F07 Identification of overall heat transfer coefficient on the convective heat transfer problem using nonparametric sensitivity analysis

Nanotechnology has become one of the fastest growing scientific and engineering disciplines. Nano fluids have been established to possess enhanced thermal and physical properties such as thermal conductivity, thermal diffusivity, viscosity and convective heat transfer coefficients. The aim of this research article is to analyze the overall heat transfer coefficient by doing an experimental investigation on the convective heat transfer and flow characteristics of a nano fluid. In this research, an attempt was made for the nano fluid consisting of water and 1% volume concentration of Al2O3/water Nano fluid flowing in a parallel flow, counter flow in shell and tube heat exchanger under laminar flow condition. The 50nm diameter Al2O3nanoparticles are used in this investigation and was found that the overall heat transfer coefficient and convective heat transfer coefficient of nano fluid to be slightly higher than that of the base liquid at same mass flow rate and inlet temperature. Three samples of dissimilar mass flow rates have been identified for conducting the experiments and their results are continuously monitored and reported. The experimental analysis results were concluded that the heat transfer and overall heat transfer coefficient enhancement is possible with increase in the mass flow rate of fluid and Al2O3/water nano fluid on a comparative basis.

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F08 Nonparametric sensitivity analysis and its application to optimal control on the unsteady convective heat transfer problem

The Proceedings of Conference of Kyushu Branch ◽

10.1299/jsmekyushu.2008.227 ◽

2008 ◽

Vol 2008 (0) ◽

pp. 227-228

Author(s):

Kazunari MOMOSE ◽

Takashi OHKUNO ◽

Genta KAWAHARA

Keyword(s):

Heat Transfer ◽

Optimal Control ◽

Sensitivity Analysis ◽

Convective Heat Transfer ◽

Convective Heat ◽

Transfer Problem ◽

Heat Transfer Problem

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Heat Transfer Coefficient in Helical Heat Exchangers under Turbulent Flow Conditions

International Journal of Food Engineering ◽

10.2202/1556-3758.1209 ◽

2008 ◽

Vol 4 (1) ◽

Cited By ~ 10

Author(s):

Pablo Coronel ◽

K.P. Sandeep

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Convective Heat Transfer ◽

Convective Heat ◽

Heat Exchangers ◽

Convective Heat Transfer Coefficient ◽

Flow Conditions ◽

Overall Heat Transfer Coefficient ◽

Turbulent Flow Conditions

This study involved the determination of convective heat transfer coefficient in both helical and straight tubular heat exchangers under turbulent flow conditions. The experiments were conducted in helical heat exchangers, with coils of two different curvature ratios (d/D = 0.114 and 0.078), and in straight tubular heat exchangers at various flow rates (1.89 x 10-4 - 6.31 x 10-4 m3/s) and for different end-point temperatures (92 - 149 °C). The results show that the overall heat transfer coefficient (U) in the helical heat exchanger is much higher than that in straight tubular heat exchangers. In addition, U was found to be larger in the coil of larger curvature ratio (d/D = 0.114) than in the coil of smaller curvature ratio (d/D = 0.078). The inside (hi) and outside (ho) convective heat transfer coefficients were determined based on the overall heat transfer coefficient and a correlation to compute the inside convective heat transfer coefficient (hi) as a function of NRe, NPr, and d/D was developed.

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