Airflow Temperature Research Articles

Evaluating the Trade-Off Between Energy Efficiency and Energy Saving in Spray Drying Operations

In this study, modelling simulations were employed to analyze the effects of inlet drying air flow rate and temperature, product feed rate, and heat recovery ratio in a spray dryer. The energy efficiency, energy savings, and final product outlet temperature were investigated. As the heat recovery ratio (by-pass ratio) increased, total energy savings improved, though energy efficiency declined at a slower rate compared to energy savings. The modelling study, conducted with five different by-pass ratios (100%, 70%, 50%, 30%, and 0%), indicated that the optimal by-pass ratio was 30%. At this ratio, energy efficiency decreased by 5%, while energy savings increased by approximately 16%. Additionally, at higher by-pass ratios, the product outlet temperature rose significantly. To maintain product quality, it was found that the maximum acceptable temperature of 60°C could be achieved at by-pass ratios of 40% or lower.

Study on the heat transfer characteristics of mine roadway surrounding rock under periodic airflow temperature: Numerical simulation and experimental validation

Study on the heat transfer characteristics of mine roadway surrounding rock under periodic airflow temperature: Numerical simulation and experimental validation

CFD Analysis of Thermal Conditions and Airflow Patterns in Commercial Laundry Facility using ANSYS Fluent Simulation

This study investigates thermal conditions optimization in a commercial laundry facility through Computational Fluid Dynamics (CFD) analysis using ANSYS Fluent. The research was conducted at Commercial Laundry X in Batu Pahat, Johor, Malaysia, employing a methodology that integrated experimental measurements with computational modelling. Using advanced instrumentation including Temp Sensor T310, Temp Data Logger H100, Thermal Camera T640, and The VelociCalc Multi-Function Ventilation Meter (Model 9565), the study collected empirical data across strategically positioned sampling locations. The data collected from the equipment and instrumentation were compared with the temperature contours and velocity streamlines generated by the computational model. The validated computational model, exhibiting relative errors consistently below 10%, with lowest relative error of 2.17%, successfully simulated complex airflow patterns and temperature distributions throughout the facility. The thermal analysis revealed that of the facility's operational areas exceeded recommended comfort temperatures (23°C - 27°C), with the most significant hotspot reaching 37.81°C near dryer units. This thermal concentration was primarily attributed to the combined effect of equipment heat generation and insufficient thermal dissipation, resulting in localized high-temperature zones that significantly impact the working environment. These findings highlight the critical influence of heat-intensive operations on the thermal environment, indicating poor temperature uniformity and inadequate dissipation of heat in these areas. This research focuses on developing a 3D model of a commercial laundry facility, incorporating geometric and operational characteristics. The model is validated by comparing computational results with experimental measurements of temperature contours and velocity profiles. The study provides valuable insights for optimizing ventilation strategies and equipment placement in commercial laundry facilities, contributing to the enhancement of worker comfort and operational efficiency.

A Bayesian computational technique for learning the airflow resistance of acoustical fibrous materials at high temperatures

This study investigates the acoustic performance of various porous materials at elevated temperatures, employing Constrained Gaussian Process Regression (CGPR) to model the relationship between specific airflow resistance and the absolute temperature. Experimental data on six fibrous material samples at 600°C are used to develop and compare CGPR models against conventional Power Law Regression (PLR) methods. The developed CGPR incorporates constraints such as boundedness, monotonicity and convexity/concavity derived from the evident relationships and prior knowledge of the specific airflow resistance versus temperature variations. The results of this study prove the outperformance of the developed CGPR over PLR methods in terms of data efficiency, predictive accuracy, uncertainty quantification, overfitting recovery and extrapolation capability. This comparative analysis outlines a significant improvement in the predictive accuracy of CGPR, achieving improved coefficient of determination values compared to PLR. CGPR also furnishes a direct strategy to quantify the uncertainty of predictions which is vital for applications at elevated temperatures. Additionally, CGPR offers valuable insights into sound absorption behaviour, highlighting its applicability in thermal acoustics and materials engineering. Prospective research avenues stem from this research as the developed CGPR technique has the potential to replace various modelling techniques in materials science and acoustic engineering applications.

Analysis of the Induced Mild Heating by Airborne Ultrasound Application on the Convective Drying of Pork Liver

AbstractEfficient use of meat by-products, such as pork liver, may entail a previous stage of dehydration for their stabilization, which involves significant energy and time investments. Airborne ultrasound application has been reported as a promising technique to accelerate the air drying of food materials. In this context, the present study addresses, for the first time, the thermal effect associated with ultrasound application on a meat by-product. For that purpose, drying experiments were conducted at 40 and 60 °C on pork liver cylinders at 2 m⋅s−1 with (US) and without (AIR) airborne ultrasound application. The modeling process was based on the principles of heat conduction and moisture diffusion, taking into account the external convection. The results showed that the use of ultrasound reduced the drying time by around 30% at 40 °C, although its impact was less pronounced at 60 °C. With the application of ultrasound, both the sample and air flow temperatures rose by about 4.5 and 2.5 °C, respectively, which partly explains the improvement of drying rate. Due to this low heating effect, airborne ultrasound application must be considered a non-thermal intensification strategy for convective drying of pork liver.

Thermal pressure ventilation analysis in a sloping high-temperature tunnel: A case study in China

Thermal pressure ventilation analysis in a sloping high-temperature tunnel: A case study in China

Freezing Characteristics of Beef Chunks by Air Blast Freezing Under Different Conditions

ABSTRACTIn order to achieve energy‐saving in fast freezing equipment, it is necessary to understand the factors that affect food freezing time. A fluid structure coupling model was established for the freezing process of beef in a freezing room. A total of 45 simulation areas were set with 9 racks and 5 beef chunks on each rack. In the model, the specific heat capacity of the packages was defined as a function of temperature. The core temperatures of the frozen load chunks instead of real beef were measured to verify the correctness of the model. The airflow velocity, air temperature and frozen product temperatures were simulated at different frozen product positions, fan outlet velocities and temperatures. The freezing rates, local Reynolds numbers and wall adjacent heat transfer coefficients were obtained for the chunks. The result shows that the uneven distribution of airflow velocity directly leads to differences in the freezing and heat transfer characteristics of each frozen product. A large vortex with lower airflow velocity and higher airflow temperature in the middle area of the quick‐freezing room causes a slower freezing rate of frozen products. The highest freezing rate is 1.67 cm/h among 45 chunks, and most chunks have a freezing rate greater than 1 cm/h. The variations of the freezing rates are basically consistent with the local wall adjacent heat transfer coefficients within the range of 17.8 to 52.2 W/m2 K. The findings of this article can help provide the appropriate freezing parameters, elucidate the freezing characteristics of beef and offer optimization suggestions for the freezing process of fast freezing rooms.

Investigating hull dryer unit performance: Experiments and modeling of drying time

Hull compaction is an important waste management practice for volume reduction of hollow metallic hull waste generated in the back end of the nuclear fuel cycle. The hull waste should be totally dried of wash solution before high pressure compaction to avoid radiolysis and corrosion phenomena.[ 1 ] In the present work, the influence of various operating parameters (volumetric air flow rate, inlet air temperature, and quantity of hull waste) on the performance of a hull dryer unit has been investigated experimentally. It was observed that drying time exhibited an inverse relationship with both air flow rate and temperature. Furthermore, an increase in the mass of hull waste within the batching can led to improved dry air utilization efficiency. To enable a more comprehensive understanding of the drying process and accurate prediction of drying times, a mathematical model was formulated. A new methodology for estimating the specific surface area of randomly packed hull pieces has been presented. A comprehensive comparison of simulated data with measured exhaust air properties (mass absolute humidity, exit air temperature) and drying times was performed. The close agreement between model predictions and experimental results, with mean absolute percentage error ranging from 2.39923 to 25.21 established strong validation of the model, confirming its predictive capability. This validated model provides a robust foundation for designing future hull dryer units by enabling the calculation of optimal process parameters for various drying time requirements. The study shows that the direct contact hot air heating is a promising technique for drying of hull waste and can be accepted in fast reactor fuel cycle.

Mathematical Modeling of Goat Meat Drying Kinetics with Thermal Oscillations.

Goat meat has a high nutritional value, since it contains up to 29% protein, as well as iron, potassium and vitamin B12. To prolong the shelf life of this food, a drying process can be applied; however, there is scarce information on the kinetics and drying parameters for this food material. The objective of this work was to characterize the thermal drying process of goat meat, through the mathematical modeling of convective drying kinetics, and its validation with experimental data obtained in a drying tunnel. The experiments were carried out with samples of loin (Longissumus dorsi) of Boer goat meat from the Mixteca region of Oaxaca (Mexico). Meat samples were subjected to air convection drying at 40, 50, 60 and 70 °C (with temperature oscillation), with air velocities of 1 and 2 m/s. Drying kinetics, air and meat temperature profiles, relative humidity and air flow velocity were recorded. Four models were analyzed: two-term, Midilli's model, Wang and Singh's model and a heuristic model with temperature dependence. The proposed mathematical models represented drying kinetics with an accurate fitting of experimental data, with standard errors (RMSE) in the range of 0.004-0.029. The estimated diffusion coefficients are consistent with the transport properties in biomaterials. The heuristic model was based on the solution of the effective diffusion equation considering the linearization of the temperature-dependent diffusion coefficient, showing a standard error in the range of 0.007-0.028, satisfactorily representing the temperature oscillations that allows a moisture diffusion reorganization, mainly when drastic temperature changes occur.

Numerical simulation of low-rank coal drying based on non-equilibrium thermodynamics

ABSTRACT Coal is considered to be one of the most significant energy sources in the world. Dewatering, upgrading, and reutilization of lignite is an essential way for the clean coal utilization. Numerical simulation is a practical method combined experimental data with fundamental theories. In this study, based on the Luikov irreversible thermodynamic model, numerical calculations were carried out using the finite volume method and total Hermite integration. The drying characteristics of lignite at different drying temperatures and airflow velocities were simulated employing the fluid computational software. Initially, in order to verify the reliability of the simulation model, the simulated results were compared and validated with the experimental data. The results indicated that the drying parameters obtained from the simulation were in good agreement with the experimental values, and the correlation coefficients were greater than 0.95. Furthermore, the influence of airflow velocity and temperature on the drying characteristics was analyzed based on the numerical results. The results revealed that the drying temperature had the greatest effect on the drying process, while the airflow velocity had a minor effect. The optimum drying conditions for lignite were in the range of 1.2–1.8 m/s for airflow velocity and in the range of 140–160°C for drying temperature.

Transient heat transfer analysis of airflow in a thermal water-bearing tunnel considering airflow turbulence and surrounding rock seepage effects

Transient heat transfer analysis of airflow in a thermal water-bearing tunnel considering airflow turbulence and surrounding rock seepage effects

Modeling Airflow and Temperature in a Sealed Cold Storage System for Medicinal Plant Cultivation Using Computational Fluid Dynamics (CFD)

Effective air circulation is crucial for plant growth, requiring adequate airflow and environmental stability. This study utilized Computational Fluid Dynamics (CFD) to analyze airflow patterns in a controlled testing chamber, focusing on how miniature fan placement affects airflow direction and temperature distribution. Ten case studies were conducted, with the CFD model validated against experimental data collected from six monitoring locations on the plant growth table. Model validation was performed using statistical analyses including coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE). The validation results showed strong agreement between simulated and experimental data, with R2 values of 0.92 for temperature and 0.89 for airflow velocity. Statistical analysis showed significant differences in both airflow and temperature models at the 0.05 level, with the CFD model validation yielding an RMSE of 2.02 and an average absolute error of 1.17. Among the tested configurations, case M1 achieved the highest air velocity (0.317 m/s) and lowest temperature (27.03 °C), compared to M2 (0.255 m/s, 27.17 °C) and M3 (0.164 m/s, 27.18 °C). The temperature variations between cases significantly impacted cold storage efficiency, with case M1’s superior airflow distribution providing more uniform cooling. These findings offer practical guidelines for optimizing ventilation system design in medicinal plant cultivation facilities, particularly in maintaining ideal storage conditions through strategic fan placement and airflow management.

Analysis and control of hybrid convection-radiation drying systems toward energy saving strategy.

Food drying is a vital technology in agricultural preservation, where hybrid drying provides efficient moisture removal. However, the transient behavior of the moisture ratio ( ) and associated drying rate ( ) could increase energy consumption if not managed with an effective energy-saving strategy. This study investigates the impacts of hybrid convection-radiation drying on , , drying time, and energy consumption. Unlike previous studies, which have not fully addressed the connections between operating conditions and drying kinetics, this work provides new insights into these relationships. Additionally, an artificial neural network (ANN) control model is applied to optimize energy consumption, offering a new approach to improving the efficiency of the drying process. During the experiment, the airflow velocity was varied from 0.7m/s to 1.5m/s, the airflow temperature was varied from 40°C to 60°C, and the radiation intensity was varied from 1500W/m2 to 3000W/m2. The results showed that the transient behavior exhibited four data groups with consistent and through the mean and statistical analysis. Increasing radiation intensity and air temperature has decreased the drying time, while higher airflow has increased the drying time. The energy indices were enhanced by increasing radiation intensity and temperature while reducing airflow velocity. The measured of all groups exhibited similar kinetics behavior, while the associated exhibited similar clustering through the self-organizing map. Those findings were further controlled using an ANN model with 99% predicting accuracy. With airborne heating at 60°C and airflow at 0.7m/s, the radiation intensity is transiently controlled, showing a 6.5% drying time reduction and a 36% energy saving. Thus, controlling the radiation intensity and its impact on the slice properties is highly desirable in future work. This work could help designers improve the processing efficiency and energy conservation of garlic slices drying.

Respiratory Rate Monitoring via a Fibre Bragg Grating-Embedded Respirator Mask with a Wearable Miniature Interrogator.

A respiration rate (RR) monitoring system was created by integrating a Fibre Bragg Grating (FBG) optical fibre sensor into a respirator mask. The system exploits the sensitivity of an FBG to temperature to identify an individual's RR by measuring airflow temperature variation near the nostrils and mouth. To monitor the FBG response, a portable, battery-powered, wireless miniature interrogator system was developed to replace a relatively bulky benchtop interrogator used in previous studies. A healthy volunteer study was conducted to evaluate the performance of the developed system (10 healthy volunteers). Volunteers were asked to perform normal breathing whilst simultaneously wearing the system and a reference spirometer for 120 s. Individual breaths are then identified using a peak detection algorithm. The result showed that the number of breaths detected by both devices matched exactly (100%) across all volunteer trials.

Performance of a curved corrugated surface Trombe wall coupled phase change material in buildings by numerical models and experiments

Performance of a curved corrugated surface Trombe wall coupled phase change material in buildings by numerical models and experiments

Simultaneous measurement of temperature by Background-oriented Schlieren and speckle interferometry: Comparison and validation

Simultaneous measurement of temperature by Background-oriented Schlieren and speckle interferometry: Comparison and validation

Design, Construction and Performance Evaluation of Cotton Fabric Layer Materials in Micro-Capillary Absorptive Evaporative Cooling

Design, Construction and Performance Evaluation of Cotton Fabric Layer Materials in Micro-Capillary Absorptive Evaporative Cooling

The Analysis of Building Thermal Comfort based on Air Flow Pattern by using SIMSCALE Simulation

Thermal condition is one of the most important elements of comfort, which can affect people’s activities and working circumstances. Thermal comfort in a room can be controlled by improving the quality of ventilation and designing air flow. This study aims to determine the thermal comfort of a building by using simulation. The data used are building design specification, air temperature, and air flow pattern. The simulation input variables are the 3D model of the room design, maximum and average air temperatures and average air flow velocity values. The expected simulation output are air temperature contour data and air flow patterns. These two values of output are then compared with Indonesia’s national standard SNI 03-6572-2001 and subjective reactions to determine comfort in the rooms. The results show that based on the air temperature contour, the wider the room the air temperature tends to be in a comfortable condition. It also shows that the ratio of the opening area to the floor area can influence the cooling of the air temperature in the room. Based on the flow pattern air, openings facing each other in a room will improve air circulation and it is influenced by the ratio of the area of the opening to the area of the room. The research results show that air temperature contours and air flow patterns can be a reference for determining thermal comfort in a room. Regarding the output of simulation, it is recommended that the energy savings calculations need to be carried out to find out how much impact the building's natural ventilation performance has on electrical energy use.

Numerical Study on Combustion Characteristics of a 600 MW Boiler Under Low-Load Conditions

Under the background of achieving carbon dioxide peaking and carbon neutrality, the rapid development of renewable energy power generation poses new challenges to the flexible adjustment capabilities of traditional power plants. To explore the furnace combustion stability and optimal operation modes during deep peak shaving, a simulation of the combustion process under low-load conditions for a 600 MW wall-fired boiler is performed utilizing computational fluid dynamics (CFD) analysis. The impact of burner combination modes on the combustion process within the furnace is explored at 25% and 35% boiler maximum continuous ratings (BMCRs). This study investigates two configurations of burner combinations. One mode operates burners in layers A, B, and C, which include the lower layers of burners on the front and rear walls of the boiler, as well as the middle-layer burners on the rear wall, referred to as OM1. The other mode operates burners in layers A and C, which include the lower layers of burners on the front and rear walls of the boiler, referred to as OM2. The results indicate that OM2 exhibits superior capabilities in orchestrating the distribution of the airflow velocity field and temperature field under the premise of ensuring no more than a 1% decrease in the pulverized coal burnout rate. When OM1 is employed, the airflow ejected from the middle-level burners hinders the upward movement of pulverized coal sprayed from the lower-level burners, causing a larger proportion of pulverized coal to enter the ash hopper for combustion. Consequently, the ash hopper attains a peak mole fraction of CO2 at 0.163. OM2 delays the blending of pulverized coal with air by enhancing the injection quantity of pulverized coal per burner. As a result, the generation of CO in the ash hopper reaches a notable mole fraction of up to 0.108. The decreased furnace temperature promotes the formation of fuel-based NOx during low-load operation. Taking the 25% BMCR as an example, the NOx emissions measured at the furnace outlet are 743 and 1083 ppm for OM1 and OM2, respectively. This study focuses on the impact of combustion combinations on the combustion stability when the boiler is operating at low loads. The findings could enrich previous research on combustion stability and contribute to the optimization of combustion schemes for power plant boilers operating at low loads.

Experimental study on the thermal insulation performance of semi-transparent materials based on convection heating method

Experimental study on the thermal insulation performance of semi-transparent materials based on convection heating method