Research of hydraulic and mechanical parameters of heat exchangers
Students Name: Pylyptsiv Pavlo Mykhailovych
Qualification Level: magister
Speciality: Food and Processing Industries Equipment
Institute: Institute of Mechanical Engineering and Transport
Mode of Study: full
Academic Year: 2020-2021 н.р.
Language of Defence: ukrainian
Abstract: Pylyptsiv P.M., Sheremeta R.M. (head). Research of hydraulic and mechanical parameters of heat exchangers. Master’s qualification work. - Lviv Polytechnic National University. Lviv, 2020. Extended annotation. Heat exchangers – equipment that is widely used in the processing and food industries. They provide a large number of technological processes. For each of them you need to choose individual parameters, such as process performance, installation capacity, temperature of the heated substance, etc. To ensure the smooth running of the process, it is necessary to ensure high reliability of the device, as well as its energy efficiency and economic feasibility of its manufacture and use. To do this, conduct a preliminary calculation of the heat exchanger. Heat exchangers are designed to transfer heat from the heating medium to another for heating it or to remove heat from the cooled medium and its transfer, for example, to the environment. The media involved in heat transfer are called heat carriers. In the first case, the heat exchanger is called a heater, and in the second - a cooler, although there is no fundamental difference between such heat exchangers. The only difference is in their purpose. However, heat exchangers differ significantly in principle and design. First of all, according to the method of heat transfer from one medium to another (from one heat carrier to another), heat exchangers are divided into recuperative, regenerative, mixing and with electric heating. In recuperative heat exchangers, heat is transferred from one heat carrier to another through the wall that separates them. In devices of this type at each point of the wall separating the coolant, the heat flow remains unchanged. If two or more heat carriers alternately come into contact with the same heat exchange surface, then such a heat exchanger is called regenerative. During the period of contact with one of the heat carriers, the walls of the heat exchanger receive heat and accumulate it. In the following period, another coolant comes into contact with the same surface, which absorbs the heat accumulated from the previous coolant and heats up. The direction of heat flow in this type of device changes periodically. Recuperative and regenerative heat exchangers form a group of surface devices. In them, the heat carriers come into contact with the surface of the solid wall (continuously or periodically), which is the surface of heat exchange. In most recuperative devices there is a continuous transfer of heat through the wall from one coolant to another. They are called devices of continuous action. Devices in which periodic heating or cooling of a medium is carried out are called devices of periodic action. Regenerative heat exchangers are mostly intermittent devices. But there are known regenerative devices of continuous action. These are devices that have movable walls or nozzles. In them, continuously moving coolants are in contact with the same part of the wall or nozzle at different times due to their transverse movement relative to the direction of movement of the coolant. In this study, the properties of shell-and-tube heat exchangers were directly investigated. Heat exchangers of this type are the most common, they are used in industry and transport as heaters, condensers, coolers for various liquid and gaseous media. The main elements of such a heat exchanger are: casing (housing), pipe bundle, chamber-covers, nozzles, shut-off and control valves, control equipment, supporting structures, frame. The tubular and intertubular spaces in the apparatus are separated, and each of them can be divided by partitions into several passages. Partitions are placed in order to increase the speed of the coolant and thus intensify heat transfer. They are used when there is a need for a large heat transfer surface. The casing of the device is welded in the form of a cylinder made of steel sheets. The wall thickness of the casing is determined by the maximum pressure of the working medium in the intertube space and the diameter of the apparatus. The object of research – heat exchangers. The subject of research – hydraulic and mechanical properties of heat exchangers. The purpose of the study: the purpose of this study is to analyze the design features of recuperative devices of continuous action, their classification, as well as the calculation of heat exchangers for strength. Key words - heat exchange, apparatus, heat carrier, calculation, pressure, strength.