The paper presents the results of a theoretical stability analysis on a vertical type natural circulation heat recovery steam generator. The evaporator of the boiler consists of four parallel horizontal tube paths, which are connected at both ends with headers. For different operation pressures and geometries the dynamic instability and in particular the density wave oscillation (DWO) was analy...

Due to the dependence of boiling heat transfer rate on heat flux, saturation pressure, mass flux and refrigerant quality, efforts made to increase heat transfer rate often cause further drop in refrigerant saturation pressure. In this study, entropy generation mechanisms associated with two-phase flow in smooth evaporator tube subject to constant surface heat flux are investigated. Refrigerant ...

In this study, the method of entropy generation minimization (i.e., design aimed at facilitating both heat, mass and fluid flows) is used to improve the evaporator geometry (aspect ratio and fin density) considering the irreversibilities produced by the heat and mass transfer, and viscous flow processes. A fully algebraic semi-empirical model was put forward to simulate the thermal-hydraulic be...

Winding is an integral operation in almost every roll to roll system. A center-wound roll is one of the suitable and general schemes in a winding mechanism. In general, the quality of wound roll is known to be related to the lateral displacement error and starring defect of a wound roll. Especially, a telescoping within a center-wound roll can cause damages such as misalignment between layers, ...

Lead–steel layered composite electrode materials have been successfully prepared by the roll bonding method. Scanning electron microscopy and energy dispersion spectroscopy (EDS) were used to analyze microstructures elements distribution at interface. The electrochemical properties of samples studied linear sweep voltammetry (LSV), Tafel curves, a weight loss analysis microstructure showed that...

The paper introduces an operation on a binary tree, called binary tree roll, or roll of a binary tree. Two versions of the binary tree roll, counterclockwise and clockwise, are presented. The operations are mathematically defined and graphically presented. It is explained how the binary tree roll actually coincides with the process of turning the entire tree 90 degrees counterclockwise or clock...