Experimental analysis of heat transfer and friction for three sides roughened solar air heater

Experimental analysis of heat transfer and friction for three sides roughened solar air heater

Vikash Kumar  Laljee Prasad 

Dept. of Mechanical Engineering, Malla Reddy College of Engineering, Secunderabad-500100, India

Dept. of Mechanical Engineering, NIT Jamshedpur, Jharkhand-831014, India

Corresponding Author Email: 
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This paper deals with the results so obtained after conducting exhaustive experimentation on 1 & 3-sides concave dimple roughened SAH in terms of Nusselt number (Nu) & friction factor (f). The geometrical & flow parameters were used as dimensionless ratio as relative dimple pitch (p/e), relative dimple height (e/Dh), relative dimple depth (e/d) and ‘Re’ in the range of 8-15, 0.018-0.045, 1-2 and 2500-13500 respectively. For various sets of roughness parameters, there exists an optimum roughness parameter, either side of which heat transfer rate decreased. The optimum roughness parameters found under present investigation is p/e=12, e/Dh=0.036 and e/d=1.5. The maximum rise in ‘Nu’ for varying ‘p/e’, ‘e/Dh’ & ‘e/d’ was respectively found to be of the order of 2.6 to 3.55 times, 1.91 to 3.42 times and 3.09 to 3.94 times than one side concave dimple roughened duct for the parameters range investigated. The maximum rise in friction factor of 3-sides concave dimple over those of 1-side roughened ones for varying ‘p/e’, ‘e/Dh’ & ‘e/d’ was respectively found to be as 1.62 to 2.79 times, 1.52 to 2.34 times and 2.21 to 2.56 times


concave dimple, relative dimple pitch, relative dimple height, relative dimple depth, nusselt number,; friction factor

1. Introduction
2. Equipments and methods
3. Data reduction
4. Validation of experimental data
5. Results and discussions
6. Conclusions

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