Eastern-European Journal of Enterprise Technologies

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Determination of heat transfer mechanisms during vacuum drying of solid-moist and liquid-viscous materials
(Kharkiv State Academy of Physical Culture, 2022-12-30)
Bakhytkul Telkhozhaevna Abdizhapparova
;
Vоlоdymyr Potapov
;
Н. С. Ханжаров
;
А. У. Шингисов
;
Bayan Khanzharova
Most drying methods combine convective, conductive and radiation heat transfer processes. The share of each type of heat transfer may vary depending on the type and mode of drying, type of product, etc. In this study, the problem of determining the heat transfer mechanism of vacuum drying of solid-moist and liquid-viscous materials is solved. The objects of the study are Jerusalem artichoke tubers, camel and mare milk. The numerical values of the heat transfer components are found experimentally and their shares in the total heat flux are determined. During vacuum drying of Jerusalem artichoke at a medium pressure of 4 kPa and a temperature of 55 °C (with a layer height of 0.01 and 0.02 m), the convective component predominates (58.55 and 67.65 %). The share of thermal conduction (18.96 and 29.39 %) and radiation (13.39 and 12.05 %) is much lower. The mechanism of thermal conduction begins to prevail with an increase in the height of the material layer (0.03 and 0.04 m). The convective component is also dominant for vacuum drying of milk: at medium pressures of 6÷10 kPa and a temperature of 40 °C, its value for mare milk reaches 78.21 %, for camel milk – 73.33 %. The second most important is the share of radiation (19.45 and 22.58 %). Conductive heat transfer has the minimum indicators (5.66 and 6.17 %). The large values of the share of thermal conduction during drying of Jerusalem artichoke compared to milk are explained by the fact that heat transfer occurs inside the tubers due to conduction, and inside milk – due to convection. Insignificant shares of radiation are explained by low and medium vacuum values in the chamber. In the studied range, heat and mass transfer occurs due to molecular diffusion and convection. The results obtained can be used to formulate criterion heat transfer equations, in engineering calculations, and optimization of the vacuum dryer operation.
Цитирования (OpenAlex) 6Цитирования (OpenCitations) 5
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Development of an atrioventricular block prediction of method for portable heart monitoring system
(Kharkiv State Academy of Physical Culture, 2022-06-30)
Ainur Bekbay
;
Zhadyra N. Alimbayeva
;
Chingiz A. Alimbayev
;
Nurlan A. Bayanbay
;
Кassymbek Ozhikenov
The object of the study is a portable system that allows real-time monitoring of the state of the heart for the timely provision of medical care. The task of detecting atrioventricular (AV) blocks in the conditions of free motor activity of the patient is being solved. To develop a method for detecting AV block, models of the electrical activity of the heart were used to take into account the spatiotemporal organization of the process of spreading excitation, analyze the dynamics of the behavior of the cardiovascular systems (CVS) for any value of the period of atrial excitation, and assess the degree of fitness of the CVS. The proposed method made it possible to determine the heart rate (HR) at which the development of AV block is possible. AV block of the III degree – heart rate 304 bpm; AV block of the II degree with the loss of half of the impulses – heart rate 260 bpm; AV block II degree with loss of individual impulses – heart rate 234 bpm; AV block of the 1st degree – heart rate 200 bpm. Prediction of AV block allows assessing the degree of “training” of the patient’s heart. The obtained quantitative results are consistent with the heart rate values known to modern health care. The developed method was implemented on the basis of a portable ECG monitoring system previously developed by the authors. Tests of the portable ECG monitoring system indicate an increase in the sensitivity and specificity of diagnosing cardiac arrhythmia and confirm the achievement of the goal of this study: improving the efficiency of diagnostics and expanding the functionality of the portable ECG monitoring system
Цитирования (OpenAlex) 1

Eastern-European Journal of Enterprise Technologies

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