Parabolic Solar Collector Research Articles

The effect of using multichannel twisted tape and nanofluid on the absorber tube's heat transfer and the efficiency of a linear parabolic solar collector

One of the most important tools for using solar energy is parabolic solar collectors (SCs). To improve the performance of these collectors, creating rotation in the fluid flow by placing twisted tape or helical paths inside the tube is an effective passive method. In this study, the role of three- and four-channel twisted tapes in increasing the rate of heat transfer (RHT) inside the collector adsorbent tube containing water-copper oxide nanofluid and its effect on energy and exergy efficiencies has been investigated numerically. Finite volume method, SIMPLE algorithm and SST k-w turbulence model for solving the equations. The study was conducted for Re = 20000–80000. Numerical results indicated that the highest Nusselt number was related to nanofluids with a volume fraction of 4% in Reynolds number of 80,000, equal to 54.7. Furthermore, the highest coefficient of thermal performance of three-channel twisted tape occurs in Reynolds of 80,000 with a volume fraction of 4%. Moreover, the best efficiency of SCs is related to nanofluid flow with Reynolds of 80,000 and volume fraction of 4%, which is equal to 26%. Furthermore, nanofluid with a volume fraction of 4% has the highest exergy efficiency.

Energetic and Exergetic performances of a parabolic solar trough collector working with TiO2 & Al2O3 nanofluids for variable temperature applications

ABSTRACT Thermal efficiency of parabolic solar trough collectors (PTCs) can be enhanced by dispersing TiO2 nanoparticles into the conventionally used heat transfer fluids. In the present experimental work, a one-dimensional mathematical model is designed to study the outcome of TiO2 nanoparticles dispersed in the base fluid for variable temperatures PTCs. The major finding of this work is that the TiO2 nanofluid enhances the thermal efficiency of the PTC slightly. Elevated working temperatures are most appropriate for nanofluids using to generate highest gain of energy discharged. It is found that the Exergetic effectiveness enhancement is most important than energetic effectiveness. The maximum exergy efficiency is achieved by TiO2 based nanofluid and is about 8.09%. The highest relative gain of thermal energy discharged is found to be 9.66% higher than the water-based collector by using 0.3% of TiO2 in the base fluid.

Modeling, Validation, and Analysis of a Concentrating Solar Collector Field Integrated with a District Heating Network

In recent years, concentrating solar collectors have been integrated with several district heating systems with the aim of taking advantage of their low heat losses. The present study investigates the Brønderslev combined heat and power plant, which consists of a 16.6 MW parabolic trough collector field, two biomass boilers, and an organic Rankine cycle system. The study focuses on the solar collector field performance and integration with the district heating network. An in situ characterization of the parabolic solar collector field using the quasi-dynamic test method found that the field had a peak efficiency of 72.7%. Furthermore, a control strategy for supplying a constant outlet temperature to the district heating network was presented and implemented in a TRNSYS simulation model of the solar collector field. The developed simulation model was validated by comparison to measurement data. Subsequently, the simulation model was used to conduct a sensitivity analysis of the influence of the collector row spacing and tracking axis orientation. The results showed that the current suboptimal tracking axis rotation, made necessary by the geography of the location, only reduced the annual power output by 1% compared to the optimal configuration. Additionally, there were only minor improvements in the annual heat output when the row spacing was increased past 15 m (ground cover ratio of 0.38).

PERFORMANCE EVALUATION OF PARABOLIC CONCENTRATOR WITH THERMAL STORAGE SYSTEM FOR DOMESTIC APPLICATIONS

Solar energy is a free natural resource but its harvesting requires a high capital investment whichprohibits its maximum exploitation. A Parabolic Dish Solar Collector (PDSC) with a thermalstorage system was been constructed and developed to harness solar beam radiation. The thermalstorage system and PDSC were constructed using locally and less cost materials such asgalvanized metal sheet and steel rods curved to obey the equation of a parabola then weldedtogether with circular support rings which was then lined with stainless steel reflector pasted forthe construction of PDSC. The receiver was made of blackened aluminium material incorporatedwith coiled copper tube carrying water as the heat transfer fluid. A parabolic dish which acts of aheat collector is used to track and reflects solar radiation at a single point (focus) on a receiverabsorber. Heat transfer from the solar collector to the storage tank was done by usingthermosyphonic principle to circulate the water (heat transfer fluid) between storage tank andheating system (receiver). The evaluation of thermal storage and analyzing the efficiency oftracking and non-tracking parabolic dish solar collector was carried out during month of June,2020 for the composite climate of Sokoto. According to the finding, the efficiency of trackingPDSC with thermal storage system and non- tracking PDSC with thermal storage tank weredetermined and obtained to be 52.9% and 50% respectively.Keywords: thermal efficiency, parabolic dish collector, solar radiation, storage system andstainless steel reflector.

Comparison of the effect of using helical strips and fines on the efficiency and thermal–hydraulic performance of parabolic solar collectors

In the near future, the construction of a solar thermal power plant will be considered an important strategy for energy supply from the point of view of environmental compatibility and sustainable development. Therefore, improving the thermal performance of parabolic collectors in these power plants has become a necessity. One of the most effective methods in connection with increasing the efficiency of the parabolic collector absorber pipe is to place the fines and spiral strips inside the absorber pipe. In this study, the numerical simulation of the thermal hydraulic performance of a linear parabolic collector absorber pipe with rectangular fines and helical strips in a stable, three-dimensional state under a turbulent flow regime with the help of Ansys Fluent software. Also, in order to model the turbulent flow and discretize the governing equations, the K-epsilon turbulence model and the simple algorithm have been used, respectively. For this purpose, geometries including 4 and 8 fins with thicknesses of 2 and 4 mm and also helical strips with steps of 0.25 and 0.5 m and thicknesses of 2, 4 and 8 mm have been used. According to the results, the average Nusselt number and the efficiency of the solar collector are strongly influenced by rectangular fines and spiral strips. Furthermore, the addition of rectangular fines and spiral strips increases the thermal performance and efficiency of the solar collector significantly compared to when the solar collector is simple. Examining the evaluation criteria of thermal hydraulic performance in the case of using rectangular fins and helical strips, it was observed that the optimal conditions in Reynolds number are equal to 10,000 and respectively using 8 fins with a thickness of 2 mm and using a turbulator with a thickness of 4 mm and a step of 0.5 mm.

Improving the efficiency of parabolic solar collector (PSC) containing magnetic nanofluid with absorber pipe equipped with square twisted turbulator

The effects of a twisted tape (TWT) with a square cut within the collector absorber pipe on heat transfer between the fluid and the absorber pipe, as well as energy and exergy efficiency, are quantitatively studied. Nanofluids (NFs) 66 -Therminol Fe3O4 with nanoparticles volume fraction (NPVF) of 1%, 2%, and 4% is used as the working fluid. For numerical simulation SIMPLEC algorithm, FVM have been used. Turbulent flow simulations are performed using the RNG k-ε model at three Re of 15000, 25000, and 35000. When compared to a pipe without a tape, the findings showed that using a square TWT improves the rate of heat transfer. The maximum thermal performance coefficient occurs at Re of 15,000 and a NPVF of 4%. The findings show that employing NPs suspended in the base fluid improves the solar collector's energy and exergy efficiency, with a volume fraction of 4% providing the greatest performance. The maximum PEC occurs at Re of 15,000 and a NPVF of 4%, which is equal to 1.59, indicating an increase of 67% compared to the performance of the absorber pipe with the same working fluid and without a TWT.

Improving the thermal-hydraulic performance of parabolic solar collectors using absorber tubes equipped with perforated twisted tape containing nanofluid

The thermal and hydraulic efficiency of a parabolic trough solar collector is investigated in this study. The collector absorber tube is equipped with twisted tape with circular holes containing water-copper oxide nanofluid with three nanoparticles volume fractions of 1%, 2% and 4%. In three modes (d/W = 0.5, 0.7, 0.9), circular holes are constructed for the ratio of the circle's diameter to the twisted tape's breadth. All turbulent flow simulations were done using the SIMPLEC algorithm, FVM and RNG k-ε model in three Reynolds numbers as 10,000, 20,000 and 30,000. Studies have shown inserting twisted tape with a circular hole increases the pressure drop and the heat transfer rate compared to a pipe without twisted tape. The highest coefficient of thermal performance occurs in Reylond number of 10,000 and a nanoparticles volume fraction of 4%. The findings indicate that using nanoparticles improves the solar collector's energy and exergy efficiency. As a result, the best collector performance was obtained when using nanofluids with an nanoparticles volume fraction of 4%.

Mini cold storage using the parabolic solar trough: An appropriate technology for perishable agricultural product

Limited storage of perishable agricultural products is a common problem for small-scale farmers. Therefore, our approach for this problem is to develop a low operating cost mini cold storage using solar energy. The integration of solar thermal energy with vapor absorption refrigeration systems was studied. In vapor absorption systems, heat energy is taken as the source of input energy and the performance characteristics depend on heat energy supplied and pump work used. The novelty of our project is that it uses a parabolic solar heat collector to run a vapor absorption refrigeration system using heat energy extracted from solar energy. In this cyclic process, the refrigerating effect is produced. By utilizing this mini cold storage system, tomatoes can be stored for four weeks whereas, with room temperature storage, it only lasts one week. This appropriate technology promises small-scale farmers to keep their perishable agricultural products for several weeks without additional storage costs.

Thermodynamic and economic investigation of an innovative multigeneration plant integrated with the solar collector and combustion chamber

Today, effective and low-emission energy systems have been needed to combat environmental problems and to satisfy the growing energy requirement in a sustainable way. In this case, it has gained importance to the production of different useful commodities with the multigeneration plant that is obtained by integrating different systems. With this viewpoint, the key objective of this work is to design and analyze the solar collector and combustion chamber-assisted multigeneration model for power, heating, hydrogen, ammonia and freshwater generation. A newly designed plant comprises a gas turbine cycle, which includes a parabolic dish solar collector and combustion chamber, a Rankine power plant, a multi-effect desalination part, a hydrogen generation part, an ammonia generation part, and a solid oxide fuel cell unit. Comprehensive thermodynamic modeling, economic analysis and multiobjective optimization are executed to observe the performance of the whole plant and sub-system by employing energetic and exergetic approaches. Moreover, a parametric investigation is addressed to review the impacts of some important point changes on the modeled plant's efficiency. Analyses consequences display that the power and hydrogen generation amounts are 12,835 kW and 0.0607 kgs−1. Also, freshwater generation capacity with desalination unit is computed as 4.89 kgs−1. Moreover, total cost rate of the modeled plant is computed as 1074 $/h. Finally, the evaluated plant's energetic and exergetic efficiency is 58.38% and 54.21%, respectively.

Experimental and theoretical study for suitability of hybrid nano enhanced phase change material for thermal energy storage applications

The present experiment and analytical study was carried out for suitability analysis of novel hybrid system of nano-enhanced Phase change material (PCM) for thermal energy storage applications. In this study, an experimental setup of a hybrid thermal energy storage system was fabricated. Parabolic dish solar collector was used as receiver of solar energy so as to store heat via PCM. And experimentation was conducted with selected nano enhanced PCM after comparing the heat storage capacity of various available nano-enhance PCMs from past literature. Further, the detailed comparison was carried out between pure paraffin wax and it's composite with CuO-MWCNT on the basis of their attributes like thermal conductivity, heat capacity, and useful temperature range. Results showed that nano-enhanced PCM exhibited 6.125% higher thermal conductivity than that of pure paraffin wax. It was also observed from the experimentation that time taken by nano-enhanced PCM for complete transformation from solid to liquid phase was 66.6% lower than the time taken by pure paraffin wax. This study also unveils that the hybrid system exhibited wide range of useful temperature band that is from 60 °C–180 °C which confirms its suitability for efficient space heating applications.

Improvement of efficiency and PEC of parabolic solar collector containing EG-Cu-SWCNT hybrid nanofluid using internal helical fins

A parabolic trough collector (PTC) with internal helical axial fines is considered as a turbulator and is analyzed numerically. This research aims to plan a new geometry of absorbent pipes containing axial helical fines, which leads to enhancing solar collector efficiency (η) by increasing Nusselt number (Nu) and decreasing pressure drop (ΔP), especially at higher Reynolds numbers (Re). For numerical simulation, finite volume method and SIMPLEC algorithm are used. The heat transfer rate (HTR) and operating properties of ((CH2OH)2)/Cu-SWCNT hybrid nanofluid (NF) with different volume fractions and Reynolds numbers are investigated. The results are obtained for two cases of axial helical fins with a different number of turns along the pipe. The results show that the maximum efficiency of 78.197% is related to the pipe with the highest number of turns when Re = 12000 and φ = 1%, while η = 71.4785% for the pipe with the lowest number of turns under the same conditions. The maximum PEC value is 4.7 and belongs to Re = 12000 for a pipe with a lower number of turns (case 2) in which φ = 1%. Therefore, using more turns is more desirable from the point of view of thermal fluid dynamics.

Advanced exergy and exergo-economic analyses of a novel combined power system using the cold energy of liquefied natural gas

In this study, a new combined power system using the cold energy of liquefied natural gas (LNG) is designed. Conventional and advanced exergy and exergo-economic analyses of the system were made. According to the research in the literature, for the first time, advanced exergo-economic analysis was applied to a combined power system using the cold energy of LNG with the Modified Productive Structure Analysis (MOPSA) method. 23% of the exergy destruction and exergy destruction cost rate of the combined system is avoidable. In both conventional and advanced exergy analysis, the highest exergy destruction and cost rate were found in the parabolic solar collector. In addition, as a result of the analyses, it has been seen that the most effective main system components with the potential to improve the performance of the combined system are the parabolic solar collector, the turbine in direct expansion cycle and the turbine in the Organic Rankine cycle, respectively. The study revealed that there is potential to improve the performance of the proposed combined power system.

The influence of the geometric shape of the symmetrical twisted turbulator on the performance of parabolic solar collector having hybrid nanofluid: Numerical approach using two-phase model

In this investigation, the influence of twisted turbulator and water-based MWCNT-MgO hybrid nanofluid on thermal–hydraulic performance (PEC), energy efficiency (ηn), and exergy efficiency (ηex) of parabolic solar collectors (PSCs) was numerically investigated using the finite volume process. The two-phase nanofluid flows at the Reynolds number (Re) ranging of 10,000–25,000, the RNG k-ε turbulence model is used to model the turbulent flow regime. The nanofluid is modeled by a two-phase mixed model. In addition, the SIMPLEC algorithm was used for simulation. The study is performed for nanoparticles concentrations (φ) of 1% to 3% and pitch ratios (PR) of 0.25, 0.5, 0.75, and 1. Re and φ of MWCNT and MgO nanoparticles were detected to augments (Nuav). It is detected that the values ​​of PEC are more than 1 for all cases. Therefore, it can be concluded that using a twisted turbulator and an enhancement of its PR intensifies PEC. In addition, the results demonstrate that ηn is enhanced and ηex is reduced with the PR of the solar collector having twisted. For case of φ = 3%, as Re increased from 10,000 to 25,000, ηnandηex are enhanced by 45.98% and 31.67% for PR = 1 and 0.25, respectively.

The effect of MoS2–Ag/ H2O hybrid nanofluid on improving the performance of a solar collector by placing wavy strips in the absorber tube

We studied the optimization of a linear parabolic solar collector with a twisted tape (strip) aimed at increasing heat transfer in this paper. This research contains three sections. The first section focuses on the geometric study of various tapes, including twisted strips, wavy strips, and plain strips with a rectangular cross-section. In the second section, we examined the tape with the best efficiency at four heights. Finally, we assessed the effect of the H2O–Ag/MoS2 hybrid nanofluid in the third section. To this end, we simulated the governing equations and nanofluid flow in the collector using the ANSYS-Fluent software by employing the K−ε RNG turbulence model. The results revealed that the use of the twisted strip model brings the highest efficiency rate than other modes. Accordingly, the heat transfer rate and the outlet temperature for the twisted strip with the highest height increase by 14.33% and 0.39%, respectively compared to the lower heights. Besides, the use of composite nanofluid with a 5% concentration in a twisted strip with a height of 40 mm provides the highest heat transfer rate. Also, the outlet temperature difference with the fluid inlet increases by 4.93% compared to lower concentrations.

Study of the effect of the position and metal of the receiver tube on the performance of a parabolic trough solar collector

In this study, the optical behavior of a parabolic trough collector solar collector has been traced, as the effect of the position and metal of the receiver tube on the optical efficiency and the average local concentration ratio of the heat flux on the receiver tube has been studied. A modeling was performed to simplify the operation of the studied system, where the codes (SOLTRACE and MATLAB) were used. In the first stage, the distribution of heat flux density on the receiver tube's surface was studied using SOLTRACE code based on the Monte-Carlo (Ray Tracing) method. Here the average heat flux on the wall of the receiver tube was obtained after Direct Normal Irradiance was reflected by the reflective mirror. This average will be used as boundary conditions in the MATLAB code, which will allow calculating the optical efficiency of the studied solar collector and the average local concentration ratio on the circumference of the receiver tube. In the second stage of the study, the effect of the metal type of the receiver tube on the optical efficiency and the average local concentration ratio of the heat flow on the receiver tube will be studied, as three metal types were taken for the receiver tubes, the first metal is Copper Black Coated, the second is Aluminum Black Coated and the third is G. Iron Black Coated. The model validation results show good agreement with the literature, with a difference of ±3.29% compared to previous numerical studies. In addition, one of the most important observations that have been reached through this study is that by moving the receiver tube downwards, the concentration area of the heat flux widens but the maximum value of the flux decreases, and the opposite is completely true. The black-coated copper receiver tube gave the best optical efficiency (89.38%) when the focal distance value was 1.88 m, while it was estimated at 75.77% with a focal distance of 1.84 m. The obtained results are very encouraging towards the necessity of carrying out experimental work in this field in order to clarify the physical concept of the behavior of the solar collector studied from the three angles numerically, modeling and experimentally.

Exergoeconomic analysis of a solar CCHP with partially porous material filled collector

In this research, a parabolic solar collector is investigated and analysed in a solar combined cooling, heating and power cycle by adding porous materials in five stages. This research focuses on the use of flat plate collectors in solar CCHP. Following this study, the exergoeconomic analysis of the system was performed for financial analysis and calculation of the payback period. The average enhancement of collector's efficiency and solar CCHP cycle using porous media is 16% and 11% respectively. By using flat solar collector fully filled porous media, the cost of the cogeneration cycle reduces up to 38% in comparison with other CCHP.

A review of parabolic collector with shell and tube heat exchanger

The ever-increasing global need for energy makes it unavoidable to support the use of essential coffers (box or cabin). The sun is one of the most abundant and almost indestructible energy sources in our world. The goal of this study is to compare three alternative materials in order to improve or maximize the efficiency and other characteristics of the solar collector. Aluminum- 6061, Stainless Steel – 304 and Mild Steel - EN24 are the three materials. Solar collectors with a parabolic trough are physical devices with an interior covering of mirrors or reflecting materials. The collector is shaped like a concave surface. These troughs have a single axis, which means they may be rotated. These troughs have a single axis, which means they can only rotate in one direction. The east–west orientation is the most common and typical direction for solar collector placement. These collectors are also used in the north–south direction in various parts of the world and by some homes. The incident radiation on the collector heats a specific fluid as it flows through the tubes or pipes of the collector. Because they are in the shape of a parabola, solar collectors are also known as parabolic trough collectors. Despite the fact that the interior surface is coated with reflecting materials, mirrors are still used. The collector's form aids in the focus of falling light or radiation on the tubes. The shape of conventional solar collectors and parabolic solar collectors is what distinguishes them. One of the solar collector's most important qualities is this distinction. Mechanical and geometrical characteristics are among them. This reduces, if not completely eliminates, losses in the collection. These characteristics enable solar collectors to work at higher temperatures.

Thermoeconomic Analysis of Solar Chimney and Wind Turbine Application to Help Generate Electricity in a Trigeneration Cycle

The main purpose of this study is to evaluate the thermodynamic and economic performance of using a solar chimney and wind turbine to help generate electricity in a multigeneration system. The proposed system is designed to generate power, heating, cooling, hot water, and steam. Parametric studies were conducted to evaluate the effects of various parameters such as Brayton cycle turbine inlet pressure, organic Rankine cycle turbine inlet temperature, solar radiation, wind speed, and absorption refrigeration cycle evaporator temperature on the system efficiency. The effects of these parameters on the energy, exergy, and economic efficiencies of the whole system were investigated. The results showed that the highest energy efficiency and total exergy of the multigeneration system were 22.12% and 11.4%, respectively. Also, the total power generation capacity of the studied system was calculated to be 2103 kW. The results also depicted that the highest rate of exergy destruction for the main components of the system is found in the parabolic dish solar collector. Increasing the turbine inlet pressure, the average wind velocity of the wind turbine and, evaporator temperature increasing of absorption refrigeration cycle has a positive effect on the efficiency of the proposed system.

Performance Enforcement of a Parabolic Solar Collector with a Separating Transparent Glass Sheet

This paper deals with the development of compound parabolic collectors (CPCs), utilizing a partial glass sheet adjacent to the absorber plate for the purpose of performance improvement. The collector under study has a parabolic shape, whose cavity is filled with air and the turbulent natural convection takes place because of the air density gradient. The main goal is the reduction of heat losses by keeping away the high-temperature region near to the absorber from the main recirculaetd convection airflow by installation of a separating glass sheet. The conservations of mass, momentum and energy as the set of governing equations for the steady and turbulent free convection airflow in the CPC’s cavity and the Laplace equation for computation of temperature distributions in solid parts including the glass cover, absorber plate, and glass sheet were numerically solved by the finite element method. The COMSOL Multiphysics software was used for the present simulation. For the computation of turbulent stress and heat flux, the κ-ε turbulence model was employed. An attempt was made to investigate the installation of a fully transparent glass sheet near the absorber plate on the thermal behavior of the studied CPC. It is expected that this factor leads to lowering the heat losses from boundary surfaces, especially from the glass cover. Numerical findings showed about a 24% increase in the efficiency of studied test cases because of the installed glass sheet. Comparison between the theoretical findings with experiment shows good consistency.

Modelling and Comparison of the Thermohydraulic Performance with an Economical Evaluation for a Parabolic Trough Solar Collector Using Different Nanofluids

This study examines the three-dimensional heat transfer and flow characteristics of nanofluids in a parabolic trough solar collector under turbulent flow conditions, whereas a non-uniform focused heat flux was applied to the absorption pipe. CuO/water, Al2O3/water, TiO2/water, and SiO2/water are studied numerically. The dynamic and thermal fields are determined by the Reynolds number varying between 50000 ≤ Re ≤ 250000, while the volume concentration of nanofluids is the following: 3% CuO, 6% Al2O3, 4.82% SiO2 and 3.15% TiO2, the nanoparticle size of 30 nm by means of Finite Element Method (FEM). Effects of various parameters such as volume fraction of nanoparticles (φ), various Reynolds numbers and type of nanoparticle on thermo-hydraulic performance of the parabolic solar collector are studied. The average Nusselt number, heat transfer coefficient, average friction factor, pressure drop, temperature and velocity distribution are illustrated using four different types of nanofluids and four different volume fractions of nanoparticles with various Reynolds numbers. According to the final results, both TiO2 and CuO nanofluids have better performance in terms of thermal and hydraulic efficiency and evaluation economic performance compared with other nanofluids studied.