科研之友
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摘要
In the present paper, the practical efficiency of using alumina water nanofluid was evaluated numerically by the method of entropy generation; pumping power and tube wall temperature were analyzed. Laminar forced convection by water-based nanofluid flow through a uniformly heated circular tube is considered. A single-phase fluid approach is adopted to investigate the behavior of nanofluid and numerical results are compared with the experimental data. Good agreement is achieved in the developed region. %26lt;br%26gt;The aim of the present study is to investigate the influence of volume fraction, duct length, Reynolds number, and tube diameter on pumping power, entropy generation, and tube wall temperature to evaluate the nanofluid overall efficiency. The results indicated that increasing volume fraction of nanofluid for heat performance increases the pumping power exponentially and decreases the entropy generation and tube wall temperature linearly, so this suggests that using nanofluid with high volume fraction is not reasonable due to the cost of pumping power. Since it was observed that entropy generation and pumping power increase and tube wall temperature decreases relative to the duct length, this suggests that increasing tube length will reduce the overall efficiency of nanofluids. However, to avoid high wall temperature, duct length cannot be too short. Also, the results showed that increasing tube diameter will decrease entropy generation and pumping power and tube wall temperature remains constant, so it can be concluded that increasing pipe diameter will enhance the overall efficiency of nanofluids. Since the product of the diameter and length is constant, the tube diameter has the maximum value at the point which shows the maximum wall temperature; also, the duct length is minimum at this point, too. Therefore, it can be concluded that the overall efficiency of nanofluid is maximum at this point.
- 出版日期2012
