Розробка та чисельне моделювання теплообмінного обладнання нової конструкції для систем підтримання мікроклімату у пташниках

Abstract

В роботі представлено розробку кожухотрубного теплообмінного аппарата нової конструкції для систем підтримання мікроклімату у пташника. Проведено чисельне моделювання процесів тепло- масообміну в теплообміннику використовуючи сучасний програмний продукт ANSYS Fluent. Отримано розподіл швидкостей, тисків і температур в каналах теплообмінника.

This article is a continuation of improvement of microclimate maintenance systems in poultry houses and the goal is to develop and numerical modeling of the shell and tube heat exchanger of a new design as an element of the ventilation system. In the development of new types of designs of heat-exchange units, factors such as their mass-overall characteristics, the efficiency of heat transfer through the surface separating the heat-carrier, the loss of pressure in the tract for each of the heat-carrier and other parameters characterizing the heat-exchange apparatus play an important role. The paper deals with the shell-tube heat exchanger with a rectangular cross-section case with a cross-sectional flow of pipe beams. The geometry of the pipes with diameters d = 10 mm is peculiar, which differs from the traditional chess, corridor and compact beams. Neighboring pipes in such close beams are displaced one relative to the other at a distance of 1 mm. Moreover, we consider three types of beam construction, in which there is a displacement of pipes in a transverse direction along the entire length of the tube beam at 10 mm, 12 mm and 15 mm. Since the displacement of a series of different distances is applied, the number of rows of tubes varies. The number of tubes in one row, 10 mm in diameter, contains 102 pcs, consisting of 2 collectors. Height of pipes is 1 m. In the numerical calculation of the problems of hydrodynamics and heat-mass transfer, the method of finite elements is used. Construction of the grid was carried out in a grid generator ANSYS Meshing on the basis of the Workbench platform. When constructing a grid for a heat-exchange apparatus of all structures, local grid control is used. The quality of the Orthogonal Quality grid for all types of heat exchangers varies from 0,599 to 0,625. The computer mathematical modeling of heat and mass transfer processes in bundles of pipes of different geometries at compact placement of pipes using the software ANSYS Fluent is carried out. The basis of the mathematical model is the Navier-Stokes equation, the energy conservation equation for convective currents and the continuity equation. In the calculations a standard k-ε turbulence model was used. The fields of velocities, temperatures, and pressure in the studied channels are obtained. The conditions of the hydrodynamic flow in the channels were analyzed and estimates of the heat transfer intensity between the hot and cold coolant through the wall separating them.The effective heat transfer surfaces are determined and the promise of application of the proposed designs of the beams of pipes in the design of heat exchangers of various applications is shown.