Numerical Investigation on Two-Phase Flow Heat Transfer Performance and Instability with Discrete Heat Sources in Parallel Channels

With the rapid development of integrated circuit technology, the heat flux of electronic chips has been sharply improved. Therefore, heat dissipation becomes the key technology for the safety and reliability of the electronic equipment. In addition, the electronic chips are distributed discretely and used periodically in most applications. Based these problems, the characteristics of the heat transfer performance of flow boiling in parallel channels with discrete heat source distribution are investigated by a VOF model. Meanwhile, the two-phase flow instability in parallel channels with discrete heat source distribution is analyzed based on a one-dimensional homogeneous model. The results indicate that the two-phase flow pattern in discrete heat source distribution is more complicated than that in continuous heat source distribution. It is necessary to optimize the relative position of the discrete heat sources, which will affect the heat transfer performance. In addition, compared with the continuous heat source, the flow stability of discrete heat sources is better with higher and lower inlet subcooling. With a constant sum of heating power, the greater the heating power near the outlet, the better the flow stability.

USAGE OF METABOLISM ENERGY IN FORMATION OF BODY THERMAL STATE OF THE CATTLE

Scientific advances in biological sciences make it possible to significantly increase the energy efficiency of productive livestock. For life, as the highest form of existence of matter, thermal energy is of particular importance. It does not only connect the actions and interactions of all types of matter, it creates order from the chaotic movements of discrete heat sources, determining the measure of irreversible energy dissipation (entropy) and the change gradient of metabolic processes, “outflow and inflow of energy”, the state of saturation and deficiency of nutrients in the body. Metabolic energy is the energy of nutrients entering the tissues and cells of the body from the digestive tract. In the process of intracellular metabolism, substances are converted into new compounds, energy is released and accumulated. Approximately half of the energy is used in the electrochemical reactions of the synthesis of substances inherent in this organism. Heredity, age, environment, condition of animals influence their quantity and quality. The second half of the energy generated in the basic metabolism is “dissipated” and released into the internal and external environment. This part of the energy, in the thermoregulation process, provides isothermal state of the body of animals. Thermal homeostasis, the range of fluctuations in body temperature within the physiological norm is a significant part of the metabolic energy consumption. The article presents results of studying such consumptions when adapting to feeding factors and changes of weather conditions of cattle of different age and productivity.

Numerical investigation of Rayleigh-Benard Natural convection and entropy generation in a cubic cavity with discrete heat sources

The Three-dimensional natural convection with isothermal discrete heat sources in a cubical cavity has been carefully studied using the 3D vector potential-vorticity formulation. Based on the finite volume method, the governing equations are solved with a home-made computational code (written in Fortran). Assuming that all cavity vertical walls are adiabatic, the upper wall of the cavity is kept at a cold temperature. However, in the bottom face, heat sources are placed under different configurations. The size of the discrete sources, their positions, and their numbers are varied for different Rayleigh numbers. The Prandtl number is fixed at 0.71. Three-dimensional distribution of the temperature iso-surfaces, the heat transfer rate, and entropy generation are evaluated. It is found that heat transfer and entropy generation are strongly affected by the arrangement of the discrete heated sources. In conclusion, the heat transfer rate is maximized, and the entropy generation is minimized for the inline arrangement of more than two heaters compared to the diagonal one.