Abstract
This paper reports the improved rotor-film evaporator with the lower arrangement of the separating space, the auger-type discharge of concentrated organic fruit and berry paste, and preheating the puree with secondary steam. The working surface of the evaporator is heated by a flexible film resistive electric heater of the radiating type with an insulating outer surface. Peltier elements installed in the device make it possible to provide low-voltage power for exhaust fans from the thermal secondary steam. The puree fed for processing is preheated by 8...10 °С by the heat from the concentrated product and secondary steam. For the experiment, fruit and berry blended puree from apples, quince, and black currants was used. The structural and mechanical properties of blended puree have been determined when the temperature changes within 55...75 °С, in particular, the effective viscosity varies in the range of 22...6 Pa∙s, the maximum shear stress ‒ 29...8 Pa. Effective regions in the fruit and berry puree concentration process have been established: Kmin=Vpaste/Vpuree=0.190; Kmax=Vpaste/Vpuree=0.725 When concentrating fruit and berry pastes with an initial solids content of 9...15 % to the resulting content (29...31 %), it is advisable to apply a surface load of 0.048...0.121 kg/m2s. By calculation, the reduction of the specific energy consumption for heating the volume of the product unit has been confirmed: a rotor-film evaporator – 547 kJ/kg over a period of 75 s, compared to the basic vacuum evaporator – 1,090 kJ/kg, respectively, over 1.08 hours. The results could be useful when designing evaporating equipment for rotor-film-type devices in order to concentrate various blends of fruit and berry raw materials under conditions of using the energy of secondary steam.
Highlights
Many countries around the world face the issue related to providing and expanding the range of functional and healthy food products employing modern innovative approaches in order to increase the resistance to chronic and infectious pandemic diseases, including COVID-19 [1]
The high-quality implementation of concentration requires modern approaches when improving rotor-film evaporators under the conditions of implementation of resource-efficient technologies providing for a high-quality technological and structural approach to maximize the preservation of natural properties and high competitiveness of products
The expediency of determining the increase in the coefficient of heat dissipation due to the introduction of resource-efficient technologies is explained, as most evaporators have a low coefficient of heat transfer, which leads to a decrease in the coefficient of resource efficiency and product quality
Summary
Many countries around the world face the issue related to providing and expanding the range of functional and healthy food products employing modern innovative approaches in order to increase the resistance to chronic and infectious pandemic diseases, including COVID-19 [1]. Agro-industrial sectors today are aimed at cultivating organic raw materials, which require high-quality processing from harvesting to getting to the consumer, which is possible under the conditions of constant development of the production link. This confirms the feasibility of implementing resource-saving processes for the production of multicomponent organic semi-finished products for use in pure form or as part of recipes for food products with high nutritional value. The high-quality heat and mass exchange processes, in particular concentrating, requires the introduction of modern engineering and design solutions aimed at increasing resource efficiency, including through the use of secondary energy to reduce the duration of heat treatment. It is a relevant task to introduce innovative engineering and technological solutions to improve rotor-film evaporators in the context of increasing the heat transfer coefficient and using secondary energy, ensuring the resource efficiency and competitiveness of the concentrated organic semi-finished products
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