Abstract
The influence of two isothermal blocks placed in a low position φm=0.18π in a cylindrical heat exchanger is numerically studied. The governing equations are discretized by the centered finite difference method using the ADI scheme. By varying Rayleigh number range between 1000 and 10000, we are interested in the local Nusselt number and the local efficiency variations as a function of the angular coordinate φ. In one hand, we found that heat transfer is important in the superior zone of the annulus for high Ra and in the central zone for low Ra. On the other hand, compared to the without blocks configuration, heat transfer in the inferior and central zones is improved for all Ra.
Highlights
The addition of fins is considered as one of the frequent methods used to enhance heat transfer inside cylindrical heat exchangers
It is composed of a cold outer cylinder at a temperature T’o and a hot inner cylinder at a temperature T’i. These horizontal coaxial cylinders are characterized by a radii ratio R = ro / ri fixed at 2
Touzani et al [4] studied natural convection improvement by the use of two isothermal blocks placed in the lower part of a cylindrical annulus
Summary
It is composed of a cold outer cylinder at a temperature T’o and a hot inner cylinder at a temperature T’i. These horizontal coaxial cylinders are characterized by a radii ratio R = ro / ri fixed at 2. The blocks are isothermal of the same temperature as the inner cylinder and placed on it. They are characterized by: a length l’, a height h’ and an angular position m. The cavity is divided into three zones as a function of the angular coordinate : inferior for 0 min , central for min max and superior for max π
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