calibration of heat flux sensors which is effective to

Calibration of heat flux sensors which is effective to evaluate heat transfer

for building materials.

Megumi Akoshima

National Metrology Institute of Japan (NMIJ), AIST

24. Nov. 2018

APMP 2018, Energy Efficiency Focus Group Workshop

@ Sentosa, Singapore

Contents

1. Background

2. Development the Heat Flux Density Standard in NMIJ – Concepts – Arrangement of the apparatus – Validation of the apparatus – Uncertainty evaluation – Example of calibration for a heat flux sensor

3. A new apparatus to evaluate sensitivity coefficient changing conditions

4. Summary

Background

Power Generation of Japan (Nuclear, Thermal, Hydroelectric, Wind, Geothermal, Solar, ….etc. ) [ Coal, Natural Gas, Oil, Biomass, ….etc. ]

出典：電気事業連合会「電源別発電電力量構成比」 http://www.fepc.or.jp/about_us/ pr/pdf/kaiken_s3_20160520_1.pdf

Since East Japan great earthquake disaster, electrical power is in crisis situation in Japan. Strategic Energy Plans

Background Strategic Energy Plans in order to realize Energy Saving in Japan – Production of Energy:

Power Generation efficiency improvement, Development of renewable energy…etc.

– Use of Energy: Buildings, Electronics, Automobiles, Train, Airplane, …..etc.

For example, The energy saving standard for buildings was enacted in 2012, for new buildings

2012 2013 2014 2015 2016 2017 2018 2019 2020

Notification and satisfaction are mandatory

Notification is mandatory



Notification and satisfaction are mandatory

Notification and Satisfaction

floor area ≧ 2000 m2

300 m2 ≦ floor area ＜ 2000 m2

floor area ＜ 300 m2

Background • energy saving standard for buildings

出典：METI Japan’s Energy Strategy http://www.enecho.meti.go.jp/en/category/brochures/pdf/energy_plan_2015.pdf

Energy Consumption + Air conditioner + Ventilation + Illumination + Hot water supply + Consumer electronics - Renewable energy

Thermal properties of walls (thermal transmittance etc)


energy saving standard value

+

energy design value

V

The satisfaction of energy saving standard is necessary for new buildings. (regulation) Quantitative evaluation of energy is important. How to measure them? → heat flux sensor is used as one of tools

Heat flux sensor = the only sensor to measure heat flux directly A sensor shows voltage correspond to heat flux which through the sensor

6

Background：Heat Flux Sensors

From Web pages of KEM,, EKO, ETO, Denso, Hioki

Use for evaluation and monitor of Heat loss • walls and windows of buildings • power control of air conditioners • walls of industrial furnaces for safe • warmth check of clothes • thermal conductivity measurement • agriculture field • automobiles field …etc.

What is a Heat Flux sensor ? • Typical sensor consists of array of bonded

two kinds materials. (like thermocouples) • The output is an electromotive force

occurred between surface and rear-surface of the sensor

• The determination of relationship coefficient between EMF and heat flux is necessary before it is used.

There is a need to check reliability of sensors. There is no standard method for calibration of it. From 2012, Energy Conservation Act of Japan was revised. Energy consumption of buildings should be checked at design before build. There is an urgent need of calibration of them.

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Purpose and Target Heat flux sensors • It is expected to become more popular according to Energy problem. (Especially, for Revised Energy Conservation Act in Japan) • Sensitive coefficient should be determined before use

– How to determine it ? ☞ There are some methods. It may depends on how high heat flux.

– Reliability ☞ Calibration are necessary. In this study, Purpose:

• Establishment of a calibration service for heat flux standard Target:

• Plate shape sensors “1D heat flux through a sensor” • heat loss evaluation from buildings “not so high heat flux” Development of Guarded Hot Plate method range of 0< q ≲ 100 W/m2 .

Calibration of Heat Flux Sensor by GHP method

Heat Flux Sensor is used in almost steady state around R.T. for heat loss evaluation of buildings Fourier’s law Thermal conductivity λ is Measured specimen (Insurator)

Meta Plate GHP GHP

Cold Plate

Hot plate to avoid heat reverse

[m] hicknessSpecimen t:][m Plate Meta of Area:A

[W] Plate Meta Power toInput :

TC,:TR

2

12

d

QRdA

QTTR ＝： λ−

=

Outline of Guarded Hot Plate apparatus Ref. JIS A 1412-1, ISO 8302

2

Specimen

Heat Flux Q=q・A

T 1

T d

Guarded Hot Plate method is useful.

( )21 TTdAq

TdQ

−⋅⋅

=∆⋅

=λ

Calibration service as heat flux standard in NMIJ Outline of the calibration service • Target: Heat flux sensors • Type: plate shape ( 20 mm x 20 mm ≦ plate ≦ 50 mm x 50 mm ) • Range of heat flux: 0 W/m2 ＜ q ≦ 100 W/m2 • Measurement environment : room temperature • Measurement method : Guarded hot plate method • Expanded uncertainty ： more than 2.0 %

The service was launched in 2015.

Measurement apparatus

Insulator

Insulator

Meta Hot Plate GHP GHP

Cold Plate


Area of Meta Plate

Joule Heat

Length Electrical

National Standard SI

Caliper DMM (I, E)

Output voltage of sensor

Apparatus

• Heat Flux ： q = Q / A = IV / L2

Q: joule heat of meta hot plate A: area pf meta hot plate • Uncertainty evaluation according to GUM

Heat flux sensor

Example of Error Budget Table (data1) q = 24.6 W/m2

Vout =0.2786 mV

Q[W], q[W/m2], I[A], V[V], L[m], A[m2]

Example of Error Budget Table (data 2)

Q[W], q[W/m2], I[A], V[V], L[m], A[m2]

q = 79.8 W/m2

Vout =0.8558 mV

Calibration service as heat flux standard in NMIJ Outline of the calibration service • Target: Heat flux sensors • Type: plate shape ( 20 mm x 20 mm ≦ plate ≦ 50 mm x 50 mm ) • Range of heat flux: 0 W/m2 ＜ q ≦ 100 W/m2 • Measurement environment : room temperature • Measurement method : Guarded hot plate method • Expanded uncertainty ： more than 2.0 %

The service was launched in 2015.

Measurement apparatus

Insulator

Insulator

Meta Hot Plate GHP GHP

Cold Plate


Area of Meta Plate

Joule Heat

Length Electrical

National Standard SI

Caliper DMM (I, E)

Output voltage of sensor

Apparatus

• Heat Flux ： q = Q / A = IV / L2

Q: joule heat of meta hot plate A: area pf meta hot plate • Uncertainty evaluation according to GUM

Heat flux sensor

◎Apparent sensitivity coefficient ・put on ⇒ no 1D heat flux

Question: Is sensitivity coefficient intrinsic?

◎Unique sensitivity coefficient ・surrounded ⇒ １D heat flux

Cold Plate

Hot Plate Hot Plate

Sensitivity coefficient is able to change dependent of environment. There are some difficulty to obtain repeatability.

The phenomena is repeatable. It is suitable for calibration.

There is a need to confirm this question.

14

Background • energy saving standard for buildings

出典：METI Japan’s Energy Strategy http://www.enecho.meti.go.jp/en/category/brochures/pdf/energy_plan_2015.pdf


Thermal properties of walls (thermal transmittance etc)


energy saving standard value

+

energy design value

V

Quantitative evaluation of energy is important.

How to measure them? → heat flux sensor is used as one of tools

Changing conditions • Temperature of hot plate • Atmosphere( air, Ar, N2, vacuum) • Emissivity (Color) of HFMs

HFMs are calibrated before. Their unique sensitivity ecoefficiency are known.

Apparatus to check apparent sensitivity coefficient

16

Data logger

Thermal camera

Test (temperature change in air and in vacuum) Apparatus to check apparent sensitivity coefficient

17

Data logger

Thermal camera

20

30

40

50

0 500 1000 1500 2000 2500 3000

Tem

pera

ture

/ ℃

Time / minutes

0

50

100

150

200

0 500 1000 1500 2000 2500 3000

Sensor①Sensor②

Hea

t flux

mea

sure

d by

hea

t flux

sens

or

/ W

m-2

Time / minutes

air vacuum air

SUMMARY

• A new regulation for new buildings was started in Japan. The heat flux sensor is one of tool to evaluate heat loss related to the energy saving standard for new building.

• NMIJ established a calibration service for a heat flux sensors • Heat Flux evaluation By GHP method • SI traceability • Uncertainty evaluation Outline of calibration service

• Sensor size : larger than 20 mm sq. and smaller than 50 mm sq. • Sensor shape : Plate shape • Range : 0 < q ≦ 100 W/m2 • Condition : at room temperature (23±5 ) oC, Relative humidity < 50 %x In the future, we have a plan to expand range of the calibration.

• NMIJ is constructing an apparatus to evaluate sensitivity coefficient of HFM changing conditions.

In the future, we will propose how to use heat flux sensors with high reliability.

calibration of heat flux sensors which is effective to

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