scholarly journals Measurement of Heat and Mass Flow Characteristics of Nanofluid in a Porous Parallel-Plate Channel by Darcy-LTNE/LTE, Brinkman-LTNE/LTE Models

Author(s):  
Mohsan Hassan
2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Siddharth D. Mhaske ◽  
Soby P. Sunny ◽  
Sachin L. Borse ◽  
Yash B. Parikh

Heat transfer and fluid flow characteristics for two-dimensional laminar flow at low Reynolds number for five in-line ducts of various nonconventional cross-sections in a parallel plate channel are studied in this paper. The governing equations were solved using finite-volume method. Commercial CFD software, ANSYS Fluent 14.5, was used to solve this problem. A total of three different nonconventional, noncircular cross-section ducts and their characteristics are compared with those of circular cross-section ducts. Shape-2 ducts offered minimum flow resistance and maximum heat transfer rate most of the time. Shape-3 ducts at Re < 100 and Shape-2 ducts at Re > 100 can be considered to give out the optimum results.


2018 ◽  
Vol 8 (9) ◽  
pp. 1413 ◽  
Author(s):  
Dan Yao ◽  
Kwongi Lee ◽  
Minho Ha ◽  
Cheolung Cheong ◽  
Inhiug Lee

A new pump, called the hybrid airlift-jet pump, is developed by reinforcing the advantages and minimizing the demerits of airlift and jet pumps. First, a basic design of the hybrid airlift-jet pump is schematically presented. Subsequently, its performance characteristics are numerically investigated by varying the operating conditions of the airlift and jet parts in the hybrid pump. The compressible unsteady Reynolds-averaged Navier-Stokes equations, combined with the homogeneous mixture model for multiphase flow, are used as the governing equations for the two-phase flow in the hybrid pump. The pressure-based methods combined with the Pressure-Implicit with Splitting of Operators (PISO) algorithm are used as the computational fluid dynamics techniques. The validity of the present numerical methods is confirmed by comparing the predicted mass flow rate with the measured ones. In total, 18 simulation cases that are designed to represent the various operating conditions of the hybrid pump are investigated: eight of these cases belong to the operating conditions of only the jet part with different air and water inlet boundary conditions, and the remaining ten cases belong to the operating conditions of both the airlift and jet parts with different air and water inlet boundary conditions. The mass flow rate and the efficiency are compared for each case. For further investigation into the detailed flow characteristics, the pressure and velocity distributions of the mixture in a primary pipe are compared. Furthermore, a periodic fluctuation of the water flow in the mass flow rate is found and analyzed. Our results show that the performance of the jet or airlift pump can be enhanced by combining the operating principles of two pumps into the hybrid airlift-jet pump, newly proposed in the present study.


Author(s):  
Р.Р. Симашов ◽  
С.В. Чехранов

В работе приводятся обобщающие зависимости коэффициентов расхода сопловых аппаратов со сверхзвуковыми осесимметричными соплами в широком диапазоне изменения определяющих геометрических и режимных параметров. Предложена двухпараметрическая функция, учитывающая влияние расположения сопел в сопловом аппарате и степени конфузорности дозвуковой части осесимметричного сопла на коэффициент расхода. Показано слабое влияние на коэффициент расхода относительного радиуса закругления стенки в узкой части сопла и относительной длины дозвуковой части сопла в области их оптимальных значений определенных по минимуму потерь кинетической энергии. Переменные режимы работы сопла учитываются зависимостью относительного коэффициента расхода в функции от числа Рейнольдса в критическом сечении сопла. Полученные в работе эмпирические зависимости позволяют использовать их при моделировании переменных режимов и многорежимной оптимизации малорасходных турбин. The research presents generalizing dependences of mass flow rates in supersonic axisymmetric nozzle diaphragms n a wide range of variation of the governing geometric and operating parameters. A two-parameter function is proposed that takes into account the influence of the location of the nozzles in the nozzle apparatus and the degree of compression of the flow of the subsonic part of the nozzle on the mass flow rate. It is shown that the relative radius of rounding of the nozzle wall in the vicinity of the throat section and the relative length of the subsonic part of the nozzle in the region of their optimal values determined by the minimum of kinetic energy losses have a weak effect on the flow rate. Variable duties of nozzle operation are taken into account by the dependence of the relative flow rate as a function of the Reynolds number in the throat of the nozzle. The empirical dependencies obtained in this work make it possible to use them in modeling variable modes and multi-mode optimization of low-consumption turbines.


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