Publications
Enhancing thermal performance of shell and tube heat exchangers using ZnO/water nanofluids: a CFD-based laminar flow study
Aug 31, 2025Journal Chemical Engineering Science
Publisher Pergamon
Volume 320
The study investigates the enhancement of heat transfer in shell and tube heat exchangers under laminar flow conditions by replacing conventional water with ZnO/water nanofluid in the inner tubes. Using computational fluid dynamics (CFD) modeling via ANSYS FLUENT, the research evaluates the impact of low-concentration ZnO nanoparticles on both heat transfer and hydrodynamic behavior. The Objective of this study is improving convective heat transfer without significantly increasing pressure drop by using ZnO/water nanofluids. The CFD simulations were conducted under Reynolds numbers ranging from 200 to 1400, with nanoparticle volume fractions of 0.1 % and 0.2 %. Both higher Reynolds numbers and increased nanoparticle concentrations led to higher Nusselt numbers, indicating improved heat transfer. Compared to pure water, the Nusselt number increased by 12 % and 17 % at 0.1 % and 0.2 % nanoparticle concentrations, respectively. The friction factor increased only slightly 1 % and 3 % for 0.1 % and 0.2 % concentrations respectively, suggesting the thermal benefits outweigh the minor hydraulic penalties. The use of ZnO/water nanofluids in shell and tube heat exchangers under laminar flow conditions can significantly enhance heat transfer with minimal increase in pressure drop, making it a promising approach for improving thermal performance in industrial applications.
Experimental Investigation of the Effect of Evacuated Tubes and Glass Cover Cooling on the Performance of the Solar Still
Jun 4, 2024Journal International Journal of Heat and Technology
DOI https://doi.org/10.18280/ijht.420320
Issue 917-923
Volume 42
Solar distillation has gained more importance as a practical and environmentally friendly solution for converting non-potable water into clean water using solar energy, in response to the increasing concern about the scarcity of clean water. In the city of Kirkuk, Iraq, located at 35.4666° N, 44.3799° E, we conducted an experiment to enhance the efficiency of a conventional solar distiller with a surface area of 1 m2 . To enhance evaporation, we incorporated 8 vacuum tubes. For improved condensation, we conducted experiments using two different cooling methods to cool the glass cover: pulse cooling (1min/15min), (1min/10min) and continuous cooling. Based on the trial findings, the productivity reached 2653 ml/day, representing a 237.5% increase in production. When vacuum tubes were attached to the solar still, the productivity increased compared to a conventional distiller. With a cooling time of (1min/15min), the productivity reached 3510 ml/day. With a cooling(1min/10min), the productivity reached 3587ml/day. When constantly cooling, the productivity reached 4980 ml/day. The productivity experienced respective increases of 332%, 386%, and 656.8% in comparison to the conventional distiller. The modified still's thermal efficiency was 21.6%, 24.6%, and 37.7%, compared to 17% for the conventional system and 18.8% for the improved system without glass cover cooling.
Experimental investigation of PV/thermal collector with theoretical analysis
Dec 1, 2018Journal Renewable Energy Focus
Publisher Elsevier
DOI https://doi.org/10.1016/j.ref.2018.09.004
Issue 67-77
Volume 27
Influence of porous media on the performance of hybrid PV/Thermal collector
Nov 1, 2017Journal Renewable Energy
Publisher Pergamon
DOI https://doi.org/10.1016/j.renene.2017.05.061
Issue 378-387
Volume 112
Porous media play an important role in the process of storage energy. In this paper, the influence of porous media on the performance of a double pass hybrid PV/thermal air collector was achieved by building an experimental set-up for this purpose. The study showed that using porous media expanded the area of heat transfer and thus increased the thermal efficiency and temperature of the exit air from the hybrid solar collector. The compound efficiency was increased (3%) after using the porous medium in the lower ducts of the double-pass hybrid collector. At the same time, the pressure drop was increased after using the porous media. In this analysis, it was concluded that the hybrid solar collector with porous media and glass cover is more thermally efficient than the other design form. The results showed a rise in the electrical efficiency with the increase of the fluid flow rate. This increase in the value of the electrical efficiency was due to the higher volumetric air flow which enhanced the PV panel cooling. Also, the results displayed that fixing a glass layer on the hybrid collector caused the rise in thermal efficiency and reduction in the electrical efficiency of the hybrid collector. The highest value for the daily thermal efficiency was 80.23% in the collector that used porous media and glass cover, while the higher value for the thermal efficiency was 51.25% without porous media and glass cover. Also, the highest value for the daily electrical efficiency was 8.7% in the collector that used porous media and the higher value for the daily electrical efficiency was 10.91% without porous media and without glass cover. The use of porous media and glass cover in the hybrid system is a desirable option when using the hybrid system for electrical generation only.
Dust effect on the performance of the hybrid PV/Thermal collector
Sep 1, 2017Journal Thermal Science and Engineering Progress
Publisher Elsevier
DOI https://doi.org/10.1016/j.tsep.2017.07.003
Issue 114-122
Volume 3
Hybrid PV/Thermal collector is one of the important modern technologies to harnessed the energy from solar energy. One of the disadvantages of solar cells is the reduction in its efficiency as a result of increasing in its temperature, especially in the warm and sunny days. Also due to the dust storms in Iraq, the dust deposition on the front surface of hybrid solar collectors is one of the greatest issues facing the researchers. In order to study the effect of the dust on the thermal and electrical performance of the hybrid solar collector, a PV/T collector was designed and manufactured. The result showed that the dust effects largely on the performance of the hybrid solar collector. The results showed the thermal efficiency decreased 13.4% in case of dust existence on the outer surface of collector. Also, the highest electrical efficiency in case of clean collector was (10.24%), whereas the highest electrical efficiency in case of dust existence it was (5.67%). Also, the total efficiency of the hybrid collector was decreased by 17.5% for the dusty collector comparable with the clean collector.