One of the problems faced by the petroleum industry is the wax deposition in pipelines during transportation of waxy crude oil. A comprehensive mathematical model for quantitative prediction of wax deposition for a multicomponent hydrocarbons mixture (oil) was developed. Deposition as a function of time was obtained as a solution of differential equations derived from the principles of mass and energy conservation, considering the thermodynamic of phase transition. Experiments were conducted using a mixture of toluene and an oil wax cut, in a laboratory flow loop. Model results on total mass of wax deposition showed conformity with experimental results in the laminar flow regime. These comparisons verified that molecular diffusion is the dominant mechanism during laminar flow.
Publication Date: 2002
Chemical Engineering Communications (00986445)189(7)pp. 959-973
A mathematical model is developed to study simultaneous heat and mass transfer in hot gas spray systems. The model is obtained by writing mass, energy, and momentum balances for both continuous and discontinuous phases. Governing equations along with suitable correlations for heat and mass transfer coefficients have been solved numerically. In order to develop a realistic model for such complicated systems, a droplet size distribution was implemented in the model instead of using an average size. A steady state spray-cooling problem is analyzed to illustrate the applicability of the model. To validate the mathematical model for this case, necessary data was collected and measured in commercial cement plants. A good agreement between plant data and the model was noticed in general, and results obtained from the model indicate that size distribution of water droplets and physical dimensions of the spray-cooling system are important parameters. This model is very useful in determining the so-called "critical operation condition" at which sludge formation at the bottom of spray-cooling systems will happen. The predicted parameters in spray-cooling systems both for droplet phase and gas phase aptly illustrate the ability of the model to treat the complex phenomena associated with two-phase flows.
Publication Date: 2002
Journal of Food Engineering (02608774)55(3)pp. 247-252
Agricultural food products and specially root vegetables undergo several physical and structural modifications during the drying process. Shrinkage of root vegetables during drying is important not only from the viewpoint of material end-use but also for simulation problems. In this paper the shrinkage of root vegetables is studied in a pilot-scale, inert medium fluidized bed dryer. Cylindrical carrot samples were utilized as the test media, providing simulants for high moisture content food systems. The effects of various parameters such as air temperature, air humidity, sample diameter, sample initial moisture content, existence of inert particles and air velocity were investigated. It was found that the shrinkage of root vegetables during drying in a fluidized bed could be well correlated with moisture content of the sample during drying. Air velocity, temperature and presence of inerts did not show significant effects on shrinkage in this system. © 2002 Elsevier Science Ltd. All rights reserved.
Publication Date: 2003
Journal of Food Engineering (02608774)59(2-3)pp. 221-227
Drying behavior of maize and green peas investigated in a pilot scale fluidized bed dryer with inert energy carriers. The variations of drying material density, size and mass diffusivity with change of moisture content were investigated. It was found that, air temperature, inert material, and air velocity had no significant effect on physical properties and therefore, shrinkage and density are only functions of moisture content, but diffusivity is a function of temperature and moisture content. Based on the experimental data obtained, some correlations were developed for variation of shrinkage, density and diffusivity of green peas and maize during drying in a fluidized bed with inert particles. The shrinkage, density and moisture diffusivity of green peas and maize could be predicted by an average accuracy of 98% by use of proposed correlations. © 2003 Elsevier Science Ltd. All rights reserved.
Publication Date: 2003
Journal of Applied Polymer Science (00218995)90(4)pp. 963-972
Poly(urethane-isocyanurate)s were synthesized by reacting toluene diisocyanate and poly(propylene glycol) with various stochiometric ratios (1-3) in the presence of different concentrations of dibutyltin dilaurate (DBTDL) and ferric acetylacetonate (FeAA). The influence of the NCO/OH ratio and the catalyst type and concentration on the extent of urethane and isocyanurate formation were examined using Fourier transform IR spectroscopy. No trimer formation was observed in the presence of the FeAA catalyst. The percentage of the trimer group and the trimer/urethane content were found to be increased with increasing the stochiometric ratio or DBTDL concentration. The thermal decomposition of the copolyurethanes in an inert atmosphere was studied by means of thermogravimetry (TG). The TG curves showed three decomposition steps with the principal degradation temperature at about 355-385°C. The effects of the NCO/OH ratio, catalyst type and concentration, and heating rate on the thermal stability of the copolyurethanes were determined. The Flynn-Wall, Kissinger, and Ozawa methods were used to calculate the activation energies of thermal decomposition. The swelling behavior of solid copolyurethanes in toluene showed that, as the DBTDL concentration and/or NCO/OH ratio increased, the swelling ratio and average molecular weight between crosslinks were decreased whereas the crosslink density was increased. The sol fraction of solid copolyurethanes was examined and found to be reduced when the percentage of DBTDL or the stochiometric ratio was raised. © 2003 Wiley Periodicals, Inc.
Publication Date: 2003
Drying Technology (15322300)21(1)pp. 83-101
A pilot scale fluidized bed dryer with an inert energy carrier (steel, glass beads ranging from 2.7 to 6.5 mm) was used to investigate the drying of carrots. The effects of sample diameter, inert material type, inert material diameter, amount of inert material, air velocity, and temperature on the rate of drying were studied. A mathematical model was proposed for predicting the drying rate and temperature of drying material. It was found that presence of inert particles enhance the rate of drying. The results of this study also revealed that, although the rate of drying increases with decreasing sample diameter, increasing the inert material thermal conductivity, and increasing air temperature, but the inert material diameter and air velocity have no significant effects on the rate of drying. The independence of rate of drying on air velocity especially in well-fluidized systems indicates that external diffusion is not a controlling step in this process. Also the presence of inert materials causes the drying material to reach more rapidly to its final internal temperature.
Publication Date: 2003
Chemical Engineering and Technology (09307516)26(1)pp. 43-49
A pilot scale fluidized bed dryer with inert particles as energy carrier was used to investigate the drying characteristics of carrot in this type of dryer. Glass beads, hollow steel balls and pieces of dry carrot were used as inert materials. The effects of sample diameter, inner material type, inert material diameter, amount of inert material, air velocity and temperature on the rate of drying were studied. It was found that the presence of inert particles enhances the rate of drying. The results of this study also revealed that, although the rate of drying increased with decreasing sample diameter, increasing of inert material thermal conductivity, and increasing of air temperature, but the inert material diameter and air velocity did not have any significant effect on the rate of drying. The independence of the rate of drying on air velocity in well fluidized systems, indicates that external diffusion is not the controlling step in this process. It was also found that the presence of inert materials caused the drying material to reach its final internal temperature more rapidly. The internal temperature of the drying material, also increased with increasing diameter and thermal conductivity of the inert materials.
Publication Date: 2003
Chemical Engineering Communications (00986445)190(4)pp. 508-518
In this paper some experimental results showing the influence of inclination of a cylindrical heating surface immersed in an air duct on heat transfer coefficient are presented. The experiments were performed in a laboratory-scaled apparatus of square cross section with dimensions 120 × 120 mm and 1400 mm in height. Heat transfer surface was an electrical heater made of brass tube with outer diameter of 19 mm and 110 mm length. In each experiment the temperatures of the front and rear side of the heating surface, inclination angle, air velocity, inlet air temperature, and heater power were measured. It was concluded that heat transfer coefficient depends on flow conditions and angle of inclination. The maximum Nusselt number (Nu) was observed to occur about 45° inclination relative to the horizon, for the range of Reynolds numbers used in experiments. The values of heat transfer coefficients in the vertical position were very nearly the same as they were in the horizontal position. Based on the experimental results, a correlation was proposed for estimation of Nu at the desired flow velocity and inclination angle, relative to Nu at zero inclination.
Publication Date: 2003
Journal of Polymer Engineering (21910340)23(4)pp. 225-240
A kinetic study of the catalyzed reaction between toluene diisocyanate (TDI) and polypropylene glycol (PPG) was carried out in the bulk state by using quantitative Fourier transform infrared (FTIR) spectroscopy. The polymerization was studied in the presence of the catalysts dibutyltin dilaurate (DBTDL) and ferric acetylacetonate (FeAA) at three different temperatures. The kinetics was shown to obey a second-order scheme and the rate plots showed a distinct break in continuity, due to diferent reactivities of NCO groups. It was concluded that the appearance of this break point is related to the use of catalyst as well as type of polyol. The rate constants (k1,k2) and the activation parameters Ea1Ea2, ΔS1#, ΔS2#) for the isocyanate groups in the para and ortho positions in TDI molecule were calculated. It was found that the reactivity of p-NCO is 5 to 8 fold higher than o-NCO. The temperature enhances the reactivity of o-NCO rather than the p-NCO. It was also concluded that the FeAA is more sensitive than DBTDL to temperature and is more selective to enhance the reactivity of the o-NCO. © 2011, by Walter de Gruyter GmbH & Co. All rights reserved.
Publication Date: 2003
International Journal of Environment and Pollution (09574352)19(6)pp. 557-566
With the aim of the economic upgrading of natural resources, this investigation examined the hydrothermal synthesis of zeolite from perlite, and the ability of the synthetic zeolite to adsorb and retain cyanide. The hydrothermal treatment of perlite with aqueous sodium hydroxide results in the formation of Na-Pc zeolite. The cation-exchange capacity of zeolite for zinc, copper and silver was respectively 2.26, 1.86 and 2.44 meq g -1. The exchange was incomplete, but equilibrium was rapidly attained. Cyanide adsorption isotherms, constructed at three different temperatures, showed that the zeolite was very selective for cyanide. The solubility products of the cyanide precipitate and the exchange capacity of zeolite for individual cations governed the adsorption capacity of the zeolite. The method also remains selective in the presence of some other anions. Kinetic data for cyanide desorption in water and sodium chloride solution indicated that zeolite retains most of the adsorbed cyanide.
Publication Date: 2004
Chemical Engineering Communications (00986445)191(3)pp. 315-334
A mathematical model has been developed for prediction of pressure drop in a Venturi scrubber. This model includes the effect of the amount of liquid film and re-entrainment of liquid droplets from liquid film. The result of the present model is compared with experimental data of Viswanathan et al. (1985) as well as with the other models (Viswanathan et al., 1985; Boll, 1973). Results of this study indicate that at high liquid to gas ratios prediction of pressure drop can be improved by considering re-entrainment and liquid film effects. Also the effects of gas velocity and liquid to gas ratio were investigated on the rate of droplet re-entrainment and pressure drop. © Taylor and Francis Inc.
Publication Date: 2004
Advances in Polymer Technology (07306679)23(3)pp. 239-255
Reactive extrusion of poly(urethane-isocyanurate) (PUIR) was studied in an intermeshing corotating twin-screw extruder. Toluene diisocyanate (TDI) and polypropylene glycol (PPG) were used as initial materials with dibutyltin dilaurate (DBTDL) as catalyst. The reaction was first examined in a batch reactor as well as in an internal mixer in order to obtain the kinetics and temperature/torque evolution trends during the formation of PUIR, respectively. For the specified screw speed and temperature profile of the extruder, a working domain can be recommended for the reactive extrusion, in terms of NCO/OH ratio (r) and catalyst concentration (C), to reach a sufficient extent of reaction. The effects of screw speed and temperature profile on the residence time parameters of the reaction mixture were investigated. It is found that the axial mixing and the RTD behavior of the reaction mixture in the extruder can be well represented by the axial dispersion model. For the reaction condition of r = 3, C = 2%, and barrel temperature profiles of 75-150°C or 90-165°C, the optimum screw rotation speed for complete NCO conversion is 20 rpm. The structures, thermal stabilities, morphologies, and physical and dynamic mechanical properties of reactively extruded PUIRs were investigated. © 2004 Wiley Periodicals, Inc.
Publication Date: 2004
2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025pp. 203-207
The role of diffusion in reducing the saturation pressure of oil in blocks located at different depths of fractured oil reservoirs has been studied. A model to describe unsteady state diffusion in a matrix block with a given geometry in fractured oil reservoirs has been developed and the results have been compared with the analytical solution. The delay time for solution gas drive due to diffusion in a block with a given shape has been calculated by using the data of Haft kel field. Copyright 2004, Society of Petroleum Engineers Inc.
Publication Date: 2005
Energy Sources (00908312)(1-2)
The precipitation of waxy constituents in petroleum mixtures subjected to a cold environment gives rise to a variety of problems well-known in the petroleum industry. A revised multi-solid phase thermodynamic model for predicting wax precipitation in petroleum mixtures is presented in this article. The Peng-Robinson equation of state is used to evaluate the phase behavior of both liquid and vapor phases. The results predicted by this model agree with the experimental data of wax precipitating for several synthetic oils and crudes.
Publication Date: 2005
Energy Sources (00908312)(1-2)
One of the problems faced by the petroleum industry is the wax deposition in pipelines during transportation of waxy crude oil. Oil companies dealing with waxy crude often spend millions of dollars in remedial procedures. An ideal design should use an accurate mathematical model that would include all salient features of wax deposition and waxy crude transport to predict wax deposition during crude oil transportation. In this article, a comprehensive mathematical model, both in laminar and turbulent flow regimes, is developed. The model couples energy equation with deposition and removal kinetics model and thermodynamic model. The k - ε turbulent flow model and energy equation were used to predict velocity and temperature distributions in the turbulent flow regime. Molecular diffusion of wax, as a mechanism of deposition and sloughing effect due to the hydrodynamic forces of fluid on deposited wax, have been considered. Parametric studies on the variation of the amount of wax deposition were performed for a mixture of toluene and oil wax cut in an experimental setup. Overall predictive ability of the proposed model is excellent for the laminar flow. For the turbulent flow regime, no necessary complete experimental data for model were available. Consequently, qualitative results were presented and discussed.
Publication Date: 2005
Canadian Journal of Chemical Engineering (00084034)83(3)pp. 401-408
A mathematical model consisting of differential equations for energy, momentum and material exchange is developed for a non-isothermal Venturi-type scrubber. By this model, the effects of heat and mass transfer on droplets concentration distribution and removal efficiency of particulate in a non-isothermal Venturi scrubber can be investigated. In order to approach a realistic model, the liquid film flow on the walls and droplet size distribution are considered. The model is validated by comparing the results of mathematical model by plant and experimental data reported in the literature. The Results section of this work reveals that the inlet humidity and temperature of the gas can affect the removal efficiency of the scrubber.
Publication Date: 2005
Polymer Engineering and Science (15482634)2005pp. 149-157
In this paper the rheokinetics of Polyurethane formation and the influence of shear rate on its kinetics have been studied. Two different linear polyurethane systems with 0% and 100% hard segments are examined in a cone and plate rheometer. The isothermal increase of viscosity during polyurethane formation has been measured at different shear rates and different temperatures and is modeled with an exponential function. The molecular weight vs. time curves and the reaction kinetic constants have been obtained for various shear rates and temperatures using gel permeation chromatography (GPC). It was concluded that kinetics of polyurethane formation is enhanced as the shear rate is increased. Phase separation is found to be responsible for irregularities in the viscosity build up due to formation of polyurethane with hard segments at high conversions.
Publication Date: 2006
Canadian Journal of Chemical Engineering (00084034)84(3)pp. 310-315
An analytical model using eddy diffusivity is applied for predicting droplet concentration distribution and liquid film formation in a Venturi scrubber. By comparing experimental data of film formation reported in literature (Viswanathan et al., 1984) and the results obtained from this model, a semi-empirical correlation for liquid droplets eddy diffusivity is obtained. The validity of this correlation is confirmed by obtaining good agreement between theoretical and experimental data of droplet concentration distribution and film formation in a Venturi scrubber (Viswanathan, 1998; Viswanathan et al., 1984).
Publication Date: 2006
Journal of Applied Polymer Science (00218995)102(2)pp. 1615-1623
Styrene butadiene rubber (SBR) was modified by the grafting reaction of maleic anhydride (MAH) in the presence of the initiator benzoyl peroxide (BPO). This modified elastomer was then blended with poly(ethylene terephthalate) (PET) bottle waste, and the mechanical and morphological properties of the resulting blends were studied. The amount of grafted MAH was determined by chemical titration. The results revealed that the concentrations of MAH and BPO strongly affected the grafting process. The morphology of the dispersed phase for blends of PET waste and SBR-g-MAH was quite different from that of a simple blend of PET waste and SBR. Dynamic mechanical thermal analysis revealed suitable compatibility between PET waste and styrene butadiene rubber-graft-maleic anhydride (SBR-g-MAH). The enhanced compatibility resulted in better impact properties. The better compatibility was concluded to result from bond formation between the carbonyl group of SBR-g-MAH and the hydroxyl or carboxyl end groups of PET. © 2006 Wiley Periodicals, Inc.
Publication Date: 2006
Chemical Engineering Science (00092509)61(8)pp. 2675-2687
The performance of continuous solid state bioreactors having two different solid substrate flow patterns, namely plug flow and completely mixed flow, is quantified for both steady-state and transient operation using a simple mathematical model. The core assumption is that each substrate particle acts as an infinitesimal bioreactor. The residence time distribution of the particles is considered in the formulation of the equations for the mixed-flow bioreactor and the error that results from neglecting it is investigated by comparing the simulation results with those of a completely mixed, continuous bioreactor for submerged liquid fermentation (a chemostat). The model is extended to include autolysis, inter-particle inoculation and contamination. Plug flow is shown to have superior performance when high product concentration is needed, if autolysis or other undesirable late emerging phenomena occur, and when non-sterile fermentation using slow-growing microorganisms is undertaken. © 2005 Elsevier Ltd. All rights reserved.
Publication Date: 2006
Journal of Radioanalytical and Nuclear Chemistry (15882780)270(2)pp. 319-324
A reconnaissance study has been made on the distribution of 238U, 232Th, 40K, 137Cs and geochemical features in soil and sediment samples at various locations in the coast of Persian Gulf. Activity concentration levels due to radionuclides were measured in 50 samples of soils and sediments collected from the coast of Hormozgan. From the measured spectra, activity concentrations were determined for 40K (range from 140 to 1172 Bq·kg-1), 137Cs (from 0 to 15 Bq·kg-1), 238U (from 29 to 385 Bq·kg-1) and 2321Th (from 9 to 156 Bq·kg-1) with the lowest limit of detection (LLD) of 68, 3.2, 4.3 and 4.3 Bq·kg-1, respectively. The dose rate from ambient air at the soil ranges was between 23 to 177 nGy·h-1 with an average of 60±7.86 nGy·h-1. © 2006 Akadémiai Kiadó.
Publication Date: 2006
Iranian Journal of Science and Technology, Transaction A: Science (10286276)30(3)pp. 259-269
A reconnaissance study has been made on the distribution of 238U, 232Th, 40K, 137Cs and geochemical features in soil and sediment samples at various locations on the coast of Bushehr in the Persian Gulf. In this study a gamma-ray spectrometer based on a High Purity Germanium detector and a PC based MCA and X-ray fluorescence (XRF) method were used. Estimation of the measured radionuclide content have been made for the absorbed dose rate of gamma radiation. The Activity concentration (A), the equivalent radium (Req), and the external hazard index (Hex) which resulted from the natural radionuclides in soil and sediment are also calculated. The base-line data of radionuclides and heavy metals in view of the commissioning of nuclear and non-nuclear industries for the coast of Bushehr, which does not yet exist, was obtained. Activity concentration levels due to radionuclides were measured in 50 soil and sediment samples collected from this region. The measurement was performed with respect to their gamma radioactivity for a counting time of 24 hour intervals. From the accumulated spectra, activity concentration were determined for 40K (range from 108 to 520 Bq Kg-1), 137Cs (from 6 to 40 Bq Kg-1), 238U (from 12 to 75 Bq Kg1) and 232Th (from 8 to 33 Bq Kg-1) with the lowest limit detection (LLD) of, respectively, 68, 3.2, 4.3 and 4.3 Bq Kg-1. The dose rate from ambient air at the soil ranges was between 14 to 44 nGy h-1 with an average of 30.56 ± 7.86 nGy h -1. © Shiraz University.
Publication Date: 2006
Food and Bioproducts Processing (09603085)84(3 C)pp. 220-226
Drying behaviour of maize and green peas was investigated in a bench scale fluidized bed dryer with an inert energy carrier (2.7 mm glass beads and steel balls). The effects of drying solid diameter, inert material type, amount of inert material, air velocity and temperature on the rate of drying were studied. A mathematical model is proposed for predicting the drying rate and temperature variation of spherical shape drying solids. It was found that presence of inert particles enhances the rate of drying. The rate of drying increases with decreasing drying solid diameter, increasing the inert material thermal conductivity and increasing air temperature. However, air velocity, amount of inert material and initial moisture content have no appreciable effects on the rate of drying in well fluidized systems. The independence of rate of drying on air velocity especially in well-fluidized systems indicates that external convection is not a controlling step in this process. Experimental results showed that drying rate decreases by increasing the mass ratio of drying solid to inert material. © 2006 Institution of Chemical Engineers.
Publication Date: 2006
Journal of Radioanalytical and Nuclear Chemistry (15882780)268(3)pp. 539-544
A nonlinear function was applied in combination with the method of mixing activity calibration for fitting the experimental peak efficiency of HPGe spectrometers in the 50-2614 keV energy range. The preparation of Marinelli beaker standards of mixed gamma- and RG-Set at secular equilibrium with its daughter radionucliedes was studied. Self-absorption was measured for the activity calculation of the gamma-ray lines for daughters of 238U series, 232Th series, as well as 137Cs and 40K in soil samples. Self-absorption in the sample depends on a number of factors including sample composition, density, sample size and gamma-ray energy. Seven Marinelli beaker standards were prepared in different degrees of compaction with bulk density (ρ) of 1.000 to 1.600 g·cm-3. The detection efficiency versus density was obtained and the equation of self-absorption correction factors was calculated for soil samples. © 2006 Akadémiai Kiadó.
Publication Date: 2006
Journal of Porous Media (19340508)9(4)pp. 373-380
The effect of heat carriers on heat transfer to a cylindrical metal bar was investigated in a lab setup fluidized bed with small spherical solids (2.7 mm glass beads and steel balls). Rods of aluminum and steel, each with 10 and 20 mm diameter and 60 mm length, were heated by means of hot air. In each experiment, the temperature of the center of solid was measured at various intervals of time. The effect of various parameters such as air velocity, air temperature, mass ratio of fluidizing material to solid, type of fluidizing material, diameter of fluidizing material, and diameter of solid were investigated. The rate of heat transfer increases with decreasing immersed solid diameter, increasing the fluidizing material thermal conductivity, decreasing fluidizing medium size, and increasing air temperature, but air velocity and amount of fluidizing material must be optimized to convert the system to a well-fluidized system and maximize the rate of heat transfer. Copyright © 2006 Begell House, Inc.
Biria, D.,
Roostaazad, R.,
Darouneh e., ,
Izadi h., Publication Date: 2007
Scientia Iranica (10263098)14(2)pp. 161-168
Rock samples from the Asmary outcrop formation of the Ahwaz oil rich zone with a porosity of 16% and permeability of 1 md and MIS crude oil with an API value of 42.5 and moderate asphaltene content of 3%, were used to study the effect of the incubation time and flow rate of the displacing fluid in MEOR operations. Five species of rod shaped, gram positive, thermophile and facultative bacteria were isolated and purified from the crude. Due to the high sweep efficiency prevailing in the core flooding system, the effect of the displacing brine flow rate on the oil recovery efficiency was found not to be significant. On the other hand, a 100% increase in incubation time from 7 to 14 days resulted in an increase from 3% to 4% in the total cumulative production. Application of a cyclic operation was not effective in promoting the efficiency of the MEOR operation, probably due to the stronger effect of flooding on the removal of valuable metabolites, as compared to undesired ones, before the stationary phase of the microbial kinetics. While qualitative measurements did not show a strong change in the water-rock contact angle, more than a 4-fold increase in capillary number occurred after microbial treatment, implying that reduction of interfacial tension was the stronger mechanism of oil recovery in this work. © Sharif University of Technology, April 2007.
Publication Date: 2007
Food and Bioproducts Processing (09603085)85(3 C)pp. 171-177
In this work, which was designed for drying of agro-food products, six varieties of potatoes (Santana, Santea, Marfona, Diamant, Koncord, Renjer) were chosen as drying material. A pilot-scale tray dryer, with and without air circulation, and a fluidized bed dryer were used for performing drying experiments. The experiments were performed with and without blanching. The changes in structure and colour of six varieties of potatoes were studied. Temperature did not show significant effect on shrinkage, but blanching time and air circulation had significant effect on shrinkage as well as on the appearance of dried product. Less shrinkage occurred in Renjer and Diamant varieties at 80°C in comparison with other varieties. Santana (at 80°C), Santea (at 70°C) and Renjer (at 80°C) had better appearance and colour after free convection drying, whereas the appearance, colour and quality of Marfona variety was not acceptable at all. The quality and appearance of Marfona variety improved by using a tray dryer with air circulation. The quality and appearance of all varieties was very good in fluidized bed dryer. Blanching was effective in improving the colour of all dried varieties. © 2007 Institution of Chemical Engineers.
