Abstract: This study deals with the modeling and the search for the optimum production capacity of a tunnel-dryer of the Californian type. The model is obtained from the heat and mass transfer balances at two levels, the product (fruits) level and inside the tunnel itself. The optimum condition is given by the maximum production capacity of a plum dryer satisfying the final product quality. This choice is determined by the fact that a large amount of fruit must be dried in a short time to have a minimum of loss. Recirculation of a proportion of the exhaust air improves the dryer efficiently in terms of energy.

Abstract: The drying of Sultana seedless grapes was investigated under intermittent and continuous operating conditions in a laboratory solar installation involving a thermal storage bed and an auxiliary heater. The effect of pretreatment, and of the a i r velocity on the drying rate of the grapes at constant temperature was also studied in relation t o the quality of the dried product. Solar drying of the grapes was accomplished in 30.5 to 60.5 h of intermittent operation, or 19 to 60 h of continuous drying, involving the thermal storage bed and the auxiliary heater. The shortest drying time (19 h ) and the highest quality dried product were obtained with grapes dipped in a hot (80 C ) solution of sodium hydroxide and ethyl oleate, which were dried continuously at 42°C and 2m/s, air temperature and velocity respectively. The mean apparent diffusivity of moisture in raisins at 6o°C and air velocity 2m/s was estimated as 1.0.10-10 m2/s.

Abstract: Vibro-fluidized bed dryers are being extensively used in the industry to dry granular particles of wide particle size distribution. For drying applications of limited air inlet temperature and hard to dry granules--high diffusion resistance of moisture inside the qranules--baffles are normally provided in these dryers to increase the residence time of particles. The residence time distribution of granules in vibro-fluidized bed dryers is of high importance to successfully model such dryers. There has been some studies reported in the literature for average residence time of granules in vibro-fluidized beds without baffles, but there has been no work reported for average residence time in vibro-fluidized beds with baffles and residence time distribution for beds with or without baffles. Experimental runs were carried out in this study in the 0.93 m2 (10 ft2 ) pilot plant vibro-fluidized bed dryer with baffles to determine the residence time distribution of dry granules and granule height profile t...

Abstract: A solar tunnel dryer with integrated collector was developed and tested. This low-cost system can be produced either by small scale industries or farmers themselves using simple tools and relatively cheap materials. Depending on weather conditions about 1000 kg grapes can be dried within 4 to 7 days. According to the drying capacity the solar drying system can be successfully applied to farms with an acreage of 0.5 to 1.0 hectare. Compared to traditional sun drying methods solar drying reduces significantly drying time and mass losses. During drying the crop is completely protected from rain, dust, animals and insects and doesn⢙ come into contact with foreign materials.

Abstract: The effects of acoustic drying of rice in a fluidized bed were evaluated at frequencies of 12 kHz and 19 kHz and air temperatures of 20.5° C and 40° C. The intensity levels were 132 and 128 dB respectively, intensities that are considerably lower than the 145 dB and higher usually applied in drying experiments of this type. The results confirmed that the effectiveness of acoustic drying is more pronounced at the lower temperatures, a significant fact especially in drying heat sensitive materials. The rate of water removal increased when acoustical energy at either frequency was applied with room temperature air. Increase in drying rate was not obvious when acoustic energy was applied at 40° C at the intensity levels of these experiments.

Abstract: High-intensity contact drying denotes drying under suf- ficiently intensive heating conditions that, following a brief warmup period, the mist paper web operates at internal tem- peratures in excess of the ambient boiling point. A simplified, two-zone analytical model is first presented. The paper is depicted as having a dry layer, of ever-increasing thickness, adjacent to the hot surface. Heat conduction through this layer (the rate-limiting step) causes evaporation at the interface with the “wet zone.” The vapor is then considered to flow through the wet zone into the ambient. Results of bench-scale experiments are discussed. Drying rates as much as twenty times conventional rates are indicated. The drying rate increases with hot surface/boiling point tem- perature difference and applied mechanical pressure. The instsn- taneous drying rate decreases continuously after a brief warmup period. The vapor pressure at the hot surfacelpaper interface rises quickly to a peak value, followed by a contin...

Abstract: Precondition of the successful application of Solar drying is the economy mainly influenced by the savings and the costs. Components of savings and costs are related to the design of the solar dryer and the drying technology to be performed. Analysis of relations between the technical solutions and the economy is presented with regard to some often neglected or undervaluated effects, i.e. savings obtained by the absolute cleanness of solar energy, quality of the dried product and, the energy effectiveness of the drying process itself. Conclusions of- fer some contributions of principle to the selection of the system of solar dryer to be used, to design of solar dryers and, to direction of the drying technology 131.

Abstract: This paper deals with the sublimation of large bodies, or “objects”, made up from a pure substance in a bubbling gas fluidized bed of considerably smaller particles, or “fines”. The influence of such parameters as the gas velocity, the bed temperature, the size and the adsorption capacity of the fines has been investigated. The results obtained clearly show that the rate of sublimation in fluidized beds is far higher than in air alone. It increases with increasing bed temperature, decreasing particle size, increasing powder mass capacity, and roughly varies as a parabolic function of time. It has also been observed that the temperature difference between the bed and the object surface, or “temperature depression”, depends on the fines characteristics as well as on bed temperature, but is independent of gas velocity when good solid mixing conditions are achieved. Bed-to-object heat and mass transfer coefficients have been deduced from data points and attempts have been made to provide a reasonable...

Abstract: The structure of a conventional Mollier’s psychrometric chart is described. The mathematics of the perspective transformation is presented. The humidity range of the transformed i,x -diagram is from 0 to ∞ and the temperature range from -20° to 400° The use of the diagram for drying calculations is illustrated.

Abstract: A natural solar drying system has been tested with wheat. Simple solar collectors give the small temperature rise needed for low temperature drying. The system, with a capacity of 35 tomes, is placed in a region of humid hot-temperate climate. It has been designed to dry all the locally produced grain (wheat, corn, soybean, sunflower, sorghum, etc.), without a supplemental heat source. Two different types of solar collectors of the same effective area were tested, with one a storage-collector and the other a bare plate collector Data from four field tests performed between 1981 and 1983 are given and discussed. The mean mass of water removed from the wheat per hour was of 6.54 kg, under an average air flow of 4.3 m3 /min. tonne

Abstract: The aim of this study is to show how a simple numerical model can improve the understanding of the thermal and hydrodynamic behaviour of a dryer working under natural conditions. This model is managed taking into account the real operating conditions of the dryer. The general procedure permits a hydrodynamic curve to be obtained and is validated by a comparison with experimental results.

Abstract: A study was made of a centrifugal pressure nozzle with large orifice diameter (8-10 nun) for producing dry milk in capacity of 2-3 tons per hour to develop some performance data on spray distribution, drop size distribution, and capacity with changing spray drying conditions such as nozzle pressure, orifice diameter and spray angle. Experimental results were shown as follows. (1) A centrifugal pressure nozzle of large capacity such as 5,000- 5,500 l/hr at 150 kg/cm2 spray pressure and 110°s ray angle was designed by using the nozzle parameter Si/dedi√di/di. (2) Atomization characteristics were greatly affected by the ratio of orifice diameter (de) to the length (L) of the nozzle core. The smaller the ratio, around 0.125, the better are the atomizing effects. (3) The large orifice can be used at least 3,000 hr in the spray drying operation for milk without any wear in the orifice although it is only made of stainless steel. As a result, a spray dryer of large capacity for dry milk has been operate...

Abstract: Developing countries with a timber resource that can be manufactured into finished products either for local use or export often lack the capital to build high-cost dry kilns. Many of these countries are in the tropics where solar radiation and ambient temperatures are high. The low-cost solar/wood energy lumber dry kiln described in this report was designed and tested for such countries where solar dry kilns can be built and operated at low cost. The design is for a 14-m"6,000-fbm capacity kiln having an insulated drying compartment, an external horizontal solar collector, and a furnace room containing a wood burner. Capacities larger or smaller than 6,000 fbm are also possible. This design allows collector and wood burner sizing to match the energy demands of the dryer. The design also incorporates low-cost controls that allow unattended drying when operated as a solar-only dryer. Manual firing is necessary when the wood-burning system is supplying the energy.

Abstract: A model for contact drying of wood veneer is presented and compared with experimental results. The model is and-dimensional and assumes that convective transport of liquid and vapor is dominant for the drying conditions examined. Model results are in good agreement with the experimental data. A parameter study indicates that total drying time is a strong function of platen temperature and veneer thickness. The model indicates that the spacing of ventilation grooves does not affect drying rate significantly, but has a large effect on pressure buildup in the veneer. Veneer permeability shoved a similar effect--with lover permeabilities resulting in slightly slower drying, but significantly higher internal pressure.

Abstract: An analysis technique is described which uses the nonlinear curve fitting capabilities of the Statistical Analysis System (SAS) to analyze batch drying data. The technique does not require any apriori assumptions about whether a constant rate period exists. Rather, the only assumptions necessary are the possible forms of the equations which can be used to describe the drying phenomenon. The program will then determine, based upon statistical techniques, where each equation should be used during the drying process in order to best describe the overall drying process. Two examples are given; the first analyzes the drying of. sand, a material having a constant rate period; the second analyzes the data describing the drying of French fried potato pieces.

Abstract: This paper describes and diacusses various impinging jet systems used commercially to aerodynamically support flat sheets (e.g. paper web). Certain design aspects of auch systems are discussed. Some mass transfer results are also presented.

Abstract: Collision of droplets; counter-current spray dryer; drying rate; heat transfer; nonphosphated detergent; spray drying The spray drying method of non-phosphated granular detergents is studied to decrease the amount of agglomerate particles The formation of agglomerates is mainly influenced by the concentration of droplets in spray cloud and the water content of droplets at the time of collision The overlaps of different spray clouds should be de- creased The drying rate near the nozzle zone is considerably faster than that calculated by Ranz-Marshal’s equation According to these phenomena, “Multi-stage spray drying” is developed, which is characterized by in stalling plural spraying stages in a spray dryer Consequently, non-phosphated detergents are manufactured with the same powder properties and productivity as phosphated detergents

Abstract: The functioning of a conventional heated platen laboratory press for paper or board press dry experiments is considered analytically and in the light of experimental results from the literature. A press dry sample dries so that the evaporation zone recedes from the edges toward the center. Since the dwell time of the web within a certain moisture content range influences the resulting strength characteristics, a conventional press dry experiment will not produce a uniformly strong web. To study the possible distribution of the strength deviation, a strength development function is generated and used in computer simulation of a web being press dried. The results emphasize the importance of dwell time as a factor in press dry strength devel oprnent. Finally, basic principles are reviewed or evolving an improved press dry laboratory device, and a model is proposed.

Abstract: A kinetic study of ice sublimation in a fluidized-bed dryer operating under atmospheric conditions is described. The influence of some experimental conditions such as temperature, air flow rate, on sublimation time was investigated. Mathematical expressions were formulated to account for variations in mass and dimensions of ice samples during sublimation. Ice temperature and temperature of fluidized-bed in which the ice is submerged are correlated; prediction bf ice temperature is demonstrated graphically from known fluidized-bed temperatures. The kinetics of ice sublimation in the atmospheric dryer is shorn to be regulated by the expression

Abstract: The paper presents the results of an investiga- tion into thermoradiation drying and film formation of a two-component solution having substantially dif- ferent boiling temperatures of the components, and being applied to a substrate under the conditions of matching the spectral emissive characteristics of the radiator with the spectral thermoradiative properties of the object of drying. The film transmissivity is found to,increase with a decrease in the mass of the solution during drying.

Abstract: The main application for solar collectors in agriculture are drying of agricultural crops. Different types of active air type solar collectors have been examlned In small scale experiments and in full scale trials. This report deals with practical applications OF solar collectors for dryers. The investigations have shown that solar collectors can replace conventional heating units based on 011, electricity etc. for the heating. The most economical and practical solution is received lf the collector is integrated in the roof or a wall of a farm building. The report gives recommendations for the construction and For the choice of materials. Design dates and operation schedules are also presented.

Abstract: The hygroscopic potential of freeze dried papaya in the form of powder and granules was studied for several temperatures (23,33 and 43PC) and relative humidities (49 to 90%). For such conditions the kinetics of water sorption was established. The results show the influence of the amount of water absorbed, the environmental relative humidity and temperature on water sorption rates for this type of product. An intriguing behavior was found far the rates of water sorption as influenced by the absolute temperature, and at the critical level of 60% relative humidity, this influence is very much reduced.

Abstract: The basic analitical method for so-called expression operation, the separation of liquid from solid-liquid systems by compression, are presented in view of the flow through compressible porous media. It has become evident that the expression mechanism consists of two flow phenomena. These types of phenomena can be analyzed by consideration of the flow mechanism through compressible porous beds, first by the filtration theory and second by the so-called consolidation theory. A simplified equation is also presented. It is shown that the simplified equation is well applicable to industrial expression problems even when the creep effects of matarials to be expressed are appreciable

Abstract: In order to reduce cross machine (CD) moisture deviations and their detrimental effects in tissue production, control components are more frequently used today. The CORRECTA hood, a high t...

Abstract: The basic analitical method for so-called expression operation, the separation of liquid from solid-liquid systems by compression, are presented in view of the flow through compressible porous media. It has become evident that the expression mechanism consists of two flow phenomena. These types of phenomena can be analyzed by consideration of the flow mechanism through compressible porous beds, first by the filtration theory and second by the so-called consolidation theory. A simplified equation is also presented. It is shown that the simplified equation is well applicable to industrial expression problems even when the creep effects of matarials to be expressed are appreciable

Abstract: The technical and economical feasibility of using solar energy for curing Virginia tobacco in the bulk barn is investigated. The results illustrate that the energy saving obtained by each type of the system studied is limited because of the nature of the tobacco curing energy requirement. From the technical point of view, the system using water as a heat transfer fluid with an evacuated solar collector shows the best performance. To be economically competitive, the systems need to be multi-purpose: for example, they can be used for space and water heating or for drying other crops during the off-season for tobacco.