Numerical simulation of a parabolic trough collector containing a novel parabolic reflector with varying focal length

Kulahli, Mehmet Canalp; Özen, Songül Akbulut; Etemoğlu, Akın Burak

doi:10.1016/j.applthermaleng.2019.114210

Cited by 19 publications

(5 citation statements)

References 31 publications

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“…Based on Figures 16–18, the method described in Section 2 shows success in optimizing the TP under different operating conditions and sun positions. While Gong et al [ 45 ] and Kulahli et al [ 47 ] improved the PTC thermal efficiency by 4.9% and 0.21%, the present method shows 8.3% higher overall efficiency compared to the PTC.…”

Section: Resultsmentioning

confidence: 58%

“…However, they reported that the increase in pumping power offsets the increase in thermal efficiency. A PTC with variable focal length was numerically investigated by Kulahli et al [ 47 ] who achieved a 0.21% increase in thermal efficiency by optimizing the flow rate. Hoseinzadeh et al [ 48 ] utilized the local concentration ratio to optimize a PTC using the Monte Carlo method.…”

Section: Introductionmentioning

confidence: 99%

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A Novel Optimized Solar Trough Profile for Better Solar Energy Collection, Storage, and Levelized Cost

Shaaban

2022

Energy Tech

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Clean and sustainable renewable energy resources provide a feasible solution for electrical power generation nowadays. This encourages many countries around the world to increase their renewable energy share. In a reference case, Egypt aims at increasing its renewable energy share in electricity generation from 9% in 2014 to 25% in 2030. [1] High rates of solar energy are available most of the year in Egypt. According to the solar atlas of Egypt, [2] the annual averaged direct normal irradiance (DNI) in Egypt is 292 W m À2 while the monthly averaged maximum DNI reaches 450 W m À2 . Moreover, Egypt has 2554 and 2208 kWh m À2 of available solar energy for concentrated solar power (CSP) and photovoltaic (PV), [2] respectively. Therefore, both the CSP and PV technologies are implemented in Egypt. While PV is cheaper than CSP, the latter is fully dispatchable. [3] Moreover, a PV with storage batteries is more expensive than a CSP with thermal energy storage (TES). [3] Therefore, recent investigations show that CSP and PV are complementary technologies rather than competitive ones. [3][4][5] However, Egypt has not integrated CSP and PV technologies in commercial power plants so far. CSP is a good choice for Egypt due to the high DNI and the hot climate conditions. Accordingly, Egypt has constructed a CSP plant in Kuraymat (100 km south of Cairo). The solar field in Kuraymat implements parabolic trough collectors (PTCs) with a total field aperture area of 130 800 m 2 . [6] Figure 1 shows the main components of the parabolic trough collector (PTC). A parabolic-shaped reflector collects the sun's rays and reflects them through a glass tube onto a receiver tube. The receiver tube absorbs the incident and reflected solar radiation and utilizes this energy to increase the temperature of a heat transfer fluid (HTF) that flows inside the receiver tube. The levelized cost of energy (LCOE) is one of the most significant parameters that indicate the feasibility of an electrical power generation technology. It is always desired to reduce the LCOE of every power generation technology to make it commercially competitive. Reducing the LCOE of the CSP plants with PTC technology can be attained by increasing the overall thermal efficiency while reducing the capital and running costs. El Hamdani et al. [7] estimated the impact of the DNI, solar multiple, mirrors efficiency, cycle efficiency, and absorber efficiency on the reduction of the LCOE of a 1MWe parabolic trough plant at different sites in Morocco. Aseri et al. [8] investigated the possibility of reducing the high capital cost of PTCs. They attained a 29.9% reduction in capital cost by implementing large aperture area PTCs with molten salt as both HTF and storage medium. Lopes et al. [9] showed a 6.3% reduction in LCOE when applying the HitecXL molten salt in a 50 MWe/7.5 h-of-storage power plant. They simulated the plant performance using NREL's System Advisor Model (SAM) software. [10] Tahir et al. [11] estimated the minimum LCOE for a 100 MW PTC power plant in six different ...

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Section: Resultsmentioning

confidence: 58%

Section: Introductionmentioning

confidence: 99%

A Novel Optimized Solar Trough Profile for Better Solar Energy Collection, Storage, and Levelized Cost

Shaaban

2022

Energy Tech

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“…In particular, at a flow rate of 3 L/min, the efficiency and the outlet temperature of the pipe with the U-tube was 34% 52.4 °C respectively, while the efficiency and the outlet temperature of the pipe without the U-tube and at the same flow rate was 28% 52 °C (see Figure 15). Researchers (Kulahli et al, 2019) present a novel parabolic reflector for the axial focal length variable Parabolic Trough Collector (PTC). The reflector contains a focal length that changes in the longitudinal direction while maintaining a fixed focal line.…”

Section: By Changing Shape Of Absorber Tubementioning

confidence: 99%

Parabolik Oluklu Solar Kollektörlerin Termal Verimliliğinin Artırılması: Genel Bakış

YEŞİLDAL,

ÖZAKIN,

BAAMEL

et al. 2023

Karadeniz Fen Bilimleri Dergisi

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This article examines various methods to enhance the thermal efficiency of parabolic trough solar collectors (PTCs), both theoretically and experimentally. These methods include increasing the surface area of the absorber tube to increase its ability to absorb solar energy, placing a tube inserts inside the tube to induce turbulence and hence improve heat transfer. Among other methods are also minimization of reflection by using selective coatings on the surface of the absorber tube. Additionally, increasing the thermal conductivity of the working fluid, or modifying or altering the shape of the absorber tube or the reflective surface have also been shown to have improved thermal performance by minimizing energy losses due to conduction, convection, and radiation. All these and similar approaches that address and improve system parameters lead to improved efficiency and thermal performance, but they also entail a pressure drop and increase the cost of the system. In this study, the techniques that are used to improve the thermal efficiency of PTCs are addressed and presented in detail along with the findings of previous studies.

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“…Authors concluded that the maximum reduction in thermal loss at the absorber temperature of 600°C was 43.8% whereas the thermal efficiency enhancement was 16.7%. Investigating the effect of the focal line is also taken into consideration by Kulahli et al in which they proposed a new design for the parabolic trough with a changing focal length in the axial direction. The maximum enhancement in the thermal efficiency was 0.21% and 0.63% improvement in the thermal gain compared with the conventional design.…”

Section: Effects Of the Collector Design On The Thermal Performancementioning

confidence: 99%

An extensive review of various technologies for enhancing the thermal and optical performances of parabolic trough collectors

Abed

Afgan

2020

Int J Energy Res

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A wide range of engineering industrial applications require both the thermal and optical efficiencies of the system to be maximized with a reasonable low penalty for the friction factor and subsequently low losses in pressure. Among the family of concentrated solar power systems, parabolic trough collectors (PTCs), which have recently received significant attention, face similar challenges. The current work presents an extensive review of the PTC systems comparing recent and past technologies, which are widely being used to improve and enhance the thermal and optical efficiencies. Furthermore, the techniques used for single and two-phase flow modeling in numerical simulations, design variables, and experimental processes have been discussed in detail. The article also presents different numerical methods and analytical approaches of implementing the nonuniform solar distribution with different design parameters. Four main technologies are comprehensively addressed to effectively enhance the thermal performance of the PTCs; changing working heat transfer fluids, replacing the working fluids by nanofluids (single and hybrid) that have higher thermal-physical properties than those of base working fluids, inserting different tabulators with various design configurations, and finally combining the advantages of nanofluids and swirl generators in the same application. The article also critically summarizes the studies investigating the enhancement of thermal performance: use of novel design of PTCs and passive heat transfer enhancement techniques. Finally, a wide range of numerical and experimental studies are proposed for the future work related to the aforementioned main technologies. K E Y W O R D Sheat transfer enhancements, nanofluids, parabolic trough solar collectors, solar thermal energy, tabulators, thermal and optical performances

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Numerical simulation of a parabolic trough collector containing a novel parabolic reflector with varying focal length

Cited by 19 publications

References 31 publications

A Novel Optimized Solar Trough Profile for Better Solar Energy Collection, Storage, and Levelized Cost

A Novel Optimized Solar Trough Profile for Better Solar Energy Collection, Storage, and Levelized Cost

Parabolik Oluklu Solar Kollektörlerin Termal Verimliliğinin Artırılması: Genel Bakış

An extensive review of various technologies for enhancing the thermal and optical performances of parabolic trough collectors

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