Entropy generation of radial rotation convective channels |
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Authors: | Email author" target="_blank">Fikret?Ali?Email author |
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Institution: | (1) Faculty of Mechanical Engineering Tuzla, Department of Thermotechnic, Tuzla, Bosnia and Herzegovina |
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Abstract: | The exchange of heat between two fluids is established by radial rotating pipe or a channel. The hotter fluid flows through
the pipe, while the cold fluid is ambient air. Total length of pipe is made up of multiple sections of different shape and
position in relation to the common axis of rotation. In such heat exchanger the hydraulic and thermal irreversibility of the
hotter and colder fluid occur. Therefore, the total entropy generated within the radial rotating pipe consists of the total
entropy of hotter and colder fluid, taking into account all the hydraulic and thermal irreversibility of both fluids. Finding
a mathematical model of the total generated entropy is based on coupled mathematical expressions that combine hydraulic and
thermal effects of both fluids with the complex geometry of the radial rotating pipe. Mathematical model follows the each
section of the pipe and establishes the function between the sections, so the total generated entropy is different from section
to section of the pipe. In one section of the pipe thermal irreversibility may dominate over the hydraulic irreversibility,
while in another section of the pipe the situation may be reverse. In this paper, continuous analytic functions that connect
sections of pipe in geometric meaning are associated with functions that describe the thermo-hydraulic effects of hotter and
colder fluid. In this way, the total generated entropy of the radial rotating pipe is a continuous analytic function of any
complex geometry of the rotating pipe. The above method of establishing a relationship between the continuous function of
entropy with the complex geometry of the rotating pipe enables indirect monitoring of unnecessary hydraulic and thermal losses
of both fluids. Therefore, continuous analytic functions of generated entropy enable analysis of hydraulic and thermal irreversibility
of individual sections of pipe, as well as the possibility of improving the thermal–hydraulic performance of the rotating
pipe consisting of n sections. Analytical modeling enabled establishing of a mathematical model of the total generated entropy
in a radial rotating pipe, while the generated entropy of models with radial rotating pipe were determined by experimental
testing, with comparisons of the achieved results. |
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