جستجوی مقالات مرتبط با کلیدواژه « hydraulic networks » در نشریات گروه « فنی و مهندسی »

This paper presents the results of the full-scale verification and validation of the mathematical model and numerical algorithm for the network computation of a single-phase flow in a highly branched pipeline chain. The essential difference of this work from others is that highly branched hydraulic networks with homogeneous and non-uniform permeability, containing more than 70 thousand branches, are considered. Such branched networks are important in many applications. Therefore, the development of algorithms for calculating flows in such networks is very important. The network model is based on hydraulic theory, and the numerical algorithm relies on the network analogue of the well-known control volume method. At the same time, obtaining reliable experimental data for testing models for calculating very branched hydraulic networks is very difficult. In this work, microfluidic technologies are used to solve this problem. Data of laboratory experiments, obtained using microfluidic models of branched networks with homogeneous and heterogeneous permeability, containing several tens of thousands of branches, as well as CFD simulation results in full 3D formulation employing the fine computational grids were used to validate the model. The Reynolds number ranged from 0.81 to 13. Conducted validation has shown a good qualitative and quantitative concordance of the results of network and hydrodynamic simulation, as well as the data of the microfluidic experiments. The error in determining the total pressure drop in the branched hydraulic network with heterogeneous permeability, containing 37,855 nodes and 74,900 branches, did not exceed 5%. It has been demonstrated that the speed of solving a single-phase flow problem in a highly branched chain using network simulation techniques is 60 times more of magnitude higher as compared to CFD simulation at virtually the same accuracy.

In this article, stream flow effectivness is based on hydraulic network studied in the shell-side of a shell and tube heat exchange as a case study. For an appropriate heat exchangers rating design to meet a specified duty, it's better to consider each stream flow separately. Using the hydraulic network principals, a set of the correlations for calculating different stream flow rates in the cross and window area, leakage from tube-bundle and shell-baffle bypass are suggested. By the presented correlations, the actual flow direction and different stream flow rates of shell-side fluid for calculating of shell-side heat transfer and pressure drop in different regions between adjacent baffles has been taken into account. Also, the effects of each stream flow in each baffle section on the overall heat transfer coefficient (HTC) and pressure drop could be investigated. The comparison results of using these correlations and results of published values, like Bell-Delaware method and Kern correlations, is reasonable, which can be used in the optimum design of shell and tube heat exchangers with segmental baffles. Also, according to the results, the cross flow stream show much better heat transfer performance with lower pressure drop behavior than window stream at the same mass flow rates. Average heat transfer performance of window-section is almost 7-12% of overall heat transfer performance for studied case study.