Abstract
Bringing together nanofluids and solar collectors has been widely discussed without any major advance or long-term study being carried out. In this context, this paper provides a useful feasibility study to help future decisions in using nanofluids in Solar Water Heating Systems (SWHSs) in different locations. The performances of SWHSs using the nanofluid-based flat plate solar collector (FPSC), evacuated tube collector (ETC), and compound parabolic collector (CPC) under the Mediterranean, arctic, and desert climate conditions are presented and discussed. The analysis is carried out using a transient-based numerical approach, solving energy balance equations for different systems. Various performance factors such as energy saving, solar fractions, and environmental impacts of auxiliary energy supplies are evaluated to feasibly assess the use of nanofluids in such devices. Simulation results demonstrate that the use of nanofluids increases the solar heater performance which reduces considerably the payback period ( P P ) of the investment in solar heating systems up to 3.34 years in Tunisian climate. Under Quebec’s climate region, the annualized solar return of the ETC system increases from 4874.65 US$ to 9785.93 US$ by adding 0.06 v% Al2O3 in water. Also, the use of nanofluids in solar collectors with electric auxiliary heaters reduces harmful CO2 emissions up to 0.49 tons/year.
Highlights
We always talk about renewable energies and energy transition to solve environmental problems, according to the latest report of the International Energy Agency [1]
It is true that Al2O3 may be used as base fluid in parabolic trough collectors (PTCs) technologies as mentioned, and we did not conduct assessment studies of these types of nanofluids in the PTC since we focused on the combination that has been experimentally tested, and its thermal performances can be implemented in the TRNSYS software
By computing the auxiliary energy Qaux needed by the system using mineral thermal oil, 0.2% MWCNT/oil, and 0.3% MWCNT/oil, we found that the auxiliary energy varies from 227.4 in August to 554.34 MJ in February, from 118.12 in August to 474.41 MJ in February, and from 86.54 in August to 448.6 MJ in February using mineral thermal oil, 0.2% MWCNT/oil, and 0.3% MWCNT/oil, respectively
Summary
We always talk about renewable energies and energy transition to solve environmental problems, according to the latest report of the International Energy Agency [1]. They used a particle size equal to 15 nm and a nanofluid mass flow rate varying from 1 to 3 L/min Their results showed that the efficiency increases using nanofluids as the working fluid compared to using water as the absorption medium. Meibodi et al [13] studied a flat plate solar collector using SiO2/ethylene glycol- (EG-) water nanofluid with volume fractions of up to 1% and mass flow rates ranging from 0.018 to 0.045 kg/s They found that SiO2 nanoparticles are able to improve the efficiency of solar collectors despite the low value of thermal conductivity compared to other usual nanoparticles. Eltaweel et al [18] analyzed experimentally the energy and exergy efficiency of the ETC using multiwalled carbon nanotubes and water nanofluid as the working fluid in this collector They performed the study with flow rates of 1 to 3.5 L/min and weight fractions of. The effect of using nanofluids in solar water heaters is evaluated with different weather conditions, and their environmental and economic influence is studied in terms of energy efficiency and CO2 emission reduction
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