Heterogeneous Temperature Distribution Research Articles

A new approach of preheating and powder sintering in electron beam powder bed fusion

Preheating is an essential process step in electron beam powder bed fusion. It has the purpose of establishing a sintered powder bed and maintaining an elevated temperature. The sintered powder bed reduces the risk of smoke and in combination with the elevated temperature improves the processability. Today, the line-ordering preheating scheme is widely used. This scheme does not take the previously built layers into account and results in an inhomogeneous elevated temperature and consequently in a variety of sinter degrees, which is disadvantageous for the process. The main challenge is now to modify this scheme to establish a homogeneous temperature distribution. This study addresses this challenge and analyses as well as optimises this scheme. A GPU-parallelised thermal model reveals a heterogeneous temperature distribution during preheating because of varying thermal conditions within a build job. In addition, a work-of-sintering model predicts that the sinter degree of the current powder layer on top of previously consolidated material is smaller than on top of the surrounding powder bed. This work aims to invert this trend to improve powder re-usage and material consolidation. Consequently, this work proposes an extension of the current scheme, compensating for the specific energy loss with local adjustments to the energy input. This adaption results in a uniform temperature distribution and advantageous sintering. Applying the proposed numerical model proves to be an effective method to analyse the evolving process conditions and tailor the local energy input, thereby improving the efficiency of the preheating step.

Numerical study of combustion flow field characteristics of industrial gas turbine under different fuel blending conditions

Numerous studies have shown that the mixture of fuel and oxidant significantly influences the flow characteristics and pollutant emissions within the combustion flow field. This study investigates the effects of various methane fuel blending ratios (0.19–0.41) on combustion flow, emission characteristics, performance parameters, and field synergies through numerical simulation. Combustion simulation employs the SST k-ω and flame-generated manifold models. The findings indicate that as the fuel blending ratio increases from 0.19 to 0.41, the temperature at the front end of the cyclone gradually rises, resulting in an average outlet temperature increase of 165 K. The outlet temperature uniformity index (γT) shows minimal variation, while the Pattern Factor (PF) and NO emissions at the outlet gradually increase. Additionally, the fuel blending ratio (α) exhibit a limited impact on CO emissions at the outlet. When α ≥ 0.39, the peak temperature is located in the cyclonic region, resulting in an extremely heterogeneous outlet temperature distribution. Under various operational conditions, NO is primarily concentrated in the high-temperature region near the wall, and the pollutant emission merit function (fe) gradually increase with α. The optimum field synergy and overall performance for the low-resistance heat transfer are attained at α = 0.37. Significant velocity shocks are observed in the near-wall regions on both sides of the combustion chamber, when α ≥ 0.35, based on DMD analysis. To achieve low NO emission, uniform outlet temperature, and ensure safe, long-term operation of the gas turbine, the fuel blending ratio of 0.3 to 0.35 is advised.

Electrothermal Simulation of the Production of Alumina by Spark Plasma Sintering

Although the spark plasma sintering (SPS) method is a very advantageous technque in many aspects, the inability to clearly read the temperature formed on the material during sintering and heterogeneous temperature distributions are the biggest problems of this process. Therefore, it is a common situation that samples taken from different regions of the produced material have different densities and mechanical properties. In this study, the temperature distributions, current density and joule heating effect of the entire setup consisting of the alumina (Al2O3) sample to be sintered, inconel electrodes, graphite dies, punches and spacers, as well as the critical regions in this setup, are modeled by using finite element software. According to the results, the temperature is maximum at the centre of the Al2O3 sample and the temperature gradient along its radius is 22.4°C. The temperature difference between the inner wall of the hole which is opened in the graphite mold to measure the sintering temperature and the centre of the Al2O3 sample is around 40°C. In addition, during the SPS process, Al2O3 is not heated directly by the joule effect and the temperature gradient in the sample occurs due to mold surface radiation.

3D Electrothermal Model for Internal Temperature Distribution in Lithium-Ion Battery Cell and Module

In recent years, lithium-ion batteries (LIBs) have been massively developed in many applications as they provide high energy and power densities, high efficiency and long lifespan compared to other battery technologies. Despite remarkable improvements, Li-ion batteries still face thermal issues, which cause performance drop, limited calendar life, safety concerns and temperature-caused degradation. Therefore, proper thermal management for a LIB is necessary to control its temperature and to extend its lifetime. Internal temperature measurement remains very challenging for LIB. So, electrothermal LIB models, developed to forecast both electrical performances and temperature distributions, seems to be a powerful and complementary tool to experiments, in particular to obtain battery temperatures in use. Most of models, assume simplified approach considering that heat sources are either located in the center of the cell or uniformly distributed in the volume of the cell and so do not consider the real internal geometry of the cells.In this work, a 3D electrothermal model of a large commercial prismatic NMC-type lithium-ion cell (25 Ah) is developed based on the internal geometry reconstructed from tomography. The electrothermal model, developed with the COMSOL Multiphysics® software with the real internal geometry as well as the anisotropy of the thermal properties, accounts for irreversible and reversible heat sources. The entropy variation profiles were estimated by Entroview™ using their patented method. The validation of the model is performed thank to temperature measurement during charge and discharge at several currents in a climatic chamber at 25°C. Simulation results highlight exothermal and endothermal behaviors related to the entropy change along with the charge and discharge stages. Moreover, the internal temperature distribution is thoroughly impacted by the internal geometry of the cell and the anisotropy of the thermal properties.Finally, the 3D electrothermal model is extended to a module of 12 cells in series (12S) to evaluate the heterogeneities of internal temperatures considering the real geometry of each cell. Once validated, simulation (as shown of figure 1) underline the heterogeneous temperature distribution at the module scale and the importance of having an efficient battery thermal management system to limit an excessive increase of the temperatures which can cause performance drops until irreversible degradations. Figure 1

Modified Pennes bioheat equation with heterogeneous blood perfusion: A newer perspective

The Pennes bioheat equation is a widely used mathematical model for predicting temperature distribution in biological tissues. However, it assumes homogeneous blood perfusion throughout the tissue, which may not accurately represent the complex perfusion patterns observed in tumors. In this study, we propose modification to traditional Pennes bioheat equation that incorporates the effects of perfusion heterogeneity by introducing a spatially varying perfusion term, represented by a perfusion coefficient, ωb(x,y,z) to account for local variations in blood flow at each spatial location within the biological tissue. Therefore, heterogeneous blood perfusion at each tumor tissue voxel location relax the uniform blood perfusion assumption. By incorporating these modifications, the model allows for a more realistic representation of the heat exchange between the biological tissue and blood flow, by predicting the non-uniform temperature distribution particularly in tumors with irregular blood vessel growth and organization, thereby facilitating treatment planning and optimization of thermal therapies, and leading to more effective therapeutic outcomes. The spatially varying perfusion coefficient can be obtained through advanced imaging techniques such as dynamic contrast-enhanced MRI or Doppler ultrasound enabling the assessment of perfusion heterogeneity in biological tissues. In conclusion, the modified Pennes bioheat equation offers a valuable tool for understanding the intricate relationship between with heterogeneous blood perfusion and temperature distribution in biological tissues, providing important insights to the thermal response of tumors and guiding the development of improved therapeutic strategies in optimizing cancer treatments.

Second cell growth optimized by heating mode during two-step supercritical CO2 foaming polymer process

The batch foaming of supercritical fluids faces numerous challenges, such as poor controllability due to dynamic temperature changes during depressurization foaming, and prolonged saturation time and heterogeneous temperature distribution during temperature rising foaming, which leads to lower productivity and non-uniform cells. To overcome these challenges, a unique two-step foaming method in combination with microwave enhancement was proposed. The two-step foaming method involved depressurization foaming for cell nucleation and initial growth, followed by temperature rising foaming for subsequent cell growth, producing foams with higher expansion ratio. Meanwhile, a conduction-microwave (C-M) heating mechanism which integrates different heating schemes to enhance heating efficiency and uniformity was innovatively proposed. The effect of the microwave radiation time, power, initial environmental temperature, and content of CO2 in polymer on the foaming by C-M heating was studied. Compared to existing methods, the foaming by C-M heating produces polystyrene (PS) foam with lower density and more uniform cells.

Key factors controlling the kinetics of secondary hydrate formation in the porous media

Secondary hydrate formation (SHF) usually occurs in hydrate formation and decomposition experiments, and its manifestations behave differently in promoting gas consumption and water-hydrate conversion. In this work, in order to investigate the kinetic processes and controlling factors of the SHF in the porous media, we conduct a series of formation and dissociation experiments in a three-dimensional cubic hydrate simulator (CHS). Hydrate dissociation is accomplished by the depressurization method after the formation experiments. The experimental results reveal that a rapid growth rate of equal magnitude in the SHF stage follows a relatively slow hydrate growth in the process of hydrate formation. The occurrence of the SHF is accompanied by a sudden pressure drop and temperature rise, and a heterogeneous temperature distribution shows significant effects on hydrate formation behaviors in the vessel. It has been verified that the SHF is controlled by hydrate thermodynamic stability at a subcooling degree of −0.8 °C during the hydrate formation. The SHF is initiated by the collapse and crack of the local thin hydrate film, which results in an accelerated triggering of gas diffusion for further hydrate formation. In the dissociation experiments, the slight temperature increase caused by the SHF can promote the hydrate dissociation rate. The subcooling degree in the hydrate formation can also be suitable for predicting SHF in the dissociation experiment. It is found that a rapid depressurization rate can effectively shorten the duration of SHF. These insights can be beneficial for the energy transition and natural gas hydrate extraction in the future.

Modular thermoelectric generation arrays reconfiguration under heterogeneous temperature distribution via improved cooperation search algorithm: Modelling, design and HIL validation

• ICSA based modular TEG arrays reconfiguration is presented. • Enhanced exploration operator and discretization are incorporated into ICSA. • Solution optimization program reduces possible unnecessary switching actions. • Feasibility of the proposed method are validated under two TEG arrays. • An RTLAB platform based real-time hardware-in-the-loop test has been carried out. • Maximum output power is increased by 146.45 W under asymmetric TEG array. This paper innovatively proposes a modular thermoelectric generation (TEG) arrays reconfiguration technique based on an improved cooperation search algorithm (ICSA), which aims to mitigate the troublesome effects of heterogeneous temperature distribution (HTD) conditions and fully exploit their power generation potential. Firstly, the original TEG array is divided into three blocks, upon which only two switch matrices are required to implement various reconfiguration, while its number of switches and construction costs can be significantly reduced. Secondly, the ratio of output power and voltage range (namely voltage imbalance factor (VIF)) between TEG columns is regarded as a fitness function to simultaneously maximize output power and minimize voltage imbalance. Furthermore, in order to solve this model, ICSA is designed to effectively and efficiently seek the global optimum. Meanwhile, three traditional discrete meta-heuristic algorithms are employed for comparison (e.g., genetic algorithm (GA), particle swarm optimization (PSO), and simulated annealing (SA) algorithm). Besides, to validate the problem formulation and solver design, both symmetric ( 15 × 15 ) and asymmetric ( 15 × 20 ) TEG arrays are tested under three typical HTD conditions, i.e., outer, centre, and random. Lastly, simulation results on MATLAB verify that ICSA can rapidly smooth the output power curves and dramatically enhance generation efficiency of TEG arrays. Specifically, the maximum output power can be increased at most by 93.77 W with a decrease of 164.02 V of VIF under symmetric case, and 146.45 W with a decrease of 111.92 V of VIF under asymmetric scenario, respectively.

Identifying the cooling heterogeneity and quality decay of Indian mangoes during cold chain export by multiphysics modeling

AbstractPrediction and analysis of temperature‐based quality evolution of those perishables subjected to extreme temperatures in a shipment can guide the stakeholders and decision‐makers regarding the final quality of shipment and export mode. This study aims to forecast the temperature heterogeneity among the perishables packed in a standard ventilated carton for sea‐borne cold chain and airways export, using Computational Fluid Dynamics (CFD) simulation. The biochemical processes affecting the fruit quality are also evaluated, and the overall quality is predicted with the help of the Kinetic rate law model. The case of an Indian mango export to United States is considered for the present study, and a preferable export mode is suggested. The model is experimentally validated with a discrepancy of 1.516 K (RMSE) and 9.504% (MAPE), respectively. The findings indicate more heterogeneous temperature distribution in the case of seaways export (nearly 3 K) compared to airways (1.5 K). The temperature‐dependent quality attributes, following different kinetics, decays by 46% and 89.6% on the 10th day of seaways export. This observation indicates that the mangoes will be spoiled in transit as seaways export to United States takes around 28 days. From these observations, under the given transit conditions, it is recommended to export mangoes via airways to the United States from India, which takes about 3 days.Practical ApplicationsMonitoring the temperature of perishables is an indispensable part of cold chain export for maintaining their quality and extending their shelf life. This study proposes a virtual or simulation‐based approach to analyze the cooling behavior of individual mangoes and hence predict the evolution of its various quality attributes, passing through different stages of the cold chain. The technique used is quite promising in predicting the export potential and export mode of the produce before the actual export process takes place, thus preventing excessive in‐transit loss. The method mentioned above is applied in an illustrative case study of Indian mango export to the United States. Its application can be further extended to the export of other perishables to various importing countries.

Roaring Storms in the Planetary-mass Companion VHS 1256-1257 b: Hubble Space Telescope Multiepoch Monitoring Reveals Vigorous Evolution in an Ultracool Atmosphere

The photometric and spectral variability of brown dwarfs probes heterogeneous temperature and cloud distributions and traces the atmospheric circulation patterns. We present a new 42 hr Hubble Space Telescope (HST) Wide Field Camera 3 G141 spectral time series of VHS 1256-1257 b, a late L-type planetary-mass companion that has been shown to have one of the highest variability amplitudes among substellar objects. The light curve is rapidly evolving and best fit by a combination of three sine waves with different periods and a linear trend. The amplitudes of the sine waves and the linear slope vary with the wavelength, and the corresponding spectral variability patterns match the predictions by models invoking either heterogeneous clouds or thermal profile anomalies. Combining these observations with previous HST monitoring data, we find that the peak-to-valley flux difference is 33% ± 2% with an even higher amplitude reaching 38% in the J band, the highest amplitude ever observed in a substellar object. The observed light curve can be explained by maps that are composed of zonal waves, spots, or a mixture of the two. Distinguishing the origin of rapid light curve evolution requires additional long-term monitoring. Our findings underscore the essential role of atmospheric dynamics in shaping brown-dwarf atmospheres and highlight VHS 1256-1257 b as one of the most favorable targets for studying the atmospheres, clouds, and atmospheric circulation of planets and brown dwarfs.

Ambient Environmental Parameter Estimation for Reliable Diffusive Molecular Communications

Molecular communication is a promising communication technology that uses biomolecules such as proteins and ions to establish a communication link between nanoscale devices. In diffusive molecular communication, which uses diffusion characteristics of transfer molecules, the diffusion mechanism is mathematically derived as a Channel Impulse Response (CIR) to design an optimal detector structure. However, an ideal environment is assumed for deriving a CIR. Hence there is a concern that developed systems based on the derived CIR may not operate well in a realistic environment. In this study, based on the finite element method (FEM), we constructed a model of the environment with heterogeneous temperature distribution and actual volume of transmitting molecules to not only demodulate the bit information via maximum likelihood sequence estimation (MLSE) but also to estimate the temperature and volume of the transmitting molecules. Furthermore, in this study, we evaluated the performance of the MLSE method and investigated the effects of ambient environmental temperature distribution and volume of the transmitted molecules on diffusive molecular communication. The evaluation results demonstrated that the proposed method can improve the communication performance by approximately 9 dB by estimating the temperature and transmit molecule volume.

Investigation on Impact Strength of Friction Stud Welded AA6061-B4C Composite/AISI 1030 Steel Joints in Inert Gas Atmosphere

A more contemporary variation of the friction welding procedure, friction stud welding, is promising for military, space, automotive and naval applications. The joining of steel/aluminium matrix composite joints has been crucial in many of these contemporary applications. In all of these applications, the strength of the dissimilar joint is a critical consideration. Heat-affected zones arise because of the heterogeneous temperature distribution and change in thermal characteristics, which weaken the strength of the joints between different materials. The presence of oxygen in the weld interfacial region of the dissimilar joint is detrimental to its strength and integrity. Hence, a new method that can strengthen the dissimilar joint is adopted in the current work. In the friction stud-welding machine, an additional set up is integrated for providing an inert atmospheric condition during the welding process. Microstructural analysis shows that an inert atmosphere is helpful to get rid of oxygen at the interface and it increases joint efficiency. The results show that the impact strength of AA6061-B4C composite/AISI 1030 steel joints tends to increase in the argon inert atmosphere from 14% to 28%.

Dynamic reconfiguration for TEG systems under heterogeneous temperature distribution via adaptive coordinated seeker

A thermoelectric generation (TEG) system has the weakness of relatively low thermoelectric conversion efficiency caused by heterogeneous temperature distribution (HgTD). Dynamic reconfiguration is an effective technique to improve its overall energy efficiency under HgTD. Nevertheless, numerous combinations of electrical switches make dynamic reconfiguration a complex combinatorial optimization problem. This paper aims to design a novel adaptive coordinated seeker (ACS) based on an optimal configuration strategy for large-scale TEG systems with series–parallel connected modules under HgTDs. To properly balance global exploration and local exploitation, ACS is based on ‘divide-and-conquer’ parallel computing, which synthetically coordinates the local searching capability of tabu search (TS) and the global searching capability of a pelican optimization algorithm (POA) during iterations. In addition, an equivalent re-optimization strategy for a reconfiguration solution obtained by meta-heuristic algorithms (MhAs) is proposed to reduce redundant switching actions caused by the randomness of MhAs. Two case studies are carried out to assess the feasibility and superiority of ACS in comparison with the artificial bee colony algorithm, ant colony optimization, genetic algorithm, particle swarm optimization, simulated annealing algorithm, TS, and POA. Simulation results indicate that ACS can realize fast and stable dynamic reconfiguration of a TEG system under HgTDs. In addition, RTLAB platform-based hardware-in-the-loop experiments are carried out to further validate the hardware implementation feasibility.

Intracellular Heat Transfer and Thermal Property Revealed by Kilohertz Temperature Imaging with a Genetically Encoded Nanothermometer.

Despite improved sensitivity of nanothermometers, direct observation of heat transport inside single cells has remained challenging for the lack of high-speed temperature imaging techniques. Here, we identified insufficient temperature resolution under short signal integration time and slow sensor kinetics as two major bottlenecks. To overcome the limitations, we developed B-gTEMP, a nanothermometer based on the tandem fusion of mNeonGreen and tdTomato fluorescent proteins. We visualized the propagation of heat inside intracellular space by tracking the temporal variation of local temperature at a time resolution of 155 μs and a temperature resolution 0.042 °C. By comparing the fast in situ temperature dynamics with computer-simulated heat diffusion, we estimated the thermal diffusivity of live HeLa cells. The present thermal diffusivity in cells was about 1/5.3 of that of water and much smaller than the values reported for bulk tissues, which may account for observations of heterogeneous intracellular temperature distributions.

Experimental Study on the Thermal Performance of 3D-Printed Enclosing Structures

Three-dimensional printing, or additive manufacturing, is one of the modern techniques emerging in the construction industry. Three-Dimensional Printed Concrete (3DPC) technology is currently evolving with high demand amongst researchers, and the integration of modular building systems with this technology would provide a sustainable solution to modern construction challenges. This work investigates and develops energy-efficient 3D-printable walls that can be implemented worldwide through energy efficiency and sustainability criteria. Numerical research and experimental investigations, bench tests with software packages, and high-precision modern equipment have been used to investigate the thermal performance of 3DPC envelopes with different types of configurations, arrangements of materials, and types of insulation. The research findings showed that an innovative energy-efficient ventilated 3DPC envelope with a low thermal conductivity coefficient was developed following the climatic zone. The annual costs of heat energy consumed for heating and carbon footprint were determined in the software package Revit Insight to assess the energy efficiency of the 3D-printed building. The thermal properties of the main wall body of the tested 3D-printed walls were calculated with on-site monitoring data. The infrared thermography technique detected heterogeneous and non-uniform temperature distributions on the exterior wall surface of the 3DPC tested envelopes.

CFD study of the reactive gas-solid hydrodynamics in a large-scale catalytic methanol-to-olefin fluidized bed reactor

Lacking the understanding of multiphase flow in the fluidized bed methanol-to-olefin (MTO) process hinders the reactor design, operation, and optimization. Accordingly, a three-dimensional multiphase particle-in-cell model is established to study hydrodynamics and thermochemical characteristics during the MTO process in a fluidized bed reactor. After model validation, the influences of several critical operating parameters on reactor performance are discussed. The results show that particles in the medium part and freeboard of the reactor have heterogeneous velocity, temperature, and heat transfer coefficient (HTC) distributions. Thermal quantities of gas and solid phases are uniformly distributed in the medium part and freeboard of the reactor. The particle-averaged HTC under ranges from 60 to 120 W/(m2·K). Increasing wall temperature enlarges the particle HTC due to the enhanced exothermic reactions. Decreasing the particle diameter gives rise to a larger particle HTC. The vertical particle dispersion coefficient (Dz) is in the range of 0.01 m2/s to 0.03 m2/s. Methanol converts into olefin in a short period. Increasing methanol to catalyst ratio and wall temperature increases olefin including C2H4, C3H6, C4H8, and C5H10, and promotes the gas thermal properties. Particles with multi-sizes show a better MTO conversion performance than those with mono-sizes regarding the particle HTC and gas products.

Simulation Study of Coaxial Treatment Chambers for PEF Pasteurization: A Critical Review

A pulsed electric field (PEF) produces pasteurized liquid foods with fresh and nutritional properties. The treatment chamber is a crucial part of the PEF processing system where a high voltage is applied, producing an electric field to treat the liquid foods. The proper construction of the treatment chamber regulates the distribution of the electrical field inside the treatment zone. Mixing of liquid inside the treatment zone is an effective tool to overcome this heterogeneous effect. The coaxial treatment chamber offers a heterogeneous electric field and temperature distribution inside the treatment zone. A helical insulator inside the coaxial treatment chamber provides a mixing effect. In this research, a numerical simulation was done to measure the electric field in different geometries of treatment chambers at different flow rates. The simulation aimed to optimize the new coaxial treatment chamber design. The modelling findings showed homogeneous electrical field strength in the helical treatment chamber. This study provides new insights for industrial-scale setup using multiple helical chambers in a continuous flow PEF treatment.

Field test of two background temperature correction methods of dual probe heat pulse method

Dual probe heat pulse (DPHP) method is a useful method to measure many soil physical properties in-situ, which play important roles in soil science, meteorology, hydrology and so on. It is essential to remove the effect of background temperature fluctuations for DPHP estimations. We compared two background temperature correction methods of DPHP method, linear trend method (LTM) and reference temperature method (RTM) in field experiments. We found that misused LTM lead to large errors in DPHP estimations with shallow burial depth. When the burial depth of temperature probe (d) of DPHP sensor is <14 mm, background temperature changes are related to environmental factors such as solar radiation and wind, and RTM can decrease the relative error (RE) in thermal conductivity (λ) from 667% to 68%. Besides, our results also showed during the period from 9:00 to 16:00, the RTM method is valuable for getting accurate DPHP estimations with the 2 mm burial depth. After replacing LTM by RTM, REs were decreased to (6 ± 28)% from (17 ± 87) % in λ, and were decreased to (9 ± 17)% from (10 ± 18)% in volumetric heat capacity (Cv). But RTM is also affected by other factors such as the spatially heterogeneous temperature distribution of tested sample and should be taken into account in the further studies.

A (Dual) Network Model for Heat Transfer in Porous Media

We present a dual network model to simulate coupled single-phase flow and energy transport in porous media including conditions under which local thermal equilibrium cannot be assumed. The models target applications such as the simulation of catalytic reactors, micro-fluidic experiments, or micro-cooling devices. The new technique is based on a recently developed algorithm that extracts both the pore space and the solid grain matrix of a porous medium from CT images into an interconnected network representation. We simulate coupled heat and mass transfer in these networks simultaneously, allowing naturally to model scenarios with heterogeneous temperature distributions in both void space and solid matrix. The model is compared with 3D conjugate heat transfer simulations for both conduction- and convection-dominated scenarios. It is shown to reproduce effective thermal conductivities over a wide range of fluid to solid thermal conductivity ratios with a single parameter set. Morevoer, it captures local thermal nonequilibrium effects in a micro-cooling device scenario.

Experimental measurements for Polish lignite combustion in a 1 MWth circulating fluidized bed during load changes

The conventional design of circulating fluidized beds mainly focuses on high process efficiency, while electricity markets increasingly target operating flexibility due to the increased penetration of renewable energy sources. In this work, the operational flexibility of the CFB furnace when applied to compensate for the feed-in fluctuations from renewable energies has been investigated experimentally. Employing a 1 MWth CFB test facility, Polish lignite was combusted over a wide range of transient operating conditions. The profiles of temperatures and pressures along the riser, the flue gas concentration and the temperature developments in the bed zone, and the outlet of the cyclone that identify the basis for operational flexibility and scale-up studies were shown. It was found that the circulating fluidized bed furnace can be operated with higher positive and negative load change rates up to ±25%/min, maintaining high combustion efficiency and low emissions. Furthermore, the temperature distribution along the riser was almost homogeneous at higher loads. By reducing the load, the temperature difference in the bed zone and after the cyclone was decreased and heterogeneous temperature distribution along the riser can be observed, resulting in a slight decrease in the combustion efficiency.