Research of the heating process of liquid food media in the food boiler
Students Name: Pasichnyk Serhii Ivanovych
Qualification Level: magister
Speciality: Food and Processing Industries Equipment
Institute: Institute of Mechanical Engineering and Transport
Mode of Study: full
Academic Year: 2022-2023 н.р.
Language of Defence: ukrainian
Abstract: The production of semi-finished products and finished products is a combination of various technological processes: mechanical, hydromechanical, thermal and physico-chemical, with the help of which raw materials are transformed into the final product. One of the main operations of this process is heat treatment of products, a type of which is cooking. Jacketed heat exchangers are one of the most common types of thermal and technological equipment used in various industries. They are widely used in the thermal equipment of public catering enterprises, in the technological equipment of food industries, in the pharmaceutical and chemical industries. The existing models for calculating the heating mode of boilers are based on the laws of the stationary mode, which contradicts the essence of the heating process. Designing devices according to such models leads to an increased duration of the heating process, a decrease in the productivity of cooking boilers, and in some cases to the impossibility of bringing the product to a boil. Therefore, the study of the heating process of food boilers, equipment and improvement of their designs is the main task, the solution of which is dedicated to the proposed work. The object of research is the working process of heating liquid food media in food boilers and its design parameters. The subject of the study is the influence of structural and technological parameters and regimes on the quality of food boilers. The goal of the work. Improvement of constructions of food boilers based on modeling of the process of heating liquid food media. In the first chapter, an overview and analysis of the designs of heat exchangers with a jacket is carried out. Their schemes were analyzed and the main shortcomings of their work were revealed. As a result of the analysis of designs and studies of heat exchange devices, it was established that one of the main directions of increasing their efficiency is the improvement of the design of the food boiling boiler. From the conducted review and analysis of literary sources, it follows that studies of the process of heating food boilers with product, especially experimental ones, were practically not carried out, and the proposed calculation methods do not correspond to the actual mode of their operation, which inhibits the improvement of equipment. In particular, the influence of the process of purging the jacket space, the temperature change of the technological environments, is not taken into account. This process has a decisive influence on the kinetics of heat transfer through the wall of the cooking vessel, and the value of the residual concentration of gas that does not condense in the jacket is decisive when setting the operating parameters (temperature, pressure of the media) in the final heating period. Tasks have been set to realize the set goal of the master’s work. In the second chapter, the design of the food-distillation boiler is substantiated and the electrical scheme of boiler purging with a capacitive sensor is proposed. Reasonable selection of the area of the heat transfer surface of the cooking vessel makes it possible to reduce the metal capacity due to the calculated decrease in the volume of the steam-water jacket, shorten the heating time of the food boiler, and reduce heat losses to the environment. Analytical studies of the food boiling boiler were carried out and a mathematical model of the heating process of food boilers was obtained to determine the duration of the product heating process, estimate heat consumption, and justify the operating parameters of the apparatus (temperature, pressure in the jacket of the apparatus). The third chapter presents the methodology and results of experimental studies of the process of heating liquid media in a food-grade boiler. As a result of conducting experimental studies on heating liquid food media with different physicochemical properties in boilers of different capacities and thermal power, the dependences of the main temperature and thermophysical parameters of the apparatus on the time of the heating process were obtained, which showed the influence of the physicochemical parameters of the product and the nature of the coefficient change heat transfer from the inner wall of the cooking vessel. Experimental studies of the heating mode of the cooking boiler made it possible to compare the existing models for calculating the heating process with the real nature of the heat transfer process. The proposed mathematical model of the heating process for finding the optimal heat transfer surface of food boilers, which allows determining the optimal area of the heat transfer surface of jacketed food appliances operating in the heating mode. The fourth chapter provides an example of calculating the main structural dimensions of the device and its improved design. In the fifth chapter, an economic evaluation of the design solution is carried out. According to calculations, the term of development and implementation of the project solution will be 80 days, the costs for development and implementation - UAH 39,867.15. The amount of annual operating costs for the project solution will be equal to UAH 56,227.5/year, the daily consumption price for the developer organization will be UAH 229.33, for the buyer organization UAH 231.45. Key words: food boiling boiler, liquid food medium, heat capacity, heating mode, temperature, heat transfer coefficient.