جستجوی مقالات مرتبط با کلیدواژه « منیفولد » در نشریات گروه « مکانیک »

This paper studied the oxygen flow distribution in a PEM fuel cell stack numerically. At first, the flow in the stack was simulated as a single phase, and the effect of gradual reduction of manifold height (tapered manifold) on improving the flow distribution between fuel cells was investigated. Standard deviation and non-uniformity coefficient have been used to measure the flow maldistribution. Gradual reduction of manifold height up to 70% in the tapered manifold improved standard deviation and non-uniformity coefficient by 6.9% and 8.4%, respectively. The results of the two-phase simulation showed that the condensation of water vapor in the saturated oxygen could cause the accumulation of liquid water at the end of the manifold. As the smaller droplets merged, the droplet radius formed at the end of the manifold increased until it detached from the manifold wall and entered the last cells. Less liquid water entered the last cell at shorter intervals in the tapered manifold. It was suggested that by creating a water chamber at the end of the manifold, condensed water be collected from the manifold and discharged from the stack. Increasing the mass flow at the manifold inlet and discharging the excess gas through the water collection chamber can push the liquid water into the chamber without causing significant changes in pressure drop.

Healthy and fresh water supply is one of the fundamental issues in different regions of the world, particularly in remote areas is dry. There are several methods for desalination of brackish waters, of which solar distillation devices can be the perfect solution for sparsely populated areas that are of sufficient intensity solar radiation. In this study, we have tried to express the necessity of providing safe drinking water, the fundamentals of performance of solar desalination dealt with the resources available. In the present study the effect of water cooling with two modes: Desalination with heat pipe and manifold (semi-active) and desalination to cooling water and heat Vlvlhhay manifold (active mode) are tested daily production was investigated. Tests in August (September) in geographical coordinates(N:35°34′,E:53°22′)is conducted. Based on the results observed The maximum rate of production of fresh water in active mode 0.43(kg / m2) per hour. As well as the daily yield semi-active mode from 1.87 (kg / m2.day) daily 2.085(kg / m2) reached in active mode.

One way to control the position of the missile is controling thrust vector that is moves with help of thrust due to exit of gas. All thrust vector control (TVC) methods are independent of aerodynamic forces of atmosphere and until the engine has thrust, maintain their performance. Secondary injection systems are one of the four major TVC methods. In this study,at first identify the components and design entire conceptualdesigning of system and the preliminary design of manifold of a type of thrust vector control system using a liquid injection thrust vector control (LITVC)has been proceed. Then the layouts of components on some components such as injectors and reservoirs, as well as detailed design of the system are discussed. Then the numerical simulation of flow and the designing and studying the sprayers in LITVC systems will be discussed. Also numerical designing and simulation in two parts: injection system and the injector spray effects into the main flow are analyzed and the results are presented and validated. The achievement of this study can be used as a model for designing and analyzing of various kinds of TVC systems with lateral fluid method on a variety of missiles with different launchers.