Note: Nuclear magnetic resonance imaging for viscosity measurements

Local determination of the constitutive law of a dense suspension of noncolloidal particles through magnetic resonance imaging

“…With regard to curvilinear flows, it is only possible in a Couette geometry as only in this geometry do we know the local value of stress, independently of the constitutive law; it would also be possible in pipe flows, where we also know the local value of stress (this property was used by Powell et al (1994) to measure the viscosity of a polymeric fluid). Our experiments may thus provide a fair experimental basis for flow predictions and for comparison with theoretical models.…”

A process for energy-efficient high-solids fed-batch enzymatic liquefaction of cellulosic biomass

“…In-line rheological measurements (Maneval et al, 1996;McCarthy et al, 1992;Powell et al, 1994) during hydrolysis were performed in situ and non-invasively using an in-line magnetic resonance imaging (MRI) flow loop as previously demonstrated Skovgaard et al, 2014;Tozzi et al, 2014). An Aspect Imaging 1.03 T permanent magnet with a 0.3 T/m peak gradient strength (Aspect Imaging, Hevel Modi'in Industrial Area, Shoham, Israel) was used to obtain all images used in rheological analyses.…”

“…The radio frequency coil encasing the imaging section of the pipe was a solenoid with three turns enclosing a volume 38 mm in diameter and 36 mm long. Velocity profiles as a function of radial position of the flowing biomass slurries were obtained throughout all experiments using a Pulsed Gradient Spin Echo (PGSE) sequence (Maneval et al, 1996;Powell et al, 1994). These velocity profiles, in conjunction with in-line differential pressure measurements, were used to obtain yield stresses during hydrolysis as shown in Tozzi et al and Skovgaard et al (Skovgaard et al, 2014;Tozzi et al, 2014).…”

Strategies for Rapid NMR Rheometry by Magnetic Resonance Imaging Velocimetry

“…Recently, several quires the acquisition of two or more planar, NMR images groups have reported the use of MRV for studying rheomeof the capillary cross section which are sensitized to the fluid tric capillary and Couette flows (1,3,(12)(13)(14)(15) imaging is not required in order to obtain radial velocity tion orthogonal to B 0 precesses about the applied field with a frequency v Å gB 0 . A subsequent magnetic field gradient profiles; in fact, radial profiles may be inferred from the bulk velocity spectrum of the capillary flow field or from one-pulse of duration d temporarily changes the local magnetic field according to B Å B 0 / rrg where B is the local dimensional, velocity sensitized, transverse projections of the circular capillary cross section.…”

“…The techniques are based on NMR velocime-nearly the entire range of shear rates (possibly three or four try of Poiseuille flow, and together with measurements of the pres-decades) present in the flow field (1,12). Velocimetric sure drop, the velocimetric data may be processed to yield mea-rheometry should be distinguished from other NMR studies sures of the shear viscosity over the range of shear rates present of rheology which exploit NMR to monitor molecular orien- regarding shear rates and boundary conditions, NMR they involve (1) direct two-dimensional imaging of the tube cross rheometry is a potentially powerful tool for fluid charactersection, (2) one-dimensional imaging of a Cartesian projection of the tube cross section followed by Abel inversion to obtain radial ization.…”