Study on Factors Affecting Physicochemical Properties of Spray Dried Mango Powder Using Taguchi Experimental Design Approach

Mango is a common fruit in tropical countries. Due to its short shelf-life, it is important to study alternative preservation and consumption methods. In this study, concentrated mango juice was used to produce mango powder by using spray drying process. Four process parameters with three levels variation each, including initial total soluble solid content (13, 14, 15◦Brix), maltodextrin content (20, 25, 30% w/w), inlet air temperature (170, 190, 210◦C), and atomization pressure (4, 5, 6 bar) were studied. Taguchi approach of L-9 (34) array was used to design the experiments. Powder yield, moisture content, color difference, and solubility of the mango powder were investigated. It was found that maltodextrin content was the greatest factor affecting powder yield and color difference. The highest powder yield was 31.81%, and the least color difference (∆E) was 3.17. Inlet air temperature and atomization pressure were the most important factor affecting to moisture content and solubility, respectively, in which average moisture content was 2.98% (w.b.) and the highest solubility value was 94.66%. For the overall production process, it was concluded that maltodextrin content was the most important parameter, while total soluble solid content provided the least impact on spray dried mango powder properties.

RESEARCH OF STARTING MODES OF THE RT-FLEX ENGINE

Starting modes are one of the most critical in the operation of marine diesel engines. Under the unsteady conditions of the flow of working processes, it is difficult to ensure their quality indicators. Of particular importance is the reliability in maneuvering. The foregoing relates, first of all, to fuel injection, which determines to a large extent the combustion process and all the operational characteristics of a diesel engine. Typical start-ups are the first fuel supply cycles [1], presented in Fig. 1 by the oscillograms of the nozzle needle movement. An oscillatory process is observed, accompanied by a partial rise of the needle. This increases the duration of injection, and an incomplete rise leads to a throttling of the fuel flow in the section under the needle. The atomization pressure decreases, the conditions of mixture formation deteriorate, which, along with the low parameters of the air charge, adversely affects the characteristics of the working process up to skipping the ignition.

Study on the Atomization and Dust-Reduction Performance of a New Type of External Pneumatic Vortex Fog Curtain Dust Removal Device in Fully Mechanized Excavation Face

To solve the problem of dust pollution in the heading face, a new type of external pneumatic vortex fog curtain dust removal device suitable for a fully mechanized excavation face is designed in this paper. Firstly, dust migration laws at different times are simulated and analyzed by COMSOL software, and the functional relationship of dust concentration distribution above 50 mg/m3 at different heights and different wind speed is derived. Aiming at the dust migration laws of the heading face, a new dust removal device was proposed, and the atomization performance of the new type of external pneumatic vortex fog curtain dust removal device under different jet wind speed, different atomization pressure, and different nozzle working angle is explored through atomization performance experiment. It is found that when jet wind speed is 30 m/s, atomization pressure is 4 MPa, and nozzle working angle is 75°, the atomization performance of the new type of external pneumatic vortex fog curtain dust removal device is the best. Through the simulation of COMSOL software, the influence of air volume on the new type of external pneumatic vortex fog curtain dust removal device is analyzed. It is found that the new type of external pneumatic vortex fog curtain dust removal device is relatively stable when the air volume at the pressure outlet is less than 400 m3/min. The dust-reduction efficiency of the new type of external pneumatic vortex fog curtain dust removal device was investigated through the dust-reduction experiment, and it is found that the new type of external pneumatic vortex fog curtain dust removal device had better dust removal performance under the condition that the ventilation conditions did not interfere with the integrity of the vortex fog curtain.

THEORY OF LIQUID DISPERSION BY THE NOZZLES

The main characteristics are considered and calculations of the main indicators of nozzle devices are given. Laboratory tests of nozzles of various configurations were carried out to determine the working width of the spot at different distances to the irrigated surface and the angle of the spray pattern, and dependencies were established to determine their effective mode of operation. As a result of testing nozzles with different spray patterns when determining the impact force of the jet, it was found that as the spray angle increases, the value of the impact force of the jet F decreases. This is due to the fact, that with an increase in the initial jet velocity, the torch length reaches a maximum, not only does the kinetic energy increase, but the sizes (diameters) of the sprayed medium drops, which leads to a decrease in droplet mass and an increase in the aerodynamic resistance of the torch jet particles. A bench for determining the impact force of a jet of various nozzles was developed and test results were obtained. During operation, due to the erosive wear of the jet holes of the nozzles, its diameter increases, as a result, the working atomization pressure drops, and the number and size of large particles increase. Therefore, periodically it is necessary to check the diameter of the nozzle holes and not to use nozzles, that have a hole diameter greater than the initial one by 10 or more percent. In the study of nozzles, the dependences of nozzles’ characteristics on the initial parameters of the outflow of the liquid jet to the dispersity and shape of the torch were established. The values of irrigation spot width are established depending on the angle of the torch and the distance from the nozzle to the irrigated surface. The magnitude of the impact force of the jet, which occurs at the point of contact of the fluid jet with the irrigated surface, is determined.

Hot-Melt Fluidized Bed Encapsulation of Citric Acid with Lipid

Acidulant encapsulation is used to prevent the unwanted acid hydrolysis of other ingredients in food industry. It is preferred to efficiently solidify the molten coatings on acidulant particles. In this article, a molten lipid was atomized in a fluidized bed of cold citric acid powder for the production of encapsulated acidulant. The effect of lipid-to-citric acid mass ratio and atomization pressure on the size distribution of encapsulated particles was investigated. The median particle size (D50) increases with lipid content, and fine particles were reduced with lipid encapsulation. The surface morphology of lipid-encapsulated citric acid particles was studied by scanning electron micrograph to gain insight into the possible encapsulation mechanism. The encapsulation efficiency increases with the lipid-to-citric acid mass ratio.