Investigation of thermal conductivity of orange and tangerine juices in non-stationary state

Lankaran State University, AZ4200 Lankaran, Azerbaijan

^* Corresponding author: mikailbyst@mail.ru

Abstract

Thermal conductivity is one of the main thermophysical properties of liquid food products, including fruit and vegetable juices. Known experimental installations measure the thermal conductivity of stationary liquids. This results in significant deviations from the actual numbers. A method of determining the thermal conductivity of a fluid in motion and an experimental installation implementing the proposed method are suggested. The developed experimental installation consists of two coaxial cylinders: internal and external. A gap between cylinders is filled with analysed liquid. The object of the study was the juices of subtropical fruits, such as oranges, tangerines grown in the subtropical regions of the Republic of Azerbaijan. In this work, the thermal conductivity of juices was also investigated during forced movement on an installation also consisting of two coaxial cylinders. Experimental measurements of thermal conductivity for orange and mandarin juices were carried out. Experiments were carried out at frequencies from 50, 100, 150 and 200 s-. A general description of the dependence of thermal conductivity on temperature, dry matter concentration and rotational speed made it possible to develop a model, in particular for orange juice. The described method and experimental installation for measuring the thermal conductivity of a liquid in a non-stationary state made it possible to develop a mathematical model describing the dependence of thermal conductivity on temperature, dry matter content and cylinder speed.