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Heat Exchange (heat + exchange)
Selected AbstractsTheoretical Investigation of Heat Transfer in Glass FormingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2001Raymond Viskanta A theoretical study to investigate internal heat transfer in glass undergoing cooling between glass and mold, as well as plunger, during and after pressing, is described. A thermal model has been formulated to simulate the cooling. The heat-transfer analysis accounts for the spectral nature of radiation in glass, the dependence of the thermophysical properties of glass on temperature, and the contact heat transfer between and after pressing, as well as subsequent cooling. Heat exchange between glass and mold by contact conduction across a very small gap and that by thermal radiation are considered separately. Numerical solutions have been obtained for typical conditions simulating symmetric and nonsymmetric cooling, and the results obtained are presented and discussed. During the dwell time, thermal-contact conduction between glass and mold is the dominant mechanism for heat extraction from glass. Results show that radiation from the surface of the glass plays a relatively small role in the heat extraction from the glass, but that radiation from the interior of the glass is much more significant. [source] The effect of gravity on surface temperatures of plant leavesPLANT CELL & ENVIRONMENT, Issue 4 2003Y. KITAYA ABSTRACT A fundamental study was conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long-term under microgravity conditions in space. To clarify the effects of gravity on heat exchange between plant leaves and the ambient air, surface temperatures of sweet potato and barley leaves and replica leaves made of wet paper and copper were evaluated at gravity levels of 0.01, 1.0, 1.5 and 2.0 g for 20 s each during parabolic aeroplane flights. Thermal images were captured using infrared thermography at an air temperature of 26 °C, a relative humidity of 18% and an irradiance of 260 W m,2. Mean leaf temperatures increased by 0.9,1.0 °C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.5 °C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was at most 1.9 °C for sweet potato leaves over 20 s as gravity decreased from 1.0 to 0.01 g. The boundary layer conductance to sensible heat exchange decreased by 5% when the gravity decreased from 1.0 to 0.01 g at the air velocity of 0.2 m s,1. The decrease in the boundary layer conductance with decrease in the gravity levels was more significant in a lower air velocity. Heat exchange between leaves and the ambient air was more retarded at lower gravity levels because of less sensible and latent heat transfers with less heat convection. [source] Seasonal variation in the energy and water exchanges above and below a larch forest in eastern SiberiaHYDROLOGICAL PROCESSES, Issue 8 2001Takeshi Ohta Abstract The water and energy exchanges in forests form one of the most important hydro-meteorological systems. There have been far fewer investigations of the water and heat exchange in high latitude forests than of those in warm, humid regions. There have been few observations of this system in Siberia for an entire growing season, including the snowmelt and leaf-fall seasons. In this study, the characteristics of the energy and water budgets in an eastern Siberian larch forest were investigated from the snowmelt season to the leaf-fall season. The latent heat flux was strongly affected by the transpiration activity of the larch trees and increased quickly as the larch stand began to foliate. The sensible heat dropped at that time, although the net all-wave radiation increased. Consequently, the seasonal variation in the Bowen ratio was clearly ,U'-shaped, and the minimum value (1·0) occurred in June and July. The Bowen ratio was very high (10,25) in early spring, just before leaf opening. The canopy resistance for a big leaf model far exceeded the aerodynamic resistance and fluctuated over a much wider range. The canopy resistance was strongly restricted by the saturation deficit, and its minimum value was 100 s m,1 (10 mm s,1 in conductance). This minimum canopy resistance is higher than values obtained for forests in warm, humid regions, but is similar to those measured in other boreal conifer forests. It has been suggested that the senescence of leaves also affects the canopy resistance, which was higher in the leaf-fall season than in the foliated season. The mean evapotranspiration rate from 21 April 1998 to 7 September 1998 was 1·16 mm day,1, and the maximum rate, 2·9 mm day,1, occurred at the beginning of July. For the growing season from 1 June to 31 August, this rate was 1·5 mm day,1. The total evapotranspiration from the forest (151 mm) exceeded the amount of precipitation (106 mm) and was equal to 73% of the total water input (211 mm), including the snow water equivalent. The understory evapotranspiration reached 35% of the total evapotranspiration, and the interception evaporation was 15% of the gross precipitation. The understory evapotranspiration was high and the interception evaporation was low because the canopy was sparse and the leaf area index was low. Copyright © 2001 John Wiley & Sons, Ltd. [source] Heat conduction and radiative heat exchange in cellular structures using flat shell elementsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2006J. B. Colliat Abstract We developed in this paper a variational formulation of heat diffusion equation applicable to the flat shell context and cellular structures. For this purpose, we introduce the average mid-surface temperature field, through-the-thickness gradient and their dual generalized fluxes. Moreover, we introduced radiative heat exchange in the same way, which leads to a non-linear and unsymmetrical thermal discrete problem. The model performance is illustrated by several numerical examples concerning cellular structures like hollow clay bricks submitted to thermal loading. Thermo-mechanical coupling for such structure which is well adapted to the shell-like modelling approach, is presented in the elastic regime with the numerical results concerning temperature field and forces. Copyright © 2005 John Wiley & Sons, Ltd. [source] Analysis of coupled seepage and temperature fields in concrete damINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 6 2002Article first published online: 28 MAR 200, Chai Junrui Abstract It is very important to investigate the coupled problem and solution of seepage and temperature fields in the concrete dam. Seepage through the concrete dam influences the distribution of the temperature field in the dam by heat exchange. The temperature field in the dam also influences the hydraulic conductivity and seepage through the dam. The mechanism of the action and reaction between the seepage and temperature fields in the concrete dam is analysed according to the seepage characteristics of the concrete dam. The continuum mathematical model for coupled seepage and temperature fields in the concrete dam is presented, and the iterative steps and the finite element numerical solution method for the coupled model are proposed. An engineering example is also given to show the applicability of the proposed model and numerical solution method. It can be shown from the example that the difference between the coupled and uncoupled solution to the two fields in the dam is about 4,5%. Copyright © 2002 John Wiley & Sons, Ltd. [source] Modeling and optimization of a novel pressurized CHP system with water extraction and refrigerationINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2008J. R. Khan Abstract A novel cooling, heat, and power (CHP) system has been proposed that features a semi-closed Brayton cycle with pressurized recuperation, integrated with a vapor absorption refrigeration system (VARS). The semi-closed Brayton cycle is called the high-pressure regenerative turbine engine (HPRTE). The VARS interacts with the HPRTE power cycle through heat exchange in the generator and the evaporator. Waste heat from the recirculated combustion gas of the HPRTE is used to power the absorption refrigeration unit, which cools the high-pressure compressor inlet of the HPRTE to below ambient conditions and also produces excess refrigeration in an amount that depends on ambient conditions. Water produced as a product of combustion is intentionally condensed in the evaporator of the VARS, which is designed to provide sufficient cooling for the inlet air to the high-pressure compressor, water extraction, and for an external cooling load. The computer model of the combined HPRTE/VARS cycle predicts that with steam blade cooling and a medium-sized engine, the cycle will have a thermal efficiency of 49% for a turbine inlet temperature of 1400°C. This thermal efficiency, is in addition to the large external cooling load, generated in the combined cycle, which is 13% of the net work output. In addition, it also produces up to 1.4 kg of water for each kg of fuel consumed, depending upon the fuel type. When the combined HPRTE/VARS cycle is optimized for maximum thermal efficiency, the optimum occurs for a broad range of operating conditions. Details of the multivariate optimization procedure and results are presented in this paper. Copyright © 2008 John Wiley & Sons, Ltd. [source] A simplified method for modelling the effect of blinds on window thermal performanceINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2006D. Naylor Abstract An approximate method is presented for predicting the effect of a louvered blind on the centre-glass thermal performance of a fenestration. The method combines a one-dimensional heat transfer model with data from a numerical simulation of the window and blind. Sample results for a blind mounted on the indoor surface of a window show the effect of blind slat angle on heat transmission. Both summer and winter conditions are considered. The results show that a louvered blind can improve the U -value of a standard double-glazed window by up to 37%. Also, the radiation heat exchange with the room can be dramatically reduced (by up to 60%), which will improve the level of occupant comfort. However, there was found to be a trade-off between U -value and occupant comfort; placing the blind closer to the window improves the U -value, but increases the radiation heat exchange with the room. The predictions from the present simplified method compare well with results from a full two-dimensional computational fluid dynamics solution of the conjugate blind/window interaction. Copyright © 2005 John Wiley & Sons, Ltd. [source] Single, twin and triple buried heating pipes: on potential savings in heat losses and costsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2005Benny Bøhm Abstract In order to make district heating systems competitive in areas with single family houses or in other areas with low heat demands it is necessary to reduce the heat losses from the pipes. In recent years the twin pipe has become popular in the Nordic countries. In the article we describe how the heat loss and the heat loss coefficients can be calculated. We introduce the triple pipe with three media pipes (two supply pipes and one return pipe). The temperature dependency and the ageing of polyurethane insulation are briefly discussed. A comparison is made for different 80 mm distribution pipes and for different service pipes with respect to heat losses and to resources, i.e. materials needed for the casing and polyurethane insulation and the gravel in the excavations. For the distribution pipe we found that an egg-shaped twin pipe can reduce the heat loss by 37% and the investments by 12% compared with a pair of single pipes. For the service pipes we found that the triple pipe reduces the heat loss by 45% compared with a common pair of single pipes and by 24% compared with circular twin pipes. The reduction in investment index is 21%. The article also addresses the question of the heat exchange between the two media pipes in a twin pipe. Copyright © 2005 John Wiley & Sons, Ltd. [source] Reducing energy availability losses with open parallel microchannels embedded in a micropatterned surfaceINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2005G. F. Naterer Abstract This article develops a new technique of reducing exergy losses of external viscous flow over surfaces, based on optimized microchannels embedded within the surface. The rate of entropy production and loss of available optimized energy are formulated by an integral solution and modified Blasius profiles of boundary layer flow. The optimized number of microchannels, width and height of each microchannel and spacing between microchannels involve a selective compromise between added heat exchange due to surface area, together with reduced friction through slip conditions within each microchannel. Mixed Knudsen numbers across each microchannel require simultaneous modelling of both slip-flow and no-slip conditions at the wall. Results involving the minimal entropy production and optimized microchannel profiles are presented and compared to other benchmark results involving classical macro-scale configurations. Copyright © 2005 John Wiley & Sons, Ltd. [source] Comparison of entropy minimization principles in heat exchange and a short-cut principle: EoTDINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2003F. Balkan Abstract In this paper the principles called ,equipartition of forces, EoF' and ,equipartition of entropy production, EoEP' are compared in minimizing the entropy production in heat exchange. Entropy production rates for various cases are calculated according to both principles. The calculations show that entropy productions calculated with EoEP principle are always smaller than those calculated with EoF principle although the differences are considerably small. It is also shown that the heat exchange with EoEP principle implied TH/TC=const. Additionally, a new approach, equipartition of temperature difference, EoTD, has been tested comparatively. Although the entropy production rates calculated by this approach are slightly larger than those of two other principles, it can be used as a new principle for quick determination. Copyright © 2003 John Wiley & Sons, Ltd. [source] Methane steam reforming at microscales: Operation strategies for variable power output at millisecond contact timesAICHE JOURNAL, Issue 1 2009Georgios D. Stefanidis Abstract The potential of methane steam reforming at microscale is theoretically explored. To this end, a multifunctional catalytic plate microreactor, comprising of a propane combustion channel and a methane steam reforming channel, separated by a solid wall, is simulated with a pseudo 2-D (two-dimensional) reactor model. Newly developed lumped kinetic rate expressions for both processes, obtained from a posteriori reduction of detailed microkinetic models, are used. It is shown that the steam reforming at millisecond contact times is feasible at microscale, and in agreement with a recent experimental report. Furthermore, the attainable operating regions delimited from the materials stability limit, the breakthrough limit, and the maximum power output limit are mapped out. A simple operation strategy is presented for obtaining variable power output along the breakthrough line (a nearly iso-flow rate ratio line), while ensuring good overlap of reaction zones, and provide guidelines for reactor sizing. Finally, it is shown that the choice of the wall material depends on the targeted operating regime. Low-conductivity materials increase the methane conversion and power output at the expense of higher wall temperatures and steeper temperature gradients along the wall. For operation close to the breakthrough limit, intermediate conductivity materials, such as stainless steel, offer a good compromise between methane conversion and wall temperature. Even without recuperative heat exchange, the thermal efficiency of the multifunctional device and the reformer approaches ,65% and ,85%, respectively. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source] Heat-exchange pressure swing adsorption process for hydrogen separationAICHE JOURNAL, Issue 8 2008Jang-Jae Lee Abstract A current focus in the energy field is on the use of hydrogen in fuel cells. Development of a hydrogen station system is important to the commercialization of fuel cells and fuel cell powered vehicles. In this study, the heat-exchange pressure swing adsorption (HE-PSA) was developed to design a compact H2 PSA process for small spatial occupancy in the hydrogen station. The adsorption dynamics and performance of the newly designed bed were compared with those of a conventional bed by using a quaternary mixture (H2/CO2/CH4/CO 69:26:3:2 vol %) which is generally obtained from the steam-reforming reaction of natural gas. Because the detrimental exothermic/endothermic heat effects accompanied by the adsorption/desorption steps were reduced by heat exchange between the adsorption beds, the separation performance of the HE-PSA was higher than that of a conventional PSA. In addition, the spatial occupancy of the beds could be significantly reduced, compared with a conventional PSA, because the single annular-type bed performed the function of two beds in the HE-PSA. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Single-particle motion and heat transfer in fluidized bedsAICHE JOURNAL, Issue 12 2006Yee Sun Wong Abstract Fluidized beds are particularly favored as chemical reactors because of their ability to exchange heat through immersed heat-exchange surfaces. However, little is known about how the heat-exchange process works on a single-particle level. The most commonly applied theory of fluidized bed heat exchange is that developed by Mickley and Fairbanks in the 1950s,the so-called packet model. The work described in this article is an attempt to understand the process of heat transfer by solids convection, using positron emission particle tracking to follow the trajectory of a single tracer particle in the bed. In particular, the residence time of particles in the vicinity of the surface is determined here for the first time. Using these data, the observed heat-transfer variations are interpreted mechanistically. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Millisecond catalytic wall reactors: I. Radiant burnerAICHE JOURNAL, Issue 5 2001J. M. Redenius Short-contact-time reactors have potential for high throughput in reactors much smaller than their traditional counterparts. While they operate adiabatically, heat can be exchanged at short contact time by integrating heat exchange into the reactor. Hot effluent of exothermic reaction systems can be redirected over feed gases to recuperate a portion of the sensible heat. Placing catalyst directly on reactor walls eliminates the resistance to heat transfer in the thermal boundary layer so that heat released by combustion can be effectively coupled to an emitter, such as in a radiant burner. A radiant heater was constructed, operated, and simulated incorporating short contact time, energy recuperation, and a catalytic wall. This burner operated stably for many hours at a firing rate from ,50 to > 160 kW/m2 at a radiant temperature of 950 to 1,150 K at a radiant efficiency of ,60% with a residence time in the reacting zone of ,10 ms. This reactor was modeled using 2-D Navier-Stokes equations including detailed models for chemistry and heat transport. Temperature and compositions predicted agreed well with experimental measurements. [source] Crystal temperature control in the Czochralski crystal growth processAICHE JOURNAL, Issue 1 2001Antonios Armaou This work proposes a control configuration and a nonlinear multivariable model-based feedback controller for the reduction of thermal gradients inside the crystal in the Czochralski crystal growth process after the crystal radius has reached its final value. Initially, a mathematical model which describes the evolution of the temperature inside the crystal in the radial and axial directions and accounts for radiative heat exchange between the crystal and its surroundings and motion of the crystal boundary is derived from first principles. This model is numericully solved using Galerkin's method and the behaviour of the crystal temperature is studied to obtain valuable insights which lead to the precise formulation of the control problem, the design of a new control configuration for the reduction of thermal gradients inside the crystal and the derivation of a simplified 1-D in a space dynamic model. Then, a model reduction procedure for partial differential equation systems with time-dependent spatial domains (Armaou and Christofides, 1999) based on a combination of Galerkin's method with approximate inertial manifolds is used to construct a fourth-order model that describes the dominant thermal dynamics of the Czochralski process. This low-order model is employed for the synthesis of a fourth-order nonlinear multivariable controller that can be readily implemented in practice. The proposed control scheme is successfully implemented on a Czochralski process used to produce a 0.7 m long silicon crystal with a radius of 0.05 m and is shown to significantly reduce the axial and radial thermal gradients inside the crystal. The robustness of the proposed controller with respect to model uncertainty is demonstrated through simulations. [source] Thermal characterisation of active layer across a soil moisture gradient in the McMurdo Dry Valleys, AntarcticaPERMAFROST AND PERIGLACIAL PROCESSES, Issue 1 2009Scott J. Ikard Abstract Heat transport into active layer soils is important to understanding potential responses to changes in surface energy balance, particularly in the context of changing climate. Here we present results of a study to characterise soil thermal properties along a soil moisture gradient adjacent to Lake Fryxell in Taylor Valley, Antarctica. Our goals were to characterise the thermal characteristics of these relatively wet soils (compared to the rest of the McMurdo Dry Valleys landscape), and to assess the response of the active layer to possible increases in soil moisture. We measured subsurface temperatures at depths from 3 to 50,cm at four locations along a natural gradient of wet to dry soils adjacent to Lake Fryxell from January 2006 to January 2007. We used a numerical model to estimate apparent thermal diffusivity (ATD) and simulate observed temperature time series. Calculations of ATD at discrete locations yielded values ranging from 1.0,×,10,9 , 2.4,×,10,5,m2,s,1, and the corresponding range of bulk (i.e. depth averaged at a single surface location) ATD was 2.9,×,10,9,1.2,×,10,7,m2,s,1. Thawed soils had a range of bulk ATD during warming of 2.9,×,10,9,3.8,×,10,8,m2,s,1, and during cooling of 2.9,×,10,9,4.8,×,10,8,m2,s,1. When soils were frozen, however, the range of bulk ATD was 7.6,×,10,9,1.2,×,10,7,m2,s,1 during warming, and 7.8,×,10,9,1.1,×,10,7,m2,s,1 during cooling. Estimated bulk ATD values were consistently greater in locations of enhanced soil moisture, so lakeside soils were more likely to conduct energy into the subsurface. Increased soil moisture across the landscape would likely increase ATD, allowing for greater heat exchange between the atmosphere and the subsurface. Copyright © 2009 John Wiley & Sons, Ltd. [source] The effect of gravity on surface temperatures of plant leavesPLANT CELL & ENVIRONMENT, Issue 4 2003Y. KITAYA ABSTRACT A fundamental study was conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long-term under microgravity conditions in space. To clarify the effects of gravity on heat exchange between plant leaves and the ambient air, surface temperatures of sweet potato and barley leaves and replica leaves made of wet paper and copper were evaluated at gravity levels of 0.01, 1.0, 1.5 and 2.0 g for 20 s each during parabolic aeroplane flights. Thermal images were captured using infrared thermography at an air temperature of 26 °C, a relative humidity of 18% and an irradiance of 260 W m,2. Mean leaf temperatures increased by 0.9,1.0 °C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.5 °C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was at most 1.9 °C for sweet potato leaves over 20 s as gravity decreased from 1.0 to 0.01 g. The boundary layer conductance to sensible heat exchange decreased by 5% when the gravity decreased from 1.0 to 0.01 g at the air velocity of 0.2 m s,1. The decrease in the boundary layer conductance with decrease in the gravity levels was more significant in a lower air velocity. Heat exchange between leaves and the ambient air was more retarded at lower gravity levels because of less sensible and latent heat transfers with less heat convection. [source] The diabatic heat budget of the upper troposphere and lower/mid stratosphere in ECMWF reanalysesTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 638 2009S. Fueglistaler Abstract We present an analysis of the diabatic terms in the thermodynamic energy equation from ERA-40 and the ECMWF reanalysis ERA-Interim. We analyse the clear-sky radiative heating, the cloud radiative effects, and the impact from latent heat exchange and mixing. The diabatic heat budget is closed with the calculation of the temperature assimilation increment. The previously noted excessive tropospheric circulation at low latitudes in ERA-40 is also reflected in the diabatic heat budget. The temperature increment acts to cool the excessive model heating. Conversely, ERA-Interim requires heating from the assimilation increment at low latitudes, suggesting too little convection. In the tropical tropopause layer (TTL), both reanalyses show a strong heating from the interaction of clouds with radiation, but lack of reliable independent estimates renders the role of clouds uncertain. Both reanalyses show cooling in the TTL by the assimilation increment, suggesting that the models may overestimate the cloud radiative heating, or that the convective parametrization scheme has difficulties in capturing the thermal effects of deep convection. In the stratosphere, ERA-40 shows unrealistic radiative heating due to problems in the temperature profile. The diabatic heat balance is dominated by the assimilation increment, and the residual circulation is much faster than in ERA-Interim. Conversely, ERA-Interim is better balanced and requires a substantially smaller temperature increment. Its structure and magnitude of radiative heating/cooling at low/high latitudes is quite realistic. Overall, ERA-Interim provides a much improved residual circulation, but uncertainties in the magnitude of terms in particular around the tropical tropopause remain large. Copyright © 2009 Royal Meteorological Society [source] Pulsed electrical stimulation for control of vasculature: Temporary vasoconstriction and permanent thrombosisBIOELECTROMAGNETICS, Issue 2 2008Daniel Palanker Abstract A variety of medical procedures is aimed to selectively compromise or destroy vascular function. Such procedures include cancer therapies, treatments of cutaneous vascular disorders, and temporary hemostasis during surgery. Currently, technologies such as lasers, cryosurgery and radio frequency coagulation, produce significant collateral damage due to the thermal nature of these interactions and corresponding heat exchange with surrounding tissues. We describe a non-thermal method of inducing temporary vasoconstriction and permanent thrombosis using short pulse (microseconds) electrical stimulation. The current density required for vasoconstriction increases with decreasing pulse duration approximately as t,0.25. The threshold of electroporation has a steeper dependence on pulse duration,exceeding t,0.5. At pulse durations shorter than 5,µs, damage threshold exceeds the vasoconstriction threshold, thus allowing for temporary hemostasis without direct damage to surrounding tissue. With a pulse repetition rate of 0.1,Hz, vasoconstriction is achieved approximately 1 min after the beginning of treatment in both arteries and veins. Thrombosis occurs at higher electric fields, and its threshold increases with vessel diameter. Histology demonstrated a lack of tissue damage during vasoconstriction, but vascular endothelium was damaged during thrombosis. The temperature increase does not exceed 0.1,°C during these treatments. Bioelectromagnetics 29:100,107, 2008. © 2007 Wiley-Liss, Inc. [source] Mischer mit mikrostrukturierten Folien für chemische ProduktionsaufgabenCHEMIE-INGENIEUR-TECHNIK (CIT), Issue 5 2004B. Werner Abstract Seit etwa 10 Jahren beschäftigt sich die Institut für Mikrotechnik Mainz GmbH (IMM) mit der Nutzung von Mikrostrukturen im Bereich der Mikroverfahrenstechnik. Deren Vorteile , effizienterer Wärmeaustausch und Massentransport , bewirken u.,a. Steigerung von Ausbeute und Selektivität bei gleichzeitiger Ressourcenschonung. Die Entwicklung von mikrostrukturierten Mischern war dabei ein Schlüssel zu verbesserten Feinchemikaliensynthesen sowie zur Herstellung von Dispersionen, Cremes, Schäumen und Emulsionen. Bislang waren diese mikrostrukturierten Mischer im Wesentlichen auf Labor- oder bestenfalls Pilotanlagen-Maßstab festgelegt , typische Maximalflussraten lagen bei 2,, 100,L/h für wasserähnliche Fluidsysteme. Mit der Einführung der StarLaminatoren StarLam300 und StarLam3000, konnte diese Grenze jetzt auf weit über 300,L/h bis in den m3/h-Bereich angehoben werden. Beide Apparate zeigen gute Mischgüten bei hohen Flüssen, die durchaus an die sehr guten Werte von bisher bekannten Niederdurchsatz(L/h)-Mikromischer heranreichen. Damit ist eine Kontinuität von ,wirklichen" Mikromischern über die hier beschriebenen Hochdurchsatz-Tools bis zu statischen Mischern mit noch höheren Durchsätzen gegeben. Eine Klassifikation der Mischeffizienz nach dem Leistungseintrag bestätigt ebenso diese Kontinuität. Mixers with Microstructured Foils for Chemical Production Purposes Since about 10 years the Institut für Mikrotechnik Mainz GmbH (IMM) is engaged with the application of microstructures for chemical micro process engineering. Their advantages , more efficient heat exchange and mass transport , lead to, among other things, an increase in yield and selectivity even while saving resources. The development of microstructured mixers thereby played a key role for carrying out advanced syntheses of fine chemicals as well as for the generation of dispersions, creams, foams, and emulsions. So far, microstructured mixers were mainly limited for laboratory-scale or at best pilot plant-scale , typical maximum flow rates were from 2 , 100 L/h for watery fluid systems. With the introduction of the StarLaminators StarLam300 and StarLam3000 this barrier could be lifted far beyond 300 L/h up to the m3/h domain. Both apparatus yield at high flow rates a mixing efficiency which reaches the high performance of today's low-capacity (L/h) micro mixers. Therefore, continuity from the "real" micro mixers over the herein described high-throughput tools to conventionally manufactured static mixers with even higher flow rates is given. [source] | |||||||||||||||||||