Flux peak (kW/m2)

690683686

Incident power (kW)

234 ±13233 ±13231 ±13

J. Ballestrín 20


DATE: 13/02/2001

GMT (hh:mm:ss)

7:31:318:05:238:10:088:14:158:19:268:45:069:20:469:45:3510:15:3410:45:0811:15:5711:45:4712:45:0613:15:1214:46:4315:16:5615:22:3315:45:3515:49:4716:20:1016:46:2716:49:5417:18:16

N° of heliostats

2525252525252525252525252525252525252525252525

Insolation (W/m2)

49070973174676684390794392197810071004984969902870855814802709604588379


10623525025527534144252744360860662562161845741239733633224918716668

Flux peak (kW/m2)

11627929430232240354464452874273276472172153748247238938829522018989

Incident power (kW)

44 + 297 + 5104 ±6106 ±6114 + 6141 ±8183 ±10218 ± 12183 ±10252 ± 14251 ± 14259 ± 14257 ± 14256 ±14189 ±10171 ±9165 ±9139 ±8138±7103 ±677 ±469 ±428 ±2

13-2-2001 Sunríse - Sunset(25 hefiostats)

-•— Insolation

-o— Solar Power

£

250-

200-

150-

O

a.& ioo-ow

50-

1000

800 5)

io"3

600 <

400

10 11 12 13 14 15 16 17 18

GIVIT ( h )

Figure 17: Sunrise-Sunset of 13-2-2001

J. Ballestrín 21


All these measurements could be concentrated in one coefficient, D., that describes the global

behavior of the Solar Power Plant. The incident power onto the receiver aperture, O , depends

lineally on the number of heliostats, N, and the insolation, I. So, this quantity can be expressed

explicitly as a function of N and I:

Q^QN I A (14)

where A is the reflective área per heliostat, 39.95 ± 0.05 m2 and I the insolation in W/m2.

At the same time this coefficient depends implicitly on other parameters of difficult obtaining

as: heliostat beam quality, cosine factor, heliostat reflectivity, etc. This coefficient has been

obtained performing a fitting of the measured data during the test campaign:

Q = 2.648 lO^4 ±0.212 10"4

This coefficient is only valid around noon when the cosine factor has similar influence. Out of

the central hours of the day the cosine factor changes reducing the incident power onto the

receiver aperture.

FLUX & POWER PREDICTIQNS

H1TREC II VOLUMETRIC RECESVER

J. Ballestrín (2001, CIEMAT-PSA)

[ N° of heliostats | Insolation (W/m2) [ Flux average (kW/m2) | Flux peak (kW/m2) | Incident power (kW) |25 950 607 664 251

Error faand (kW)

271231

Figure 18: MDF Excel tool

The result is a simple Excel tool with two inputs that allows the operator to know the number of

heliostats required to maintain a fix power onto the receiver aperture for a certain insolation.

This kind of empirical tools will be welcome in the ftiture Solar Power Plants for the day-to-day

operation in opposition to the detailed codes more adequate during the design period of the

plant.

J. Ballestrín 22


6 SUMMARY

A direct flux measurement system, MDF, has been designed, constructed and mounted on top of

the SSPS-CRS tower at the Plataforma Solar de Almería (PSA) in addition to an indirect flux

measurement system based on a CCD camera. It's one of the main fiiture objectives to compare

systematically both measurements of the concentrated solar power, increasing in this way the

confidence in the estímate of this quantity. Today everything is prepared to perform the direct

flux measurement on the aperture of solar receivers: calorimeter array, data acquisition system

and software. The geometry of the receiver determines the operation and analysis procedures to

obtain the incident power onto the defined área.

The study of previous experiences with direct flux measurement systems has been useful to

define a new, simpler and more accurate system. A description of each component of the MDF

system is included, focusing on the heat-flux sensors or calorimeters, which enables these

measurements to be done in a few seconds without water-cooling.


receiver Hitrec II are supplied by the above-mentioned MDF system. The first results obtained

during the evaluation of this solar receiver have been presented including a sunrise-sunset test.

All these measurements have been concentrated in one coefficient that describes the global

behavior of the Solar Power Plant.

• Becker, M., Bohn, M., Gupta, B., Meinecke, W., "Solar Energy Concentrating

Systems", Applications and Technologies, 1995.

© Carasso, M., Becker, M. "Performance Evaluation Standars for Solar Central

Receivers". Springer-Verlag, 1990.

• Ajona, J.I., Balsa, P., Becker, M., Blanco, J, Blezinger, H, Macías, M., Malato, S.,

Martínez, D., Richter, C, Sánchez, M., Valverde, A., Weinrebe, G., Zarza, E.,

"Solar thermal test facilities", SolarPaces Report III-5/1995.

« Aguado, M., Ajona, J.I., Gómez, V., Heller, P., Kjibus, A., Neumann, A., Schiel,

W., Silva, M., Tamme, R., Zarza, E., "Solar thermal electricity generation",

Lectores from the summer school at the Plataforma Solar de Almería, The clean

way to genérate electricity and produce chemicals, July 1998.

J. Ballestrin 23


• Winter, Sizzmann y Vant-Hull: (Eds.), "Solar Power Plants". Springer-Verlag,

1991.

• Becker, M.; Gupta (eds.); Meinecke, W.; Bonn, M.,"Solar Energy Concentrating

Systems". Ed.: C.F.Müller, 1995.

o Becker y Funken (Eds); "Solar Thermal Energy Utilization. Germán Studies on

Technology and Applications". Springer-Verlag, 1998.

• Shikin, E; Plis, A; "Handbook on Splines for the User". CRC Press 1995.

Reports

• Ballestrín, J; Maillard, R; "Medida Directa de Flujo (MDF) en un receptor solar.

Diseño y puesta a punto". R-07/00 JBB-RM, 2000.

• Ballestrín, J; "Direct Flux Measuring system (MDF) for the Hitrec II receiver

evaluation". Solair project report TSRC/SOLAIR/ITE-02/2000. September 2000.

• Ballestrín, J; Borretzen; "First results of the Direct Flux Measurement system

(MDF)". Solair project report TSRC/SOLAIR/ITE-03/2001. February 2001.

o Hoffschmidt, B; Pitz-Paal, R; Bohmer, M; Fend, T; Rietbrock, P; "200 KWth open

volumetric air receiver (HitRec) of DLR reached 1000°C average outlet

temperature at PSA". IEA-SolarPACES on Solar Technology and Applications,

Odeillo, France, 1998.

• García, G., "Descripción del software del sistema de medida de flujo del receptor

volumétrico (MFV)". Internal report R-17/88GG, 1988.

• Diessner, F; "Operation manual for the measurement activities with Heat Flux

Distribution (HFD) system". DFVLR (Deutsche Forschungs- und Versuchsanstalt

für Luft- und Raumfahrt), Cologne, June 1981.

• Use of the Vatell Heat flux Microsensor. Vatell Corporation, September 1999.

• Thermateq"-nology. Technical notes. Vatell Corporation, September 1997, June

2000.

• National Instruments: "The Measurement and Automation", Catalog 2000.

o Biggs, F; Vittitoe, Ch; "The HELIOS model for the optical behavior of reflecting

solar concentrators". SAND76-0347, Sandia Laboratories, Alburquerque, USA,

1979.

J. Ballestrín 24


APPEND1X 1: CALIBRATION SHEETS

fATELL CORPORATION

Certifícate of Calibration

Model Number:Serial Number:

Date Calibrated:

Recalibration Due Date:

Sensor Coating:

HFM-7E/L0806

5-5-2000

5-5-2001

Zynolyte

Heat Flux MIcrosensor Calibration DataThe following coefficients are for use with equations in the document, "Use of Vatell Heat FluxMicrosensor Calibration Equations", enclosed. This document should be completely read toeflectively understand sensor measurements. These coefficients apply only to the sensor with theserial number above.

COEFF.

ab

cd

ef

gh*

VALUÉ

0.0

0.0

3.17522

-473.018

0.3'l4939

148.9717

-0.007623

196.8309

UN1TS

xlO"5

xlO"3

n/°cnuV/W/cm2/°C

uV/W/cm2

Resistance Temperature Sensor (RTS)Resistance (@ 22°C): 155 Q.Calibrated Range: 30°C-180°C

Heat Flux Sensor (HFS)Resistance (@ 22°C): 2.94 k Q.Calibrated Heat Flux: 12.963 W/cm2

Sensitivity ¡£ for incident heat flux based on an emissivity of 0.94 at 2 microns.

These calibrations were performed using instrumentswhose accuracy is traceable to the National Institute ofStandards and Technology (NIST) and followin;procedures set in the Vatell Quality Assurance Manual.

Calibrated

LAWRENCEW.LM6LEYNo. 16702

l-l-MAIL: V;II<.-1I(!!-IH.-V.IICI I IOMK l 'Aí i l : : hllp://\vwU'.C¡3.ncl/vaiell/ FAX: (540) 953-30 I O PIIÜNB: (540) 9(¡l-2O()!PO KOX C)(j. Cl IKlSTIANSUlilíC;. VA 24068 • 240 JENNELLE ROAD. CIIRISTIANSBURG. VA 24O7?,

J. Ballestrín 25


ATELL CORPORATION


Model Number:Serial Number:Date Calibrated:Recalibration Due Date:Sensor Coating:

HFM-7E/L08074-27-20004-27-2001

Zynolyte

Heat Flux Mfcrosensor Calibration DataThe following coefiScients are for use with equations in the document, "Use of Vatell Heat FluxMicrosensor Calibration Equatíons", enclosed. This document should be completely read toeffectively understand sensor measurements. These coefficients apply only to the sensor with theserial number above.

COEFF.

abcdef

gh*

VALUÉ

0.0

0.0

3.29167

-489.062

0.303797

148.5755

0.130902

115.9932

UNÍTS

xlO"5

xlO"3

Q/°C

Q

uV/W/cm2/oC

uV/W/cm2

Resistance Temperature Sensor (RTS)Resistance (@ 22°C): 168 OCalibrated Range: 30° C -180° C

Heat Flux Sensor (HFS)Resistance (@ 22°C):Calibrated Heat Flux:

1.77 kQ12.373 W/cm2

: Sensitivity is for incident heat flux based on an emissivity of 0.94 at 2 microns.

These calibrations were performed using instmmentswhose accuracy is traceable to the National InstituteStandards and Technology (NIST) and followinprocedures set in the Vatell Quality Assurance Manual.

Cahbrated by;

1I-MAIL: vaicll<S'lx;v.nc:l l-IOMIi PAGlí: hlip:/Avw\v.G3.nei/vaielI/ FAX: (540) 953-3OR) PHONE: (540) fi(il-2()OiVQ BOX 66. CHHISTIANSUUKC;. VA 24068 • 240 JENNELLE ROAD. CHRISTIANSBURG. VA 24O73

J. Ballestrín 26


rATELL CORPORATION



HFM-7E/L08084-27-20004-27-2001

Zynolyte

Heat Flux Microsensor Calibration DataThe foUowing coefficients are for use with equations in the document, "Use of VateU Heat FluxMicrosensor Calibration Equations", enclosed. This document should be completely read toeffectively understand sensor measurements. These coefficients.apply only to the sensor with theserial number above.

Resistance Temperature Sensor (RTS)Resistance (@ 22°C): 145 QCalibrated Range: 30° C -180° C

Heat Flux Sensor (HFS)Resistance (@ 22°C): 2.36 k D.

COEFF.

ab

cdef

gh*

VALUÉ •

0.0

0.0

3.38048

-471.91

0.295816

139.5983

0.1665

156.0635

UNITS

xlO"5

xlO"3

Í2/°C

nuV/W/cirf/°C

uVAV/cm2

Calibrated Heat Flux: 12.318 W/cmz

* Sensitivity is for incident heat flux based on an emissivity of 0.94 at 2 microns.

These calibrations were performed using instrumentswhose accuracy is traceable to the National InstituteStandares and Technology (NIST) and followinprocedures set in the Vatell Quality Assurance Manual.

Calibrated by:

LAWBEMCEW.UWSGIEYNo. 16702

E-MAIL: [email protected] HOME PAG ti: hlip:/AV\vw.G3.nei/vatell/ FAX: (540) 953-3O1O PHONE: (540) ÍX5I-2OOIPO BOX 06, Cl IRISTIANSBURG. VA 24068 • 240 JENNELLE ROAD. CHRISTIANSBURG. VA 24073

J. Ballestrín 27


ATELL CORPORATION



HFM-7E/L08155-5-20005-5-2001Zynolyte

Heat Flux Microsensor Calibration DataThe following coefficients are for use with equations in the document, "Use of Vatell Heat FluxMicrosensor Calibration Equations", enclosed. This document should be completely read to

effectively understand sensor measurements. These coefHcients apply only to the sensor with the

serial number above.

COEFF.

abcd

ef

9h*

VALUÉ

0.0

0.0

3.73253

-486.369

0.267915

130.3053

0.122747

117.7029

UNITS

xlO"5

xlO"3

n/°cQ.

uV/W/cm2/°C

uVAV/cm2

Resistance Temperature Sensor (RTS)Resistance (@ 22°C): 134 QCalibrated Range: 30° C - 180° C


4.72 k Q

12.929 W / c m 2


These calibrations were performed using instrumentswhose accuracy is traceable to the National Institute ofStandards and Technology (NIST) and followiniprocedures set in the Vatell Quality Assurance Manual.

Calibrated by:y

(7

F . - M A I I . : V Í I K ' I K P I X ' V . I K ' 1 I l ( i M I - ; P A l i l - l : I ) H | > : . ' / w \ v \ v . ( YA. I K . - ¡ / V ; I K ' 1 I / l r . - \ X : i r > 4 O | í ) r > ; í - 3 ( > I o I ' I l ( ) N [ i : ( f i - H ) ] < H ¡ I - l í o u l

i 'onoxiiii. ci ii-;isTiA\sni'fic;. \v\ J-KKÍK • ^-K).II:.NNI-:LLI; HOAU. CHRISTIANSBUKG. \V\ 2-1.07;',

J. Ballestrín 28


r/ATELL CORPORATION



HFM-6C/L05855-5-20005-5-2001Zynolyte

Heat Flux MIcrosensor Callbratlon DataThe following coefficients are for use with equations in tfae document, "Use of Vatell Heat FluxMicrosensor Calibration Equations", enclosed. This document should be completely read toeffectively understand sensor measurements. These coefBcients' apply only to the sensor \vith theserial number above.

Resistance Temperature Sensor (RTS)Resistance (@ 22°C): 84 • D.Calibrated Range: 30° C -180° C

COEFF.

abcdef

gh*

VALUÉ

0.0

0.0

5.51703

-438.464

0.181257

79.4746

0.050514

57.1253

UN1TS

xlO"5

xlO"3

Q/°C

D.uV/W/em2/°C

uV/W/cm2


2.73 k Q.

12.951 W / c m 2

* Sensitivity is for incident heat flux based on an ernissivity of 0.94 at 2 microns.

These calibrations were performed using iastrumentswhose accuracy is traceable to the National Institute ofStandards and Technology (NIST) and followinprocedures set in the Vatell Quality Assurance Manual.

Calibrated by:

LAWRENCEW.UKGLEYNo. 16702

E-MAIL: vaiell<s>l)c:v.nri HOMI-; PACJl-I: l)tl|J:/Av\v\v.G3.ncl/vaiell/ FAX: (540) 953-30 I O PI-IONE: (540) 9U1-2CKHPü BOX CiCi. Cl IRISTIANSBLJRG. VA 24068 • 240 JENNELLE ROAD. CHRISTIANSBURG. VA 24O73

J. Ballestrín 29


r/ATELL CORPORATION

Certifícate of CalibrationModel Number:Serial Number:

Date Calibraíed:


Sensor Coating:

HFM6CL0838

7-20-2000

7-20-2001

Zynolyte

Heat Flux Microsensor Callbration DataThe following coefficients are for use with equations in the document, "Use of Vateil Heat FluxMicrosensor Calibration Equations", eaclosed. This document should be completely read toeffectively understand sensor measurements. These coefficients apply only to tlie sensor with theserial number above.

Resistance Temperatura Sensor (RTS)Resistance (@ 22°C): 130 OCalibrated Range: 30°C-180°C

Heat Flux Sensor (HFS)Resistance (@ 22°C): 3.28 k f l

COEFF.

abcd

ef

gh*

VALUÉ

0.00.0

3.81764

-475.3660.261942

124.5183

0.040492

.46.9813

UNITS

xlO-5

x l0 J

n/°cnuV/W/cm7°C

uV/W/cm2

Calibrated Heat Flux: 12.61 W/crrf

' Sensitivity is for incident heat flux based on an emissivity of 0.94 at 2 microns.

These calibrations were performed using instrumentswhose accuracy is traceable to the National Institute ofStandards and Technology (NIST) and followingprocedures set in tlie Vateil Quality Assurance Manual.

Calibrated by:

li-MAIL: \-;iK-IK«i)fV.lu-l IIOMlí i\\< ¡I-.: hll| >:/7\v\v\v.r,:', ncl/Víltcll/ lv\X: I>HII !).">>:«> lo l'l l ( l \ ' ! i : 154OI ÍM¡ I -2(11) Ii'O BOX (¡(i. Ci 1HISTIANSHI¡I«¡. VA 2-KK)S • 2-U) JENNIii.LH HOAL). Cl IRISTIANSBL'!«'.. VA 2-KI7.'.

J. Ballestrin 30


'ATELL CORPORATION


Model Number:Serial Number:

Date Calibrated:


Sensor Coating:

HFM7EL0817

7-26-2000

7-26-2001

Zynolyte

Heat Flux Microsensor Calibration DataThe following coefficients are for use with equations in the document, "Use of Vatell Heat FluxMicrosensor Calibration Equations", enclosed. This document should be completely read toefiectively understand sensor measurements. These coefficients apply only to the sensor with theserial number above.

Resistance Temperature Sensor (RTS)Resistance (@ 22°C): 130 fiCalibrated Range: 30°C-180°C

Heat Flux Sensor (HFS)Resistance (@ 22°C): 4.26 k O

COEFF.

ab

cd

ef

gh*

VALUÉ

0.0

0.0

3.91142-487.196

0.255661

124.5573

0.190739

186.306

UN1TS

xlO'5

xl0°

O/°C

Q

uV/W/cm2/°CuV/W/cm*

Calibrated Heat Flux: 12.627 W/crrf


These calibrations were performed using instrumentswhose accuracy is traceable to the National Institute ofStandards and Technology (NIST) and followingíprocedures set in the Vatell Quality Assurance Manual. \ LAWREHCE W. IAMSLEY'

No. 16702

Calibrated by:

I:.-M.\!l.- VilU'llwhrv ncl I U i.MI-. I '.M ¡l-l llll|>://\v\v\\\( ü¡ Jld/valcl l / FAX. ITI-KII 9G:i-."!( 111) I'I lONlí: (fi-Mll !«i i -2(HHI'O B( IX <,!.. ( I [l-;iSIl.-\NSIU:H<i. \V\ J-VlKiK • 2-Kl J I lNNI- lUiHOAD. U IHISTIANSBUI-ÍC i. VA 1Í-I-O7:!

J. Ballestrín 31


fATELL CORPORATION

Certifícate of CalibrationModel Number:Serial Number:Date Calibrated:Recalibration Due Date:Sensor Coating:

HFM7EL08527-27-20007-27-2001Zynolyte

Heat Flux Microsensor Calibration DataThe following coefficients are for use with equations in the document, "Use of Vatell Heat FluxMicrosensor Calibration Equations", enclosed. This document should be completely read toefíectively understand sensor measurements. These coefficients apply only to the sensor with theserial number above.

COEFF.

ab

cd

e

f

9h*

VALUÉ

0.0

0.0

3.77309-490.257

0.265035

. 129.9353

0.093488

126.734

UN1TS

xlO"

xlO'3

n/°co.uV/W/cm2/°CuV/W/crrf

Resistance Temperatura Sensor (RTS)Resistance (@ 22°C): 135 OCalibrated Range: 30°C-180°C


3.18 k Q.12.635 W/cm 2

• Sensitivity is for incident heat flux based on an emissivity of 0.94 at 2 microns.

These calibrations were performed using instruments

whose accuracy is traceable to the National Institute of

Standards and Technology (NIST) and following

procedures set in the Vatell Quality Assurance Manual.

Calibrated I

I--MAII.- v;ilrl|í"-l)i-v.|j<-t IUIMI-: l'ACil-:. hll|)://ww\v.(;:i.l lcl/v;ilrll/ FAX: (."4OI <);"">:•!-:!<> I (> HI-IONli: lf>4()| !i ' o i i o x (i(>. <:i i n i s n . \ N s i ' , r i « i . V A 2 4 ( M J S • a-K) JI:NNI-:LI.I-: K O A U .

J. Ballestrín 32

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