In this study, condensation heat transfer coefficients of R-410A were obtained in flattened stainless tubes made from 5.0 mm inner diameter round tubes. The test range covered saturation temperature 45 , heat flux 10 °C kW/m, mass flux 100~400 kg/ms and quality 0.2~0.8. Results showed the effect of aspect ratio on condensation heat transfer coefficient was dependent on the flow pattern. For ann...

A theoretical model for nanofluid flow, including Brownian motion and thermophoresis, is developed and analysed. Standard boundary layer theory is used to evaluate the heat transfer coefficient near a flat surface. The model is almost identical to previous models for nanofluid flow which have predicted an increase in the heat transfer with increasing particle concentration. In contrast our work...

The single-phase flow and thermal performance of a double pipe heat exchanger are examined by experimental methods. The working fluid is water at atmospheric pressure. Temperature measurements at the inlet and outlet of the two streams and also at an intermediate point half way between the inlet and outlet is made, using copper-constantan thermocouple wires. Mass flow rates for each stream are ...

In this paper an attempt is made to evaluate the convective mass transfer coefficient during drying of jaggery in a controlled environment. In this method, different masses of jaggery were used. The jaggery was dried in the roof type even span greenhouse with a floor area of 1.2x0.8 m in natural and forced convection mode at atmospheric pressure till it attained almost no variation in mass. The...

Mathematical models play an essential role in simulation of dynamic processes as they provide insights into the description and behaviour of real systems. Models of chemical processes are derived from laws of conservation, thermodynamic, and control design. In the present paper, we study the modelling of dissolution process determining the quasi steady state material balance for velocity profil...

plate heat exchangers are widely used in industries due to their special characteristics, such as high thermal efficiency, small size, light weight, easy installation, maintenance, and cleaning. the purpose of this study is to consider the effect of depth, angle, and pitch of hemispheric chevrons on the convective heat transfer coefficient and pressure drop. in the simulation of the heat exchan...

This paper presents an entirely new tuning method of PI controller with a desired damping coefficient. We consider a plant model described by a first-order lag plus deadtime system in the process control. The ultimate sensitivity method presented by Ziegler and Nichols has been still widely used, but it has a disadvantage that gives an oscillatory response. In recent years a less oscillatory re...