PTC System Research Articles

Preliminary analysis of a parabolic trough concentrating solar power system integrated with radiative cooling

Abstract Parabolic trough concentrating (PTC) solar power generation is the most technologically mature way of concentrating solar power technology. PTC plants are generally located in flat desert areas, with sufficient sunshine but lacking water for condenser cooling. Herein, a novel cooling system, radiative cooling (RC) integrated with a parabolic trough reflector, is proposed for the PTC system, which means that the waste heat generated during power generation can be radiated to the colder universe by the parabolic reflectors instead of being entirely dissipated to ambient air without water evaporation or land occupation. The simulation results demonstrate the potential of the proposed cooling system to serve as an independent cooling system by adjusting the temperature difference between radiator and ambient within −4.1 to 9.3°C, with 100% water savings and a water pump power consumption rate of 1.8–2.1%. The capital cost of implementing this new cooling system is estimated to be $27.4–54.5/kWe. Furthermore, an annual average of 86.1% of total cooling capacity is dissipated through thermal radiation, with 14.4% directly sent to the cold universe through the atmosphere window, providing a possible method to solve the water problem of power plants in torrid-arid areas and curb global warming if large-scale applications are used.

Global minimum and a heap of low-lying isomers with planar tetracoordinate carbon in the CAl3MgH2- system.

A global minimum and a heap of low-lying isomers with planar tetracoordinate carbon (ptC) are identified in the CAl3MgH2- system by computational quantum chemical investigations. The nature of the chemical bonding in the global minimum ptC isomer is examined using the conceptual quantum chemical tools. The atoms in molecule (AIM) analysis reveals that the global minimum isomer possesses a ptC geometry. Additionally, the adaptive natural density partitioning (AdNDP), electron localization function (ELF), and nucleus-independent chemical shifts (NICS) analysis corroborate the presence of delocalization in the ptC isomer. The delocalization of electron density in the global minimum ptC isomer contributes to attaining structural stability. The results also suggest that the bridging hydrogen plays a crucial role in stabilizing the ptC system. Furthermore, the ab initio molecular dynamics study supports the structural stability of the ptC isomer.

Exergy-economic analysis of a hybrid combined supercritical Brayton cycle-organic Rankine cycle using biogas and solar PTC system as energy sources

Environmental negative impacts of the fossil fuels and intermittent feature of the renewable energies have made their hybrid configurations as a potential solution to overcome their both weaknesses. This research focuses on exergetic, and economic evaluation of a novel hybrid combined supercritical Brayton Cycle-Organic Rankine Cycle in which Solar PTC system and Biogas are considered as the energy Sources. The exhaust heat from the Bryton cycle runs the Organic Rankine cycle while either solar energy (during the daylight hours) or biogas energy (overnight hours) supply additional heat into the Brayton cycle. Sensitivity analyses were carried out in order to ascertain the influence that the system's input characteristics. The total exergy destruction of the system as well as its second law efficiency are computed. The process was not complete until exergoeconomics was used, and it was during this stage that the initial investment rate, the exorgoeconomic component, and the investment return rate are figured out. The findings of these analyses are compiled into a result report. It was concluded that combining the PTC system with the source of the biogas could be an effective way to achieve the desired level of heat delivery to the system.

Performance comparison of PTCs with nanoparticles in water and nanoparticle in thermal oil

The use of nanoparticles to improve the thermal efficiency of PTCs has become a popular area of research. In this study, we present a comparative analysis of the effects of nanoparticles on the thermal performance of PTCs using water and thermal oil as heat transfer fluids. To obtain accurate temperature estimates, we developed a mathematical model that considers heat transfer in both axial and radial directions. The model includes a two-phase flow homogenous model for the liquid phase, as well as nanoparticle concentration, to achieve the best temperature estimation. We validated our model using experimental data and found that the maximum relative error was 2.3% for water and a lower error of 1.5% for thermal oil. Our analysis of thermal efficiency and exergetic efficiency showed that the addition of Al2O3 nanoparticles led to greater improvements in the thermal efficiency for water, even at the same range of nanoparticle concentration. Furthermore, our results demonstrated that exergetic efficiency was generally higher for water than for thermal oil. Overall, this study highlights the potential benefits of using nanoparticles to enhance the thermal efficiency of PTCs. Our findings could help guide the design and optimization of PTC systems in various applications.

An absorber of parabolic trough collector for hydrogen production in a solid oxide fuel cell

Sustainable energy development is a globally attractive and indispensable research area. An effective design process and good sustainable sources are crucial for meeting the objective. This investigation utilizes solar energy by utilizing an effectively designed the integration of two-parabolic trough collector (PTC) with an area of 2.8 m2 to operate Rankine cycle-based fuel cell for hydrogen production. The heat transfer rate is optimized for maximum net energy production to operate the solid oxide fuel cell (SOFC) to maximize the hydrogen production by experimenting with the solar heating system with 3 different heat transfer fluid (HTF) flow rates such as 0.12 kg/s, 0.27 kg/s, and 0.38 kg/s. The experimental outcomes at each flow rate setting were analyzed in such a way that solar radiation received, inlet and outlet temperatures of HTF with respect to clock time, Useful heat gain and Thermal efficiency of solar heating system with respect to solar radiation received and rate of Hydrogen production (kg/s) and Net power output (kW) by sustainable solar power generation arrangement were analyzed with respect to solar radiation received. The results recommended that the flow rate of 0.38 kg/s recorded the highest thermal efficiency 82%, for the heat gain of 27589 kW. Increasing the flow velocity of HTF improves both the solar collector's efficiency and the electrical energy for the fuel cell. As a result, more solar energy is falling on the absorber and enhances the rate of hydrogen production. A preliminary cost analysis was conducted for the PTC system integrated with the hydrogen production system to determine the electric cost based on the solar advisor model (SAM). A black coating material was used to absorb more solar radiation from the PTC.

Ternary CE2Ba2 (E = As, Sb) Clusters: New Pentaatomic Planar Tetracoordinate Carbon Species with 18 Valence Electrons.

18-valence-electron (ve) rule is one important guide for us to design planar tetracoordinate carbon (ptC) species. Using the "polarization of ligands" strategy, the new pentaatomic ptC species CE2Ba2 (E = As, Sb) with 18 ve are designed in this work. Computer structural searches and high-level calculations reveal that the ptC CE2Ba2 (E = As, Sb) species are global minima (GMs) on the potential energy surfaces, whose C center is coordinated by the interspaced E and Ba atoms. CE2Ba2 (E = As, Sb) are also kinetically stable. Chemical bonding analyses reveal that the ptC core is stabilized by two localized C-E σ bonds, one delocalized five-center two-electron (5c-2e) σ bond and one delocalized 5c-2e π bond. One π and three σ bonds collectively conform to the 8-electron counting, which determines the stability of ptC CE2Ba2 (E = As, Sb) species. Interestingly, the delocalized 2π and 2σ electrons render the ptC systems π/σ double aromaticity. Additional 10 electrons contribute to peripheral lone pairs of E and E-Ba bonding.

A research of micro-pulse tube cryocooler with displacer phase shifter

• The phase relationships in the whole displacer PTC system were analyzed. • Three different sizes of a displacer type micro PTCs have been designed. • A 2D CFD model was constructed and used to characterize the displacer micro PTC. • A displacer provides a good phase shifting for a small-cooling-power micro PTC. • A cooling power of 1.5 W@80 K and a COP of 20.96% is obtained by the second micro PTC. Investigations of phase shifters and power recovery mechanisms are of sustainable interest for developing Stirling pulse tube cryocoolers (SPTC) with more compact design and higher efficiency. The warm displacer type SPTC has been demonstrated with a very promising theoretical efficiency benefiting from its strong phase shifting and work recovery functions. Extending this same phase shifting approach to miniature pulse tube refrigerators may provide advantages over the other alternatives, since inertance tubes are severely limited in their phase shifting capability when the associated acoustic power decreases below 20 W. A comprehensive investigation regarding the micro-pulse tube cryocooler with a displacer phase shifter is carried out in this work, including the design of the major components of the cryocooler, theoretical analysis regarding the phase relationship in the whole displacer type cryocooler system, and 2D simulation work addressing the performance of the cryocooler systems. In the optimum phase angle conditions of the 3 mm pulse tube size cryocooler, the mass flow rate leads the pressure wave by 28.8° at the regenerator warm end, and lags the pressure wave by 27.7° at the regenerator cold end. A cooling power of 1.5 W at 80 K and a COP (Coefficient of Performance) of 20.96% is obtained with an input power of 7.4 W.

Effect of receiver geometry on the optical and thermal performance of a parabolic trough collector

AbstractIn this study, the optical and thermal performance of a Parabolic Trough Collector PTC system is investigated theoretically. A series of numerical simulations and theoretical analysis has been conducted to investigate the effect of the receiver geometry and location relative to the focal line on its optical performance. The examined receiver geometries are circular, square, triangular, elliptical and a new design of circular‐ square named as channel receiver. The thermal performance of PTC is studied for different flow rates from (0.27 to 0.6 lpm) theoretically. Results showed that the best optical design is the channel receiver with an optical efficiency of 84% while the worst is the elliptical receiver with an optical efficiency of 70%. Thermally the best design is the elliptical receiver with a thermal efficiency of 85% while the worst is the circular receiver with a thermal efficiency of 82%.

REVIEW PAPER ON POSITIVE TRAIN CONTROL TECHNOLOGY

This review paper focuses on the positive train technology also referred to as PTC (a technology which serves to ensure efficiency, safety and reliability during the train operations in the track) by automatically stopping the train when the train operator seems not to take the required appropriate action when need be, it serves mainly to get rid of accidents caused due to negligence of the train operator or inability to control the freedom of mobility of the train. It looks into the technologies such as Chinese train control systems, Communication based control systems, European train control system all of which can be considered to be part of the Positive train control, other than that, this paper tries to look into what led to creation of this system, the building units and operational layers of a complete PTC system, analyses each unit and its operations and looks further into the challenges affecting the operations of a PTC system try to explore the future trends in this field.

How to Accomplish a Square C(N)4 Substructure of the Planar Tetracoordinate Carbon.

Nitrogen-based groups are usually not used as ligands to coordinate to the ptC atom. However, here we reported only nitrogen-based ligands to accomplish a theoretically successful square planar C(N)4 substructure. The first difficulty in accomplishing a square ptC(N)4 substructure is to conquer the tremendous strain from the planar to tetrahedral arrangements, and the second is to restrict it in a suitable system with the right symmetry. We designed several neutral molecules with the square ptC(N)4 substructures, and the molecules were studied using the density functional theory method at the B3LYP/6-311++G(3df,3pd) and TPSSh/6-311++G(3df,3pd) level of theory. The results of this work show that the molecules are all real minima on the potential energy surface and successfully achieved the square ptC(N)4 substructure in the theoretical method. The group orbitals among the square ptC(N)4 arrangement in the D2d symmetry have been discussed and used to investigate the bonding interactions among all atoms in the square ptC(N)4 substructure. Usually, the ptC systems have 18 valence electrons, but the present ptC systems mentioned in this work have 24 valence electrons, which is unusual for ptC.

Cotton Fabric-Supported Cationic Acrylate Polymer as an Efficient and Recyclable Catalyst for Williamson Ether Synthesis Reaction in Solid-Liquid-Liquid Phase Transfer Catalysis System.

Cotton-based catalytic fabric (CCF) was prepared by the simple padding-drying method with the copolymer of five functional monomers as the modifier and was applied in the solid–liquid–liquid phase-transfer catalysis (SLL-PTC) system. Effects of the structure of the function monomer, the content of the cation, and the loading amount on the catalytic activity of CCF were investigated. The lipophilicity, disperse extent of cationic center, and the accessory to the ion for CCF were influenced by the structure and content of the function monomer. The organic phase was adsorbed on the surface of the catalytic fabric, and the novel catalytic cycle in the PTC system was initiated. The anion in the aqueous phase diffuses through the interfacial region to the site for ion exchange. Bond-forming reaction was initiated in the interfacial region between the organic phase on the fabric and the aqueous phase. The conversion rate for Williamson ether synthesis reaction reached 92%, and CCF could be reused five times in this SLL-PTC system.

Interatomic potentials for Pt-C and Pd-C systems and a study of structure-adsorption relationship in large Pt/graphene system

Graphene-supported platinum (Pt) and palladium (Pd) nanoclusters have attracted attention as electrocatalysts for proton exchange membrane fuel cell (PEMFC) because of their high activity and resistance to CO poisoning. However, metal nanoparticles are weakly adsorbed to the graphene and easily migrate on the surface, causing sintering and loss of chemical activity. A thorough understanding of structure-adsorption relationship is important to design robust catalysts with high adsorption ability to stabilize metal nanoparticles, but this relationship is still not well understood, particularly in large scale systems (2–5 nm). Therefore, to investigate the structural evolution at atomic scale with atomistic simulations, we have developed interatomic potentials for the Pt-C and Pd-C binary systems, based on the second nearest-neighbor modified embedded-atom method (2NN MEAM) formalism. These potentials reproduce various fundamental properties of the alloy systems in reasonable agreement with the experimental data and first-principles calculations. Molecular dynamics simulations employing the 2NN MEAM potential were carried out to analyse structural factors that have decisive effect on the adsorption energy, by changing the symmetry of the nanoparticles and the configuration of the nanoparticles adsorbed to graphene. These factors were characterized via coordination numbers, number of Pt atoms in contact with the graphene and adsorption site. The results of our study suggest avenues for stabilizing and immobilizing metal clusters on graphene in large systems.

Coagulation, anticoagulation and fibrinolytic system of blood in patients with acute ischemic heart disease and features of changes in combination with diabetes mellitus (cohort prospective study)

Aim. To evaluate the clotting, anticoagulant and fibrinolytic activity of blood in patients with acute coronary heart disease (ACHD) and to determine the peculiarities of changes when combined with ACHD and DM2.Materials and methods. 60 persons were diagnosed MI with ST-segment elevation, MI without ST-segment elevation, unstable angina. Among them: 30 patients with ACHD (Group I), 30 patients with ACHD in combination with DM2 (Group II) and 15 practically healthy subjects (control group). The average age of the patients is 64.2±10.01 years, the number of men is 30 (50 %), and women – 30 (50%). Patients were diagnosed with hemostatic parameters in venous blood.Results. With a general similarity of changes in the anticoagulant system in both groups, attention was drawn to the significant exacerbation of antithrombin activity in patients in group II, which was accompanied by oppression of the PtC system. Thus, the content of ATIII in this group was lower than the control group by 27.8 % (65.5 [54.0; 76.0], p <0.001), and PtC decreased by 37.2 % (0.66 [0, 6, 0,7], p <0,001), whereas in patients of group I anticoagulant activity decreased only at the expense of ATIII-78,0 [74,0; 82.0] versus 90.0 [80.0; 110,0], p<0,01), while the level of PtC did not undergo significant changes. The indicated changes took place against the suppression of fibrinolytic activity in the two groups under study. At the same time, XIIa fibrinolysis appeared to be the most prolonged in group II, namely, 1.6 times in comparison with the same indicator in group І (20.4 [18.5; 23.7] vs. 13.05 [12.6; 13, 7], p<0.001) and 2.6 times different from control (8.0 [7.0; 11.0]; p<0.001).Conclusions. Changes detected as a result of studying the coagulation linkage of hemostasis in the study groups indicate acceleration of blood coagulation at all stages of coagulation. The presence of DM2 is characterized by a number of changes from the system of hemostasis, which determine the increased risk of thrombotic complications

Energy harvesting using solar ORC system and Archimedes Screw Turbine (AST) combination with different refrigerant working fluids

In this research, an energy harvesting system was developed for power generation using a combination of an Archimedes Screw Turbine (AST) and a solar Organic Rankine Cycle (ORC) system. An AST was numerically used and optimized for producing mechanical power as an energy harvesting technique. Different structural parameters including the screw inclination angle, number of flights and the screw length were considered. A parabolic trough concentrator was numerically modeled as a heat source of the ORC system. Two different types of absorber were considered using a smooth and corrugated tube. Different ORC working fluids were investigated in the solar ORC system including R134a, R245ca, R245fa, R152a, R113, R11, and R114b. The results of numerical modeling were validated with experimental results and good agreement was found. The results revealed that R113 at the saturated condition at turbine inlet gave the highest ORC net power, ORC efficiency, and total efficiency compared to the other investigated working fluids. The solar PTC system with the corrugated tube showed the higher ORC net power, and overall efficiency compared to the smooth tube as the PTC receiver. The highest efficiency resulted in the screw length of 1.5 m was 58.24% with inclination angle of 25° and flight number of 1. Finally, the optimized characteristics of power generation system including a solar ORC system and a screw turbine (hybrid system) were presented to harvest energy. Application of the presented hybrid system is an acceptable way for increasing and optimizing the ORC power generation.

Catalytic Process for the Hydroxide-Initiated Reaction of the “Weakly Acidic” Substrate in the Third-Liquid Phase-Transfer Catalytic System

Generation processes of the third phase and the carbanion for Horner−Wadsworth−Emmons (HWE) reaction of the “weakly acidic” substrate in the third−liquid PTC (TLPTC) system were investigated. The third phase was consisted of Et2PO4− (diethyl phosphate anion), Br− and TBA+ (tetrabutylammonium), and the mole of Et2PO4− was 6.65 times of that of TBA+. The true catalyst was the complex of TBA+Et2PO4− and TBAB. Excess Et2PO4− could be associated with TBA+Et2PO4−, resulting the generation of the third phase. The “true” catalyst showed a higher catalytic activity and the reaction equilibrium constant for the third phase cycle was 26−times of that for the organic phase cycle. Results from background reaction, interfacial tension and H−D exchange reaction experiments suggested that the phosphonate were deprotonated by “naked” OH− without help of the catalyst. These novel generation processes of the third phase and the carbanion were the key factors for this efficient TLPTC system.

Structure and Bonding in CE5- (E=Al-Tl) Clusters: Planar Tetracoordinate Carbon versus Pentacoordinate Carbon.

The structure, bonding, and stability of clusters with the empirical formula CE5- (E=Al-Tl) have been analyzed by means of high-level computations. The results indicate that, whereas aluminum and gallium clusters have C2v structures with a planar tetracoordinate carbon (ptC), their heavier homologues prefer three-dimensional C4v forms with a pentacoordinate carbon center over the ptC one. The reason for such a preference is a delicate balance between the interaction energy of the fifth E atom with CE4 and the distortion energy. Moreover, bonding analysis shows that the ptC systems can be better described as CE4- , with 17-valence electrons interacting with E. The ptC core in these systems exhibits double aromatic (both σ and π) behavior, but the σ contribution is dominating.

Energy, Exergy and Economic Feasibility Analyses of a 60 MW Conventional Steam Power Plant Integrated with Parabolic Trough Solar Collectors Using Nanofluids

The present study focuses on the detailed technical and cost-effective feasibility analyses of a 60 MWe steam power plant integrated with parabolic trough solar collectors. Aluminum oxide (Al2O3) nanoparticles are mixed with thermal oil to be used as a heat transfer fluid in the collector loops. The electric power is generated using steam Rankine cycle. For this purpose, the steam turbine of 60 MWe production capability of Teknecik power plant located in Northern Cyprus has been analyzed and an integrated solar steam turbine system is presented which generates electric power. Detailed energy and exergy assessment of the solar thermal plant is carried out. The important parameters are examined including overall energy and exergy efficiencies, exergy destruction rate and system performance by varying direct normal irradiation (DNI), mass flow rate of the collector, ambient and inlet temperatures. Furthermore, thermal power available from the solar field at various solar multiples is assessed, and levelized energy cost has been calculated. Results show that turbines are the main source of exergy destruction (63855 kW) followed by feedwater heaters and boiler. Overall energetic and exergetic efficiencies of the system are observed to be 22.64 and 23.83%, respectively. The integration of PTC system with conventional plant results in a reduction in fuel consumption which significantly brings down the CO2 emissions by almost 33%.

Performance Comparison of Parabolic and Flat Plate Solar Collectors Utilizing in the Heating System of a Room-An Experimental Investigation

In the present study, two solar heating systems, including flat plate solar collector (FPC) and parabolic solar collector (PTC) for heating a room were experimentally studied and compared with each other. For doing this, an experiment was conducted in the winter and the performance of these two systems was first measured and then compared with each other. It should be mentioned that the PTC system was manufactured and tested in this study. The ambient temperature, solar radiation intensity, and working fluid temperature in different locations of the two heating systems were measured. The results showed that the PTC solar heating system has higher collector and total efficiencies compared to the FPC heating system. The total efficiencies of the FPC and PTC systems were 6% and 12%, respectively. It was also indicated that the PTC system with lower occupied space can produce higher thermal energy quality compared to the FPC heating system. It was also concluded that the PTC solar heating system is very suitable and efficient to utilize in the heating system of the building.

Numerical Study and Optimization of Parabolic Trough Solar Collector Receiver Tube

In this study, the parabolic trough collector's (PTC) performance is analyzed. In order to achieve this goal, the adopted procedure comprises two main steps. In the first step, the concentrated solar heat flux densities in the solar concentrator focal zone are calculated by soltrace software. In the second step, computational fluid dynamics (CFD) simulations are carried out to analyze and to optimize the thermal performance of the tube receiver. The calculated heat flux densities by soltrace software are used as wall heat flux boundary conditions for the receiver tube. The effect of the receiver tube diameter variation on the PTC thermal performance is studied. A new type of receiver tube is tested. This latter is covered with a metallic thickness. The performance of tube receiver covered with a metallic layer for different diameters is compared to those of the same diameters without the addition of metallic thickness. It has been found that increasing tube metallic thickness enhances the performance of PTC system comparing to the tubes of the same diameter and crossed by the same flow rates.

Mechanism and kinetics of Horner–Wadsworth–Emmons reaction in liquid–liquid phase-transfer catalytic system

Liquid–liquid phase-transfer catalytic (LL-PTC) system suitable for symmetric distyryl compounds could not be used to synthesize asymmetric derivates. Relatively low value, the time-dependence of the interfacial tension with only phosphonate in the organic phase and high background reaction rate demonstrated that “weakly acidic” phosphonate was adsorbed on the interfacial layer and deprotonated by excess “naked” OH− without the help of the catalyst. Phase-transfer catalyst participated in the transfer process of the carbanion and accelerated the bond-forming reaction. However, the distributing region for the carbanion ion-pair in this PTC system was dependent on the usage of the catalyst and the mechanism would change from the interfacial mechanism to the extraction mechanism. Accordingly, the mechanism including adsorption, deprotonation, ion-exchange reaction, distribution and bond-forming reaction was proposed, and the kinetic model was performed. The activation energy and the dependence of catalytic activity on lipophilicity and accessibility parameter also supported the proposed mechanism. The rate-determining step was not the bond-forming reaction for each mechanism and the apparent reaction rate was relevant to the generation rate of the carbanion and the ion-exchange reaction rate.