MULTIForm facility

MULTIform is a research facility based in the School of Chemical and Process Engineering at the University of Leeds specialising in experimental investigation and providing state of the art equipment for the study of multiphase flows in water/acidic systems and high temperature molten salt systems; at a scale that is representative of a real system.

What does real mean?

Water, acid, solids (materials), steel pipes, with flanges/joints and bends (environment), pipe sizes and flowrates comparable with plant (scale).

MULTIform’s three components

  1. A pilot scale rig, based on water/acid [pressure (=<5atm), temperature (=<100°C)]. 
  2. A pilot scale rig, based on molten chloride [pressure (=<5atm), temperature (=<550°C)],  
  3. A bank of high precision, state of art, instruments for measuring a wide range of fluid flow properties that can be employed in a water and/or a molten chloride system. 

Both rigs can be reconfigured to include specialist instrumentation for fluid flow measurements and have the capability to include bespoke equipment for development. 

MULTIform is part of the UK’s National Nuclear User Facility, created by Government investment in the UK’s nuclear future, providing state-of-the-art experimental facilities for research and development in nuclear science and technology. NNUF was launched in March 2013 and new facilities have been created with funding from EPSRC through a UK Government award of £80m.

What MULTIform offers

Pilot scale water loop

This consists of a main reservoir vessel, which has temperature control and agitation for work with solids. The reservoir serves a pipework loop that can be configured into a range of different flow paths, plus two separate legs (horizontal and vertical) for gas/liquid experiments.

The complex machinery that makes up the water loop, featuring an array of pipes affixed to a wall.

The water loop has the following capabilities:

  • 50mm nb, stainless steel pipework
  • Water or low pH systems
  • 2m inter-changeable test sections for instrument use or installation of bespoke experiments
  • 5x angles: 0°, 30°, 45°, 60° and 90°
  • 10x pipe geometries
  • Reversible flow to test the effect of gravity
  • Local boiling at test points
  • Horizontal and vertical gas injection with 2 bubble sizes (1mm and 4mm) and three injection points
  • Installed instrumentation: mass flow, volumetric flow, temperature, pressure

Table 1: Water loop operating conditions

Parameter low high units
Temperature 15 90 °C 
Acid concentration 0.0 2.0 mol/L
Flow rate 67 267 L/min
Pressure 1 <5 bar
Particle size 0.1 <500 mm
Particle concentration 0.0 100 g/l


Pilot scale molten salt loop 

This consists of a main salt supply cabinet, a bespoke unit supplied by Copenhagen Atomics, consisting of a melting vessel, reservoir and salt pump. The salt supply cabinet serves two pipework loops, one horizontal and one vertical, with flow in either direction.

The salt loop's complex machinery, featuring metal pipes and a large metal control box.

The salt loop has the following capabilities:

  • 38mm nb, stainless steel pipework
  • LiKCl eutectic, melting point 382°C, recommended operating temperature 450°C
  • 2m inter-changeable test sections for instrument use or installation of bespoke experiments
  • 2x angles: 0° and 90° 
  • Reversible flow to test the effect of gravity
  • Installed instrumentation: volumetric flow, temperature, pressure

Table 2: Salt loop operating conditions

Parameter low high units
 Temperature  400  550  °C
 Flow rate  100  300  L/min
 Pressure  1  <2  bar
 Particle size  0.1  <500  mm
 Particle concentration  0.0  100  g/L


Specialist instruments 

As well as the capability to accommodate bespoke experiments, MULTIform has a range of specialist technique available to the researcher to analyse all manner of different characteristics of multiphase flows. The two loops have been designed to accommodate most of the instruments and all can be operated as standalone.

MULTIform has the following instruments available:

  • Particle imaging velocimetry (PIV): LaVision StereoScopic PIV
  • Laser Doppler Velocimetry (LDV): Dantec Dynamics FiberFlow LDA system with dual laser
  • Focussed Beam Reflectometry (FBRM): Mettler Toledo ParticleTrack G400
  • X-ray dispersion separation analyser: LUMiReader X-ray
  • High speed imaging camera: Phantom VEO1310
  • Rheometer: TA Instruments HR-20 Discovery, with environmental test chamber

Tables 3a and 3b: Measurement techniques available and their use

3a: Fluid properties: Multiphase velocity profiling (includes solids)

Technique Water Salt
 Particle imaging velocimetry (PIV)  Yes  No
 Laser doppler velocimetry (LDV)  Yes  Yes


3b: Solids/gas properties

Solids/gas properties Technique Water Salt
Size, coalescence and breakage Focused beam reflectometry (RBFM)  Yes  No
Sedimentation/creaming X-ray dispersion separation analyser  Yes  No
Particle/bubble tracking High-speed imaging camera  Yes  Yes
Fluid/slurry viscosity Rheometer  Standalone  Standalone


Access for researchers

MULTIform has been created with ease of access in mind. There are three ways to run your experiment. 

  1. You run it in house. After a period of safety and operating training, your researcher will work in the MULTIform facility to run their own experiment, under the supervision and supported by our Operations Team. 
  2. You run it remotely. After a short period to set up the experiment your researcher can return to their home institution and our Operations Team will run their experiment. Remote access to monitor the experiment in real time and access to our secure network for data transfer, will be granted. 
  3. You let us run it. Our Operations Team will work with you to design, set up and run your experiment. Your researcher need not be present, and we can provide remote access to monitor the experiment in real time and access to our secure network for data transfer. 

MULTIform is a TRAC facility and so researchers will be charged for its use. Bookings are based on a day rate, but there will be minimum periods for booking both loops for operational reasons. Charge rates are calculated based on your requirements, so please contact our Operations Team for an estimate.

Contact the MULTIform facility team

For further information visit, the MULTIform facility LinkedIn page or contact Dr Alastair Baker via

Project website