Optimum geometry of parabolic trough collectors with optical and thermal criteria

2017 ◽  
Vol 8 (1) ◽  
pp. 45-50 ◽  
Author(s):  
S. Pavlovic ◽  
E. Bellos ◽  
V. Stefanovic ◽  
C. Tzivanidis
Keyword(s):  
Steady State ◽  
Optimum Design ◽  
Thermal Performance ◽  
Focal Length ◽  
Flow Simulation ◽  
Inlet Temperature ◽  
Exergetic Efficiency ◽  
Parabolic Trough ◽  
Optimum Geometry ◽  
The Impact

The objective of this work is to investigate the impact of the geometric dimensions of parabolic trough collector (PTC) in the optical, energetic and exergetic efficiency. The module of the commercial LS-3 PTC is examined with SOLIDWORKS FLOW SIMULATION in steady-state conditions. Various combinations of reflector widths and receiver diameters are tested. The optical and the thermal performance, as well as the exergetic performance are calculated for all the examined configurations. According to the final results, higher widths demands higher receiver diameter for optimum performance. For inlet temperature equal to 200 °C, the optimum design was find to be 3000 mm width with 42.5 mm receiver diameter, with the focal length to be 1840 mm (this is kept constant in all the cases). The results of this work and the presented methodology can be used as guidelines for the design of optimum PTC in the future.

Thermal and exergetic evaluation of parabolic trough collectors with finned absorbers operating with air

2017 ◽  
Vol 231 (7) ◽  
pp. 631-644 ◽  
Author(s):  
Evangelos Bellos ◽  
Christos Tzivanidis ◽  
Ilias Daniil
Keyword(s):  
Flow Simulation ◽  
Global Maximum ◽  
Inlet Temperature ◽  
Simulation Tool ◽  
Exergetic Efficiency ◽  
Parabolic Trough ◽  
Pressure Losses ◽  
Two Factors ◽  
Reverse Relationship ◽  
Fin Length

The objective of this work is to evaluate energetically and exergetically the use of internal longitudinal fins in parabolic trough collectors operating with air. Nine different finned absorbers are compared with the smooth absorber for various inlet temperatures up to 500℃. More specifically, the use of 4, 8, and 16 fins with lengths 5 mm, 10 mm, and 15 mm are examined. The simulation tool is Solidworks Flow Simulation and the examined parabolic trough collector is the Eurotrough module. According to the final results, the global maximum exergetic efficiency is 43.65% and it is achieved for 4 fins with 15 mm length, while the inlet temperature of the air is equal to 350℃ and the thermal efficiency is 67.98%. Moreover, in the cases of 8 and 16 fins, the optimum lengths exergetically are 10 mm and 5 mm respectively, a fact that proves the reverse relationship between the number of fins and the fin length. Finally, it is also important to be stated that greater number of fins and higher fin length not only lead to higher thermal performance but also to higher pressure losses; two factors are taken into consideration in the exergetic performance, which is the main evaluation index of this study.

Thermal performance comparison of different sun tracking configurations

2019 ◽  
Vol 88 (2) ◽  
pp. 20902
Author(s):  
O. Achkari ◽  
A. El Fadar
Keyword(s):  
Thermal Performance ◽  
Electricity Generation ◽  
Arid Regions ◽  
Performance Comparison ◽  
Water Desalination ◽  
Parabolic Trough ◽  
Parabolic Trough Collector ◽  
The Impact ◽  
The Mathematical Model ◽  
Good Agreement

Parabolic trough collector (PTC) is one of the most widespread solar concentration technologies and represents the biggest share of the CSP market; it is currently used in various applications, such as electricity generation, heat production for industrial processes, water desalination in arid regions and industrial cooling. The current paper provides a synopsis of the commonly used sun trackers and investigates the impact of various sun tracking modes on thermal performance of a parabolic trough collector. Two sun-tracking configurations, full automatic and semi-automatic, and a stationary one have numerically been investigated. The simulation results have shown that, under the system conditions (design, operating and weather), the PTC's performance depends strongly on the kind of sun tracking technique and on how this technique is exploited. Furthermore, the current study has proven that there are some optimal semi-automatic configurations that are more efficient than one-axis sun tracking systems. The comparison of the mathematical model used in this paper with the thermal profile of some experimental data available in the literature has shown a good agreement with a remarkably low relative error (2.93%).

Thermal Assessment of Cooling System Incorporating Heat Sink and Embedded Heat Pipes for Testing High Power Microelectronics

2005 ◽  
Author(s):  
Victor Adrian Chiriac ◽  
Tien-Yu Tom Lee
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Pipes ◽  
Optimal Operation ◽  
Operating Conditions ◽  
Peak Temperature ◽  
Testing System ◽  
The Impact

A numerical study was conducted to model the transient thermal behavior of a complex testing system including multiple fans, a mixing enclosure, copper inserts and a leaded package dissipating large amounts of power over short time durations. The system is optimized by choosing appropriate heat sink/fan structure for the efficient operation of the device under constant powering. The intent of the study is to provide a better understanding and prediction of a transient powering scenario at high powering levels, while evaluating the impact of alternative cooling fan/heat pipe designs on the thermal performance of the testing system. One design is chosen due to its effective thermal performance and assembly simplicity, with the package embedded in heat sink base with multiple (5) heat pipes. The peak temperature reached by the modified design with 4 cooling fans is ~95°C, with the corresponding Rja thermal resistance ~0.58°C/W. For the transient study (with embedded heat pipes and 4 fans), after one cycle, both peak temperature (at 45 s) and the end temperature (at 49 s) decrease as compared to the previous no heat pipe/single fan case (the end temperature reduces by ~16%). The temperature drop between peak and end for each cycle is ~80.2°C, while the average power per transient cycle is ~31.27W. With this power, the design with 5 perpendicular heat pipes, 4 fans and insert reaches a steady state peak temperature of ~98°C. Applying the superposition principle to the steady state value and 40.1°C fluctuation, the maximum transient temperature after a large number of cycles will not exceed ~138.1°C, satisfying the thermal budget under the current operating conditions. The benefit of the study is related to the possibility to extract the maximum and minimum temperatures for a real test involving a large number of heating-cooling cycles, yet maintaining the initial and peak temperatures within a certain range for the optimal operation of the device. The flow and heat transfer fields are investigated; using a combination of numerical and analytical methods, the thermal performance of the device undergoing large number of periodic thermal cycles is predicted. The comparison between measurement and simulation shows good agreement.

Thermal performance optimization of a parabolic trough collector operating with various working fluids using copper nanoparticles.

2021 ◽  
pp. 1-35
Author(s):  
Yasser M. Abdullatif ◽  
Eric Chekwube Okonkwo ◽  
Tareq Al-Ansari
Keyword(s):  
Copper Nanoparticles ◽  
Thermal Performance ◽  
Performance Optimization ◽  
Volume Flow Rate ◽  
Liquid Sodium ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Parabolic Trough ◽  
Pressurized Water ◽  
Working Fluids

Abstract This study presents a thermal performance comparison of various working fluids in Parabolic Trough Collectors. Fluids such as gases (helium, carbon dioxide, and air), liquid sodium, and liquids (pressurized water, Therminol VP1, Syltherm 800) are evaluated. This study also examines the efficiency enhancement obtained from the dispersion of copper nanoparticles in water, Therminol-VP1, and Syltherm 800 base fluids. The optimum parameters for nanoparticle concentration, volume flow rate, and inlet temperature to obtain the maximum efficiencies for each working fluid were evaluated in this study. The thermal model used in this study was modelled after the commercially available LS-2 collector, which was designed in the engineering equation solver (EES) and validated with results found in literature. The results of the study show that the Cu/Syltherm 800 nanofluid showed the most enhancement in thermal efficiency with 0.62% while Cu/water and Cu/Therminol VP1 had enhancements of 0.3% and 0.2% respectively.

Thermal Performance Intensification of Car Radiator using SiO2/Water and ZnO/Water Nanofluids

2021 ◽  
pp. 1-25
Author(s):  
Hussein Maghrabie ◽  
Hamouda Mousa
Keyword(s):  
Heat Transfer ◽  
Working Conditions ◽  
Flow Rate ◽  
Thermal Performance ◽  
Cooling System ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Coolant Temperature ◽  
Inlet Temperature ◽  
The Impact

Abstract Recent progress in nanotechnology has lead to a revolution in the automotive cooling system. In the present work, enhancement of car radiator thermal performance was investigated using different nanofluids named SiO2/water, ZnO/water nanofluids as cooling mediums. The present study mainly aims to investigate the impact of (5 wt.%) from SiO2 and ZnO nanoparticles (NPs) dispersed in water based on car radiator heat transfer with spherical and hexagonal morphology, respectively. The experiments were performed in two working conditions of the nanofluids i.e coolant temperature and volume flow rate, moreover the present results were compared with the previous studies. The experimental working conditions were set at coolant inlet temperature (tc,i) ranged from 45 oC to 80 oC and the coolant volume flow rate (V) ranged from 3.5 lit/min to 6.5 lit/min. The experimental results show that the hexagonal ZnO/water nanofluid was superior towards enhancement of car radiator thermal performance comparing to that of SiO2 NPs. Additionally, at 6.5 lit/min and 45 °C, the enhancements of car radiator effectiveness due to using SiO2 and ZnO based water nanofluids and compared with that for the based water were 13.9% and 16%, respectively. The present study used the multiple regression analysis (MRA) and hence empirical correlations are suggested to estimate the overall heat transfer coefficient (U) for all coolants as functions of volume flow rate (V) and the coolant inlet temperature (tc,i) with a maximum STDEV of ± 1.85%.

Parabolic Trough Collector with Internal Fractal Fins in Receiver to Increase Thermal Performance in Working Fluid

2020 ◽  
Author(s):  
Angelica Palacios ◽  
Dario Amaya ◽  
Olga Ramos
Keyword(s):  
Thermal Performance ◽  
Flow Simulation ◽  
Simulation Software ◽  
Working Fluid ◽  
Concentrated Solar Power ◽  
Parabolic Trough ◽  
Parabolic Trough Collector ◽  
Internal Fins ◽  
Parabolic Collector ◽  
Production Industry

Abstract Concentrated solar power technologies have been studied in recent years as a potential solution for energy production industry , however this kind of systems face different challenges in order to increase thermal performance and efficiency. This paper presents the results of a thermal analysis on a parabolic trough collector with different receivers internal fins configurations, systems were studied in CFD Solidworks® flow simulation software and compared with a traditional parabolic collector with cylindrical receiver. Results shows that the lowest thermal performance was achieved with a cylindrical pipe, instead fractal fins receiver with 5 internal fins achieves a temperature increase of 27% and the best pipe configuration was fractal Descartes with 12 internal pipes which e the cylindrical temperature in 29%.

Impact of Tile Design on the Thermal Performance of Open and Enclosed Aisles

2018 ◽  
Vol 140 (1) ◽  
Author(s):  
Sadegh Khalili ◽  
Mohammad I. Tradat ◽  
Kourosh Nemati ◽  
Mark Seymour ◽  
Bahgat Sammakia
Keyword(s):  
Thermal Performance ◽  
Inlet Temperature ◽  
Open Area ◽  
Cfd Simulations ◽  
Physical Separation ◽  
Hot Air ◽  
Airflow Distribution ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact ◽  
Lower Noise

In raised floor data centers, tiles with high open area ratio or complex understructure are used to fulfill the demand of today's high-density computing. Using more open tiles reduces the pressure drop across the raised floor with the potential advantages of increased airflow and lower noise. However, it introduces the disadvantage of increased nonuniformity of airflow distribution. In addition, there are various tile designs available on the market with different opening shapes or understructures. Furthermore, a physical separation of cold and hot aisles (containment) has been introduced to minimize the mixing of cold and hot air. In this study, three types of floor tiles with different open area, opening geometry, and understructure are considered. Experimentally validated detail models of tiles were implemented in computational fluid dynamics (CFD) simulations to address the impact of tile design on the cooling of information technology (IT) equipment in both open and enclosed aisle configurations. Also, impacts of under-cabinet leakage on the IT equipment inlet temperature in the provisioned and under-provisioned scenarios are studied. In addition, a predictive equation for the critical under-provisioning point that can lead to a no-flow condition in IT equipment with weaker airflow systems is presented. Finally, the impact of tile design on thermal performance in a partially enclosed aisle with entrance doors is studied and discussed.

Thermal Performance Evaluation of New Power QFN (Quad Flat No Lead) Packages for Automotive Applications

2004 ◽  
Author(s):  
Victor Chiriac ◽  
Tien-Yu Tom Lee
Keyword(s):  
Steady State ◽  
Thermal Performance ◽  
Numerical Study ◽  
Peak Temperature ◽  
Junction Temperature ◽  
Automotive Applications ◽  
Isothermal Boundary ◽  
Die Attach ◽  
Transient Thermal ◽  
The Impact

An extensive 3-D conjugate numerical study is conducted to assess the thermal performance of the novel Power Quad Flat No Lead (PQFN) packages for automotive applications. Several PQFN packages are investigated, ranging from smaller die/flag size to larger ones, single or multiple heat sources, operating under various powering and boundary conditions. The steady state and transient thermal performance are compared to those of the classical packages, and the impact of the thicker lead frame and die attach material on the overall thermal behavior is also evaluated. Under one steady state (1W) operating scenario, the PQFN package reaches a peak temperature of ~106.3°C, while under 37W@40ms of transient powering, the peak temperature reached by the corner FET is ~260.8°C. With an isothermal boundary (85°C) attached to the board backside, the junction temperature does not change, as the PCB has no significant thermal impact. However, when the isothermal boundary is attached to package bottom, it leads to a drop in by almost 20% after 40 ms. Additional transient cases are evaluated, with an emphasis on the superior thermal performance of this new class of power packages for automotive applications.

scholarly journals Assessment and Evaluation of the Thermal Performance of Various Working Fluids in Parabolic Trough Collectors of Solar Thermal Power Plants under Non-Uniform Heat Flux Distribution Conditions

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3776 ◽  
Author(s):  
Nabeel Abed ◽  
Imran Afgan ◽  
Andrea Cioncolini ◽  
Hector Iacovides ◽  
Adel Nasser
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Molten Salt ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Thermal Stresses ◽  
The Other ◽  
Inlet Temperature ◽  
Parabolic Trough ◽  
Pure Fluids

Changing the heat transfer fluid (HTF) is a viable approach to study the corresponding effect on the thermal and hydraulic performances of parabolic trough collectors (PTC). Three categorized-types of pure fluids are used in this study; water, Therminol® VP-1 and molten salt. The parametric comparison between pure fluids is also studied considering the effect of various inlet fluid temperatures and different Reynolds ( R e ) numbers on the thermal performance. Two low-Reynolds turbulence models are used; Launder and Sharma (LS) k-epsilon and Shear Stress Transport (SST) k-omega models. In order to assess the performance of each fluid, a number of parameters are analyzed including average Nusselt ( N u ) number, specific pressure drop distributions, thermal losses, thermal stresses and overall thermal efficiency of the PTC system. Results confirmed that changing the working fluid in the PTC enhances the overall heat transfer thereby improving thermal efficiency. For a temperature-range of (320–500) K, the Therminol® VP-1 performed better than water, resulting in higher N u numbers, lower thermal stresses and higher thermal efficiencies. On the other hand, for the common temperature-range, both Therminol® VP-1 and molten salt preformed more or less the same with Therminol® VP-1 case depicting lower thermal stresses. The molten salt is thus the best choice for high operating temperatures (up to 873 K) as it does not depict any significant reduction in the overall thermal efficiency at high temperatures; this leads to a better performance for the Rankine cycle. For the highest tested Reynolds number for an inlet fluid temperature of 320 K, a comparison of heat transfer performance (Nusselt number) and the overall thermal efficiency between Therminol® VP-1 and water showed that Therminol® VP-1 is the best candidate, whereas the molten salt is the best choice for a higher inlet temperature of 600 K. For example, at an inlet temperature of 320 K, the Nusselt number and overall thermal efficiency of therminol VP-1 were 910 and 49% respectively as opposed to 443 and 38% for water. On the other hand, at the higher inlet temperature of 600 K, these two parameters (Nusselt number and overall thermal efficiency) were recorded as 614 and 41 % for molten salt and 500 and 39 % for Therminol® VP-1.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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