Experimental and numerical investigations of thermal performance of Al₂O₃/water nanofluid for a combi boiler with double heat exchangers

Abstract

Purpose This study aims to focus on usage of Al2O3/water nanofluid as working fluid in a combi boiler. The plate heat exchanger located at the bottom of the combi boiler has been used for heating the domestic water in the present study. Al2O3/water nanofluid has also been used in obtaining of the heat energy provided from combustion. Therefore, thermal performance of Al2O3/water has been determined by comparing water and nanofluid-water mixture. The present study also investigates heat transfer rates as numerical and experimental for varying cold side outlet temperatures, comparatively. Design/methodology/approach The present study has included both experimental and numerical methodologies. The experimental setup consists of main heat exchanger, atmospheric burner, circulation pump and plate-type heat exchanger in which the Al2O3/water nanofluid was used as working fluid to heat the domestic water. In the numerical part of the study, a commercial computational fluid dynamic code has been used to model heat rate and thermal efficiency of the heat exchanger used. Findings It has been concluded that the predicted results are in satisfactorily good agreement with the measured data. In the experimental part of the study, the flow rate of Al2O3/water nanofluid was kept constant during the experiments. The flow rates of the water by which the heated Al2O3/water nanofluid mixture was cooled via the plate heat exchanger have been changed as 3, 4, 5 and 6 lpm. The domestic water temperatures that were kept constant have also been changed as 40°C, 45°C, 50°C, 55°C and 60°C. It has been concluded that the Al2O3/water nanofluid thermal efficiency has been 16 per cent better than pure water. Originality/value The main originality of the present study is that thermal efficiency of the plate-type heat exchanger when Al2O3/water mixture nanofluids are used as there are limited studies related to the usage of Al2O3/water mixture nanofluids in the plate-type heat exchanger not only experimental but also numerical methodologies.

A comparative study on utilizing hybrid-type nanofluid in plate heat exchangers with different number of plates

“…Obtained heat transfer rate in this research varied in the range of 7102-19.532 W. In a study done by Ozdemir and Ergun [5], Al 2 O 3 /water nanofluid was experimentally tested in PHE with 16 plates and achieved heat transfer rate between 3000 and 14,000 W. In another study conducted by Variyenli [3], the performance of using fly ash nanofluid in PHE with 16 plates was analyzed and heat transfer rate obtained was 2500-10,800 W. Also, Khanlari et al [2] experimentally tested TiO 2 /water and Kaolin/ water nanofluids in PHE and found heat transfer rate in the range of 5000-20,000 W. Figure 7 demonstrates the variation in OHTC with respect to Reynolds number in PHE with eight plates. Hybrid nanofluid utilization in this HE increased the OHTC averagely as 10.5%.…”

“…Plate shape, plate thickness and channel geometry are the major parameters that affect the efficiency of PHE [1]. There are lots of studies available that analyzed the effects of various factors on thermal behavior of PHE [2][3][4][5].…”

Heat and mass transfer analysis in unsteady MHD flow of aluminum alloy/silver‐water nanoliquid due to an elongated surface

“…Later, Vishnu et al 5 examined the entropy spawn analysis on a flow caused due to a stretched surface under slip effects. Experimental and theoretical analysis on improving heat transport feature of aluminum oxide‐water nanoliquid used in a Combi boiler was carried by Ozdemir and Ergun 6 . They revealed that the use of aluminum oxide‐water nanofluids has a better thermal efficiency of 16% over the pure water.…”

Thermal Performance Improvement of the Heat Pipe by Employing Dolomite/Ethylene Glycol Nanofluid

“…), a base fluid in which nanoparticles are doped and a surface-active agent (surfactant) to prevent agglomeration of nanoparticles. It was observed in latest studies that nanofluids have been successfully employed as working fluid in various systems (Chen et al 2013, Ghanbarpour et al 2015, Kim and Bang 2015, Sözen et al 2016, Khanlari et al 2019, Baïri and Laraqi 2019, Ozdemir and Ergun 2019, Dagdevir et al 2019, Sözen et al 2019a, Sözen et al 2019b) more in particular in heat pipes (Huminic and Huminic 2013, Venkatachalapathy et al 2015, Tharayil et al 2015, Sözen et al 2018, Gürü et al 2019. To illustrate; Hassan et al (2015) analysed influence of accumulation on the heat pipe wick porosity following the alumina (Al2O3) nano fluid usage as the working medium.…”