ABSTRACT
In this study, the effects of variations in geometrical parameters of shielded twisted tape within the inner cylinder of the absorber tube on the performance enhancement of the parabolic trough collector (PTC) have been investigated. The objective is based on the prediction of the optimized value of geometrical parameters for the modified parabolic trough collector (MPTC) showing the best thermal performance among them. Numerical simulation techniques with Ansys-Aim2020R1 have been used for this investigation. It is desired to determine whether it is advantageous to use inner shielding around the inserts within the absorber tube; and if so, which geometrical parameter plays a crucial character in the prediction of the best possible thermal performance of the system. It was found that with a twisted tape thickness of 0.002 m, twisted tape gap of 0.001 m, inner cylinder center distance of 0.020 m, and the number of twists of the twisted tape of 50 turns the PTC has shown the best possible performance of the system. These findings reflect optimized geometrical parameters of the twisted tape insert shielded by an inner cylindrical tube. The thermal efficiency (η) of the MPTC was found to be 86.5% and approximately 2.063 times that of the conventional PTC. It is a novel endeavor regarding the approach of utilizing the shielding around the inserts within the absorber tube.
Nomenclature
A | = | Area ( |
= | Specific heat capacity (J/kg. K) | |
CPTC | = | Conventional parabolic trough collector |
d | = | Absorber tube diameter (m) |
D | = | Glass cover diameter (m) |
f | = | Friction factor |
G | = | Modified geometric parameter |
h | = | Convective heat transfer coefficient (W/m2-K) |
HTF | = | Heat transfer fluid |
I | = | Insolation (W/m2) |
k | = | Thermal conductivity (W/m2-K) |
L | = | Receiver tube length (m) |
= | HTF mass flow rate (kg/s) | |
MPTC | = | Modified parabolic trough collector |
Nu | = | Nusselt number |
P | = | Parameter |
PTC | = | Parabolic trough collector |
Q | = | Heat energy (W) |
T | = | Temperature (K) |
TEI | = | Thermal enhancement index |
v | = | Velocity at the inlet of the absorber (m/s) |
V | = | Velocity of surrounding air over the receiver (m/s) |
Subscripts | = | |
ab | = | Absorber tube |
be | = | Beam radiation |
cn | = | Convection |
ga | = | Gain |
gl | = | Glass cover |
i | = | Inlet |
in | = | Inner lateral surface |
ls | = | Loss |
mn | = | Mean |
o | = | Outlet |
ou | = | Outer lateral surface |
p | = | Parameter |
pa | = | Projected area |
rd | = | Radiation |
se | = | Selective |
si | = | Insolation |
su | = | Surroundings |
sy | = | Sky |
va | = | Variable |
0 | = | CPTC reference |
Greek letters | = | |
α | = | Absorptivity |
= | Boundary layer | |
ρ | = | Density (kg/m3) |
µ | = | Dynamic viscosity (Pa-s) |
= | Emissivity or turbulent dissipation rate | |
η | = | Thermal efficiency |
= | Transmissivity | |
σ | = | Stefan-Boltzmann constant (W/m−2-K−4) |
Disclosure statement
No potential conflict of interest was reported by the author(s).
Additional information
Notes on contributors
Ipsita Mishra
Ms. Ipsita Mishra is a Ph.D. scholar in the Department of Mechanical Engineering at the Institute of Technical Education & Research, Bhubaneswar, India. She worked as an Assistant Professor in the Department of Mechanical Engineering at Centurion University of Technology and Management, Odisha, India. Her research area includes Biofuel, Solar thermal energy, and Computational fluid dynamics.
Pragyan Senapati
Dr. Pragyan Senapati is currently working as an Associate Professor in the Department of Mechanical Engineering at the Institute of Technical Education & Research, Bhubaneswar, India. She completed her Ph.D. in the Department of Mechanical Engineering at the Institute of Technical Education & Research, Bhubaneswar, India. Her research area includes Nanocomposites, Composite coatings, Renewable energy, Computational fluid dynamics, Convective heat transfer, and Finite element analysis.
Mukundjee Pandey
Dr. Mukundjee Pandey is currently working as an Associate Professor in the Department of Mechanical Engineering at Centurion University of Technology and Management, Odisha, India. He also worked as a HoD of Aerospace Engineering at the same university. He completed his Ph.D. in the Department of Mechanical Engineering at the International Institute of Information Technology, Bhubaneswar, India. His research area includes Solar thermal energy, Computational fluid dynamics, Convective heat transfer, and Finite element analysis.