28 research outputs found
Two Functions Used in the Analysis of Crossflow Exchangers, Regenerators and Related Equipment
a response exhibits a step when t = P and thus t' = t a . The first cross-sectional fluid a lamina that enters at time zero with a temperature of unity sees fluid b at zero temperature. (The wall is "transparent" when its thermal capacitance is zero.) This lamina therefore has a temperature of exp(-AOc). When it reaches its exit plane {x -1) at time /" its temperature is exp (-N), which is the magnitude of the jumps seen in The solution with zero core capacitance is much easier and faster to compute than the Spiga and Spiga solution. It is therefore of interest to estimate the upper range of V a or V b that is reasonable for an exchanger. Suppose that fluid a flows inside tubes. Then for thin wall tubes V a -£>y/(4A) in which D and A are the tube diameter and wall thickness and v is the ratio of the volummetric heat capacities of the fluid and tube materials. This ratio has the exceptionally large value of 1.7 for water and aluminum. Using this material combination gives V a -0.4D/A. Thus an aluminum tube with 25 mm diameter and 1 mm wall thickness gives V a = 10. The parameters V a and V b can, of course, vary over a wide range, but this illustration indicates that the simplicity of the zero core capacitance solution can sometimes be enjoyed with acceptable accuracy. References Anzelius, A., 1926 Introduction This note focuses on the transport in aiding laminar mixed convection flow adjacent to a vertical isothermal surface. The direction of forced flow is taken to be upward for the heated surface. This situation causes the flow to be predominantly forced at the leading edge, primarily natural far downstream, and mixed in the middle. In the intermediate region of mixed convection Merkin (1969) reported a finite difference solution for Pr = 1
A Review of Fiber-Reinforced Injection Molding: Flow Kinematics and Particle Orientation
The existing flow and particle orientation models applicable to fiber- reinforced injection molding are reviewed. After a brief description of injection molding, previous studies on the flow kinematics and fiber reinforcement are presented. Basics of Hele-Shaw flows are described Including the commonly used viscosity models and foun tain flow effects. Some of the existing models for particle orientation are analyzed with particular emphasis on the amsotropic description of the material system. Concentration regions for short fiber suspensions are defined and relevant constitutive equations are dis cussed. A few example solutions are also given which describe the three-dimensional ori entation field for the filling of a sudden expansion cavity, depicting skin-core orientation structure.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline