Experimental and computational investigation of heat transfer in a microwave-assisted flow system

Microwave technology is gaining popularity as a tool for chemical process intensification and an alternative to conventional heating. However, in flow systems non-uniform temperature profiles are commonly encountered and hence methods to characterise and improve them are required. In this work, we studied the effects of various operational parameters-microwave power, inlet flow rate, tube orientation and pressure-on the electric field and temperature profiles of water flowing in a PTFE tube (2.4 mm internal diameter), placed in a commercial single-mode microwave applicator. A finite element model was developed to estimate the longitudinal temperature profiles and the absorbed microwave power, while in situ temperature monitoring was performed by a fibre optic probe placed at multiple locations inside the tube. The water temperature inside the tube increased by increasing the microwave power input and temperature profiles stabilised beyond 20 W, while the percentage absorbed microwave power showed the inverse trend. When changing the tube orientation or decreasing the inlet flow rate, microwave absorption decreased significantly. When the pressure was increased to 2.3 bara, water temperature increased by ~ 20 o C. Results from this study provide valuable insights on achievable temperature profiles and energy efficiency of microwave-assisted flow synthesis systems.

Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles

We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles

Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles

We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles

Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles

We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles

Development of flow reactors for tuneable gold nanoparticle synthesis: Towards continuous manufacturing

Gold nanoparticles (Au NPs) are gaining increasing attention in various sectors, such as electronics, catalysis and biomedicine. However, nanomaterial synthesis is considered a bottom-up process, which means that the desired particle structure, size and yield depend on the thermodynamics and kinetics of the fabrication process. Therefore the current challenges in nanomaterial manufacturing are related to understanding, controlling and integrating different operating units for continuous operation, while maintaining narrow particle size distribution, uniform size and high yield. This thesis is aimed at investigating the use of microwave heating for the flow synthesis of gold nanoparticles and developing a manufacturing platform for the continuous synthesis of high quality Au NPs of desired sizes. Initially, an alternative form of heating using microwaves was investigated to address the control of the longitudinal temperature profile and evaluate the heating efficiency in a milli-scale tube by varying the process parameters. The study was conducted both experimentally and computationally – by developing a finite element method (FEM) model – in a commercial single-mode microwave applicator. Varying the input microwave power, the medium (water) temperature inside the tube increased. However, the temperature profile plateaued and remained unaffected by the increase of the input microwave power beyond a certain value, as there was an excess of microwave power which could not be absorbed by the system. Microwave efficiency increased by increasing the inlet flow rate, due to the volumetric nature of microwave heating, without decreasing the temperature profile significantly. Changing the tube orientation both the microwave absorption and temperature profile decreased, while increasing the system pressure (from 1 bara to 2.3 bara), the temperature of the medium increased (by ~ 20 oC). The outcomes of this study provide in-depth understanding of the operating parameters on the temperature profile and energy efficiency of microwave-assisted flow synthesis systems. Then, the potential of microwave heating for the synthesis of spherical Au NPs via the reduction of the gold precursor (tetrachloroauric acid) by trisodium citrate (namely Turkevich method) was investigated. For that reason, two synthesis platforms were developed, using microwave heating only (one-stage system) or using microwaves for reaction initiation and conventional heating in series as growth stage (two-stage system). In the latter system, increasing the microwave power from 0 (only conventional heating) to 25 W, the particle size varied between 20 – 25 nm. A Welch’s unpaired t-test was conducted indicating that the particle sizes obtained at different input microwave powers were statistically significant. Varying the residence time under microwave heating had no significant effect on final particle size, despite a small change on the temperature profile inside the microwave reactor. The large particle size distribution (> 18 %) of the synthesised Au NPs in flow under microwave heating was attributed to the non-isothermal longitudinal temperature profile, the particle deposition on reactor walls and the residence time distribution deviating from a plug flow reactor profile. The aforementioned results indicate the shortcomings of the microwave technology for nanoparticle synthesis in flow. Existing mathematical models describing the kinetics of Au NPs synthesis via the Turkevich method were not applicable for designing continuous milli-fluidic flow reactors due to the complexity of the synthesis route. Therefore, two statistical correlations were developed for the estimation of the particle size and reaction time for the targeted synthesis of 10 – 20 nm Au NPs. The influence of order of reactant addition and synthesis pH on the particle size and reaction time was investigated. The developed models take into account the reactant speciation, concentrations and temperature, while the final pH of the colloidal solution was ~ 5.6, to ensure highly reproducible synthesis, yielding targeted spherical and monodisperse Au NPs. The developed statistical correlations could be used as a tool to engineer the flow process for a tuneable Au NPs synthesis. Finally, based on the developed statistical correlations a continuous milli-scale manufacturing platform was constructed for citrate-capped Au NPs synthesis (Turkevich method) under conventional heating. Using a two-phase flow system (using heptane as continuous phase) prevented the fouling in the reactor walls. A membrane separator and a UV-Vis spectrometer were integrated into a single standalone flow platform. The in-house designed membrane separator allowed the downstream separation of the organic and the aqueous streams, while the inline UV-Vis spectrometer ensured the quality control in flow via online monitoring of the synthesised particles (size, yield and process stability). Recycling of the heptane was tested, showing that re-using the collected heptane without further purification, increased the polydispersity of the colloidal solutions (~ 23 %). This platform is considered as a viable option towards scalable continuous manufacturing of nanoparticles

Effect of Ethanol and ETBE in Gasoline Fraction Properties

188 σ.Στην παρούσα διπλωματική εργασία μελετήθηκε η επίδραση που έχει η προσθήκη οξυγονούχων συστατικών στις ιδιότητες κλασμάτων βενζίνης. Τα οξυγονούχα πρόσθετα που χρησιμοποιήθηκαν είναι η αιθανόλη (EtOH) και το ΕΤΒΕ, το οποίο προέρχεται από την αντίδραση της EtOH, ή βιοαιθανόλης, με το ισοβουτυλένιο που παράγεται κατά την καταλυτική πυρόλυση της μονάδας FCC στα διυλιστήρια πετρελαίου. Τα συστατικά αυτά χρησιμοποιούνται ως ανανεώσιμα υποκατάστατα της βενζίνης. Τα οξυγονούχα πρόσθετα χρησιμοποιούνται εκτενώς ως βελτιωτικά των ιδιοτήτων των βενζινών, προς αύξηση της αντικροτική ικανότητας και μείωση των περιεχόμενων αρωματικών στην βενζίνη. Η προσθήκη της EtOH και του ΕΤΒΕ προκαλεί τη μεταβολή των ιδιοτήτων της βενζίνης, και κυρίως της πτητικότητα, που σχετίζεται με προβλήματα ατμόφραξης του συστήματος μεταφοράς καυσίμου και ψυχρής εκκίνησης, και της αντικροτικής συμπεριφοράς, προς αποφυγή του «κτυπήματος» του κινητήρα. Τα δείγματα καυσίμων που προσομοιάζουν τις ιδιότητες της βενζίνης και παρασκευάστηκαν στο Εργαστήριο Τεχνολογίας Καυσίμων και Λιπαντικών αποτελούνται από την ανάμιξη των κλασμάτων καταλυτικής αναμόρφωσης νάφθας (Reformate), καταλυτικής πυρόλυσης ρευστοποιημένης κλίνης (FCC) και ισομερισμού νάφθας (Isomerate) στις εξής αναλογίες: 40 % v/v Reformate + 40 % v/v FCC + 20 % v/v Isomerate (B1) 50 % v/v Reformate + 30 % v/v FCC + 20 % v/v Isomerate (B2) 30 % v/v Reformate + 50 % v/v FCC + 20 % v/v Isomerate (B3) 35 % v/v Reformate + 45 % v/v FCC + 20 % v/v Isomerate (B4) 30 % v/v Reformate + 45 % v/v FCC + 25 % v/v Isomerate (B5) 35 % v/v Reformate + 35 % v/v FCC + 30 % v/v Isomerate (B6) 30 % v/v Reformate + 30 % v/v FCC + 40 % v/v Isomerate (B7) Οι συστάσεις των δυαδικών μιγμάτων των δειγμάτων βάσης Β1 – Β7 με την EtΟΗ και το ΕΤΒΕ αποτελούνται είτε από την προσθήκη EtOH στις βενζίνες βάσης σε αναλογίες 2,5, 5, 7,5 και 10 % κ.ο. είτε από την προσθήκη ΕΤΒΕ σε αναλογίες 5, 10 και 20 % κ.ο. μίγματος. Τα τριαδικά μίγματα δειγμάτων βάσης με ταυτόχρονη προσθήκη EtOH και ΕΤΒΕ που εξετάστηκαν στην παρούσα εργασία είχαν τις εξής συστάσεις: 92 % v/v Δείγμα Βάσης + 2 % v/v ΕtOH + 6 % v/v ETBE 93 % v/v Δείγμα Βάσης + 3 % v/v ΕtOH + 4 % v/v ETBE 84 % v/v Δείγμα Βάσης + 4 % v/v ΕtOH + 12 % v/v ETBE 86 % v/v Δείγμα Βάσης + 6 % v/v ΕtOH + 8 % v/v ETBE 94,5 % v/v Δείγμα Βάσης + 1 % v/v ΕtOH + 4,5 % v/v ETBE 96 % v/v Δείγμα Βάσης + 2 % v/v ΕtOH + 2 % v/v ETBE 85 % v/v Δείγμα Βάσης + 3 % v/v ΕtOH + 12 % v/v ETBE 89 % v/v Δείγμα Βάσης + 5 % v/v ΕtOH + 6 % v/v ETBE Η μελέτη των ιδιοτήτων των παραγώμενων δυαδικών και τριαδικών μιγμάτων αφορά την πτητικότητα αυτών, και έγινε μέσω της καμπύλης απόσταξης με τη μέθοδο ASTM D–86 (ΕΝ ΙSO 3405) και της τάσης ατμών RVP σύμφωνα με τη μέθοδο ASTM D–323 (ΕΝ 13016). Ακόμη εξετάστηκαν η πυκνότητα και το ιξώδες (δυναμικό και κινηματικό), στους 0 oC και 15 οC, βάσει της μεθόδου ASTM D–7042 (EN ISO 12185), ενώ τέλος πραγματοποιήθηκε ποιοτική και ποσοτική ανάλυση των μιγμάτων με τη χρήση του οργάνου GS-1000 της PetroSpec, ως προς τον αριθμό οκτανίου και την σύσταση των μιγμάτων σε ποσοστό οξυγόνου, οξυγονούχων προσθέτων και είδος και αναλογία των υδρογονανθράκων, απο τους οποίους αποτελείται κάθε μίγμα. Κατά την ανάλυση, έγινε συγκριτική μελέτη των υπό εξέταση ιδιοτήτων βάσει του Ευρωπαϊκού Προτύπου ΕΝ 228. Κατά την μελέτη των καμπυλών απόσταξης, χαραχθηκαν και μελετήθηκαν οι δείκτες Ε70, Ε100 και Ε150, που αναφέρονται στο ανακτηθέν ποσοστό % κ.ο. στις θερμοκρασίες 70 oC, 100 oC και 150 oC, αντίστοιχα, καθώς και ο Δείκτης DI, που σχετίζεται με την μεταβολή της πτητικότητας του μετωπικού και μεσαίου κλάσματος. Κατά την ανάλυση των αποτελεσμάτων παρατηρήθηκε μείωση της κλίσης των καμπυλών, δηλαδή αύξηση της πτητικότητας, η οποία είναι μεγαλύτερη στα λιγότερο πτητικά δείγματα βάσης, δηλαδή μικρότερο ποσοστό Isomerate στο μίγμα, με την αύξηση της προσθήκης EtOH, ενώ παρατηρήθηκε plateau στην περιοχή των 70 oC. Από την άλλη στα δυαδικά μίγματα Δείγμα Βάσης/ΕΤΒΕ δεν εμφανίζεται πλατώ, ωστόσο αυξάνεται ελάχιστα η πτητικότητα του μέσου κλάσματος, κάτι που δεν παρατηρήθηκε στην περίπτωση της EtOH, ενώ και στα δύο είδη μιγμάτων δεν μεταβλήθηκε η πτητικότητα ουράς. Κατά τη μελέτη των τριαδικών μιγμάτων έγινε εμφανές πως η ταυτόχρονη προσθήκη EtOH και ΕΤΒΕ προκαλεί αύξηση της πτητικότητας του μίγματος, αλλά δεν εμφανίζεται plateau στην καμπύλη απόστασξης. Ο Δείκτης Ε70 για τα δυαδικά μίγματα μεταβλήθηκε κατά 7,5 – 21 μονάδες για περιεκτικότητα 2,5 - 10 % κ.ο. EtOH και ο Δείκτης Ε100 μεταβλήθηκε κατά 4 – 11 μονάδες για περιεκτικότητα 5 - 20 % κ.ο. EΤΒΕ, ενώ στα τριαδικά μίγματα η μεταβολή του Δείκτη Ε70 είναι 6,5 – 17 μονάδες και του Ε100 είναι 3 – 11,5 μονάδες, περίπου. Η τάση ατμών των μιγμάτων αυξήθηκε κατά 10 – 21 % στα δυαδικά μίγματα Δείγμα Βάσης/EtOH, ενώ το ΕΤΒΕ μειώνει την τάση ατμών των βενζινών και η μέγιστη που παρατηρήθηκε στα δυαδικά μίγματα Δείγμα Βάσης/ΕΤΒΕ είναι της τάξης του 12 – 15 %. Στα τριαδικά μίγματα σημαντικό ρόλο κατέχει η συγκέντρωση κάθε οξυγονούχου συστατικού, καθώς σε παραπλήσιες συγκεντρώσεις παρατηρείται σημαντική αύξηση της τάσης ατμών έως 18 %. Βάσει της μελέτης της αντικροτικής συμπεριφοράς, μέσω των αριθμών RΟΝ και ΜΟΝ, βλέπουμε πως και τα δύο πρόσθετα αυξάνουν τον αριθμό οκτανίου RON, ωστόσο το ΕΤΒΕ αυξάνει και το ΜΟΝ. Μάλιστα, σε ίδιες αναλογίες προσθέτου, η παρατηρούμενη αύξηση με την προσθήκη του ΕΤΒΕ, είναι παραπλήσια ή ελαφρώς μεγαλύτερη από εκείνη που παρατηρείται λόγω της προσθήκης EtOH. Στα τριαδικά μίγματα, η παρατηρούμενη αύξηση είναι μεγαλύτερη ή παρόμοια με την αύξηση που επέρχεται μόνο με την προσθήκη του ΕΤΒΕ. Επιπλέον, η μελέτη της πυκνότητας έδειξε πως η αύξηση της ΕtOH στα δυαδικά μίγματα προκαλεί αύξηση της πυκνότητας, ενώ με την προσθήκη του ΕΤΒΕ δεν παρατηρείται μεταβολή της τιμής της, εκτός από την περίπτωση υψηλής περιεκτικότητας Isomerate στο δείγμα βάσης. Στα τριαδικά μίγματα η μεταβολή της πυκνότητας είναι ενδιάμεση εκείνης που παρατηρείται στα δυαδικά μίγματα, ενώ όσον αφορά το ιξώδες, δεν παρουσιάζεται κάποια σημαντική αύξηση ή μείωση, καθώς η μεταβολή που επέρχεται βρίσκεται γύρω από μία μέση τιμή, μεταξύ 0,50 – 0,60 mPa•s για το δυναμικό ιξώδες και 0,68 – 0,72 mm2/s για το κινηματικό ιξώδες. Η αύξηση της προσθήκης οξυγονούχων, προκαλεί αύξηση της πυκνότητας και του ιξώδους στα δυαδικά και τριαδικά μίγματα. Τέλος, έγινε σύγκριση των αριθμών οκτανίων με των τιμών που προκύπτουν από τον γραμμικό τύπο υπολογισμού της αντικροτικότητας, και μεταξύ των πειραματικών τιμών της πυκνότητας και εκείνων που προκύπτουν από την γραμμική ανάμιξη των πυκνοτήτων των συστατικών.The purpose of this thesis is to study of the effect of ethanol (EtOH) and ETBE blends on the properties of gasoline. For the production of gasoline three different refinery fractions were used, catalytic reformed heavy naphtha (Reformate), isomerized light naptha (Isomerate) and naphtha from the fluidized catalytic cracking unit (FCC Naphtha), in seven different proportions. The blends can be divided in two main categories, the binary systems which include gasoline/ΕtOH mixtures in four different percentages and gasoline/ETBE mixtures in three different percentages, and ternary systems which include gasoline/EtOH/ETBE mixtures in eight different percentages. The impact of ΕtOH and ETBE additives was examined through volatility, which is examined through distillation curve and Reid Vapor Pressure (RVP), octane numbers and the density of the produced blends. As it was shown through this study, the increase of ethanol proportion in gasoline/EtOH blends increases the volatility and the plateau of the distillation curve at 70 oC, which is formed due to the azeotropic behavior of gasoline/EtOH blends. It was also observed that the increase of ethanol in the blend increases the RON number of gasoline at about 2 – 4 units. The addition of ETBE in the binary mixtures reduces the front-end volatility of the gasoline while it increases poorly the mid-range volatility. Also, it was shown that the RON and MON numbers were increased at about 5 and 3 units, respectively. Gasoline/EtOH/ETBE mixtures displayed properties different form the binary mixtures, while there was no plateau on the distillation curve and the RVP results were intermediate of those of the binary mixtures. However, the octane numbers increased as such in the binary gasoline/ETBE mixtures and the density of both types of mixtures showed increase about 1 – 2 % because of the presence of EtOH. The results of this study were compared and analysed according to the European Standard EN 228.Σπυρίδων-Παναγιώτης Α. Δαμήλο

Employing Nanosafety Standards in a Nanomaterial Research Environment: Lessons Learned and Refinement Potential

Extensive research is currently being conducted on nanotechnologies worldwide, and the applications of nanomaterials are continuously expanding. Given their unique intrinsic characteristics, such as their small size and increased reactivity, nanomaterials may pose an occupational, environmental or consumer hazard. Therefore, a highly important aspect of ensuring the sustainable use of nanotechnologies is the establishment of proper health and safety practices. The area of nanosafety research has produced significant outcomes the last decades, and many of these achievements have been reflected in the standardization field. In this work, a discussion of prominent nanosafety standards (ISO/TS 12901-2:2014 and ISO/TR 12885:2018) is presented, based on the barriers faced during the endeavor to apply their principles within a research context. A critical viewpoint regarding their application is presented, and gaps faced in adapting the standards to the materials and processes applied are noted. Additionally, approaches that were followed to circumvent these gaps are also highlighted as suggestions to potentially overcome these barriers in future standardization efforts

Employing Nanosafety Standards in a Nanomaterial Research Environment: Lessons Learned and Refinement Potential

Extensive research is currently being conducted on nanotechnologies worldwide, and the applications of nanomaterials are continuously expanding. Given their unique intrinsic characteristics, such as their small size and increased reactivity, nanomaterials may pose an occupational, environmental or consumer hazard. Therefore, a highly important aspect of ensuring the sustainable use of nanotechnologies is the establishment of proper health and safety practices. The area of nanosafety research has produced significant outcomes the last decades, and many of these achievements have been reflected in the standardization field. In this work, a discussion of prominent nanosafety standards (ISO/TS 12901-2:2014 and ISO/TR 12885:2018) is presented, based on the barriers faced during the endeavor to apply their principles within a research context. A critical viewpoint regarding their application is presented, and gaps faced in adapting the standards to the materials and processes applied are noted. Additionally, approaches that were followed to circumvent these gaps are also highlighted as suggestions to potentially overcome these barriers in future standardization efforts

Facilitating Safe FFF 3D Printing: A Prototype Material Case Study

Three-dimensional (3D) printing has introduced a paradigm shift in the manufacturing world, and it is increasing in popularity. In cases of such rapid and widespread acceptance of novel technologies, material or process safety issues may be underestimated, due to safety research being outpaced by the breakthroughs of innovation. However, a definitive approach in studying the various occupational or environmental risks of new technologies is a vital part of their sustainable application. In fused filament fabrication (FFF) 3D printing, the practicality and simplicity of the method are juxtaposed by ultrafine particle (UFP) and volatile organic compound (VOC) emission hazards. In this work, the decision of selecting the optimal material for the mass production of a microfluidic device substrate via FFF 3D printing is supported by an emission/exposure assessment. Three candidate prototype materials are evaluated in terms of their comparative emission potential. The impact of nozzle temperature settings, as well as the microfluidic device’s structural characteristics regarding the magnitude of emissions, is evaluated. The projected exposure of the employees operating the 3D printer is determined. The concept behind this series of experiments is proposed as a methodology to generate an additional set of decision-support decision-making criteria for FFF 3D printing production cases

Fused Filament Fabrication 3D Printing: Quantification of Exposure to Airborne Particles

Fused Filament Fabrication (FFF) has been established as a widely practiced Additive Manufacturing technique, using various thermoplastic filaments. Carbon fibre (CF) additives enhance mechanical properties of the materials. The main operational hazard of the FFF technique explored in the literature is the emission of Ultrafine Particles and Volatile Organic Compounds. Exposure data regarding novel materials and larger scale operations is, however, still lacking. In this work, a thorough exposure assessment measurement campaign is presented for a workplace applying FFF 3D printing in various setups (four different commercial devices, including a modified commercial printer) and applying various materials (polylactic acid, thermoplastic polyurethane, copolyamide, polyethylene terephthalate glycol) and CF-reinforced thermoplastics (thermoplastic polyurethane, polylactic acid, polyamide). Portable exposure assessment instruments are employed, based on an established methodology, to study the airborne particle exposure potential of each process setup. The results revealed a distinct exposure profile for each process, necessitating a different safety approach per setup. Crucially, high potential for exposure is detected in processes with two printers working simultaneously. An updated engineering control scheme is applied to control exposures for the modified commercial printer. The establishment of a flexible safety system is vital for workplaces that apply FFF 3D printing