Determination of the heat transfer coefficient of a rotary film evaporator with a heating film-forming element

Andrii Zahorulko,Aleksey Zagorulko,Alla Solomon,Nataliia Nozdrina,Roman Yakobchuk,Oleksander Cherevko,Olena Dromenko,Oksana Bondarenko

doi:10.15587/1729-4061.2021.247283

Abstract

A model of a rotary film evaporator with a film-forming element with a reflective heated surface has been developed. This will allow stabilizing the hydraulic movement of the cut wave flow due to the reflective surface of the geometric shape for the forced direction of the cut raw material to the heating surface. Autonomous heating of the reflective surface additionally provides a temperature effect in the conditions of movement of particles of raw materials after cutting. The analysis of the experimental and theoretical parameters of heat transfer made it possible to substantiate the criterion equation for determining the heat transfer coefficient of an evaporator with the proposed film-forming element and a reflective heated surface for calculating the coefficient from the working surface to the raw material. The resulting equation takes into account the influence of the vertical component of the motion of the raw material film, centrifugal movement during the rotation of the film-forming element, mixing of the boiling film of the raw material with steam bubbles, and the geometric characteristics of the film-forming blade on the hydrodynamic flow of the raw material. The calculation of the rotary-film evaporator was carried out using the criterion equation and the obtained useful heat exchange surface – 0.75 m2. The specific metal consumption in a rotary film evaporator with a film-forming element having a reflective surface is 57 kg/m2, compared to the vacuum evaporator traditionally used in canning industries (410 kg/m2), which is 7.1 times less. The duration of the temperature effect on the raw material is also reduced: a rotary film evaporator – 200 s and 3600 s in a traditional apparatus. The data obtained will be useful for the design of rotary-film devices of different geometric parameters using articulated blades with a reflective plate.

Highlights

In many areas of the processing and food industries, in the implementation of technological operations in the production of various products, heat and mass transfer operations are used
In connection with environmental and pandemic challenges, the issue of production of functional and physiological ingredients of a high degree of readiness and health-improving and prophylactic products of high quality of organic plant origin is acute today [2]. Since this raw material is a natural source of biologically active substances, micro- and microelements, dyes and original organoleptic properties, which will minimize the use of synthetic impurities in technological operations
In work [13] isometric fields of the wavelike flow of the suspension were determined under the conditions of determining the vortex flow from the blades due to the lack of research on obtaining the uniformity of the distribution of raw materials after cutting. This may be due to the complexity of modeling the above-mentioned parameters that were not taken into account, their technical implementation will increase the heat transfer coefficient, especially when providing a heated reflective surface of the shearing blade

Summary

Introduction

In many areas of the processing and food industries, in the implementation of technological operations in the production of various products, heat and mass transfer operations are used (heating, holding, boiling, etc.). For the implementation of resource-efficient heat and mass transfer processes of concentration, an urgent task is to ensure the quality of the products obtained through the use of modern engineering and technological solutions in the context of reducing the duration of technological operations. One of such solutions is the substantiation of the criterion equation for determining the heat transfer coefficient of rotary film evaporators, which will allow obtaining the calculated values with the maximum reliability of describing the real picture of the heat and mass transfer process. The introduction of optimal modeling and forecasting of rational heat and mass transfer operations, including for increasing the heat transfer coefficient, will ensure the production of high-quality products while ensuring their competitiveness

Literature review and problem statement

The aim and objectives of research

Materials and methods of research

Conclusions