Green Processing and Synthesis 2020; 9: 595–649 Review Article Pablo D. Tagle-Salazar, Krishna D.P. Nigam, and Carlos I. Rivera-Solorio* Parabolic trough solar collectors: A general overview of technology, industrial applications, energy market, modeling, and standards https://doi.org/10.1515/gps-2020-0059 received May 28, 2020; accepted September 28, 2020 Nomenclature Abstract: Many innovative technologies have been devel- oped around the world to meet its energy demands using Acronyms renewable and nonrenewable resources. Solar energy is one of the most important emerging renewable energy resources in recent times. This study aims to present AOP advanced oxidation process fl the state-of-the-art of parabolic trough solar collector ARC antire ective coating technology with a focus on different thermal performance CAPEX capital expenditure fl analysis methods and components used in the fabrication CFD computational uid dynamics ffi of collector together with different construction materials COP coe cient of performance and their properties. Further, its industrial applications CPC compound parabolic collector (such as heating, cooling, or concentrating photovoltaics), CPV concentrating photovoltaics solar energy conversion processes, and technological ad- CSP concentrating solar power vancements in these areas are discussed. Guidelines on DNI direct normal irradiation fi - ff commercial software tools used for performance analysis FDA nite di erence analysis fi - of parabolic trough collectors, and international standards FEA nite element analysis related to performance analysis, quality of materials, and FO forward osmosis fi durability of parabolic trough collectors are compiled. FVA nite volume analysis Finally, a market overview is presented to show the im- GHG greenhouse gasses portance and feasibility of this technology. We believe the GNI global normal irradiation compilation of reviews related to the above aspects will HPC heterogenous photocatalysis fl further provide impetus for the development of this tech- HTF heat transfer uid nology in the near future. IEA International Energy Agency LCOE levelized cost of energy Keywords: Solar energy, parabolic trough collector, indus- LFC linear Fresnel collector trial application, energy market, performance modeling MED multieffect distillation MSF multistage flash NCC nonconcentrating collectors O&M operational and maintenance - * Corresponding author: Carlos I. Rivera Solorio, Tecnologico de PD parabolic dish Monterrey, School of Engineering and Sciences, Ave. Eugenio Garza PFP photo-Fenton process Sada 2501, Monterrey, N. L., México, 64849, e-mail: [email protected] PTC parabolic trough collector Pablo D. Tagle-Salazar: Tecnologico de Monterrey, School of PVC photovoltaic concentrator Engineering and Sciences, Ave. Eugenio Garza Sada 2501, RO reverse osmosis Monterrey, N. L., México, 64849 SC selective coating Krishna D.P. Nigam: Tecnologico de Monterrey, School of s-CO supercritical carbon dioxide Engineering and Sciences, Ave. Eugenio Garza Sada 2501, 2 Monterrey, N. L., México, 64849; Department of Chemical SHIP solar heating industrial process Engineering, Indian Institute of Technology, Delhi, New Delhi, SG steam generation 110016, India ST solar tower Open Access. © 2020 Pablo D. Tagle-Salazar et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 International License. 596 Tagle-Salazar et al. TES thermal energy storage 4 inner surface of cover glass T-PVC thermal-photovoltaic concentrator 5 outer surface of cover glass A atmosphere C sky S outside of the brackets (extended surface) Symbols a123,,aa coefficients of thermal losses A aperture area (m2) 1 Introduction Cr concentration factor ( ) Fc soiling factor dimensionless In the last few decades, the energy demand of industries ( 2) Ib beam direct solar radiation W/m and commercial sectors has substantially increased. Most ff ( 2) Id di use solar radiation W/m of the energy has been generated by using fuel fossil fi K K(θ) incident angle modi er as function of technologies that have increased the emission of pollu- θ incidence angle tants to the atmosphere, contributing to global warming ( ) Q heat received W and deterioration in the health of humankind. Solar en- fl q̇ab,type type heat transfer ow per length from ergy is one of the green energy resources that can be used a b ( ) boundary to boundary W/m to reduce the consumption of fuel fossils to meet the fl q̇a incident heat transfer ow per length at demands of the industrial and the commercial sectors. a ( ) boundary W/m Further, the cost of energy of solar photovoltaic (PV) ( ) q̇ l heat losses of receiver W/m and solar thermal power has tended to fall as their per- a ( ) Ta temperature at boundary °C formance efficiency increased in late years [1–3]. Many ( Tr reduced temperature ΔcosTIfb/( ( θ )), technologies are used in industry to convert solar energy 2 ) m K/W into thermal and electrical energies. These technologies ( ) vw wind velocity m/s are classified and represented in Figure 1. Solar technol- ogies can be classified as either passive or active, de- pending on the type of system, with active technologies requiring external components, such as pumps or elec- Greek letters tronic control, to convert energy. The type of energy sup- plied to the process is the energy produced directly from αsc absorptivity of the selective coating the solar collection system used in the industrial process, γ interception factor which can be either thermal or nonthermal (e.g., PV). ff - ΔTab temperature di erence between average ab Solar collector type is determined based on the total ra- - sorber temperature and ambient tempera diation transmitted to the reception area compared to the ( ) ture °C radiation received in the collection area. Solar concentra- ff fl ΔTf temperature di erence between average uid tion is achieved by reflecting or refracting solar radiation ( ) temperature and ambient temperature °C from a large area (collection) to a smaller one (receiver) ffi η overall e ciency using mirrors or lenses. The concentration factor is the ffi ηop optical e ciency ffi ( ) ηop,0 peak optical e ciency at normal incidence η peak thermal efficiency peak Solar Energy fl ρm re ectance of the mirrors Technologies τcg transmittance of the cover glass Energy of System Collecon process Boundaries Acve Thermal Concentrated Non- fl Passive Non-thermal 1ave uid mean bulk Concentrated 2 inner surface of pipe 3 outer surface of pipe Figure 1: Classification of solar energy technologies. Parabolic through solar collectors: A general overview of technology 597 ratio between the collection area and the receiver area, so types of solar tracking are used in PTCs namely, north- it is a dimensionless geometric factor having a value south and east-west, as represented in Figure 3. Tracking greater than 1 for concentrating technologies. Parabolic methods are so named based on the direction of rotation trough collectors (PTCs) have a common concentration of collector’s aperture plane. In north-south tracking, the ratio above 10 and lesser than 100, which is considered receiver (parallel to tracking axis) is aligned to east-west as “medium concentration” [4]. To realize energy conver- direction, so the collector’s aperture plane rotates from sion, concentrating technologies require external compo- north to south and vice versa. The opposite case is the nents, which are generally related to fluid transport or east-west tracking type in which the receiver is aligned to solar tracking, and so they are considered active. north-south direction and the aperture plane rotates from In industrial applications, solar concentration (col- east to west. The north-south tracking method has the lectors) technologies are divided into four technologies: advantage of lower tracking energy consumption, but PTCs, linear Fresnel collectors (LFCs), solar towers (STs), with a higher end- effect. For east-west tracking systems, and parabolic dishes. Table 1 represents the principal the opposite is the case (lower end effect and higher en- differences between these technologies based on their ergy consumption). functionality. The receiver can be mobile or stationary These collector systems have the following advantages: depending on the concentration process, and the shape - Low emissions to the environment during the system’s of the focus (where the sunlight is concentrated) can be life cycle: Right from the manufacture of components either a line or a point. Concentration factor is one of the (structure, electronic components, anodized mirrors, most important parameters which differs among these etc.), to their use in final deposition, the environmental technologies. This factor is usually smaller than 100 for impact from the life cycle of these collectors is lower PTCs and LFCs, whereas for the others it can be greater than that from energy technologies using fossil fuels. than 1,000. Table 2 displays the main technical and op- Burkhardt et al. [5] realized a life cycle assessment of erational characteristics of these four technologies. PTC about a 103-MW concentrating solar power (CSP) plant and ST have some advantages, such as maturity and ty- based on PTC when comparing some plant designs. pical capacity, making them the most important technol- Klein and Rubin [6] realized a similar life cycle study ogies used for solar energy conversion. Nowadays, PTC is with a 110-MW CSP plant. Both studies reported an the most deployed technology and has major share in the estimation of between 30 and 70 kg