Hukseflux BLK Series User Manual
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Hukseflux BLK Series User Manual

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Hukseflux
Thermal Sensors
USER MANUAL BLK - GLD
STICKER SERIES
Black and gold stickers for measuring
convective and radiative heat flux separately
Copyright by Hukseflux | manual v2214 | www.hukseflux.com | info@hukseflux.com

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Summary of Contents for Hukseflux BLK Series

  • Page 1 Hukseflux Thermal Sensors USER MANUAL BLK - GLD STICKER SERIES Black and gold stickers for measuring convective and radiative heat flux separately Copyright by Hukseflux | manual v2214 | www.hukseflux.com | info@hukseflux.com...

  • Page 2: Cautionary Statements

    Cautionary statements Cautionary statements are subdivided into four categories: danger, warning, caution and notice according to the severity of the risk. DANGER Failure to comply with a danger statement will lead to death or serious physical injuries. WARNING Failure to comply with a warning statement may lead to risk of death or serious physical injuries.

  • Page 3: Table Of Contents

    Contents Cautionary statements Contents List of symbols Introduction Ordering and checking at delivery Ordering BLK – GLD stickers Included items Instrument principle and theory Introduction Normal use: moderate-accuracy and comparative measurements Advanced use: high-accuracy measurements Introduction Spectral properties of BLK and GLD stickers BLK and GLD sensors on the same heat sink BLK and GLD sensors at different temperatures Surface temperature correction at high flux levels...

  • Page 4: List Of Symbols

    List of symbols Quantities Symbol Unit Heat flux Φ W/m² Voltage Sensitivity V/(W/m Temperature °C or K Temperature dependence of sensitivity Thermal resistance per unit area K/(W/m²) thermal,A Heat transfer coefficient by convection (W/m Area Reflection factor Absorbance α Emissivity ε...

  • Page 5: Introduction

    Introduction Heat flux measurement is a powerful tool to gain insights into processes involving thermal energy. Heat is transported to an object by convection and radiation. Studying thermal processes, the cause of temperature changes or heat transport, you may wish to separate radiative and convective heat flux.
  • Page 6 Figure 0.3 BLK – GLD sticker series is a range of accessories for use with Hukseflux heat flux sensors of the FHF05 series and HFP01. The stickers have matching sizes and are designed to be applied by the user to the sensor.
  • Page 7 NOTICE The GLD sticker will not perfectly reflect radiation from sources with blackbody temperature higher than 4000 K. Solar radiation is in this category. When in doubt, consult this manual or Hukseflux. See also: • BLK – GLD sticker application...

  • Page 8: Ordering And Checking At Delivery

    Ordering and checking at delivery 1.1 Ordering BLK – GLD stickers The BLK – GLD sticker series is a range of accessories for use with Hukseflux heat flux sensors of FHF05(SC) series and HFP01. The ordering codes of the different versions in the series are BLK-10X10, BLK-15X30, BLK- 50X50, BLK-15X85, BLK-85x85, BLK-80, GLD-10X10, GLD-15X30, GLD-50X50, GLD- 15X85, GLD-85X85 and GLD-80.
  • Page 9 pre-application of the sticker to the sensor(s) of your choice at the factory • When opting for pre-application at the factory, please use the following ordering code: product code sensor with cable length indicated + product code sticker example: HFP01-05-GLD-80 for model HFP01 with 5 meters of cable and a pre-applied gold sticker BLK - GLD sticker series manual v2214 9/47...

  • Page 10: Included Items

    1.2 Included items Arriving at the customer, the delivery should include: BLK – GLD sticker version(s) as ordered • application procedure instruction sheet • prostrated IPA (Isopropyl Alcohol) wipe • See the instruction sheet included with your delivery, the instruction movie on our YouTube channel or Section 4.1 of this manual for instructions how to apply the BLK –...

  • Page 11: Instrument Principle And Theory

    Instrument principle and theory 2.1 Introduction BLK and GLD stickers series are accessories to FHF05 series and HFP01 heat flux sensors. These stickers allow the heat flux sensors to be used to separately measure radiative and convective heat flux. As a first approximation, BLK black stickers absorb all radiation, as Figure 2.1 shows. Figure 2.1.1 BLK black stickers absorb all radiation In contrast to BLK black stickers, GLD gold stickers as a first approximation reflect all radiation.
  • Page 12 BLK black stickers are sensitive both to radiative and convective heat flux, whereas GLD gold stickers, reflecting all radiation, are sensitive to convective heat flux only. See Figure 2.1.3. Figure 2.1.3 Both BLK and GLD stickers are sensitive to convective heat flux Summarising, radiative and convective heat flux are absorbed by the black sticker.

  • Page 13: Normal Use: Moderate-Accuracy And Comparative Measurements

    2.2 Normal use: moderate-accuracy and comparative measurements As a first approximation, you may assume that both sensors are at the same temperature and have perfect absorption and emission. This approach leads to moderate-accuracy results. These may be sufficient for the average user. This moderate-accuracy approach is also often used to compare two situations, for example with a source switched [on] or [off].

  • Page 14: Advanced Use: High-Accuracy Measurements

    Advanced use: high-accuracy measurements 3.1 Introduction The following sections explain what should be done to attain a high-accuracy measurement with BLK and GLD stickers. For high accuracy measurement it is essential to understand that: absorption and reflection of both BLK and GLD stickers may not be perfect •...
  • Page 15 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 wavelength [nm] Figure 3.2.1.1 BLK and GLD reflection factors as a function of wavelength Typical values of the average reflection factors for common radiation sources are given in table 2.2.1.1. For more details on spectral properties of the stickers, see the Appendix on the subject.

  • Page 16: Blk And Gld Sensors On The Same Heat Sink

    Emittance is the amount of thermal energy emitted by an object. Numerically, emissivity is the same as absorption. ε = α ε = α Table 3.2.2.1 Typical absorption factors for common radiation sources RADIATION SOURCE α α UV radiation 0.98 0.65 Solar radiation, Xenon lamps 0.98...
  • Page 17 Measure: , ambient air temperature • , the heat sink temperature • heat flux measured by the black heat flux sensor (output voltage divided by • Φ BLK , sensitivity) Φ heat flux measured by the gold heat flux sensor (output voltage divided by •...
  • Page 18 3.3.1 Measurement of convective flux The purpose is to calculate the convective heat flux Φ convective transferred by ambient air at a certain temperature and speed • to an object at the heat flux sensor location • to an object at the heat flux sensor temperature •...
  • Page 19 As a first approximation we assume that the heat transfer by convection to the BLK and GLD sensors is identical, because their surface temperatures are the same, see 2.3.1. Φ = Φ = Φ (3.3.3.1) convective convective BLK convective GLD The measured radiative flux Φ...

  • Page 20: Blk And Gld Sensors At Different Temperatures

    We assume: = 0.89 (3.3.3.2.3) ε BLK, emitted α = 0.95 (3.3.3.2.4) BLK, incoming Φ = (1.05∙Φ + 0.94∙σ∙(T + 273) (3.3.3.2.5) incoming radiative BLK 3.3.4 Characterising a radiative source: T equivalent blackbody blackbody temperature The equivalent blackbody source temperature assumes that the heat flux sensors face an imaginary, uniform blackbody source •...

  • Page 21: Surface Temperature Correction At High Flux Levels

    3.5 Surface temperature correction at high flux levels A similar correction as in 3.4 should also be considered when there is a large heat flux. In that case the sensor surfaces may be hotter than the temperature measurement. The correction depends on the heat flux Φ through the sensor and on the thermal resistance, , between the point at which the temperature is measured to the sensor surface.
  • Page 22 The corrected temperature for the sensor with GLD sensor becomes + 5.5 x 10 ∙Φ (3.5.1.6) GLD, corrected + 5.5 x 10 ∙(U (3.5.1.7) For FHF05 we recommend correcting if: 12 x 10 ∙(U ) > 2 ˚C (3.5.1.8) 5.5 x 10 ∙(U ) >...

  • Page 23: Optional Correction For Sensor Temperature Dependence

    See the product manuals for up-to-date estimates of temperature dependence for your sensor model. The calibration reference temperature for Hukseflux sensors is 20 °C. Temperature dependence may be corrected. This is worthwhile only if the error is of the same order as calibration uncertainty, i.e., correction is recommended only if the...

  • Page 24: Working With High Colour Temperature Sources; The Sun, Xenon Lamps

    3.7 Working with high colour temperature sources; the Sun, Xenon lamps The colour temperature of solar radiation and of Xenon lamps is around 6000 K. For this spectrum, the GLD sticker no longer is a perfect reflector. Heat flux of a direct solar beam on a clear sunny day may be in the order of 1000 W/m². The absorption of GLD is 20 %, that of BLK 98 %, see section 2.2.

  • Page 25: Examples Of Blk And Gld In Use

    Examples of BLK and GLD in use 4.1 Outgoing radiation heat flux on metallic / reflective surfaces Every object emits radiation. Only very hot objects, hotter than 400 ˚C, emit radiation that is visible to the eye. Although not visible, heat flux sensors with BLK stickers emit a significant amount of radiative energy too, while GLD stickers have a low emission so that the emitted radiation is negligible.

  • Page 26: Sources Covering Part Of The Sensor Field Of View; The View Factor

    Figure 4.1.1 Measuring with BLK – GLD stickers; application of a BLK black sticker and a GLD gold sticker on FHF models for measuring radiative and convective heat flux on an espresso machine. The machine has a polished metal surface of about 45 ˚C. The IR image on the right shows that the black sticker on the left, as well as the sensor wires and connector blocks, emit radiation.
  • Page 27 For example, assuming that the sensors can be represented as a point under the source, for the round infra-red radiator in figure 4.2.1 below, the view factor, f, is determined with f = sin(θ) (4.2.2) Figure 4.2.1 measuring radiative heat flux of a round source. The sensor is situated on a heat sink at T .

  • Page 28: Heat Flux Measurement To Characterise Ovens, Thermal Profiling

    Φ radiative, incoming, source (Φ [SOURCE ON] - Φ [SOURCE OFF] + f∙α ∙Φ radiative radiative BLK, Tambient radiative, ambient /α (4.2.7) BLK, Tsource In case f is sufficiently small, indicating that only a small portion of the ambient space is shaded by the source, or in case the radiative flux from ambient sources to the sensor is small because is close to T , the term f∙ε...
  • Page 29 local air speed, expressed as the heat transfer coefficient [C ] (characterising heating • by air) local equivalent blackbody temperature, or incoming radiative heat flux • (characterising heating by radiation) [T blackbody In some cases, it is sufficient for comparative purposes only, to establish a fingerprint using only a single BLK sensor.
  • Page 30 because both the convective and the radiative heat flux level and the ratio between these two depends on the product surface temperature. The heat flux sensor surface temperature may not be representative. 4.3.2 Equations typically applied in TP experiments with FHF05 series To determine the main measured quantities T , Φ...
  • Page 31 The incoming radiative flux: Φ = 1.05∙Φ +0.94∙σ∙(T +273) (4.3.2.11) incoming radiative may also be calculated, but that parameter is of less use than the C Φ convective, incoming because it is valid only for an object with a certain surface temperature T surface Φ...

  • Page 32: Specifications Of Blk - Gld Sticker Series

    Specifications of BLK – GLD sticker series 5.1 Specifications of BLK – GLD stickers BLK – GLD sticker series can be applied to a heat flux sensor. BLK stickers provide the sensor with a black absorbing surface so that it measures convective and radiative heat flux, in W/m².
  • Page 33 Table 5.1.1 Specifications of BLK – GLD sticker series (started on previous page, continued next page) Adhesive ARcare 8026 silicone transfer tape ® Sticker thickness 0.05 x 10 Sticker thermal resistance 3.5 x 10 K/(W/m Sticker thermal conductivity 1.45 x 10 W/(m·K) GENERAL SPECIFICATIONS Effect on sensor sensitivity...

  • Page 34: Dimensions Of Blk - Gld Stickers

    Table 5.1.1 Specifications of BLK – GLD sticker series (started on previous pages) VERSIONS AND ORDER CODES BLK-10X10 / GLD-10X10 to be used with model FHF05-10X10 BLK-15X30 / GLD-15X30 to be used with model FHF05-15X30 BLK-50X50 / GLD-50X50 to be used with model FHF05-50X50 BLK-15X85 / GLD-15X85 to be used with model FHF05-15X85 BLK-85X85 / GLD-85X85...
  • Page 35 Figure 5.2.2 The dimensions of the BLK – GLD stickers match the dimensions of the corresponding heat flux sensors FHF05 series and HFP01 Figure 5.2.3 Layer build-up for the BLK - GLD sticker series. Depicted is BLK/GLD- 50X50 protective foil BLK / GLD sticker release liner with peeling tab BLK - GLD sticker series manual v2214...

  • Page 36: Installation Of Blk - Gld Sticker Series

    Installation of BLK – GLD sticker series 6.1 Application procedure For the best possible measurement of heat flux sensors with BLK - GLD stickers applied, it is important that the application is done correctly. The stickers must be aligned with the sensor, without leaving scratches, (finger) grease, or inclusion of air pockets.
  • Page 37 Partially peel and cut the release liner (approximately 1 cm). Do not remove the release liner completely. Position the sticker on the release liner sensor surface. removed Make sure no air bubbles are enclosed. release liner still attached If the sticker does not align properly or if air bubbles are enclosed, remove the sticker and go back to step 3.

  • Page 38: Site Selection And Sensor Installation

    6.2 Site selection and sensor installation Table 6.2.1 Recommendations for installation of sensors with BLK – GLD stickers Location choose a location that is representative of the process that is analysed avoid direct exposure to the sun Positioning when using multiple sensors with BLK and GLD stickers, place them side by side on the same heat sink (a metal plate) so that they have approximately the same temperature Surface cleaning and...
  • Page 39 Figure 6.2.1 Installation of model FHF05-50X50 with BLK sticker using tape to attach the sensor and FHF05-50X50 connection block serving as strain relief. Extra strain relief on the wires is provided using cable tie mounts equipped with double-sided adhesive tape. As also indicated in the sensor manual, tapes for mounting of the sensor should only cover the passive guard area and not over the sensing area (the latter indicated by a dashed line).

  • Page 40: Maintenance And Trouble Shooting

    BLK stickers: do not use any solvents. In case of damage, users may remove stickers and replace them by a new sticker. Sensors may also be sent to Hukseflux to apply a new sticker. BLK - GLD sticker series manual v2214 40/47...
  • Page 41 For sensor maintenance: consult the sensor manual. Here are some general recommendations. Table 7.1.2 General recommended maintenance of heat flux sensors. If possible, the data analysis is done on a daily basis GENERAL: MINIMUM RECOMMENDED HEAT FLUX SENSOR MAINTENANCE INTERVAL SUBJECT ACTION 1 week...

  • Page 42: Trouble Shooting

    On-site (field) calibration is possible by comparison to a calibration reference sensor. Usually mounted side by side, alternatively mounted on top of the field sensor. Hukseflux main recommendations for on-site calibrations are: 1) to compare to a calibration reference of the same brand and type as the sensor that is...

  • Page 43: Appendices

    Appendices 8.1 Reflection versus wavelength and source temperature Figures 8.1.1 and 8.1.2 show the reflection of the BLK and GLD stickers as a function of wavelength of the incoming radiation. Upon request, the data from these graphs are also available in CSV format. 0.18 0.16 0.14...
  • Page 44 Usually, the spectral composition of the source is not known exactly. If the source can be reasonably described as a blackbody source of a certain temperature T, an average reflectance factor can be calculated by integrating the reflectance of the sticker with the blackbody spectrum.
  • Page 45 Table 8.1.1 average reflection factors of BLK and GLD for various blackbody source temperatures blackbody source average reflection average reflection temperature [°C] factor BLK factor GLD 0.13 0.99 0.12 0.99 0.12 0.99 0.12 0.99 0.12 0.99 0.11 0.99 0.11 0.99 0.11 0.99 0.11...

  • Page 46: Eu Declaration Of Conformity

    8.2 EU declaration of conformity Hukseflux Thermal Sensors B.V., Delftechpark 31, Delft, The Netherlands hereby declare under our sole responsibility that: Product model BLK GLD sticker series, all models* Product type Stickers is in conformity with the following directives: 2011/65/EU...
  • Page 47 © 2022, Hukseflux Thermal Sensors B.V. www.hukseflux.com Hukseflux Thermal Sensors B.V. reserves the right to change specifications without notice.

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