Olive Leaf-Synthesized Nanofluids for Solar Parabolic Trough Collector—Thermal Performance Evaluation

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Eric C. Okonkwo ◽  
Edidiong A. Essien ◽  
Doga Kavaz ◽  
Muhammad Abid ◽  
Tahir A. H. Ratlamwala
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Olive Leaf ◽  
Parabolic Trough ◽  
Leaf Extracts ◽  
Comparison Of The Results

This study presents a novel performance evaluation of the commercially available LS-2 collector operating with an oil-based olive leaf-synthesized nanofluid. The nanoparticles were synthesized experimentally from olive leaf extracts (OLEs): OLE-ZVI and OLE-TiO2. The thermophysical properties of the nanoparticles were then added to Syltherm-800 thermal oil, and its performance on the parabolic trough solar collector (PTC) was evaluated numerically. The PTC under study was modeled on the engineering equation solver (EES) and validated thermally with results found in the literature. The synthesized nanoparticles were also found to possess anticorrosion properties, nontoxic, and less expensive to produce when compared to commercially available ones. The use of the nanofluids (Syltherm-800/OLE-ZVI and Syltherm-800/OLE-TiO2) was evaluated against the parameters of thermal and exergetic efficiencies, heat transfer coefficient, thermal losses, and pressure drop. The study shows that an enhancement in thermal performance of 0.51% and 0.48% was achieved by using Syltherm-800/OLE-ZVI and Syltherm-800/OLE-TiO2 nanofluids, respectively. A heat transfer coefficient enhancement of 42.9% and 51.2% was also observed for Syltherm-800/OLE-TiO2 and Syltherm-800/OLE-ZVI nanofluids, respectively. Also, a mean variation in pressure drop of 11.5% was observed by using the nanofluids at a nanoparticle volumetric concentration of 3%. A comparison of the results of this study with related literature shows that the proposed nanofluids outperform those found in literature.

Overall Thermal Performance of a Rectangular Channel With an Array of Elongated Pedestals

2013 ◽  
Author(s):  
S. Huang ◽  
Y. Y. Yan ◽  
J. D. Maltson ◽  
E. Utriainen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Rectangular Channel ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Flow Area ◽  
Coefficient Distribution

Experiments have been conducted to investigate the overall thermal performance of a rectangular channel implemented with an elongated pedestal array. The staggered pedestals were elongated in the spanwise direction in order that the jet flow from between the pedestals impinges at the centre of the pedestals in the downstream row. The average heat transfer coefficient of the pedestal and the local heat transfer coefficient distribution of the bottom channel wall were investigated for different geometrical arrangements. The pressure drop across the pedestal bank was measured. The transient liquid crystal method was used to obtain the local heat transfer coefficient distribution on the bottom channel wall and the lumped capacitance method was used to measure the average heat transfer coefficient of the pedestals in the last two rows of the bank. Five pressure taps were arranged on the centerline of each gap between two pedestal rows to measure the pressure drop. The heat transfer coefficients were measured over the Reynolds number range from 10,000 to 30,000. The minimum flow area to the channel cross-section flow area ratio ranged from 0.149 to 0.333. The effects of pedestal geometry and array distribution were investigated in detail showing the relationship between the pedestal array geometry, heat transfer enhancement and pressure drop. Conclusions were drawn on the effects of geometry and flow conditions on overall thermal performance of the respective channels.

scholarly journals Numerical Analysis of Heat Transfer and Pressure Drop in Helically Micro-Finned Tubes

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 754
Author(s):  
Muhammad Ammar Ali ◽  
Muhammad Sajid ◽  
Emad Uddin ◽  
Niaz Bahadur ◽  
Zaib Ali
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Thermal Performance ◽  
Finned Tube ◽  
Smooth Tube ◽  
Working Fluid ◽  
Finned Tubes

In this study, the pressure drop and heat transfer characteristics of smooth tube and internal helically micro-finned tubes with two different fin-to-fin height ratios i.e., equal fin height and alternating fin height, are computationally analysed. The tube with alternating fin height is analysed for proof of concept of pressure drop reduction. A single phase steady turbulent flow model is used with a Reynolds number ranging from 12,000 to 54,000. Water is used as working fluid with inlet temperature of 55 °C and constant wall temperature of 20 °C is applied. Friction factor, heat transfer coefficient, Nusselt number, and Thermal Performance Index are evaluated and analysed. The numerical results are validated by comparison with the experimental and numerical data from literature. The results showed that the thermal performance is enhanced due to helically finned tube for a range of Reynolds numbers, but at the expense of increased pressure drop as compared to a smooth tube. The helically finned tube with alternating fin heights showed a 5% decrease in friction factor and <1% decrease in heat transfer coefficient when compared with the equal fin heights tube, making it a suitable choice for heat transfer applications.

scholarly journals THERMAL PERFORMANCE EVALUATION OF ROOM AIR CONDITIONERS EVAPORATORS

2005 ◽  
Vol 4 (1) ◽  
pp. 56 ◽  
Author(s):  
A. C. Piske ◽  
L. M. Moura ◽  
N. Mendes
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Condensation Process ◽  
Physical Parameters ◽  
Air Conditioners ◽  
Overall Heat Transfer Coefficient ◽  
Systematic Effects

This work presents a thermal performance evaluation of a fin-and-tube evaporator - that is widely used in packaged air conditioning equipment - using a balanced calorimeter developed to simulate similar running conditions. The calorimeter determines the heat rate absorbed by the evaporator, providing qualitative analysis of performance for a given geometry. The calorimeter inside air is dried out due to the condensation process on the evaporator under test during the transient period. By this way it is possible to preview the humidity of the calorimeter domain and its influence with the instrumentation measurement. The heat transfer rate absorbed by the evaporator is obtained by a lumped approach using the energy conservation that is applied to the calorimeter domain, and is taken on the boundaries of the equipment. Physical parameters such as overall heat transfer coefficient for several types of fins can then be predicted in order to provide information for improving the energy-efficiency-oriented design. The uncertainties are estimated by the propagation of relative effects. Uncertainties are evaluated taking into account the systematic effects. Results are shown in terms of evaporator overall heat transfer coefficient and heat transfer rate as a function of inlet air temperature.

scholarly journals CFD Analysis on the Air-Side Thermal-Hydraulic Performance of Multi-Louvered Fin Heat Exchangers at Low Reynolds Numbers

2017 ◽  
Author(s):  
Arslan Saleem ◽  
Man-Hoe Kim
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Reynolds Numbers ◽  
Hydraulic Performance

The air side thermal hydraulic performance of multi-louvered aluminium fin heat exchangers is investigated. A detailed study was performed to analyse the thermal performance of air over a wide range of Reynolds number i.e. from 30 to 250. Air-side heat transfer coefficient and air pressure drop were calculated and validated over the mentioned band of Reynolds numbers. Critical Reynolds number was determined numerically and the variation in flow physics along with the thermal and hydraulic performance of microchannel heat exchanger associated with R_cri has been reported. Moreover, a parametric study of the multi-louvered aluminium fin heat exchangers was also performed for 36 heat exchanger configurations with the louver angles (19-31&deg;), fin pitches (1.0, 1.2, 1.4 mm) and flow depths (16, 20, 24 mm); and the geometric configuration exhibiting the highest thermal performance was reported. The air-side heat transfer coefficient and pressure drop results for different geometrical configurations were presented in terms of Colburn j factor and Fanning friction factor f, as a function of Reynolds number based on louver pitch.

scholarly journals A Hybrid Nanofluid of Alumina and Tungsten Oxide for Performance Enhancement of a Parabolic Trough Collector under the Weather Conditions of Budapest

2021 ◽  
Vol 11 (11) ◽  
pp. 4946
Author(s):  
Otabeh Al-Oran ◽  
Ferenc Lezsovits
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Rate ◽  
Thermal Performance ◽  
Radiation Intensity ◽  
Hybrid Nanofluid ◽  
Intensity Level ◽  
Parabolic Trough

Recently, there has been significant interest in the thermal performance of parabolic trough collectors. They are capable of operating and generating highly variable temperature ranges, which can be used in various applications. This paper, therefore, addressed the thermal performance model of using a parabolic trough collector under the radiation intensity level found in Budapest city, as well as the effect of inserting a hybrid nanofluid as the thermal fluid. First, a new modified hybrid nanofluid of alumina and tungsten oxide-based Therminol VP1 is used to enhance the thermal properties of the thermal fluid to be more efficient to use. This enhancement is performed under various volume concentrations and has a volume fraction of 50:50. Second, in order to demonstrate the effectiveness of the thermal element, mathematical energy balance equations were solved and simulated using MATLAB Symbolic Tools. The simulation is presented for two cases: one under a constant radiation intensity and the other under the radiation intensity level of Budapest. For both cases, the results of the dimensionless Nusselt number, heat transfer coefficient, pressure drop, exergy efficiency, and energy efficiency are described. The major findings show that a volume concentration of 4% (Al2O3 and WO3) based Therminol VP1 was the most efficient volume concentrations in both cases. For the first case, the maximum enhancement of the Nusselt number and the heat transfer coefficient are 138% and 169%, respectively. These results enhanced the thermal and exergy efficiencies by 0.39% and 0.385% at a temperature 600 K, flow rate of 150 L/min, and radiation intensity of 1000 W/m2. For the second case, the maximum exergy and energy values are recorded at midday under Budapest’s summer climatic conditions and reach 32.728% and 71.255%, respectively, under the optimum temperature of 500 K and flow rate of 150 L/min. Accordingly, the mean improvement in thermal and exergy efficiencies approximately equal to 0.25% at a high concentration, regardless of the season (summer or winter).

scholarly journals Application of Nanofluids in Thermal Performance Enhancement of Parabolic Trough Solar Collector: State-of-the-Art

2019 ◽  
Vol 9 (3) ◽  
pp. 463 ◽  
Author(s):  
Hamed Olia ◽  
Mohammadamin Torabi ◽  
Mehdi Bahiraei ◽  
Mohammad Hossein Ahmadi ◽  
Marjan Goodarzi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Entropy Generation ◽  
Thermal Efficiency ◽  
Performance Enhancement ◽  
Volume Fraction ◽  
Working Fluid ◽  
Parabolic Trough

The present review paper aims to document the latest developments on the applications of nanofluids as working fluid in parabolic trough collectors (PTCs). The influence of many factors such as nanoparticles and base fluid type as well as volume fraction and size of nanoparticles on the performance of PTCs has been investigated. The reviewed studies were mainly categorized into three different types of experimental, modeling (semi-analytical), and computational fluid dynamics (CFD). The main focus was to evaluate the effect of nanofluids on thermal efficiency, entropy generation, heat transfer coefficient enhancement, as well as pressure drop in PTCs. It was revealed that nanofluids not only enhance (in most of the cases) the thermal efficiency, convection heat transfer coefficient, and exergy efficiency of the system but also can decrease the entropy generation of the system. The only drawback in application of nanofluids in PTCs was found to be pressure drop increase that can be controlled by optimization in nanoparticles volume fraction and mass flow rate.

scholarly journals THERMAL PERFORMANCE EVALUATION OF ROOM AIR CONDITIONERS EVAPORATORS

2005 ◽  
Vol 4 (1) ◽  
Author(s):  
A. C. Piske ◽  
L. M. Moura ◽  
N. Mendes
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Condensation Process ◽  
Physical Parameters ◽  
Overall Heat Transfer Coefficient

This work presents a thermal performance evaluation of a fin-and-tube evaporator - that is widely used in packaged air conditioning equipment - using a balanced calorimeter developed to simulate similar running conditions. The calorimeter determines the heat rate absorbed by the evaporator, providing qualitative analysis of performance for a given geometry. The calorimeter inside air is dried out due to the condensation process on the evaporator under test during the transient period. By this way it is possible to preview the humidity of the calorimeter domain and its influence with the instrumentation measurement. The heat transfer rate absorbed by the evaporator is obtained by a lumped approach using the energy conservation that is applied to the calorimeter domain, and is taken on the boundaries of the equipment. Physical parameters such as overall heat transfer coefficient for several types of fins can then be predicted in order to provide information for improving the energy-efficiency-oriented design. The uncertainties are estimated by the propagation of relative effects. Uncertainties are evaluated taking into account the systematic effects. Results are shown in terms of evaporator overall heat transfer coefficient and heat transfer rate as a function of inlet air temperature.

Heat Transfer and Pressure Drop in a Converging Lattice Structure for Airfoil Trailing Edge Cooling

2008 ◽  
Author(s):  
Krishnendu Saha ◽  
Sumanta Acharya ◽  
Chiyuki Nakamata
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Turbine Blade ◽  
Thermal Performance ◽  
Lattice Structure ◽  
Lattice Structures ◽  
Performance Factor ◽  
The Heat Transfer Coefficient

Lattice-matrix structures have distinct advantages in enhancing heat transfer in the cooling channels of a gas turbine blade. Lattice structures not only enhance heat transfer coefficient but also provide structural rigidity to the turbine blade. Stationary tests were performed for a 12 times scaled up model at four Reynolds numbers (4,000 &lt; Re &lt; 20,000) in a converging lattice structure. A narrow band liquid crystal technique is used to determine the heat transfer coefficient in the channel. The results shows very high heat transfer coefficient enhancement in the impingement regions. The average heat transfer coefficient enhancement for a channel with lattice structures is also higher (Nu/Nu0 = 1.9–3) than a pin fin cooling configuration channel (Nu/Nu0 = 1.7–2.2). The heat transfer coefficient enhancement decreases with increasing Reynolds number. Pressure data are taken at some specific points throughout the channel. High pressure drop due to the turning of the flow in the lattice structure is observed. Friction factor and overall thermal performance factor are calculated. The overall thermal performance factor lies in the range 0.64–1.

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