Effect of gap width on thermal performance of solar air heater having arc-shaped ribs with symmetrical gaps: an experime
- PDF / 1,693,958 Bytes
- 21 Pages / 439.37 x 666.142 pts Page_size
- 44 Downloads / 183 Views
Effect of gap width on thermal performance of solar air heater having arc‑shaped ribs with symmetrical gaps: an experimental investigation Sheetal Kumar Jain1 · Rohit Misra2 · Ghanshyam Das Agrawal1 Received: 1 May 2019 / Accepted: 18 October 2019 © Springer Nature B.V. 2019
Abstract In this paper, thermal performance of a solar air heater (SAH) having arc-shaped ribs with symmetrical gaps has been investigated experimentally and compared with that of smooth SAH. An experimental investigation has been carried out to observe the effect of various gap widths on heat transfer and friction characteristics. The investigation includes the roughness parameter; relative gap width (g/e) ranging from 2 to 5 and flow parameter; and Reynolds number ranging from 3000 to 18,000. The fixed parameters for this study were relative roughness height (e/D) of 0.047, arc angle (α) of 60° and relative roughness pitch (P/e) of 12. Results of the present work have also been compared with previously published work. Nusselt number and friction factor for roughened absorber surface is found to be 3.66 and 2.77 times higher than that obtained for smooth plate, respectively. Maximum value of thermo-hydraulic performance parameter is found to be 2.66 at g/e = 4. Heat transfer and friction factor correlations for proposed roughness have also been developed. Keywords Thermal performance · Arc-shaped ribs with symmetrical gaps · Relative gap width · Heat transfer · Correlation development · Solar air heater List of symbols Ap Absorber area (m2) Ao Orifice area (m2) Cp Specific heat (J/Kg K) Cd Coefficient of discharge D Hydraulic diameter (m) d/W Relative gap position e+ Roughness Reynolds number f Friction factor G Heat transfer function g/e Relative gap width
* Sheetal Kumar Jain [email protected]; [email protected] 1
Mechanical Engineering Department, MNIT Jaipur, Jaipur, India
2
Mechanical Engineering Department, Government Engineering College, Ajmer 305002, India
13
Vol.:(0123456789)
S. K. Jain et al.
H Height of duct (m) h Heat transfer coefficient (W/m2 K) k Thermal conductivity of air (W/m K) L Length of test section (m) ṁ Mass flow rate (kg/s) Ng Number of gaps Nu Nusselt number P/e Relative roughness pitch ∆Pd Pressure drop across the test section (Pa) ∆Po Pressure drop across the orifice plate (Pa) Qu Useful heat gain (W) R Roughness function Ti Inlet temperature of air (K) Tfm Mean temperature of fluid (K) Tpm Mean temperature of absorber plate (K) To Outlet temperature of air (K) V Velocity of air (m/s) W Width of duct (mm) W/H Aspect ratio Greek symbols ρa Density of air (kg/m3) α Arc angle (°) β Ratio of orifice diameter to pipe diameter μ Absolute viscosity of air (m2/s) Subscripts d Duct r Roughened s Smooth Abbreviations CFD Computational fluid dynamics SAH Solar air heater THPP Thermo-hydraulic performance parameter
1 Introduction The burgeoning need for energy and increasing environmental anxiety is a challenge to manhood. Hence, other substitutes to conven
Data Loading...
