Food Chilling Methods and CFD Analysis of a Refrigeration Cabinet as a Case Study

This chapter presents the most significant facts about food chilling. For food chilling, the chilling medium in mechanically cooled chillers may be air, water or another secondary cooling agent (slurry ice), or metal surfaces (heat exchangers). Ice chilling is also presented. CFD simulation is applied to a vertical display cabinet with four shelves. In order to evaluate the temperature gradient, the following stages are taken into account: preprocessing—geometry set-up and design of the discretization scheme; processing—introduction of the boundary conditions and calculation; and post-processing—visualization of the velocity and temperature fields

Experimental determination of the wear resistance of devices used for cutting the stalks of agricultural plants

The paper presents researches on the wear resistance of the blades integrated in the combine cutter for the harvesting of agricultural plants. The wear of the combine cutters causes production losses at harvesting both during operation and stopping machines to change the blades. Experimental determination of wear was made for blades on cutting attachment of three types of combines studied. The parameters determined in the wear study were the hardness, mass and roughness of both the new blades and the blades used for 100 hours of harvest operation. The analysis of the data on the degree of wear of the blades both quantitatively by determining the mass and qualitatively by studying the roughness of the used surfaces under identical conditions of operation, presents differential losses for the three combines that correlate with the blade hardness

Research on the influence of air speed on the kinetics green malt drying

In breweries its know that malt is made from barley blank, and is a natural product rich in enzymes and vitamins. In order to optimize the work for drying green malt has been investigated in laboratory conditions. The malt subjected to drying was achieved using Jacobsen germination table. Research on dryng malt were made in the laboratory with a vertical air drying with a drying agent, heated air. The main goal in this work was to monitor the work process for drying green malt moisture of 46.31 % and a thickness of 1 cm. Dehydration was carried out at different speeds of the drying agent in order to observe how and when the evaporation of water. We have used four samples of malt obtained under the same conditions from the same batch of barley with the same parameters of final moisture, but which has been dried in the same diagram of temperatures but at different speeds of the drying agent (warm air). The speed of drying agent was 1.1 m/s, 1.5 m/s, 2.1 m/s and 2.5 m/s. The air temperature in the dryer was between 44 oC and 80oC. The time consumed for drying of each of the four samples was the same for each. It should be mentioned that all the four samples of malt had the same mass and the same parameters (moisture content W = 46.31) and temperature (21 °C) at the beginning of the drying. The results obtained at the end of the drying process shows different values of the humidity in the final malt, very close to the value of the air velocity at 1.1 m/s and 1.5 m/s. It should be mentioned that the lowest moisture content is obtained if the speed experience hot air was 2.5 m/s. The conclusion is that the drying agent used at the same temperature but with a higher circulation rate (in this case 2.5 m / s) to facilitate the evaporation of large quantities of wate

Computational hemodynamics in a patient - specific cerebral aneurysms models

Backgrounds: Hemodinamic factors are known to play an important role in initiation, growth and rupture of intracerebral aneurysms. Thorough knowledge of hemodynamic parameters in cerebral arteries and aneurysms are very useful in understanding of pathophysiology and clinical evaluation of cerebral aneurysms. We describe a methodology of computational analysis of hemodinamics in a patient specific aneurysms models. Aneurysms are segmented from CT angiography images. Method: A total of 6 cerebral aneurysms models were developed from CT angiography images. A computational fluid dynamics analyses were accomplished under realistic flow conditions. We selected only patients with multiple intracerebral aneurysms and conducted hemodynamic studies in un-ruptured aneurysms. We tried to evaluate the rupture risks for these aneurysms. In our series were five middle cerebral artery aneurysm and one basilar artery aneurysm.Results: We succeed to set up a methodology in patient specific aneurysms models hemodynamic study. Computational analyses of hemodynamic factors were performed for each of these 6 aneurysms models. The results were then processed to determine the average pressure on the arterial wall and inside the aneurysm, stream lines and region of greater impact of hemodynamic forces.Conclusions: Wall shear stress plays an important role in initiation, growth and rupture of cerebral aneurysms. In vivo measurements of WSS values had become most popularly in last decade. Aneurysm geometry influences the characteristics of flow conditions.&nbsp

The impact of agricultural vehicles rolling system on soil

The paper establishes the value of the average pressure at the contact surface level between the soil and the tires of the following vehicles and trailers: the U- 650 and Valtra T-190 tractors, the 2RB5AT and 7RBAT trailers and the large dump capability Iveco Trakker 8x4. The wheelground pressure is determined as the report between wheel corresponding weight and the contact surface area with soil. This area was obtained by calculation, using 12 types of equations established by different authors. In this paper, we used the average of the 12 versions, both for the wheel-soil surface and for the wheel-ground pressure. It was found that the lowest wheel-ground pressures are recorded for the Valtra U-650 and T-190 tractors (63,535 ... 142,821 kPa) and the highest in the case of the 7RBAT and 2RB5AT trailers and the Iveco Trakker 8x4 dump (432,692. .. 623,414 kPa), the maximum imposed limit by agricultural requirements being 100 kPa. Regarding the tractors, the exceeding of the imposed limit (100 kPa) is recorded for all the wheels of the Valtra T-190 tractor and only for the front wheels of the U-650 tractor. These excesses are quite small (10 ... 42 kPa), so practically will not affect soil properties. For the trailers and dump, the wheel-ground pressure is 4,3 ... 6,2 times higher the upper limit imposed for agricultural soil, 100 kPa. These high pressures don’t affect the asphalt or concrete roads, but will adversely alter the physical properties of agricultural soils

Studies on the Physical Changes in Corn Seeds during Hybrid Drying (Convection and Microwave)

Hybrid seed drying technology, based on convection and microwave drying, is a modern method, and the research on the physical changes in cereal seed resulting from hybrid drying is still in its infancy. The aim of the present paper is to study the uniformity of the drying process by examining the physical changes occurring in corn seeds. An innovative drying equipment, combining convective and microwave drying, was used to dry corn seeds (variety DKC5068). The convective drying was performed during the pneumatic transport of the seeds, using hot air at a maximum temperature of 50 °C; the microwave-based drying was performed using 2.45 GHz microwaves. Thus, the seeds were volumetrically heated at a temperature which does not exceed 44 °C. The physical changes in corn seeds were measured in terms of moisture, volume, cracking and color. The results regarding the moisture and volume changes in the seeds during the drying process proved that moist seeds are more homogeneous than dry seeds. The change in volume also changed the stiffness of the seeds, which showed greater homogeneity after drying compared to wet seeds. Hybrid drying led to an average shrinkage of 8.76% compared with the original seed volume, while the percentage of seeds showing cracks after drying increased by 22%. Generally, the drying process also led to color changes, but in the case of hybrid drying the results were inconclusive. Hybrid drying of corn seeds requires a shorter time and does not significantly influence physical characteristics, compared to other drying technologies

Research on the influence of geometry of cutting device on harvesters during the cutting process

The paper presents a study of the influence of the constructive parameters of the blades on the cutting machines from the harvesters during the cutting process.The research focuses on the angle of sharpening of the cutting edges of the blades and the angle of inclination of the stalk during the cutting process. The blades used in the experiment have smooth and jagged cutting edges with a usual angle of 20° and modified angles of 10° and 15°. The tests were carried out using maize stalks (Zea mays) with tilt angles of 45° and 90°. The diagrams of variation of force, displacement and mechanical work during the cutting of maize stalks are presented and discussed

Cercetări privind uzura şi fiabilitatea maşinilor pentru combaterea bolilor şi dăunătorilor din plantaţiile viticole

The HERBST ED-900 stand functioning isbased on the liquid collection on each nozzle of the herbicide sprayer in vineyards and orchards by means of collectors that are mounted on each nozzle of the machine. Usingthis stand one can test sprayers for vineyards and orchards with 10 nozzles each, on a ramp. After the measurements made on the herbicide sprayer in vineyards and orchards, the liquid quantities collected in each cylinder are partially transmitted to the computer through the wireless system and are stored in a data basis. From here they may be either accessed as absolute values and sent in a text file, or a graph of the distribution variation may immediatelly be visualized