Absorber Tube Research Articles

Nanofluid-based photovoltaic thermal solar collector with nanoparticle-enhanced phase change material (Nano-PCM) and twisted absorber tubes

Photovoltaic thermal (PVT) collectors convert solar energy into thermal and photovoltaic energy. The thermal performance of a PVT collector with a twisted absorber tube and nanoparticle-enhanced phase change material (Nano-PCM) was evaluated. The experiments were aimed to evaluate the photovoltaic, thermal and combination photovoltaic thermal efficiencies using an indoor solar simulator. Circular and twisted absorber tubes with Nano-PCM were evaluated in two designs. The working fluid was water with 0%, 0.3%, and 0.6% volume fractions of SiC nanofluids. The highest photovoltaic, thermal, and combined photovoltaic thermal efficiencies for the PVT-PCM with twisted tube and 0.6% nanofluids were 9.57, 84.74, and 94.31, respectively. The use of twisted absorber tubes with Nano-PCM increased the efficiency of the PVT collector.

Performance analysis of a parabolic trough collector using partial metal foam inside an absorber tube: an experimental study.

This paper offers an experimental investigation of the effect of metal foam on the thermal and hydrodynamic performance of a parabolic trough collector (PTC). Metal foams play a crucial role in heat transfer improvement due to their high thermal conductivity. Three different arrangements of metal foams are applied inside the absorber tube of the PTC. The flow regime in the absorber tube is laminar at different Reynolds numbers of 422, 844, 1267, and 1689. Experimental tests are designed with Design-Expert software in which the response surface method is utilized. Experimental results revealed that maximum enhancement in thermal efficiency is related to the periodic array arrangement of the metal foam inside the tube. This arrangement leads to a 14% increase in thermal efficiency. However, in this arrangement, the friction factor increases considerably compared to a plain receiver tube.

Numerical simulation for impact of implement of reflector and turbulator within the solar system in existence of nanomaterial

Turbulent flow of oil based hybrid nanofluid within an absorber tube of concentrated solar system has been evaluated in this article. To concentrate the solar irradiation, the parabolic plate has been located below the tube and variable heat flux was considered as the boundary condition of the tube. The presence of a turbulator within the circular tube causes secondary flow to increase. Both thermal (Sgen,th) and frictional (Sgen,f) components of irreversibility were reported in outputs. As Re increases, the residence time decreases and lower outlet temperature has been achieved. Sgen,th decreases about 57.36% with growth of Re while Sgen,f increases about 17.44 times. As the number of rows of tapes increases, the value of Sgen,f enhances about 69.23% while the value of Sgen,th decreases around 3.67%. Increase of pitch ratio causes Sgen,th to decrease about 11.25% while frictional component increases around 76.7%.

Heat transfer analysis of turbulent forced-convection flow in a wavy absorber tube containing a molten salt-based hybrid nanofluid filled with a porous material

The thermal performance of turbulent forced-convection flow was investigated in a wavy absorber tube containing a hybrid nanofluid consisting of salt molten filled with a porous material. The nanoparticles dispersed in the working molten salts are Al2O3 and graphene, which have a spherical shape and a diameter of less than 100 nm. The assessments were performed under turbulent forced convection flow conditions using k--ε model with enhanced wall treatment. The effects of porous media features, nanoparticle concentrations, and molten salt type on flow, thermal exchange, drop pressure, pumping power, skin friction factor, and efficiency are discussed. Outcomes indicated that boosting the values of increases friction coefficient, drop pressure, pumping power, and and system efficiency. Molten Hitec salt has a lower friction coefficient and pressure loss than Hitec XL and solar salt. The use of solar salt improved the heat transfer rate by and compared to Hitec and Hitec XL, respectively.

Performance Evaluation of an Absorber Tube of a Parabolic Trough Collector Fitted with Helical Screw Tape Inserts Using CuO/Industrial-Oil Nanofluid: A Computational Study

Improvement of the performance of renewable energy harvesters is a crucial and complicated task. Among currently utilized renewable energy harvesters, parabolic solar collectors are some of the most promising and widely used apparatuses. However, researchers are still facing some issues regarding the optimization of PTC performance, including the enhancement of heat flux absorption by the absorber tubes. Among the proposed methods to overcome this drawback, the implementation of helical screw tape (HST) and nanofluids has proven to be most effective. In the present study, the CFD simulation of an absorber tube with HST is conducted. CuO/oil nanofluid with a nanoparticle volume fraction of 1 to 3% was chosen as the working fluid. The simulation is based on the realistic operational condition of a PTC absorber tube with corresponding nonuniform solar heat flux based on the local concentration ratio. The effects of the mass flow rate (Re), HST width and nanofluid volume fraction on pumping power and heat transfer are studied. Moreover, to combine the effect of both parameters, the performance evaluation criterion (PEC), a dimensionless variable, is calculated for all of the studied cases. Enhancement of the PEC parameter by the implementation of nanofluid and HST in comparison to base fluid passing through a plain tube is also determined and reported. According to the obtained results, with the implementation of the CuO/oil nanofluid, the PEC can be enhanced by 57.3–70.8, 68.7~86.4, and 83.4~105.9% for volume fractions of 1, 2, and 3%, respectively.

Improving the thermal efficiency of parabolic trough collector equipped with combined turbulator containing two-phase magnetic hybrid nanofluid

A parabolic trough collector (PTC) is a beneficial device for collecting heat from the sun. Increasing the efficiency of these devices in recent years has attracted the attention of researchers to a significant extent. The present study has been carried out to increase the thermal efficiency in the PTC by using a new geometric form of compound turbulator and magnetic hybrid nanofluid. In this study, MWCNT-Fe3O4-Cu/Water magnetic hybrid nanofluid is prepared using a two-step method. Then its thermophysical properties are used as a working fluid in the present study. The absorber tube of the studied PTC is equipped with three different geometric shapes of the compound turbulator (Case A, B, and C). Case A and B geometric shapes differ in their vertical or horizontal position. Therefore, a circular coil is wrapped around the compound turbulator in Case C. Magnetic hybrid nanofluid is simulated in the Reynolds range of 18,000 to 42,000 and volume fraction 1.25 and 2.25% of nanoparticles considering the two-step method. The results show that using a magnetic hybrid nanofluid with three MWCNT, Fe3O4, and Cu nanoparticles in the PTC always causes the heat transfer rate to be higher than the water. Adding the compound turbulator has caused, unlike the laminar flow in which the movement of fluid particles is in the form of layers, the fluid particles in the direction perpendicular to the movement path are also mixed and create a random movement. The analyzed results of the thermal–hydraulic performance evaluation criteria describe that in this study, using the compound turbulator in the absorber tube of the PTC always has a favorable role. Finally, the maximum exergy efficiency and energy efficiency are related to the absorber tube equipped with a combination of a compound turbulator and circular coil.

Modeling and Experimental Validation of the Performance of Electromechanical Height Adjustment Vehicle Suspension with Eccentric Mounted Screw System

This paper describes the modeling and experimental validation of the performance of two height adjustment suspensions with concentrically and eccentrically mounted screws. In the former solution, an anti-rotation system is required for the generation of reaction torque on the power screw–nut mechanism. The anti-rotation represents the main drawback of such mechanisms. In contrast, the eccentric solution attempts to solve this problem by placing the screw–nut mechanism eccentrically with respect to the shock absorber tube axis. In this paper, the working principle of the eccentric solution is explained. Its performance is compared to the concentric counterpart through simulations and experiments. Although the efficiencies of eccentric and concentric systems are very similar at the power screw, overall efficiencies differ substantially. During lifting, average efficiencies are around 3.4% and 6.5% for concentric and eccentric systems, respectively. When lowering, these values are 6.2% and 26%. The higher overall efficiency of the eccentric screw system is attributed to the anti-rotation system and the balancing of the bending moment due to the offset application of the load. To yield a complete perspective on the eccentric mounted screw solution, four prototypes are installed and tested on a demo vehicle.

Numerical analysis and RSM modeling of the effect of using a V-cut twisted tape turbulator in the absorber tube of a photovoltaic/thermal system on the energy and exergy performances of the system

The application of V-cut twisted tape turbulator inserted in the absorber tube of a photovoltaic thermal (PVT) system was investigated through a 3-D numerical analysis. The objective was to determine the effect of turbulator pitch distance (50 mm, 77 mm, and 100 mm) and Re number (500, 1000, 1500, and 2000) on the PVT energy and exergy performances. The results were compared with those obtained for the absorber tube without turbulator. Our findings demonstrated that the pressure drop and PV temperature, respectively, escalates and diminishes by 78–84% and 5.69–6.68% for the case with turbulator (pitch of 100 mm) as Re increases from 500 to 2000. In consequence, the overall energy efficiency and overall exergy efficiency improve by 15.76–14.27% and 12.01–8.68%, respectively, for the increase in Re within the studied range. In addition, the application of turbulator with a pitch of 100 mm improves the overall energy and exergy efficiencies of the PVT system by 3.04–7.70% and 4.03–13.08% at the Re range of 500–2000 as compared to the without turbulator case. Moreover, the greatest useful thermal and electrical efficiencies were obtained for the PVT with turbulator pitch of 100 mm and at Re=2000, which yields the highest overall thermal and exergy efficiencies of 75.46% and 16.34%, respectively. Furthermore, RSM technique is utilized to obtain a model for the overall energy and exergy efficiencies versus Re and P.

Effects of geometric and optical irregularities on the flux distribution on an absorber tube of a parabolic trough collector

A parabolic trough collector is the most widely implemented concentrated solar heat collecting device. The performance of the same critically depends on how far the actual optical setup differs from the mathematical ideality. Such a study enables one to quantitatively compare the relative significance of different irregularities and channelize the engineering effort to address the critical ones within a threshold of added cost. The following irregularities are tested in the present work, both individually and simultaneously: absorber tube misalignment, random profile error, narrowed and widened reflector profile, tracking error. A grid and ray independent model as implemented in COMSOL Multiphysics 5.4 is employed. It is duly validated against prior studies. The tested collector parameters are the same as that of SEGS LS2 PTC. It is observed that a tracking error up to 10 mrad causes minimal loss of performance. Misalignment error and narrowing of reflector profile not only cause loss of total heat interception but also produce abnormally high local heat flux which may lead to damage to the absorber tube coating and cover system. Simultaneous occurrence of multiple irregularities can lead to major loss of performance (in the current study ∼50%); hence, calls for intervention and remediation.

Performance analyses of supercritical carbon dioxide-based parabolic trough collectors with double-glazed receivers

Supercritical carbon dioxide is becoming a hot research topic as a potential heat transfer fluid in parabolic trough concentrators since it enables operating the solar system at high temperatures for a higher quality of energy. However, the corresponding inflated thermal losses necessitate alternative receiver designs. This work examines four double-glazed receivers, with each annular space being evacuated or non-evacuated, in terms of the absorber tube's diameter (53–80 mm) and the diameter ratios of the two glass shells (1.2–2.0). An analytical model is developed and validated for this purpose, and the four designs are further examined using ground-level solar and meteorological measurements. The results demonstrate higher performance in the case of fully evacuating the receiver and using the smallest possible diameters of the three concentric cylinders, where the energy and exergy efficiencies reach 65.3 and 40.3%, respectively. Yet, evacuating only the inner annular space is sufficient to achieve virtually the same performance level. This energy efficiency decreases to 62% in case of increasing the tube diameter to 80 mm. As the operating temperature increases from 423 to 850 K, the specific thermal losses increase by 3.98–4.34 folds, depending on the receiver design. Double glazing the receivers is favorable only at high operating temperatures of sCO2, where the reduction in thermal losses overcomes the drop in optical efficiency. For an inlet sCO2 temperature of 850 K, thermal losses are reduced by 33.64 and 53.92%, compared to evacuated and non-evacuated single-glazed receivers, respectively. Throughout the year, the fully evacuated and fully non-evacuated double-glazed receivers have energy efficiencies of 54.96 and 52.39%, exergy efficiencies of 33.64 and 32.06%, and thermal losses of 348.8 and 402.5 W/m, respectively.

A comprehensive numerical study on the effectiveness of a rotational-based PTC collector integrated porous foam and PV module

Integrating Photovoltaic modules with Parabolic Trough Solar Collector (PTC) (PTC-PV) is a method boosting the operating performance of the noticed collector. The PTC-PV unit is not only able to maintain the needed thermal energy but also can provide a tremendous amount of electricity. In this study, the exergy and energy outputs of a PTC-PV unit are enhanced by integrating it with porous metal foam and moving the absorber tube rotationally. The studied cases include a PTC-PV unit, rotational PTC-PV (RPTC-PV) unit, rotational PTC-PV unit integrated with ten separate porous metal foam layers (RPTC-PV-SPF), and rotational PTC-PV unit integrated with a uniform porous metal foam layer (RPTC-PV-UPF). Because of identifying the best unit, the consequence of key factors, namely, solar radiation, inlet mass flow level, and inlet temperature on the outputs of the units, are studied respecting thermodynamic rules. Additionally, the effect of nanoparticles mass fraction, the rotational speed, and metal foam thickness on the outputs of the best unit (RPTC-PV-UPF) are evaluated. According to the results, the highest energy and exergy outputs among the simulated cases belong to the RPTC-PV-UPF unit. At the base case condition, the net energy effectiveness of the PTC-PV, RPTC-PV, RPTC-PV-SPF, and RPTC-PV-UPF units is 58.95%, 90.35%, 89.46%, and 91.42%, respectively. Also, the overall exergy efficiency of these units is 8.43%, 3.37%, 9.48%, and 11.89%, respectively. It is found that the VP-1/MWCNT is the best working fluid for the RPTC-PV-UPF unit. By declining the void fraction of MWCNT nanofluid, the overall exergy and energy performance of the system, respectively, elevates by 9.74% and 0.25%. The nanofluid-based RPTC-PV-UPF unit foam thickness of 8 mm, and rotational speed of 0.5 rad/s, has the highest performance among the studied cases from the exergy viewpoint. The energy and exergy outputs of the RPTC-PV-UPF unit at the optimum operating condition are 67.41% and 77.47% higher than that of the PTC-PV unit.

Numerical simulation of solar parabolic trough collector with twisted tape insertion shielded within inner cylindrical tube

ABSTRACT In this study, the effects of variations in geometrical parameters of shielded twisted tape within the inner cylinder of the absorber tube on the performance enhancement of the parabolic trough collector (PTC) have been investigated. The objective is based on the prediction of the optimized value of geometrical parameters for the modified parabolic trough collector (MPTC) showing the best thermal performance among them. Numerical simulation techniques with Ansys-Aim2020R1 have been used for this investigation. It is desired to determine whether it is advantageous to use inner shielding around the inserts within the absorber tube; and if so, which geometrical parameter plays a crucial character in the prediction of the best possible thermal performance of the system. It was found that with a twisted tape thickness of 0.002 m, twisted tape gap of 0.001 m, inner cylinder center distance of 0.020 m, and the number of twists of the twisted tape of 50 turns the PTC has shown the best possible performance of the system. These findings reflect optimized geometrical parameters of the twisted tape insert shielded by an inner cylindrical tube. The thermal efficiency (η) of the MPTC was found to be 86.5% and approximately 2.063 times that of the conventional PTC. It is a novel endeavor regarding the approach of utilizing the shielding around the inserts within the absorber tube.

Experimental Investigation of Absorber Design on the Performance of a Solar Tracking Distillation System

The problem of water scarcity, especially in North Africa and Libya, has been reviewed. A distillation apparatus has been proposed that uses solar energy as a source of unlimited energy. It should be noted that most countries in North Africa to a relatively favourable area between 35° north latitude and 37° south latitude. Because of this, they can rely on sunlight as an unwavering source of fresh water. The setup used in the experiment uses a solar parabolic concentrator, which collects solar radiation and concentrates it on an evaporator. The parabolic reflector increases the amount of incoming solar radiation and its concentration on the evaporator, thereby increasing the heat output and production rate of the solar still, thereby increasing the efficiency of the solar still. The suggested distillation unit-body consists of a parabolic reflector, an evaporator (Tube absorber) which was placed on the focal line of the parabolic reflector, and a pyramidal glass frame that acts as a condenser. Motors and electronics that expose the reflector to the sun's rays throughout the day from sunrise to sunset. The results show that increases in solar intensity, ambient temperature, and evaporation area increase specific productivity. Using the tracking system as an automatic control unit to make the reflector the sun rays all over the day from sunrise to sunset.

A progressive review of hybrid nanofluid utilization in solar parabolic trough collector

The most reliable, cleanest, and accessible alternative energy source today is solar energy. Alternative forms of solar energy cause the least environmental damage. The period demands the use of renewable resources due to the depletion of fossil fuels and the rising cost of electricity. Additionally, unlike these renewable sources, fossil fuels emit CO2. Therefore, the usage of alternate sources assists to diminish greenhouse gases and prevent climate warming. Through the process of using solar energy, which is then transformed into electrical energy and then thermal energy with the aid of a steam turbine, the typical heat transfer fluids have a moderate thermal conductivity; in this case, solid nanomaterials are used to boost this conductivity, and nanofluids play a crucial role. The most widely used solar concentrating technique worldwide is the parabolic trough collector (PTC). In order to present various models and media used to assess the consequences of nanofluids on thermal characteristics for PTC delivering an optimal result, this study compares work conducted earlier in the field. The study also demonstrates that the thermal and optical properties can be improved by utilizing hybrid nanofluids as the heat transfer fluid (HTF) inside the absorber tube of the PTC. Numerous experimental experiments have shown that employing hybrid nanofluids improves thermal characteristics more significantly than using monofluids.

Impact of Stearic Acid as Heat Storage Material on Energy Efficiency and Economic Feasibility of a Vacuum Tube Solar Water Heater

The overheating of heat pipes, poor transfer of heat across the absorber and finned heat pipes, and inability to provide hot water in the late evening hours are major problems associated with conventional heat pipe vacuum collector systems. The amalgamation of highly conductive storage material between the absorber tube (heat collecting surface) and the heat pipe is an effective way to overcome these problems. In this study, a stearic acid amalgamated vacuum tube solar collector system was designed and fabricated and its thermal output compared with a conventional vacuum tube system without storage material under the same environmental conditions. The experimental results showed that the amalgamation of stearic acid as storage material enhanced the thermal output of the solar system compared to the conventional one. The desired heat gain of the solar system with storage material increased by 31.30, 23.34, and 18.78% for Test 1_40 °C, Test 2_45 °C, and Test 3_50 °C, respectively. The technoeconomic analysis showed that almost 118.80 USD in revenue could be earned by the proposed solar system at the end of 15 years. The total running cost of ELG and the developed solar system was observed to be 202.62 and 86.70 USD, respectively. On average, the cost of hot water production using the solar system and ELG was found to be 0.0016 and 0.004 USD/L, respectively. The value of LEC was found to be 0.062 USD/electricity unit, which was much lower than the LEC value of ELG (0.116 USD/electricity unit). The value of NPW (73.73 USD) indicated high acceptability of the proposed system. The payback time is lower than the life of the system, indicating its suitability for use in the commercial sector. Therefore, the proposed solar system is highly recommended over conventional water heating systems in urban and rural areas.

Examination of long-time aging process on volatile organic compounds emitted from solid fuel combustion in a rural area of China

Volatile organic compounds (VOCs) emitted from solid fuels combustion (e.g., biomass and coal) are still the dominant precursors for the formation of tropospheric ozone (O3) and secondary organic aerosols (SOAs). Limited research focused on the evolution, as known as atmospheric aging, of VOCs emitted during long-timescale observations. Here, freshly emitted and aged VOCs from common residual solid fuel combustions were collected onto absorption tubes before and after passing through an oxidation flow reactor (OFR) system, respectively. The emission factor (EF) of freshly emitted total VOCs is in descending order of corn cob ≥ corn straw > firewood ≥ wheat straw > coals. Aromatic and oxygenated VOCs (OVOCs) are the two most abundant groups, accounting for >80% of the EF of total quantified VOCs (EFTVOCs). Briquette technology shows an effective reduction of the VOC emission, demonstrating a maximum 90.7% lower EFTVOCs in comparison to that of biomass fuels. In contrast, each VOC shows significantly different degradation in comparison to EF of freshly emitted and after 6- and 12-equivalent day aging (actual atmospheric aging days calculated from aging simulation). The largest degradations after 6-equivalent days of aging are observed on alkenes in the biomass group (60.9% on average) and aromatics in the coal group (50.6% on average), consistent with their relatively high reactivities toward oxidation with O3 and hydroxyl radical. The largest degraded compound is seen for acetone, followed by acrolein, benzene, and toluene. Furthermore, the results show that the distinction of VOC species based on long-timescale (12-equivalent day aging) observation is essential to further explore the effect of regional transport. The alkanes which have relatively lower reactivities but high EFs could be accumulated through long-distance transport. These results provide detailed data on fresh and aged VOCs emitted from residential fuels which could be used to explore the atmospheric reaction mechanism.

Impact of installation error and tracking error on the thermal-mechanical properties of parabolic trough receivers

As the solar energy utilization technology for renewable clean energy, actual parabolic trough receivers are subject to tracking errors and absorber tube installation errors, and the bellows and Kovar ring under these errors have a significant impact on the receiver's safety. Based on the MCRT-FVM-FEM principles in this paper, a receiver's optical-thermal-stress mathematical model is modeled and the thermal-stress performance and safety of the receiver's key components under two errors are evaluated. The correlation between the bellows and Kovar ring's performance and the two errors is analyzed. The results demonstrate that the lower tracking errors and larger installation errors markedly increment the absorber's deformation and have a negative impact on the receiver safety. Bellows and Kovar ring's asymmetrical temperature distribution causes variable swell and uneven stress under tracking and installation errors. Temperature gradient variation of bellows is more sensitive under errors than Kovar rings. Kovar ring's compressive stress rises substantially as the Y-directional installation error varied from −15 mm to 15 mm compared to other errors. With tracking errors exceeding 8 mrad, bellows' tensile stress and Kovar ring's compressive stress diminish under installation error. Thus, larger tracking errors significantly reduce the threat to the receiver when installation errors exist.

Performance augmentation strategy of Parabolic trough collector by employing MXene-based solar absorbing coating

The investigation intends to study the performance of Direct Absorption Parabolic Trough Collector for low-temperature practices. From the ages, the pathway for strengthening the efficiency of solar collector is been obstructed by state-of-the-art parabolic trough collectors undergoing severe re-radiation losses. Based on this, a novel strategy to coat the absorber tube and its performance (Energy, Environment, and Economy) is investigated. In this regard MXene particles with Black paint are used on the inner layer of coating followed by dip coating of MgF2 and SiO2 particles; furthermore, MXene/ water is used as heat transfer fluid. The highest thermal efficiency is reported to be 58.5% followed by 53% and 48% in coated and normal absorber tubes. The size reduction of the collector also drops in coated by 38.64%, 3,2.7%, and, 25.18% in coated and normal absorber tubes this lays a foundation for the calculation of embodied energy, and further emissions were studied and maximum drop per kg reported in MX/ BP with SiO2 coated absorber tube. Our retrofitted PTCs have a payback period of 2.324 and 2.322 for MgF2 and SiO2 outer layer coatings, respectively.

Experimental investigation on a solar parabolic collector using water-based multi-walled carbon-nanotube with low volume concentrations

A limited experimental work was on multi-walled carbon nanotube (MWCNT)—water nanofluid with surfactant in the solar parabolic collector at low volume concentrations. At high-volume concentrated nanofluid, the pressure drop was more due to an increase in the viscosity of the working fluid and an increase in the nanoparticle cost; hence it is not economical. This report attempted to use Sodium Dodecyl Benzene Sulfonate (SDBS) surfactant in the low-volume concentrated MWCNT-water nanofluid to establish effective heat transfer in solar parabolic collector applications. The stable MWCNT-water nanofluid was prepared at 0.0158, 0.0238, and 0.0317 volume concentrations. The experiments were conducted from 10:00 to 16:00 at 6, 6.5 and 7 L/min flow rates concerning ASHRAE Standards. At the 7 L/min flow rate of the working fluid, having a minimum temperature difference between the working fluid and absorber tube leads to better heat transfer. The increased volume concentration of MWCNT in the water enhances the surface area interaction between water and MWCNT nanoparticles. This results in maximum solar parabolic collector efficiency at 0.0317 vol% with a 7 L/min flow rate and 10–11% higher than the distilled water.

Computational model of a Calcium-looping fluidized bed calcination reactor with imposed concentrated solar irradiance

The Calcium-looping process is a promising option for thermochemical energy storage in concentrating solar power plants. A crucial element of this process is the solar calcination reactor, where the endothermic reaction of CaCO3 calcination occurs with formation of CaO and CO2. The solar energy that is chemically stored in the reaction products can be retrieved by the exothermic reaction of CaO carbonation when needed. In this article, a new computational model is developed for the solar calcination reactor in this Calcium-looping process. The calcination reaction takes place in the riser of a continuous circulating fluidized bed that corresponds to an absorber tube exposed to concentrated solar radiation, which allows the reaction chamber to be indirectly heated. A core-annulus heat transfer model and a modified version of the Kunii–Levenspiel fluid dynamics model are used. In contrast to previous models found in the literature, the change in the mass flow rate of the species and in the density of the phases due to the reaction is considered. Simulation studies are performed with a fixed and imposed concentrated solar irradiance on the reactor wall, which varies in both the axial and angular directions. Wall conduction in the angular direction is also considered. The results show that nearly complete calcination can be achieved with a reactor of 4 m of height. A sensitivity analysis with respect to the model parameters and inlet conditions shows that the calcination conversion is mostly affected by the solids mass flow rate and the bed temperature at the inlet.