MONODISPERSE DROPLET GENERATOR FOR INDUSTRIAL & UNIVERSITY RESEARCH APPLICATIONS

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1 MONODISPERSE DROPLET GENERATOR FOR INDUSTRIAL & UNIVERSITY RESEARCH APPLICATIONS

PAGE 3 PRELIMINARY REMARKS MONODISPERSE DROPLET GENERATOR PAGE 4 PROCEDURES AND APPLICATIONS PAGE 5

development activities in the field of spray technology, FMP TECHNOLOGY GMBH has gained theoretical and

new procedures for the production of sprays.

2 PAGE 3 PRELIMINARY REMARKS MONODISPERSE DROPLET GENERATOR PAGE 4 PROCEDURES AND APPLICATIONS PAGE 5 FMP-PRODUCTS PAGE 7 GENERAL SPRAY DEVELOPMENTS PAGE 8 ABOUT FMP TECHNOLOGY GMBH Through long-term research and development activities in the field of spray technology, FMP TECHNOLOGY GMBH has gained theoretical and experimental knowledge which can be applied to analyze and improve existing spray methods but also to provide new procedures for the production of sprays. We do not carry out developments by intuition but base our entire work on theoretically substantiated knowledge. Prof. Dr. Dr. h.c. Franz Durst Founder & managing director of FMP TECHNOLOGY GMBH Page 2

PRELIMINARY REMARKS Monodisperse droplet generator type MTG-01-G1 A huge number of industry sectors use dispersed fluids in various production processes and systems.

3 PRELIMINARY REMARKS Monodisperse droplet generator type MTG-01-G1 A huge number of industry sectors use dispersed fluids in various production processes and systems. The atomisation of the fluids is done largely through dies that produce uncontrolled polydisperse sprays, or rather a spectrum of droplet sizes whose specific diameters cannot be altered. The generated droplet size distributions are usually not best suited for the process flow, as the diameters of the droplets vary significantly across the spectrum from smallest to largest. MONODISPERSE DROPLET GENERATOR The exact calculation of the resulting droplet diameter permits a targeted design of the generator and a simple determination of the appropriate operating parameters. FMP TECHNOLOGY GMBH owns patented processes both to produce droplets and particles of constant size and to produce particle dispersions of discrete diameters by using aperture plates of different diameters. The process of generating droplets by excitation of the disintegrating jet allows the controlled production of monodisperse or discrete polydisperse sprays with adjustable droplet diameters. Monodisperse sprayer technology, however, allows discrete and specific monodisperse or polydisperse sprays with adjustable droplet diameters to be generated. This droplet formation is based on the Rayleigh decay of multi-layered liquid jets. By introducing vibratory disturbances in liquid jets, this easy-to-manage mechanism allows droplets of known size to be produced. Single-droplet generators, as depicted below, can generate up to 10,000 single monodisperse droplets per second through the use of die plates with centrally arranged micro-drilled holes laid out in a specific geometry. By adjusting the die diameter, the generator can selectively produce the desired droplet diameter. A large range of droplet sizes can be generated. Thus applies: d = 1,89 D. The basic rule is that decay occurs in a droplet within a jet once the forces of inertia acting on the droplet are greater than the forces of surface tension acting to stabilise and hold the jet together. The technology developed allows for the controlled disintegration of a jet through the application of defined interference waves. It is important that low-amplitude interference signals are sufficient to control the disintegration of the jet. At a given jet velocity U, vibrations at frequency f produce interfering waves of wavelength λ = U/f. Interfering waves lead to the regular production of identically sized droplets of predictable diameter d. If the nondimensional wavelenght k = πd/λ is between 0.3 and 0.9. The optimal brake-up occurs at k=0,7. Liquid supply Buffer Filter Droplet generator Drain Piezoceramic oscillator Signal generator U = velocity D = diameter die f G = generator frequency Nozzle plate holder Droplets Page 3

Monodisperse droplet generator, type MTG-01-G1 PROCEDURES APPLICATION Apart from producing single droplets, the spray generators are also suitable for producing large streams of droplets.

The distribution chamber ensures an even flow through all die holes. Droplet generators with up to 613 individual dies have already been manufactured and successfully tested.

4 Monodisperse droplet generator, type MTG-01-G1 PROCEDURES APPLICATION Apart from producing single droplets, the spray generators are also suitable for producing large streams of droplets. These can be configured for the desired flow-rate via the many holes in a die that are evenly supplied with fluid from a distribution chamber and that thus form separate droplet chains. The distribution chamber ensures an even flow through all die holes. Droplet generators with up to 613 individual dies have already been manufactured and successfully tested. The theoretical configuration of these multi-jet generators is also based on the Rayleigh decay of a liquid jet. Achievable fluid flow-rates with such nozzles currently stand at 250 litres per hour, depending somewhat on the desired droplet diameter, however. Coating of single droplets and lines of droplets Production of granulates Testing Agricultural applications Controlled dosing of liquids Spray cooling Rapid Prototyping use of the precisely controllable droplet diameter to construct specific forms out of liquid metal-melt droplets Pharmacy creation of polymer particles as medication carriers Spray-drying production of high-quality dry products with the lowest particle-size distribution Calibration of instruments for measuring droplet sizes and speeds R & D tasks in production technology Image of chain of droplets Image of multi-jet generator Image of die drilling The result of a Rayleigh jet disintegration, which is controlled by periodic disturbances, is a chain of monodisperse droplets. These are essentially characterised by three parameters: U δp dp where U is the speed of the droplets, dp the droplet diameter and δp the distance between adjacent droplets. Multi-jet monodisperse generator Following this basic principle of spray control, the flow-rate can be determined: (volume flow-rate) This applies to the entire operating range of the generator that results from the condition for the instability of a fluid jet: Where λ denotes the wavelength of the applied generator signal and D the hole diameter of the die. This knowledge allows the formation of droplets to be tailored to the individual needs of processes. Where n designates the number of die holes and f G the excitation frequency of the piezoelectric crystal. Page 4

FMP-PRODUCTS DROPLET GENERATOR Together with the generator for monodisperse droplets, FMP TECHNOLOGY also provides not only the basic device and associated electronics but also the pressure vessel

FMP TECHNOLOGY also offers a strobecamera setup to capture images of the individual droplets. All this equipment is shown below.

sprays with predetermined droplet diameter spectrum Creation of microdroplets from 40 µm to 1000 µm Efficient control of evaporation- and combustion behaviour of droplets Identical, well-understood

5 FMP-PRODUCTS DROPLET GENERATOR Together with the generator for monodisperse droplets, FMP TECHNOLOGY also provides not only the basic device and associated electronics but also the pressure vessel with the necessary filtration equipment. Die plates with holes of different sizes and/or individual plates with multiple holes are likewise available. FMP TECHNOLOGY also offers a strobecamera setup to capture images of the individual droplets. All this equipment is shown below. Vibrational excitation of the jets to induce the formation of droplets via a piezoelectric element Predictable, controlled production of monodisperse droplets or targeted production of polydisperse sprays with predetermined droplet diameter spectrum Creation of microdroplets from 40 µm to 1000 µm Efficient control of evaporation- and combustion behaviour of droplets Identical, well-understood dynamic behaviour for all droplets CONTROL ELECTRONICS Frequency range: 0,5 Hz bis 5 MHz Signal shapes: Sine, triangle, rectangle, positive and negative impulse, variable symmetry Signal input and output: SYNC OUT; VCO IN; OCV OUT; EXT IN Suitable electronics for the control of the piezoelectric transducer and easy entry of the frequency and amplitude of the excitation signal for the formation of droplets CCD camera and stroboscope are triggered to visualize the droplet formation optimally NOZZLE PLATES O-Ring Pin hole Support plate Mounting sleeve Cap nut Variabley adjustable die plate for the production of droplets of different diameters Dies fitted with special inlet contour to ensure optimum flow and droplet formation Layout of the number and arrangement of die holes for desired droplet diameter spectra and required flow Page 5

Possible operating termperature: (min.) +10 C up to (max.

pressure control unit and filter Guarantees are continuous and pulsation-free

pressure control FLOW METER Precise measuring device to measure the smallest

75 l/min and thus adjust the desired droplet diameters Programmable flow

6 FMP-PRODUCTS FLUID SUPPLY Max. inlet pressure: 10 bar Possible operating pressure: 6 bar Capacity: 4,9 Liter Possible operating termperature: (min.) +10 C up to (max.) +50 C Our standard scope of supply comprises a pressure vessel incl. pressure control unit and filter Guarantees are continuous and pulsation-free fluid supply Adjustment of the system pressure by means of a manometer with pressure control FLOW METER Precise measuring device to measure the smallest volume flows l/min and thus adjust the desired droplet diameters Programmable flow controller to indicate the current flow and the total flow Flow-rate measurement devices in the range of l/min are available STROBOSCOPE CAMERA Camera system for process monitoring, consisting of CCD camera with microscope lens and strobe Opportunity to monitor the formation of droplets from a standard PC Droplets are visualized by triggering the stroboscope and the camera simultaneously Page 6

GENERAL SPRAY DEVELOPMENTS DOUBLE-JET SPRAYS It is a general rule that turbulences within a liquid jet result in the deformation of the surface and thus, generally, in the formation of interferences.

Based on this knowledge, a spray mechanism was developed where an impulse exchange of two clashing liquid jets results in the atomization of the fluid.

This mechanism allows the production of sprays with predictable droplet sizes, depending on the nozzle diameter, the impact angle, pressure applied and fluid properties.

7 GENERAL SPRAY DEVELOPMENTS DOUBLE-JET SPRAYS It is a general rule that turbulences within a liquid jet result in the deformation of the surface and thus, generally, in the formation of interferences. These are reinforced by aerodynamic processes at the jet-rim and lead to the formation of droplets. Based on this knowledge, a spray mechanism was developed where an impulse exchange of two clashing liquid jets results in the atomization of the fluid. Hereby, two liquid jets are directed towards each other at a certain angle. The turbulence caused by the impulse exchange triggers the decay of both jets and the spreading of a spray cone. This mechanism allows the production of sprays with predictable droplet sizes, depending on the nozzle diameter, the impact angle, pressure applied and fluid properties. FMP test rig for the testing of sprays The production of droplets and the production of sprays does not only require suitable spray nozzles which are easy to operate but also profound knowledge of possible mechanisms which can be applied for the production of sprays. Depending on the required size of the droplets, different mechanisms of spray production have to be applied. Some are only suited to produce droplets with polydispersed size distributions. Others, in turn, are suited for the production of monodispersed size distributions, i.e. the production of droplets of the same size. Mono- and polydispersed sprays are widely used in industrial and medical applications and in the human environment. Double-jet mechanism Our highly qualified engineers and innovative products help to reliably meet the quality requirements which the producers and users of spray technology are faced with. Modern, numerical computation methods ensure that reliable statements about the design of spray nozzles to achieve optimal droplet sizes can be made without time-consuming empirics. Dipl.-Ing. Martin Gillert Founder & managing director of FMP TECHNOLOGY GMBH Page 7

FMP TECHNOLOGY GMBH was honoured with the following awards Gründerpreis Mittelfranken (Founder Award Central Franconia) Bayerischer Gründerpreis (Bavarian Founder Award)

Innovation champion at Würzburg Automotive Summit Großer Preis des Mittelstandes (Major Award of the Mid-Sized Companies) ABOUT FMP TECHNOLOGY GMBH In 2006, FMP TECHNOLOGY GMBH was

It has the aim to take up basic scientific developments and to develop them into novel, innovative products and to market these.

drying technology. Sources of some Materials: [1] G. Brenn, F. Durst, C. Tropea: Monodisperse Sprays for Various Purposes - Their Production and Characteristics. Part. Part. Syst.

[3] R. Brodkey: The Phenomena of Fluid Motions. New York: Dover Publications, 1967. [4] F.

For coating technology the development of FMP TECHNO- LOGY GMBH concerns novel coating dies.

Coating dies currently available on the market need to be specially designed to suit a specific coating fluid, so that, up to now, users had to invest in many different coating dies.

8 FMP TECHNOLOGY GMBH was honoured with the following awards Gründerpreis Mittelfranken (Founder Award Central Franconia) Bayerischer Gründerpreis (Bavarian Founder Award) IHK-Gründerpreis (Founder Award from the German Chamber of Industry and Commerce) Prize winner of the local initiative of industry and Federal Government Germany - Land of ideas Innovation champion at Würzburg Automotive Summit Großer Preis des Mittelstandes (Major Award of the Mid-Sized Companies) ABOUT FMP TECHNOLOGY GMBH In 2006, FMP TECHNOLOGY GMBH was founded as a spin-off of the insitute of Fluid Mechanics at the University of Erlangen. It has the aim to take up basic scientific developments and to develop them into novel, innovative products and to market these. In the different FMP TECHNOLOGY GMBH business areas, which are all based on the principles of fluid dynamics, ground-breaking developments could be made, especially for coating and drying technology. Sources of some Materials: [1] G. Brenn, F. Durst, C. Tropea: Monodisperse Sprays for Various Purposes - Their Production and Characteristics. Part. Part. Syst. Charact. 13 (1996) [2] G. Brenn, T. Helpiö, F. Durst: A new apparatus for the production of monodisperse sprays at highflow rates. Chem. Eng. Sci., Vol.52, No.2 (1997) [3] R. Brodkey: The Phenomena of Fluid Motions. New York: Dover Publications, [4] F. Puschmann: Experimentelle Untersuchung der Spraykühlung zur Qualitätsverbesserung durch definierte Einstellung des Wärmeübergangs. Magdeburg, For coating technology the development of FMP TECHNO- LOGY GMBH concerns novel coating dies. In contrast to conventional coating dies, it is possible for the first time to coat various fluids with only one coating die without any quality reduction. Coating dies currently available on the market need to be specially designed to suit a specific coating fluid, so that, up to now, users had to invest in many different coating dies. These additional expenses can be avoid with the coating die developed by FMP TECHNOLOGY GMBH. Erlangen Copyright 2011 FMP TECHNOLOGY GMBH Fluid Measurements & Projects Am Weichselgarten 34 D Erlangen Fon: +49 (0) Fax: +49 (0) info@fmp-technology.com Web: Würzburg Wetterkreuz Wetterkreuz Am Weichselgarten Reutleser Weg Berlin München Regensburg Production FMP TECHNOLOGY GMBH Photography Kurt Fuchs, Graphic design lars kienle werbung, Reproduction All rights reserved. It is not permitted to copy parts of this brochure. Nürnberg

Droplet size measurement of liquid atomization by the immersion liquid method (droplet coalescence and solution into the immersion liquid)

Advances in Fluid Mechanics X 191 Droplet size measurement of liquid atomization by the immersion liquid method (droplet coalescence and solution into the immersion liquid) T. Fujimatsu, M. Kito & K. Kondo