СТАТИКА, КІНЕТИКА ТА ЕНЕРГОЕФЕКТИВНІСТЬ ПРОЦЕСУ СУШІННЯ БАНАНІВ ДО НИЗЬКОЇ ЗАЛИШКОВОЇ ВОЛОГОСТІ

• Datum: 2025
• Hauptverfasser: Sniezhkin, Yu., Dabizha, N., Husarova, O., Malashchuk, N.
• Format: Artikel
• Sprache: Ukrainisch
• Veröffentlicht: Institute of Engineering Thermophysics of NAS of Ukraine 2025
• Online Zugang: https://ihe.nas.gov.ua/index.php/journal/article/view/646
• Назва журналу: Thermophysics and Thermal Power Engineering

Bananas are the most important agricultural crop after rice and wheat. One-fifth of bananas are discarded annually due to their unsuitable appearance, which makes them unsuitable for sale. Finding ways to preserve and process surplus raw materials into food products with a longer shelf life is a pressing issue. The purpose of the work is to study the statics and kinetics of convective drying of banana flesh to low residual moisture content, determine the energy characteristics of the process, and develop an energy-efficient dehydration mode. Research methods. Bananas with ripeness levels of 2…3 and an initial relative humidity of 75…80% were selected for the study. The bananas were cut into 5×5×5 mm cubes and 5…6 mm thick and 65…75 mm long slices. The process was carried out until the material reached a low moisture content of 6…7%. The hygrothermal equilibrium state of bananas was studied using the Van Bamel tensometric (static) method. The study of the kinetics of bananas drying process was performed on an experimental convective stand with a system of automatic recording and processing of information at a drying agent temperature of 100, 80, 60, 100/60 ºC, speed 1.0 m/s, moisture content 11 g/kg dry air. Based on experimental data, drying kinetics curves u = f(τ), drying rate curves du/dτ = f(u) obtained by numerical differentiation of drying curves, as well as material heating temperature curves t = f(τ) were constructed. Results and conclusions. According to the results of experimental studies on hygrothermal equilibrium (statics) at a temperature of 20 °C in the range of relative pressures p/ps from 0.4 to 0.9 using the characteristic curve method, the isotherms of water vapor sorption by bananas at temperatures from 20 to 80 °C were obtained, which allows determining the equilibrium moisture content that is achieved at given thermal and moisture parameters of the air. Based on sorption isotherms for the hygroscopic region, the dependence of the partial pressure of water vapor on the surface of a banana on moisture content and temperature in the range u = 0.03…1.11 kg/kg dry weight and t = 50…80 °C was obtained. The effect of temperature on the kinetics of the drying process of banana cubes in a layer was experimentally investigated. It was determined that a drying agent temperature of 100 °C intensifies the banana dehydration process, but the organoleptic indicators of the material are unsatisfactory. Based on studies of the kinetics of moisture exchange during the drying of banana cubes, a formula for calculating the total duration of the process was obtained. The obtained dependencies of the optimization criterion and the density of heat flows on the surface of the material on the moisture content of the banana during drying at different temperatures. Based on the analysis of the obtained dependencies, the necessity of reducing the temperature at the finishing stage is justified and the expediency of using stepwise dehydration modes is proved. Based on heat transfer kinetics data, the specific heat consumption for evaporating 1 kg of water during the drying of banana cubes in a layer at different temperatures was determined. It was found that the most energy-efficient mode is the step mode at drying agent temperatures of 100/60 °C.