Instrumentation

& Equipment

Gas-phase thermocouples

1.5 mm K-type thermocouples are used to measure temperatures in the gas-phase of the compartment.

Layout

Solid-phase thermocouples

1.5 mm K-type thermocouples are used to measure temperatures in different depths of the wall and ceiling panels at different cluster points.

Different density of measurements are proposed depending on whether the panel is exposed or protected with an encapsulation system. Additionally, multiple single measurements are proposed for the glue-line and below the plasterboard.

Layout for high-density in-depth measurements

Robot for drilling in CLT

Design by Felix Wiesner from the University of Edinburgh.

GRBL drilling.mp4

Internal heat flux sensors

Thin Skin Calorimeter (TSC) will be used to measure the internal heat flux in different positions of walls and ceiling panels.

Instrument design

The TSC consists of a 100 mm diameter calcium silicate disc acting as insulation core and a 9.6 mm diameter stainless steel disc. Two wires of a K-type thermocouple are welded to the back surface of the metallic disc, separated by a distance of approximately 1 mm. The metallic element is embedded onto the surface of the insulation core, and the insulation core (the whole TSC) will be embedded into the first lamella of the CLT panel to achieve a flush surface at the exposed face. The thermocouple wires are passed through the insulation core and through the remaining section of the CLT panel and finally connected to a data logger.

Layout drawings for TSC positions:

External Heat Flux Sensors

To be confirmed by George Kanellopolous and Angus Law from the University of Edinburgh.

Velocity measurements

(a) Probes

It is proposed to utilise bi-directional probes (as per the McCaffrey design) in order to capture the flow data at the opening of the compartment, and at the compartment boundaries. Probes positioned at the opening will be used to measure the inflow and outflow gas velocities, which will be useful when characterising the fire dynamics (i.e. identification of the neutral plane, or mass flow of the outflow gases). Thermocouples will be positioned at the opening plane in the same locations as the bi-directional probes. Probes and thermocouples at the opening will be positioned (from the floor, z = 0.0m) at z = 0.625m, 0.950m, 1.275m, 1.6m, 1.80m, 2.00m, 2.20m.

Probes positioned within the compartment will be useful for later studies into convective heat transfer correlations and will be suitable given that Test #1 represents a completely encapsulated compartment. Three probes will be positioned along the centreline of the ceiling (approx. 50mm from the roof) at (x = 0.85m, 1.70m, 2.55m) and three probes will be positioned along the centreline of the back wall at varying heights at z = 0.450m, 1.35m, 2.25m. Penetrations through the timber and plasterboard will be made to position the probes.

Components

13 x bi-directional flow probes.
20 meters of 6 mm (OD) stainless steel tubing.
13 x Swagelok stainless steel compression fittings (6mm).
13 x differential pressure transducers.
Raspberry pi camera modules & boards (in stock).
1x FLIR Radiometric Leptopn Dev Kit.

Layout

(b) Particle Image Velocimetry (PIV)

To be confirmed with Alexander Belt from the Institute for Advanced Simulation at the Jülich Supercomputing Centre (JSC).

Internal video imaging

We will implement a system that allows us to use HD cameras close to the fire to capture compartment fire dynamics through interval pictures. However, the main issue is getting close to the fires is a risk for the cameras due to high heat fluxes. We looked at how NIST does it (https://www.youtube.com/watch?v=UbRIicM3uP4) in order to propose our design and adapt it to our needs. Some of the design features are listed below and we will be conducting basic resistance tests to check the performance of our design before the actual tests.

(a) Main issues

Insulation: air gaps should be included; NIST uses plasterboard encasing, too big and messy though
Container: must resist high heat fluxes while being transparent, e.g. Pyrex glass
Cooling system: refrigerant (transparent) fluid pumped in the camera exterior
Battery duration: the tests can run for several hours, so the camera and its setup must be selected accordingly

(b) Other potential issues

Higher temperature can lead to lower battery time
Reduced options for locating the cameras, i.e. reduced visual range
Possible high soot concentration

External video imaging

Raspberry Pi video imaging will aim at capturing the external flaming height, and the thickness of the flaming protruding from the opening plane. Further, it is proposed to modify 1 x cameras with IR modules in order to capture thermal imaging data of the gas-phase temperatures from the reference of the opening of the compartment. Prior to each experiment, the cameras will be calibrated.

3 x handicams will be used to record general footage of the experiment (two targeting the interior of the compartment, and the other recording the entire compartment). This footage will not be used for data capture purposes.

Layout

Gas analysers

Sensors

The gas analysers correspond to the 2018 Summer Research version of the low-cost gas analyser (3rd generation), which will be used to measure the concentration of oxygen, carbon oxygen, dioxide, carbon monoxide, and hydrocarbons (i) in the buoyancy calorimeter, (ii) at the door opening and (iii) inside the compartment.

Oxygen sensor: AO2 CiTiceL electrochemical cell developed by City Technologies and supplied by Shawcity.
CO/CO2/HC sensor: Non-Dispersive IR (NDIR) developed by Crestline Instruments.

Design

The design of the Gas Analyser (3rd generation) uses a customised 3D printed PLA box (210 mm x 140 mm x 100 mm) that was designed specifically to accommodate all the components in the most efficient possible way. To minimise costs, the Analyser uses a direct connection form the NDIR to a COM serial port that transfers the collected data to a computer.

Layout

2 gas analysers installed in the buoyancy calorimeter.
3 gas analysers installed at the top of the door centre-line.
5 gas analysers installed within the compartment, close to the CLT in ceiling and walls.

Sampling of gases

To be completed by Hangyu.

Moisture sensors

Sensors

The GS3 Decagon Soil Moisture Sensor will be utilized to measure the volumetric water content (VWC) on CLT panels. Furthermore, this instrument can also measure temperature and electrical conductivity (EC) independently. An electromagnetic field is used to measure the dielectric permittivity (ε) of the surrounding medium. The dielectric value is then converted to substrate water content by calibration equation.

Layout