ABSTRACT
The current solar concentrating collectors can be driven by water gravity without using a torque motor. It saves the electricity required to drive the large solar concentrating collectors. The objective of this study is to simulate and experimentally evaluate a novel hybrid system that combines photovoltaic and thermal technology with a hydro-powered solar tracking unit. The device consists of a hybrid solar collector, which is a multi-reflector compound parabolic collector (MRCPC), an evacuated tube receiver, photovoltaic (PV) panels, and a tracking system. The tracking mechanism attaches the tracking weights to both sides of a chain and sprocket. This hybrid collector rotates around its axis by adjusting the weight of the water in each of the monitoring weights. The system integrates a 12-volt direct current pump (operated by photovoltaic power) for tracking, with flow rate control. A mathematical model is developed and applied to determine the ideal tilt angle for a solar concentrating collector. The model was then used to compare the actual tilt angle and minimize errors in tracking. An experimental investigation used a flow rate of 0.8 LPM. The study achieved a mean tracking error of 2.05º, a maximum thermal efficiency of 43.65%, a maximum solar PV efficiency of 11.30%, and a maximum overall efficiency of 29.81%. An analytical method was developed to simulate the collector’s outlet temperature.
Notations
Acronyms | = | |
MRCPC | = | Multi-reflector compound parabolic collector |
ETC | = | Evacuated Tube Collector |
CPC | = | Compound Parabolic Collector |
PV | = | Photovoltaic |
LPM | = | Liters per minute |
DC | = | Direct current |
PTC | = | Parabolic Trough Collector |
CG | = | Center of gravity |
MATLAB | = | Matrix Laboratory |
HTF | = | Heat transfer fluid |
Symbols | = | |
WE | = | Eastern tracking weight, kg |
WW | = | Western tracking weight, kg |
WC | = | Collector weight, kg |
WCW | = | Counterweight, kg |
L | = | Spring length at normal position, m |
k | = | Spring constant, N/m |
r | = | Radius of circle formed by the end of the spring |
e | = | Offset from the axis of rotation, m |
D | = | Diameter of sprocket, m |
Dh | = | Hydraulic diameter, m |
PW | = | Wetted perimeter, m |
AC | = | Net free flow area, m2 |
di | = | Copper tube inner diameter |
do | = | Copper tube outer diameter |
Di | = | Evacuated tube inner diameter, m |
Re | = | Reynold’s number |
= | Mass flow rate | |
Pr | = | Prandtl number |
Nu | = | Nusselt number |
h | = | Average heat transfer coefficient |
Ib | = | Average hourly beam radiation |
rb | = | Tilt factor for beam radiation |
A | = | Aperture area |
W | = | Upper aperture width |
w | = | Lower aperture width |
f | = | Height of focal point from bottom parabola |
Ul | = | Overall heat loss coefficient |
FR | = | Rate of heat removal |
S | = | Heat flux falling on the evacuated tube, W/m2 |
C | = | Concentration ratio |
ql | = | Rate of heat loss |
hw | = | Convective heat transfer coefficient between the glass cover and surrounding air, W/m2 |
qu | = | Useful heat gain rate for the absorber |
Cp | = | Specific heat |
T1 | = | Temperature at the collector inlet |
T2 | = | Temperature at the collector outlet |
T3 | = | Temperature of storage tank |
Greek Symbols | = | |
ζ | = | Spring angle with horizontal plane |
β | = | Collector tilt angle |
χ | = | Spring tilt angle |
ρ | = | Reflectivity |
υ | = | Kinematic viscosity |
μ | = | Dynamic viscosity |
τ | = | Transmissivity |
α | = | Absorptivity |
σ | = | Stefan-Boltzmann constant |
δ | = | Declination angle |
ω | = | Hour angle |
φ | = | Local Latitude |
θ | = | Incidence angle |
γ | = | Azimuth angle |
η | = | Efficiency |
ψ | = | Rim angle |
ε | = | Emissivity |
Subscripts | = | |
ref | = | Reference |
amb | = | Ambient |
fi | = | Inlet fluid of collector |
fo | = | Outlet fluid of collector |
gc | = | Glass cover |
amb | = | Ambient |
Acknowledgements
The authors acknowledge the project grant of the Department of Science and Technology (DST), New Delhi, India (DST/TMD/CERI/RES/2020/38(G)) under Applied Research Solar Stream.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Additional information
Funding
Notes on contributors
Tangellapalli Srinivas
Dr. Tangellapalli Srinivas is a Professor in the Department of Mechanical Engineering at the Dr. B.R. Ambedkar National Institute of Technology in Jalandhar, Punjab, India. He received his PhD from JNT University College of Engineering and was a postdoctoral fellow at the University of Ontario Institute of Technology. Dr. Srinivas is the principal investigator for research projects funded by CSIR, SERB, SERB (IMPRINT), and DST. He has industrial consulting experience in solar thermal energy and thermal systems, has one granted patent, two copyrights, and published five patents. He has authored four books, three edited books, 15 book chapters, 125 journal publications, and 90 conference proceedings. Dr. Srinivas has supervised five Ph.D. students, 40 master’s theses, and 45 UG projects.
Aakash Kumar Nimesh
Aakash Kumar Nimesh is pursuing a PhD affiliated with the Department of Mechanical Engineering at Dr B.R. Ambedkar National Institute of Technology in Jalandhar, Punjab, India.
Shivam Tiwari
Shivam Tiwari is a postgraduate scholar from the Department of Mechanical Engineering, Dr B.R. Ambedkar National Institute of Technology, Jalandhar, Punjab, India.
Rajan Kumar
Dr. Rajan Kumar is an Assistant Professor in the Department of Mechanical Engineering at the Dr. B.R. Ambedkar National Institute of Technology, Jalandhar, Punjab, India. He is currently working on laminar micro-convection of gas and liquid with variations in fluid properties. His research interest includes micro-convective flow, micro-electronic cooling, and heat exchanger, numerical investigation of variation in thermophysical properties, and computational fluid dynamics.
Parmvir Singh
Parmvir Singh is pursuing a PhD affiliated with the Department of Mechanical Engineering at Dr B.R. Ambedkar National Institute of Technology in Jalandhar, Punjab, India.