CONSTRUCTION-TECHNOLOGICAL SCHEME AND PARAMETERS OF EQUIPMENT FOR ULTRASOUND DISINTEGRATION OF PLANT RAW MATERIALS

Purpose of the study. Improving the efficiency of ultrasonic disintegration of plant raw materials based on the search for rational (in terms of ensuring the required level of disintegration of plant raw materials) parameters of the cavitation chamber, properties of the suspension, and processing modes. Research methods. Methods of analysis and generalization of the results of scientific research of the processes of ultrasonic treatment of liquids and suspensions were used to substantiate the rational design and technological scheme and parameters of equipment for ultrasonic disintegration of plant raw materials. The results of the study. Acoustic piezoelectric cavitators with a low (up to 5.0 W/cm2) intensity of ultrasound, which is introduced into the liquid or suspension through the bottom (walls) of an open non-resonant cavitation chamber, are the most suitable for cavitation treatment of aqueous suspensions of plant bioresources. Ultrasonic emitters in this case are rigidly attached to the outside of the bottom (walls) of the cavitation chamber. Based on the analysis of research results, the design of a device for ultrasonic treatment of suspensions of plant raw materials was proposed. Conclusions. It is established that the main parameters determining the efficiency of the process of ultrasonic disintegration of plant raw material suspensions are the presence of an effective layer and rational intensity of ultrasonic influence on the medium in the cavitation chamber, which depends on the physical and mechanical properties of the treated medium. Based on the analysis, a structural and technological scheme of the device for ultrasonic treatment of suspensions is proposed.

Effect of Pulsed Ultrasound on Plasma Morphology and Its Changing Mechanism

Arc plasma shape under pulsed and continuous ultrasound field were studied in this research using self-developed welding device which combines arc and ultrasound field coaxially. The results show that, compared with the arc of conventional tungsten inert gas welding, the shape of arc under pulsed ultrasound field relate to the pulse frequency. From 1 Hz to 20 Hz, the arc plasma expands and contracts periodically in one pulse. When more than 20 Hz, the arc plasma contracts as the pulse frequency increases. During high pulse frequency, the arc shape become steady and similar to those in continuous ultrasound field. When in 500 Hz, the contraction ratio of arc projected area under pulsed ultrasound field reaches 38 %, comparing with 30 % of the same power continuous ultrasound field, i.e., in high frequency, low power pulsed ultrasound can obtain arc control effect similar to high power continuous ultrasound, raising ultrasound energy efficiency. The mechanism of ultrasonic influence on arc is analyzed based on sound pressure and acoustic streaming.

Detection of the cavitation component in the total increase of reducing sugars as a result of inversion of sucrose under ultrasonic influence on vegetable and fruit purees

The article presents the results of a study of the process of inversion of sucrose in apple, carrot and pumpkin puree, occurring under ultrasonic action on them, with the formation of the total amount of reducing sugars, as well as with the identification of the autonomously manifested cavitation component that occurs simultaneously with thermal inversion. The relevance of research consists in identifying the quantitative value of reducing sugars formed due to a separately flowing cavitation component in the general inversion of sucrose, when exposed to ultrasound with specified parameters, in order to obtain new types of products with different physicochemical parameters and organoleptic characteristics, depending on changes in parameters processing. To identify the part of reducing sugars formed by the cavitation effect alone, in the total inversion of sucrose occurring during ultrasonic exposure to the product, it is necessary to exclude part of the increase in reducing sugars from the total amount of increase detected by thermal exposure. As a result of the calculations, the following values of the increase in the amount of reducing sugars (relative to the original data), obtained only due to the cavitation effect during ultrasonic processing of puree, were obtained. In natural apple puree the increase was 240 mg per 100 g, and in puree with added sucrose – 495 mg per 100 g, which is 2 times higher. In carrot puree the natural increase was 74 mg per 100 g, and in puree with sucrose it was 150 mg per 100 g, which is twice higher and confirms the same pattern as in apple puree. In natural pumpkin puree the increase was 27 mg per 100 g, and in puree with sucrose it was 84 mg per 100 g, which is more than 3 times higher than in natural. The results obtained allow us to conclude that when processing the product with ultrasound, the process of sucrose inversion is intensified; including its component obtained due to the cavitation effect, and the inversion is more deeply manifested in puree with added sucrose.

RESEARCH RESULTS OF THE PROCESS OF CLEANING POTATO TUBERS AND CARROT ROOT CROPS USING ULTRASOUND

The most promising of the known ways to reduce the content of soil bolsters during machine harvesting of tuberous roots should be considered pre-harvest moisturization of the soil layer in which the tuberous root are located. This significantly reduces the content of soil impurities in harvested tuberous roots. However, atomized spray of water, even under pressure, is not able to ensure its instant flow to the depth of tuberous roots and, moreover, to moisten the soil to the state that provides further intensification of the process of separation of tuberous roots from soil bolsters that are comparable to them. To eliminate this defect, it is necessary to provide an intensification of the water spraying process by one of the methods of physical influence, which provides instant soil moisture to the depth of tuberous roots. The article presents instrumentation for research of technological parameters of ultrasonic treatment on the quality of the cleaning roots crops from soil impurities, the method and results of laboratory studies of ultrasound effect on the cleaning process of potato tubers of the "Red Scarlet" variety and carrot root crops of «Shantane» variety . The optimal parameters of ultrasound influence that intensifies the process of cleaning root crops from soil impurities were determined. The results of comparative laboratory studies of cleaning potato tubers and carrot root crops from various root crops on the physical and mechanical composition of soil impurities (sandy loams and loam soils) allow us to conclude that the best indicators of intensification of ultrasonic influence with increase in the completeness of cleaning, despite the weight and type of contamination, are observed when processing carrot root crops, the completeness of cleaning is on average higher by 13...20 %.

PECULIARITIES OF HIGH-AMPLITUDE ULTRASONIC CLEANING OF PARTS

One of the most efficient methods for parts cleaning is an ultrasonic method. During ultrasonic influence on of the most significant factors defining cleaning quality is oscillation amplitude. The paper reports the formulation of the conclusion on the presence in a sound field a high-amplitude radiation formed in liquid by a piston radiator of three (technological) cavitation areas different their effectiveness.