https://orcid.org/0000-0002-0851-1417
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ABSTRACT
In this work, the thermo-fluid performance of a liquid flat-plate collector (FPC) has been analyzed using experimental and computational methods. A closed-loop active flat-plate solar water heater (AFPSWH) was tested under quasi-static and laminar flow operating conditions, where a maximum instantaneous collector efficiency of 62.82% and an outlet temperature of 45.2°C were attained in the winter with flow rates of 0.012 and 0.004 kg/s, respectively. Raising the flow rates from 0.004 kg/s to 0.008 and 0.012 kg/s reduces the energy loss parameter [FRUL] by 23.77% and 34.61%, whereas the absorbed energy parameter [FR(τα)n] improves by 10.48% and 21.55%, respectively. The suggested axisymmetric numerical model was validated with outcomes of an in-house developed lab scale experimental setup, with less than 1.5% deviations for all studied cases. In addition, the overall thermal efficiency of the solar thermal system (STS), Nusselt number (Nu), and friction factor (f) have been analyzed for a comprehensive understanding of the system’s thermo-fluid performance.
Nomenclature
| AC | = | gross area of the collector (m2) |
| D | = | internal diameter of the riser tube (m) |
| cp | = | specific heat at constant pressure (J/kg K) |
| FR | = | collector heat removal factor |
| f | = | friction factor |
| hbs | = | bottom convective heat transfer coefficient (W/m2 K) |
| ηc | = | instantaneous collector efficiency |
| ηo | = | overall thermal efficiency |
| IT | = | solar irradiance (W/m2) |
| k | = | thermal conductivity of the fluid (W/m K) |
| ṁ | = | mass flow rate of the fluid (kg/s) |
| Nu | = | Nusselt number |
| Pr | = | Prandtl number |
| Qu | = | useful heat gained by the fluid (W) |
| = | conductive heat flux (W/m2) | |
| = | convective heat flux (W/m2) | |
| = | constant wall heat flux (W/m2) | |
| Tin | = | fluid temperature at the inlet (K) |
| Tamb | = | ambient temperature (K) |
| Tout | = | fluid temperature at the outlet (K) |
| Ti | = | initial temperature of the tank water (K) |
| t | = | time duration of the experiment (s) |
| Tf | = | final temperature of the tank water (K) |
| UL | = | collector overall heat loss coefficient (W/m2 K) |
| u | = | velocity component (m/s) |
| V | = | velocity of the fluid flow (m/s) |
| Vw | = | wind speed (m/s) |
| XNUM. | = | numerical outcomes |
| XEXPT. | = | experimental outcomes |
| Greek symbols | = | |
| α | = | absorptivity |
| ρ | = | density (kg/m3) |
| τ | = | transmissivity |
| µ | = | dynamic viscosity (Pa s) |
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Notes on contributors
Sukanta Nayak
Sukanta Nayak is a doctoral candidate in the Department of Mechanical Engineering, NIT Jamshedpur, India. He completed his B.Tech from B.P.U.T Odisha and M.Tech from NIT Rourkela, India in Mechanical Engineering. His research areas are renewable energy, heat transfer and application of nanofluids in solar thermal systems.
M. A. Hassan
M. A. Hassan is currently working as Assistant Professor in the Department of Mechanical Engineering, NIT Jamshedpur, India. He obtained his B.Tech from Aligarh Muslim University, Aligarh in Mechanical Engineering and PhD from IIT Patna in the field of complex fluid heat transfer. His areas of research include heat transfer, thermo-fluid behaviour of complex fluid and nanoparticles.
Manikant Paswan
Manikant Paswan serves as Professor in the Department of Mechanical Engineering, NIT Jamshedpur, India. He obtained his B.E. from NIT Patna and M.Tech from NIT Jamshedpur in Mechanical Engineering. He received his Ph.D. from NIT Jamshedpur in 2002. His areas of research interest are renewable energy, heat transfer and composite materials.