IEC 62693 Edition 1 0 2013 06 INTERNATIONAL STANDARD NORME INTERNATIONALE Industrial electroheating installations – Test methods for infrared electroheating installations Installations électrothermiqu[.]
General
3.1.1 installation class group within a type of installation, using the same principle for processing the workload and the size of this as well as the production capacity
3.1.2 production capacity measure of the production rate capability of equipment in normal operation
EXAMPLE Flow, mass or volume
Note 1 to entry: The capacity does not refer to the volume of the working space
Electroheating efficiency refers to the ratio of the usable enthalpy increase in the workload to the electric energy supplied to the equipment This measurement is taken during a cycle of batch operation or stationary operation over a suitable time period.
[SOURCE IEC 60050-841:2004, 841-22-70, modified – The term itself has been modified and details with respect to the kind of operation have been added.]
Electric conversion efficiency is defined as the ratio of the available electric active power output used for workload transfer to the electric input active power sourced from the supply network, specifically under normal operating conditions.
Note 1 to entry: The concept does not apply to conversion of electric energy to infrared radiation by heated elements
3.1.5 intended workload quality product quality degree to which a set of inherent characteristics of a processed workload fulfils requirements
Note 1 to entry: All workload that does not attain the intended workload quality is regarded as scrap or undergoes rework to reach intended workload quality.
States and parts
The cold start-up process involves energizing equipment from a cold state to achieve hot standby operation, encompassing all necessary start-up operations to ensure the equipment functions as intended.
This operational mode is relevant in situations where substantial energy is required to prepare the equipment for effectively handling the workload.
3.2.2 holding power electric power consumption during which the workload is kept in the treatment chamber at a specified temperature
Note 1 to entry: The temperature is typically maintained during a time intended to equalize the workload temperature
Note 2 to entry: This mode of operation is not applicable for certain types of electroheating equipment
3.2.3 hot standby operation mode of operation of the installation occurring immediately after normal operation
Note 1 to entry: This mode of operation of the installation is with its hot state remaining, without workload, and with the means of operation ready for prompt normal operation
3.2.4 normal operation range of output settings with the normal workload in allowable working conditions of the installation, as specified in the manufacturer’s documentation
3.2.5 shut-down operation process by which the installation is de-energised safely into the cold state
3.2.6 port entrance or exit opening in the treatment chamber or enclosure through which the workload moves
The term 3.2.7 refers to all structural components of the infrared electroheating installation that can be opened or removed without the need for tools, allowing for easy access to the interior of the system.
Workload
3.3.1 normal workload object intended to be processed as specified in the manufacturer’s documentation
Note 1 to entry: The workload is called “charge” in some electroheating contexts
Note 2 to entry: The workload includes any container, holder or other device necessary for the processing and which is directly or indirectly subjected to the output power
3.3.2 dummy workload artificial workload with known thermal properties, designed for accurate enthalpy increase measurements by absorbing the available output power
IDW dummy workload intended to mimic the physical behaviour of the workload, especially its radiation absorption behaviour, allowing for the effective measurement of specific parameters of the process
Note 1 to entry: Example for a specific parameter is the homogeneity of processing of the surface of the workload
Note 2 to entry: This note applies to the French language only
4 Boundaries of the installation during tests
Energy considerations
Defining the boundaries of an installation is crucial for accurate energy calculations and fair comparisons between batch and continuous systems Key considerations include: a) the inclusion of energy from the compression or decompression of gases in the process chamber; b) the incorporation of exo- or endothermic chemical energy from reactive gases; c) the accounting of energy used for cooling from excess reactive or inert gases; and d) the separate reporting of energy used to cool the processed workload to ambient temperature or for further treatment Additionally, any recycling of thermal energy back into the process must be reported distinctly to facilitate comparisons with similar installations that do not utilize this feature, while thermal energy used externally should be excluded from the reporting.
Batch type installations
Batch type installations involve discontinuous processing, where access points are opened to place a workload into the treatment chamber After normal operation, the access points are reopened to remove the workload The installation then either enters a hot standby mode with closed access or restarts the process with a new workload.
Normal operation always includes heating and can also include one or more of the following sub-processes:
• closing and opening of means of access;
• pressurising of the treatment chamber;
• transport of the workload – this includes for example wobbling movement during operation;
• holding the workload at a specified temperature for a specified time;
• introducing reactive or protective gases into the treatment chamber – including deposition processes;
• free or forced cooling of the workload – for example, if cooling is necessary to avoid damage by exposing the hot workload to ambient atmosphere
The energy consumption associated with various sub-processes must be accounted for within the installation's spatial boundaries This includes the entrance port, where the workload is initially placed or transported into the treatment chamber, and the exit port, where the workload is removed post-operation Additionally, all intermediary equipment, such as switchgear, pumps, and cooling systems essential for the operation, is also considered part of the installation and its energy usage.
NOTE In vacuum equipment, the boundary between the infrared installation and another installation is typically a valve
The cycle of batch operation relevant for measurement shall begin after hot standby operation.
Continuous type installations
Continuous type installations feature ongoing or semi-ongoing processing, where the workload is transported through the treatment chamber during standard operations Treatment steps occur sequentially within the installation as the workload moves through, such as in roll-to-roll or sheet feed systems Typically, these installations enter a hot standby mode when there is no workload being processed.
The normal operation always includes heating and can include one or more of the following sub-processes which occur at separated spatial positions inside the installation:
• holding the workload at a specified temperature;
• introducing reactive or protective gases – including deposition processes;
• free or forced cooling of the workload – for example if cooling is necessary to avoid damage by exposing the hot workload to ambient atmosphere
The energy required for these processes must be accounted for, with the installation boundary defined by the entrance and exit ports, as well as all intermediary equipment, such as switchgear, pumps, and cooling systems essential for the operation of the equipment.
The energy consumption of transport or roll handling in stand-alone installations is included in the used energy It shall be stated separately in the calculations
5 Types of tests and general test conditions
General
No tests are specified for installations in a cold state, as all such tests pertain to safety and fall outside the scope of this standard Relevant safety-related tests are detailed in the appropriate documentation.
List of tests
During the commissioning and normal operation of the installation, as well as at specified intervals, several tests must be conducted in the hot state These tests include assessing the influence of supply voltage on performance, measuring energy consumption during cold start-up, standby, holding, and shutting down operations, and evaluating energy usage during regular maintenance and normal operation Additionally, the tests will analyze energy consumption throughout a full operation cycle and peak power consumption.
The production capacity is detailed in section 7.9, while the efficiency of energy transfer to workload can be found in Annex A The processing range necessary for the installation's intended operation is outlined in section 7.11 Additionally, the homogeneity of workload processing is discussed in Annex B, and the distribution of infrared radiation within the installation is covered in Annex C.
Additional tests may be specified in the commissioning and operation manuals issued by the manufacturer or may be agreed between the manufacturer and user.
Test conditions
Testing conditions must align with normal operational parameters to accurately represent the manufacturer's intended use of the installation This excludes extreme usage scenarios, intentional misuse, or unauthorized alterations to the installation or its operating settings.
All tests must be conducted under standardized environmental conditions, specifically at ambient temperatures ranging from 5 °C to 40 °C and with air relative humidity below 95% Alternatively, testing may occur at the installation's point of use, adhering to the specified environmental conditions present there.
The environmental conditions must remain within the specified limits for the intended installation purpose During testing, all environmental factors that could influence measurement results should be monitored and included in the measurement report.
• air temperature and humidity near the installation;
• temperature and humidity of cooling air drawn into the installation;
• temperature of the workload when entering the installation;
• moisture content of the workload when entering the installation, if applicable
The supply voltage shall not exceed the limits defined for the intended purpose
NOTE Limits of variation of line voltage are set in IEC 60038 [1]
The supply voltage to the installation shall be monitored during the tests
All measurements of specific electrical values, such as power consumption or current shall include the data of the supply voltage.
Infrared dummy workload
The following aspects shall be considered when using an infrared dummy workload (IDW):
• in case of a planar workload, the IDW shall be planar;
The IDW must match the size in batch processes or the width in continuous processes of the intended workload to effectively test the effects across the entire usable capacity of the installation.
• in case it is intended to process workloads with a complex shape, the IDWs shape shall include all relevant geometrical features of the normal workload;
• for the measurement of temperature homogeneity, the IDW shall have a comparable heat absorbing capacity, i.e the factor of volume, density and heat capacity c p ;
• for the measurement of evaporation homogeneity, the IDW shall be made of the same material as the workload and be prepared with a comparable amount of evaporable substance;
• for the measurement of crosslinking homogeneity, the IDW shall be made of the same material as the workload
General
For accurate testing, it is advisable to conduct multiple measurements as outlined in this standard Time-resolved measurements should utilize a data logger or a multi-channel electronic data acquisition system to automatically capture and store the required data in a format compatible with computers.
Time resolution
The time resolution of measuring equipment and the data saving rate of storage devices are determined by the installation and specific tests being conducted It is essential that the measurement and storage frequency is sufficiently high to capture all significant signal variations.
Measurements of electric data
All equipment for voltage measurement shall be of class 2.0 or better The measuring
6.3.1 equipment for a.c current shall be able to show true rms independently of the waveform
All equipment for current measurement shall be of class 2.0 or better The current
6.3.2 measuring equipment for a.c current shall be able to measure true rms independently of the waveform
All equipment for energy consumption measurement shall be of class 2.0 or better
The measuring equipment shall be able to measure active and reactive energy independently of the waveform
All equipment for power consumption measurement shall be of class 2.0 or better
The measuring equipment shall be able to measure active and reactive power independently of the waveform
Measurements of all electric values, which are part of a test of energy or power use
6.3.5 of the installation shall be performed at the power inlet to the installation
Measurements of all electric values, which are part of a test of energy or power use
The installation of infrared emitters must be conducted at the power outlet of the switchgear linked to the emitters This includes transformers, capacitor circuits, or similar devices essential for operating the emitters, which are integral components of the switchgear.
Measurements of all electric values, which are part of a test of energy or power use
6.3.7 of auxiliary equipment, shall be performed at the respective power outlet of the switchgear connected to that equipment
Specific access points may be installed during manufacturing of the installation
Measuring equipment may be part of the switchgear; its energy use is considered as part of the energy use of the switchgear.
Temperature measurement
The kind of equipment used for temperature measurement depends for example on the task, temperature range, available information on the surfaces being measured, and accessibility
Contact thermocouples are user-friendly and dependable, delivering accurate results when they maintain close, non-detachable contact with a high-mass object that has good thermal conductivity.
Pyrometers and infrared cameras, classified as thermographic methods, are effective for measuring elevated surface temperatures when the surface's emissivity is accurately known and behaves as a lambertian surface, adhering to the cosine law of angular emissivity It is essential to include the utilized emissivity value, the measurement wavelength, and the estimated emissivity error in all measurement reports.
The relative measurement error for all temperature measurements in compliance with this standard shall not exceed 5 % of the temperature of the measured value stated in °C
Measurement accuracy shall be included in the measurement report
NOTE The German VDI/VDE 3511 series [19 – 26] provides information on best practices for temperature measurement in industry
Installation performance dependence on supply voltage
The performance of infrared electroheating installations is significantly affected by the actual supply voltage or its fluctuations, particularly when infrared emitters are powered directly or through fixed transformers This impact becomes more pronounced when there is a discrepancy between the actual or declared supply voltage and the rated supply voltage.
The power consumption of individual infrared emitters varies based on their applied working voltage and the type of emitter This information is typically provided by the manufacturer, detailing how power consumption changes with the actual working voltage.
• shall either be calculated using this data,
The performance of the installation can be evaluated by monitoring the supply voltage and power consumption of both the installation and its emitters over an extended period, while maintaining consistent settings.
NOTE The future standard on infrared emitter tests [11] will consider the measurement of variation of power consumption depending on voltage
Variation of power with the actual working voltage affects other parameters of the installation as well – for example wall temperature, processing time, heating up time
The actual supply voltage can affect the results of all tests as well; it shall be part of the test report.
Energy consumption and time of cold start-up operation
For measuring cold start-up time and energy consumption in installations designed for this operation, the following criteria must be met: a) The installation must be heated from ambient conditions as specified in section 5.3.2 b) The installation should operate without a workload, if applicable c) Any necessary preheating of the treatment chamber or zone should be conducted to achieve a state close to hot standby operation, if applicable d) Finally, the total electric energy consumption and time for the cold start-up must be accurately measured.
Cold start-up energy consumption can be measured for
If the installation is intended to be heated up safely with workload only, this shall be considered.
Power consumption of hot standby operation
To measure hot standby power consumption, the installation must operate without workload when applicable, maintain the conditions of hot standby operation, and record both the total energy consumption and the duration of the hot standby period.
Hot standby power can be measured for
Power consumption of holding operation
The holding feature of an installation is usually needed to achieve workload temperature equilibration after the process proper and does not exist in some types of installations
The key distinction between hot standby and holding is that in holding, the workload is active and capable of emitting radiation or providing convective or conductive energy to its surroundings To regulate the workload temperature, adjustments are typically made to the external energy supply.
For measuring power consumption during temperature holding operations with a workload, the following criteria must be met: a) the test is relevant when holding is integral to normal operations; b) the installation must operate with a preheated workload; c) the workload temperature should remain constant through specific control settings; and d) both the total energy consumption during the holding period and the duration of the holding time must be recorded.
Holding power can be measured for
Shut-down operation energy consumption and time
For measuring energy consumption during shut-down operations, it is essential to follow the manufacturer's specified shut-down procedures This includes recording the total energy consumed during the shut-down period along with the duration of the shut-down itself.
Shut-down power consumption can be measured for
• the infrared emitters only – if applicable;
Energy consumption during a regular maintenance operation
For accurate measurement of maintenance energy consumption and time, it is essential to adhere to the manufacturer's specifications for installation maintenance Additionally, both the total energy consumed during maintenance operations and the duration of these maintenance activities must be recorded.
Maintenance power consumption can be measured for
• the specific maintenance equipment only.
Energy consumption during normal operation
All measurements of electric energy consumption must accurately reflect the specific usage by designated parts of the installation over a defined time period or operation Key reporting elements include: a) the energy consumption of a batch-type installation during a single cycle, which can be averaged over multiple cycles, with the number of cycles and variations documented in the test report; b) the energy used by a continuously operating installation while processing a specified workload; and c) the total energy consumption over a complete production cycle, such as a workday, week, or year.
Normal operation energy consumption can be measured for
Cumulative energy consumption and peak power consumption
Measuring time-resolved power consumption of the installation allows for the calculation of cumulative energy usage and peak power consumption Testing should be conducted by monitoring the power consumption over: a) one cycle, if the installation cools down between cycles; b) one shift, if it operates for several hours and cools down at the end of the workday; or c) the entire heating period plus one hour of operation for continuous operation.
The internal electric conversion and switchgear of the installation are engineered to accommodate specified peak power consumption, which determines the rated power for designing and sizing the electric power supply The actual peak power consumption is measured throughout a complete process cycle, from heating to cooling.
Peak power consumption of the installation can be reached during one of the following stages:
• preheating of continuous processing installation;
• heating up of a batch type installation;
• or during other modes of operation
A process phase resolved mapping of power consumption is essential for implementing smart and energy-efficient control in installations This approach enables the reduction of energy peaks by shifting high consumption processing intervals to times of lower energy demand or reduced electricity costs.
Net production capacity
Net production capacity assesses the output efficiency of an installation based on the quality of the intended workload It evaluates only the components of the workload that meet the desired quality after completing the specified processes.
The workload will be measured at two key stages: first, when it is delivered to the installation and must meet quality standards to avoid rejection, and second, when it exits the installation, ensuring it meets the intended quality after processing.
The amount of workload shall be
• stated as unit mass per time, when not countable, or
• stated as unit area per time, when being in sheet form
The net production rate, which focuses solely on the processed workload of intended quality, should be specified for either a single batch process or a designated time frame This rate is calculated by dividing the amount of workload that meets the intended quality by the total workload processed.
Scrap rate is defined as amount workload not of intended quality divided by all workload processed.
Efficiency of energy transfer to the workload
The estimation of the efficiency of energy transfer to the workload is typically a complex task
Test methods concerning the efficiency of transfer from the installation to the workload are given in Annex A of this standard.
Processing range of intended operation
The processing range of an installation is defined by the upper and lower limits of set parameters, ensuring that the processed workload meets the desired quality Despite this defined range, processing conditions may still fluctuate within the installation and across the workload's surface.
The processing range can be determined by two key steps: First, operate the installation with a workload while gradually increasing the power setting until the entire workload is effectively processed, identifying the lower limit where the least infrared radiation is received Second, continue to increase the power setting until the workload begins to overheat, marking the upper limit where the most infrared radiation indicates potential damage.
Homogeneity of the processed workload
Testing the homogeneity of processing across the workload surface is a complex challenge, as the methods employed depend on the specific quantity or quality objectives of the installation process Detailed specifications can be found in Annex B.
Infrared radiation distribution in the heating chamber
Testing the distribution of infrared radiation within the operating installation is essential for evaluating the infrared electric conversion efficiency and identifying sources of uneven workload processing Detailed test methods for assessing infrared radiation distribution are provided in Annex C.
General
The results from the tests given in Clause 7 allow calculation of relevant efficiency values of the installation
The minimum theoretically needed energy per piece, unit mass or unit area of the workload undergoing the intended process is
E min = ⋅ p ⋅∆ + eva + (1) where m is the mass of the workload;
( ) T c p is the specific heat of the workload;
∆T is the temperature change from ambient to maximum process temperature;
E eva is the energy needed for evaporation of solvents during the process for a mass of m of the workload;
R is the energy needed for intended chemical reactions to occur for a mass m of the workload
To determine the minimum energy required for a specific process, Formula (1) is utilized, assuming that there is no energy loss and that energy is neither reused nor recycled within the system.
Infrared electric conversion efficiency
Infrared electric conversion efficiency measures how effectively electric power is transformed into infrared radiation within industrial electroheating installations This efficiency is crucial, as it serves as the primary method of energy transfer in these systems It is defined as inst conv irr.
= E η (2) where ηconv is the electric-to-infrared conversion efficiency;
E irr is the radiation energy irradiated onto the workload;
E inst is the energy consumption of the installation
This efficiency may either be stated for energy consumption of the complete installation or of the infrared emitters only
A first step is the definition and calculation of the electric-to-infrared conversion ability
- ηcon is the electric-to-infrared conversion ability of the installation; conv
, η i is the electric-to-infrared conversion efficiency of the i-th emitter;
E i is the energy consumption under test conditions of the i-th emitter
NOTE A test method for measuring the conversion efficiency of a single emitter will be given in future
The value mentioned does not indicate conversion efficiency; rather, it reflects the amount of infrared radiation produced by the emitters under single emitter test conditions These conditions can significantly differ from the actual operational environment of the installation Additionally, the electrical conversion efficiency of the equipment varies from its electrical conversion capability.
• the difference in operating conditions of the single emitters at test condition for measuring the single emitter electrical conversion efficiency and the actual measurement conditions in the installation;
• re-absorption of radiation between the emitters;
• absorption of radiation by gases or fumes inside the equipment;
• absorption of radiation inside the equipment;
• loss of radiation from the equipment through openings;
• reflection of radiation from the workload;
The emission of radiation from various surfaces within the equipment significantly impacts conversion efficiency This efficiency can vary, often being less than the inherent conversion ability, although it generally trends towards being smaller.
The infrared conversion efficiency can be estimated using data from measurements outlined in Annex C, provided that both the variation and the actual irradiation are monitored, along with any effects caused by the workload However, these comprehensive measurements often exceed the capabilities of the industry.
The electroheating efficiency as defined in 8.3 or in Annex A is usually applied (more accessible and with a smaller error margin).
Electroheating efficiency
The electroheating efficiency is calculated using inst min inst = E E η (4)
The efficiency shall be stated
• for the infrared emitters only.
Power usage efficiency
The efficiency of power usage is defined as max nop power =P P η (5) where power η is the efficiency of power usage;
P nop is average power consumption during normal operation;
P max is the peak power consumption (see 7.6)
The processing capacity of the installation serves as an indicator of its potential for future process modifications Additionally, it reflects the design quality, particularly in terms of accurately predicting the energy consumption of the installation.
Energy consumption of the workload
The energy consumption for processing a workload is determined by considering the total energy used by the installation, which includes start-up, holding, hot standby, and shut-down energy This value is calculated by dividing the average total energy consumption of the installation by the amount of workload produced at the desired quality during the measurement period.
• energy consumption per piece, when the workload is countable, or
• energy consumption per unit mass, or
• energy consumption per unit area when the workload is a continuous sheet
The calculation shall be made based on data from the test defined in 7.8 The reported value shall include the time base of the test
Efficiency of energy transfer from the installation to the workload is defined as
E proc is the electric energy used by the installation for the process
The measurement of temperature rise of the workload and the energy consumption by the installation shall be made according to Clauses 6 and 7
The efficiency of energy transfer from the installation to the workload during processing is influenced by various particular features of the installation and the workload, such as the following:
• the emission spectrum of the emitter, depending on voltage and thus its operating conditions;
• the wavelength dependent absorption of the workload, which can change during the processing;
• the surface structure and the angular absorptivity of the workload, which can change during the processing;
• the relative orientation between workload and infrared emitter, which can change in continuously operating installations during the processing;
• the absorption by the atmosphere between emitter and workload, which can change during the processing due to evaporation of solvents;
• the convective transport of heat inside the installation and out of the installation – this includes intentional cooling of parts of the installation;
• losses through heat conduction from the workload or the heating chamber to the outside;
• windows, protective gratings, meshes, etc between the emitter and workload;
• reflection or absorption of stray radiation by the installation
Energy transfer efficiency therefore varies with test conditions and with the equipment, as considered byE proc in Formula (6)
The test conditions outlined in section 5.3 must be strictly followed It is essential to closely monitor these conditions and minimize any external factors that could impact the test results, especially those that are not controlled or observed.
A.2 Rationales for the measurement method
Different infrared installations serve various processes, but only a few enable precise measurement of energy transferred to a workload Capturing process parameters during processing can be challenging For instance, the heat energy stored in the workload can be calculated using the temperature rise, provided the mass and specific heat (\$c_p\$) are known Additionally, evaporation energy can be estimated if the temperature, evaporated mass, and specific heat are available.
To estimate the energy required for chemical reactions, it is essential to know the mass of the workload involved and the energy necessary for the reaction Additionally, the temperature and the enthalpy of evaporation of the solvent are crucial factors in this process.
Tests using an Inverse Distance Weighting (IDW) method yield accurate results when the IDW accurately reflects the physical properties of the workload and the installation parameters align with the process characteristics Any significant mismatch between the workload and IDW can render the test results meaningless Examples of such discrepancies include variations in workload characteristics or misalignment of installation parameters.
• A workload heated only from one side shows a temperature gradient inside the material
This temperature gradient depends on the thermal conductivity of the material k and the surfaces where energy is absorbed in the material
Energy absorption at the surface leads to temperature variations within a material, governed by thermal conduction based on depth When radiation is absorbed at various depths, the resulting temperature profile is influenced by both the exponentially decaying penetration of radiation and the material's thermal conductivity.
Evaporation measurements are typically conducted by weighing the IDW before and after processing If any solvent is left in the IDW post-process, evaporation will persist during the cooling phase of the IDW.
A.3 Use of a test installation instead of a production installation
Measurements performed in an installation used for production have limitations, since:
Once the installation design is complete, conducting tests at this stage can demonstrate the installation's functionality, but it does not offer essential feedback for the design process.
• completed installations can usually not be changed in performance or layout;
• completed installations can usually not be used for any tests after commissioning – for example, due to safety issues
However, experience and data can be used for the design of the next generation of this kind of installation
To ensure effective testing prior to designing new installations, it is recommended to utilize a test installation rather than conducting trials on outdated systems, provided certain criteria are met A test installation must be equipped to accurately replicate the intended process, featuring components such as a conveyor belt with appropriate speed and sufficient power capacity Additionally, it should include a diverse range of infrared emitters that vary in spectral output, radiation power, and geometric design The installation must also allow for adjustments in process conditions, such as air flow and thermal insulation, and possess adequate switchgear to operate at the required power levels while enabling variations in the infrared emitters' output.
Test equipment featuring a single emitter type and limited to one specific spectral range provides only one technical solution for testing, making it less valuable and inadequate for comprehensive testing needs.
A.4 Preparation of the dummy workload
The IDW shall either be a prepared piece of the intended workload, or it shall be prepared using the following considerations, as far as possible:
• it shall have an identical surface material as the workload;
• it shall have an identical surface structure as the workload;
• if only a coating is applied to a IDW that mimics the surface of the workload, the thermal contact between coating and IDW shall be good over the complete surface;
• it shall be planar or of another simple shape;
• it shall be comparable in size to the intended workload;
• it shall have a high thermal conductivity, if applicable
If the IDW is made of a material with high thermal conductivity, a single sensing point on the front or back side is sufficient
If a temperature gradient inside the IDW is expected, the temperature shall be measured on the exposed side and on the back side of it
If the thickness of the IDW allows and its thermal conductivity is low, thermocouples can be placed inside to assess the temperature gradient inside
When using thermocouples to measure temperatures, it is essential to ensure they are securely fixed to maintain low thermal resistivity contact with the IDW during the measurement period Additionally, the placement of thermocouples should not affect the irradiation or convection within the installation They should only be positioned on the irradiated side of the IDW if pyrometric measurement is not an option.
Fixture of thermocouples may be done by:
• cement, or temperature resistant glue;
• heat bonding onto a thermoplastic material;
• placing the thermocouples in bored holes
A.5 Tests for optimisation of the process
The goal of the test is:
• to characterise a specific installation to be used for a defined process, or
• to seek the optimum process parameters for a specific installation, or
• to prepare the design of a new installation by investigating relevant parameters – for example those listed in A.1
To ensure that the test is relevant, the following applies: a) All environmental parameters shall be documented throughout the measurement process
The test installation must have all settings documented, including any variations during measurements, which should be recorded using a data logger Documentation should encompass both the intended settings and the actual measured values, such as voltage, current, or power Additionally, temperature measurements of the workload or dummy workload must be captured with a data logger that has adequate time resolution for all measurement points Any other changes to the installation and relevant observations during the test should also be thoroughly documented.
For preparation of tests or for limiting the number of tests, numerical calculations may be used Annex CC of IEC 60519-12:2013 states minimum requirements for good practice
To assess the homogeneity of processing within the installation, various parameters can be measured across the surface of the workload or the infrared dummy workload (IDW).
• the residual content of a solvent on the workload, for an assessment of the evaporation of that solvent;
• the obtained extent of crosslinking of a polymer or lacquer;
• the amount of deposited substance or coating on the surface;
• the mass loss of the surface;
• the obtained extent of chemical reaction, which may include phase changes;
• any other surface related parameters
Measuring various parameters requires different equipment and methods While some measurements are best conducted using 2D techniques like infrared cameras, others necessitate intricate pointwise analysis Whenever feasible, simpler measurement methods are favored, especially when a clear relationship between effects is established For instance, if a chemical reaction is highly dependent on temperature, a 2D assessment of temperature homogeneity will suffice.
An IDW specifically prepared for the test may be used, see Annex A
In typical operations, the goal is to ensure that the entire usable surface or volume of the workload achieves a specified value for at least one of the parameters, while preventing any parts of the workload from overheating or undergoing destructive processes.