Inlet Air Temperature Research Articles

Optimization of adiabatic flame temperature of natural gas combustion under different conditions

AbstractThe combustion of natural gas consisted of methane , ethane , and propane is theoretically investigated to obtain the optimum adiabatic flame temperature (AFT). The investigation includes the development of combustion equations that take into consideration different compositions of natural gas. The final equation to calculate the AFT is derived and used in the optimization study. The optimization study using genetic algorithm investigates the effect of changing the composition of the gas mixture, the inlet temperature of used air, and the amount of excess air used on the AFT. It is possible to get the required composition of each component, the air inlet temperature, and the excess air by reading the chart to get the required AFT. The heat capacity of all reactants and products is used as a function of temperature. Results showed that the optimum values for , percentages in the gas mixture, air inlet temperature, and the amount of excess air are 0.478, 0.166, 0.356 mol %, 1.848, 382.104 K, respectively. These optimum values lead to a value of about 1300 K for the AFT. The derived equation shows the AFT at different natural gas compositions along with different process parameters such as the amount of excess air. Thus, the required combustion temperature can be controlled by adjusting the natural gas composition or the combustion temperature can be specified based on the provided composition of the natural gas stream by using either the derived equations or output chart. (R1. 1).

Impact of the drying rate on product properties of spray dried emulsions to enable a targeted product design

Spray drying of emulsions is a widespread encapsulation technique to produce a large variety of powdered formulations. The oil droplet size (ODS) in the powder is critical for product quality, influencing key product parameters such as the encapsulation efficiency (EE) of the oil. To expand the understanding of changes in ODS and structure formation during the drying step. For this purpose, model oil-in-water emulsions were spray-dried at varying air inlet and outlet temperatures. The powders were characterized regarding ODS and EE. Smaller ODS were observed for parameter combinations where higher drying rates are expected due to decreased coalescence. The results for the EE revealed no clear trend. An increase of air outlet temperature first led to a small decrease in EE followed by a distinct increase of EE. The first decrease may indicate a collapse of the particle morphology but more detailed investigations are necessary to explore these phenomena.

Experiments and modeling on thermal performance evaluation of standalone and M-cycle based desiccant air-conditioning systems

This study aims to evaluate the performance of standalone and Maisotsenko-cycle based desiccant air-conditioning systems with silica gel through experimental and explainable artificial intelligence methods. In order to examine the desiccant systems' performance, deep neural networks have been constructed based on the optimal hyper-parameters provided by the Bayesian surrogacy. The influential factors, such as regeneration air temperature and relative humidity, primary air temperature and relative humidity, among other system features like regeneration temperature and humidity, are chosen as the inputs using feature engineering and correlation heat maps. The results indicated that with the right framework and training data, the proposed model can forecast the performance of the standalone and M-cycle-based desiccant air conditioning systems with a great accuracy (i.e. R2 = 0.99). In addition, regeneration temperature and humidity, and inlet regeneration air temperature are considered to be the primary parameters that affect the thermal performance of Maisotsenko-cycle and stand-alone desiccant systems. The regeneration conditions are shown to have a positive correlation with the primary and regeneration outlet temperatures while having a negative correlation with the primary and regeneration outlet relative humidity. The primary inlet relative humidity has the greatest impact on the primary outlet relative humidity while the regeneration inlet temperature has the highest impact on the regeneration outlet relative humidity of the system. In addition, the primary inlet relative humidity is found to have positive correlations with the outlet regeneration and primary relative humidity and outlet regeneration temperature. Also, the primary air inlet temperature is found to be directly associated with the outlet primary relative humidity and temperature for the considered systems.

Experimental investigation of multi-burner array with lean lifted spray flames in inline and inclined configurations

Lean combustion in gas turbines garners attention for emissions reduction, yet it faces stability challenges demanding careful design considerations. In this study, a novel CHAIRLIFT combustor concept, which integrates low swirl lean lifted spray flames known for substantial nitrogen oxides emissions reduction, into a Short Helical Combustors (SHC) arrangement, is investigated. A comprehensive experimental test campaign explores key parameters, including staggered arrangement offset, equivalence ratios, and air inlet temperature, to evaluate its performance. The results reveal exceptional stability in low swirl, lifted flames compared to moderate swirl flames with larger inner recirculation zones. The unwanted flow deflection of highly swirled flames in the SHC arrangement is effectively avoided with the investigated low swirl, lifted flames. The study emphasizes the significant influence of fuel droplet evaporation time on flame stability near the flame root under low air inlet temperatures. Furthermore, at high air inlet temperatures, the complex flame stability mechanism in inclined configurations is controlled by various parameters, including outer recirculation zone size, air inlet temperature, and additional vortices generated by pressure differences near the wall. OH∗ chemiluminescence results corroborate these stability mechanisms, showing that at lower temperatures, the flame stabilizes closer to the nozzle exit due to local rich pockets near the shear layer. Conversely, at the same tilt angle, higher air inlet temperatures lead to an increased flame lift-off height due to faster evaporation and enhanced mixing. Exhaust gas analyses confirm the potential of the investigated lean lifted spray flames in a multi-burner arrangement to achieve very low NOx emissions over a wide range of operating conditions for all investigated burner inclinations. These findings may facilitate the future development and optimization of lean combustion technology for aircraft engines.

Experimental and numerical investigation on the charging and discharging process of a cold energy storage for space cooling of buildings

To address the current issue of the difficulty to use the hot outdoor environment during summer nights to provide coolness for phase change materials (PCM) and thus reduce building energy consumption in hot summer areas, a novel cold energy storage unit has been proposed. It replaces the hot outdoor environment with other free or cheap cold sources. An experimental setup is built to investigate the cold storage and release performance of the PCM storage unit. Later, the well-validated numerical model is conducted to further explore thermal performance of the PCM storage unit. The numerical result indicates that the cold storage process can be completed from 64.33 min to 96.56 min when the water inlet temperature varies from 10 °C to 16 °C. Further, during the cold release process, the PCM storage unit can reduce the temperature of the hot air by a maximum of about 8–12 °C when the air inlet temperature ranges from 32 °C to 38 °C. The cold release efficiency is varied between 81.65 % and 96.44 %. In conclusion, the findings provide a promising way for cold storage and space cooling of buildings in hot summer areas through the cold energy storage unit.

Investigation of the performance of cold-end system in direct air-cooled power units under the influence of ambient winds

Direct air-cooled condensers in power plants rely on heat transfer with the atmospheric environment to discharge thermal energy. The heat transfer process becomes complicated in practical operations when ambient wind is involved. To examine the impact of wind on the heat transfer performance of direct air-cooled condensers, this paper took into consideration three different wind directions, namely, headwind, crosswind and tailwind, as well as four different speeds (3 m/s, 6 m/s, 9 m/s, and 12 m/s), and numerically investigated their influences on the thermal performance of a 600 MW direct air-cooled power unit. The variation in ventilation rates and inlet air temperatures among the cells under the influence of ambient winds are also studied. Simulation results indicated that ambient winds induced thermal air re-circulation and air backflow phenomena in the air-cooled island. The cells located on the windward side were significantly affected in all three wind direction conditions. The ventilation rates and inlet air temperatures among the cells were not uniform, showing an overall increasing trend. In particular, negative pressure zones were generated under tailwind conditions, severely impacting air-flow rates at the fan inlet, and inlet air temperatures of cells. These phenomena became more pronounced with increasing wind speeds.

INCREASING THE EFFICIENCY OF FUEL-FIRED PLANTS WITH DUSTY WASTE GASES

The results of a set of thermal calculations of the air-heating heat exchanger of the dusty waste gases of the thermal disposal of household waste are given. The initial data for the calculations were taken in the practical range when incinerating 1t/h of household waste from the experience of using the specified installations. The heat-recovery unit is designed to heat air for combustion by recovering the heat of the exhaust gases leaving after the turbine of this installation. Its design solution is characterized by the possibility of cleaning work surfaces from deposits of technological dust. The thermal indicators (temperatures of coolants and heat productivity) of the proposed heat-recovery unit under the conditions of its use for waste incineration plants were investigated. Calculations were performed in different modes of operation of the heat-recovery unit during the year, namely: at inlet temperatures of air and exhaust gases in the range from -20 to +20 ºС and from 200 to 300 ºС, respectively, the coefficient of excess air in waste gases from 1.5 to 2, 5 and different levels of dust on the heating surface. The influence of dustiness on the thermal parameters was characterized by the coefficient k, which determined the level of reduction in the thermal efficiency of the heat exchanger as a result of dust deposits on the specified surface and varied in the range from 1 to 0.5. Under the considered conditions was established, that use of the proposed air heater it provides heat output of 72 ÷ 263 kW, cooling of flue gases to a temperature of 107 ÷ 245 °С and heating of air to 96 ÷ 220 °С. At such levels of flue gas cooling, the efficiency of the thermal disposal of household waste increases by 2 ÷ 5%. In the case of a decrease in the heat-recovery capacity of the heat-recovery unit to technologically unacceptable levels, it is necessary to carry out its forced cleaning with compressed air, as provided for in the technical solution of such an air heater.

Energy conservation of HVAC systems in isolation rooms using heat pipe heat exchangers

Isolation rooms are crucial in healthcare facilities to prevent the spread of infectious diseases. Infectious diseases can be transmitted to humans from humans or through animals known as zoonoses. With the increase in the number of COVID-19 cases, isolation rooms have become one of the most critical facilities in hospitals. Maintaining the correct temperature and humidity in these isolation rooms is a challenge, considering the heating, ventilation, and air conditioning (HVAC) systems that continuously consume large amounts of energy. With the application of energy conservation methods, the total energy consumption of HVAC systems can be reduced. Many studies have shown that the heat pipe heat exchanger (HPHE) technology can contribute significantly to energy savings using HVAC systems. In this study, the effectiveness of an HPHE on an HVAC system in an isolation room was examined, and the total energy reduction was quantified. The HPHE consisted of two rows with ten heat pipes in each row, arranged in a staggered configuration with fresh air temperature and mass flow variations. The inlet fresh air temperatures varied at 32, 35, 37, and 40 °C and fresh air velocities at 1.2, 1.6, 2.2, and 2.6 m/s. Using a chiller, the inlet fresh air was cooled to a comfortable temperature zone, approximately 24.4–25.2 °C, in the isolation room. Notably, higher velocities decreased the effectiveness of the HPHE. An increase in the flow rate enhanced the system, thereby improving the heat recovery value. The increase in the inlet fresh air temperature from 32 °C, that yielded an energy saving of 1.23 W, to 40 °C, resulted in a further energy saving of 1.85 W. The application of the HPHE in the HVAC system in isolation rooms represents a significant innovation that contributes to a reduction in total energy consumption.

Enhancing polytetrafluoroethylene (PTFE) coated film for food processing: Unveiling surface transformations through oxygenated plasma treatment and parameter optimization using response surface methodology.

Spray drying fruit juice powders poses challenges because sugars and organic acids with low molecular weight and a low glass transition temperature inherently cause stickiness. This study employed a hydrophobic polytetrafluoroethylene (PTFE) film to mimic the surface of the drying chamber wall. The Central Composite Design (CCD) using response surface methodology investigated the impact of power (X1, Watt) and the duration of oxygenated plasma treatment (X2, minutes) on substrate contact angle (°), reflecting surface hydrophobicity. To validate the approach, Morinda citrofolia (MC) juice, augmented with maltodextrins as drying agents, underwent spray drying on the improved PTFE-coated surface. The spray drying process for MC juice was performed at inlet air temperatures of 120, 140, and 160°C, along with Noni juice-to-maltodextrin solids ratios of 4.00, 1.00, and 0.25. The PTFE-coated borosilicate substrate, prepared at a radio frequency (RF) power of 90W for 15 minutes of treatment time, exhibited a porous and spongy microstructure, correlating with superior contact angle performance (171°) compared to untreated borosilicate glass. Optimization data indicated that the PTFE film attained an optimum contact angle of 146.0° with a specific combination of plasma RF operating power (X1 = 74 W) and treatment duration (X2 = 10.0 minutes). RAMAN spectroscopy indicated a structural analysis with an ID/IG ratio of 0.2, while Brunauer-Emmett-Teller (BET) surface area analysis suggested an average particle size of less than 100 nm for all coated films. The process significantly improved the powder's hygroscopicity, resistance to caking, and moisture content of maltodextrin-MC juice. Therefore, the discovery of this modification, which applies oxygen plasma treatment to PTFE-coated substrates, effectively enhances surface hydrophobicity, contact angle, porosity, roughness, and ultimately improves the efficacy and recovery of the spray drying process.

Effect of air preheating temperature on the dynamic behaviour of a swirled spray flame

The effects of the air inlet temperature on the dynamic behaviour of a spray flame are reported for different air flow rates. Dodecane droplets are generated through a pressurised nozzle and introduced in the combustion chamber fed with air via two co-rotating swirlers. The flow rate of dodecane is kept constant (1.24gs-1) while the air flow rate is changed from 28gs-1 to 35gs-1 and its temperature from 70°C to 220°C. Microphones are used to record the different dynamics observed while a camera and a Phase Doppler Anemometry system allow to monitor the flame and the fuel spray.For low flow rates (between 28gs-1 and 32gs-1, leading to an overall equivalence ratio ranging between 0.6 and 0.7), the pressure fluctuations start by increasing with an increase of the temperature until, for a given temperature, the pressure fluctuations suddenly drop. This threshold temperature depends on the air flow rate. When displaying the pressure fluctuation level as a function of the bulk velocity (taking both air flow rate and temperature into account), the curves collapse into a similar shape. The instability frequency monotonically increases with the bulk velocity. For high flow rates (between 32gs-1 and 35gs-1, leading to overall equivalence ratio ranging between 0.5 and 0.6), a hysteresis phenomenon is found. Pressure fluctuations are relatively high for constantly decreasing temperature conditions and have almost similar levels as those obtained for lower flow rates. When constantly increasing the temperature, the levels are much lower, showing a bi-stable behaviour for the pressure fluctuations at a given operating point. A simple analysis based on the acoustic energy balance equation allows to qualitatively retrieve the behaviour of the pressure fluctuations amplitude and frequency for the low flow rate cases.

热气流风机的数值模拟及试验

The value of high moisture content crops is higher and the planting area is wider. However, in the harvest process, due to the high moisture content, the cleaning loss is greater. In order to reduce the adhesion between the crop extraction mixture and improve the cleaning performance, a method of hot air cleaning was proposed. By using the fan design theory and thermodynamics, the prototype design of the hot air fan was completed. Through orthogonal test, the most suitable parameter combination is 1445r/min fan speed and 85℃ air inlet temperature. Computational fluid dynamics (CFD) was used to observe the air velocity and air temperature of the outlet under the optimal combination of parameters to check whether it meets the requirements of hot air cleaning. The reliability of numerical simulation was tested by bench test. Finally, a field experiment was carried out with the hot air fan to observe the difference between the cleaning effect and the fan under the optimal parameter combination, and compare the cleaning loss rate.

Evaluation of Phase Change Materials for Pre-Cooling of Supply Air into Air Conditioning Systems in Extremely Hot Climates

This research investigates the use of phase change materials (PCMs) in thermal energy storage (TES) unit-based cooling systems to increase the efficiency of air conditioners (ACs) by reducing the air inlet temperature. This study aims to evaluate different configurations of PCM enclosures, and different PCMs (paraffin and salt hydrate), by changing the speed of inlet air to achieve heat reduction of inlet air. The study includes experimental and simulation investigations. Every configuration simulates the hot-season atmospheric conditions of the UAE. A duct containing enclosures of paraffin RT-31 and salt hydrate (calcium chloride hexahydrate) was used for the simulation study using ANSYS/Fluent. A conjugate heat transfer model employing an enthalpy-based formulation is developed to predict the optimized PCM number of series and optimum airflow rate. Four designs of the AC duct were modelled and evaluated that contained one to four series of PCM containers subjected to different levels of supplied air velocities ranging from 1 m/s–4 m/s. The simulation study revealed that employing four series (Design 4) of PCM enclosures at a low air velocity of 1 m/s enhanced the pre-cooling performance and reduced the outlet air temperature to 33 °C, yielding a temperature drop up to 13 °C. The performance of salt hydrate (calcium chloride hexahydrate) was observed to be better than paraffin (RT-31) in terms of the cooling effect. Characterization of paraffin wax (RT-31) and salt hydrate was performed to establish the thermophysical properties. The experimental setup based on a duct with integrated PCM enclosures was studied. The experiment was repeated for three days as the repeatability test incorporating RT-31 as the PCM and a 3 °C maximum temperature drop was observed. The drop in the outlet air temperature of the duct system quantifies the cooling effect. Net heat reduction was around 16%.

Characterization and effect of optimized spray-drying conditions on spray-dried coriander essential oil

Coriander (Coriandrum sativum L.) essential oil (CEO) has many beneficial features, including antimicrobial and antifungal properties along with good aroma. It also has an important role in food processing and preservation. However, CEO is highly volatile and sensitive to external factors (heat, light and oxygen), as well as susceptible to lipid oxidation due to environmental and general processing conditions. This limits water solubility, making it difficult to incorporate CEO into aqueous food matrices, which further limits their industrial application. Spray-drying encapsulation may prevent CEO oxidation, increase CEO oxidative stability and improve their physicochemical properties. In this study, spray-dried CEO (SDCEO) was prepared using a mini laboratory-scale spray-dryer and the processing conditions were optimized. The SDCEO were characterized in respect to free fatty acids (FFA), peroxide values (PV), fatty acid (FA) profiles, Fourier-transform infrared spectroscopy (FTIR) and physical morphology by scanning electron microscopy (SEM). Results indicated that the maximum value of FFA, PV, fatty acid composition (including petroselinic, linoleic and oleic acids) in SDCEO were observed at the following spray-drying conditions: an inlet-air temperature (IAT) of 140 °C, needle speed (NS) of 2 s and the wall-material (WM) at 25%. The minimum values were observed at an IAT of 180 °C, NS of 4 s and WM of 30%. Analysis of variance and the interaction effects of independent factors showed that IAT and WM significantly positively influenced the response for good oxidative stability. Thus, SDCEO is likely to be used as a natural active ingredient in the food processing, cosmetic, nutraceutical and pharmaceutical industries with high stability, and may be stored for a long time without evaporation or oxidation.

Predicting Temperature and Humidity in Roadway with Water Trickling Using Principal Component Analysis-Long Short-Term Memory-Genetic Algorithm Method

The heat dissipated from high geo-temperature underground surrounding rocks is the main heat source of working faces, while thermal water upwelling and trickling into the roadway will notably deteriorate the mine’s climate and thermal comfort. Predicting airflow temperature and relative humidity (RH) is conductive to intelligent control of air conditioning cooling and ventilation regulation. To accommodate this issue, an intelligent technique was proposed, integrating a genetic algorithm (GA) and long short-term memory (LSTM) based on rock temperature, inlet air temperature, water temperature, water flow rate, RH, and ventilation time. A total of 21 input features including over 200 pieces of data were collected from an independently developed modeling roadway to construct a dataset. Principal component analysis (PCA) was conducted to reduce features, and GA was used to tune the LSTM and PCA-LSTM architectures for best performance. The following research results were yielded. The proposed PCA-LSTM-GA model is more reliable and efficient than the single LSTM model or hybrid LSTM-GA model in predicting the air temperature Tfout and humidity RHout at the end of the water trickling roadway. The importance scores (ISs) indicate that Tfout is mainly influenced by the surrounding rock temperature (IS 0.661) and the inlet air temperature (IS 0.264). While RHout is primarily influenced by the rock temperature in the water trickling section (IS 0.577), the inlet air temperature (IS 0.187), and the trickling water temperature and flow rate (total IS 0.136), and it has an evident time effect. In addition, we developed relevant equipment and provided engineering practice methods to use the machine learning model. The proposed model, which can predict the mine microclimate, serves to facilitate coal and geothermal resource co-mining as well as thermal hazard control.

Analysis of Cavity Disk Heat Transfer by Solving Inverse Heat Transfer Problem

Abstract The flow and heat transfer within compressor rotor cavities of aero-engines is a conjugate problem. The operating conditions buoyancy forces, caused by radial temperature difference between the cold throughflow and the hotter shroud, can influence the amount of entrained air significantly. By this, the heat transfer depends on the radial temperature gradient of the cavity walls, and in turn, the disk temperatures are dependent on the heat transfer. In this article, disk Nusselt numbers are calculated in reference to the air inlet temperature and in comparison to a modeled local air temperature inside the cavity. The local disk heat flux is determined from measured steady-state surface temperatures by solving the inverse heat transfer problem in an iterative procedure. The conduction equation is solved on a 2D mesh using a validated finite element approach, and the heat flux confidence intervals are calculated with a stratified Monte Carlo approach. An estimate for the amount of air entering into the cavity is calculated by a simplified heat balance. The major influences on the Nusselt number were found to be the mass flowrate entering the cavity and the density of the fluid inside the cavity.

POTENTIAL OF RICE BRAN PROTEIN POWDER PRODUCTION TO INCREASE PADDY INDUSTRY PRODUCTIVITY

The demand for alternative protein sources has been steadily increasing due to concerns about sustainability and animal welfare. Rice bran, a byproduct of rice milling, is a potential source of protein with high nutritional value. This study aims to investigate the production of rice bran protein powder using a pilot-scale ultrasonic spray dryer.The research methodology involves several key steps. First, rice bran is collected from the milling process and undergoes a series of pretreatment steps, including defatting and protein extraction. The extracted protein solution is then concentrated and purified to remove impurities and enhance protein content. The resulting protein solution is then fed into a pilot-scale ultrasonic spray dryer for powder production. The pilot-scale ultrasonic spray dryer offers advantages such as precise control over particle size, improved solubility, and reduced agglomeration. The drying conditions, including inlet air temperature, feed rate, and atomization pressure, are optimized to obtain a high-quality protein powder with desirable physicochemical properties. The produced rice bran protein powder is characterized for its protein content, amino acid profile, functional properties (such as solubility, emulsifying capacity, and foaming ability), and particle size distribution. These properties are evaluated to assess the feasibility of using rice bran protein powder in various food applications, including bakery products, beverages, and nutritional supplements. The results of this study provide insights into the potential of rice bran protein as an alternative protein source and highlight the effectiveness of pilot-scale ultrasonic spray drying as a production method. The findings contribute to the development of sustainable protein ingredients and support the utilization of rice bran, a byproduct that would otherwise be underutilized or discarded.

Yearly hour-by-hour performance evaluation of a SIEMENSE gas turbine power plant for Australia’s climate condition with and without a novel intake air pre-cooling strategy

The power production, fuel consumption and revenue of any gas turbine (GT) power plant are greatly affected by variations in ambient conditions (entering air into the compressor). This paper simulates and reports the power output and efficiency of a gas turbine-based power plant (SGT-750 SIEMENSE) using around 8000 h-by-hour yearly weather data of two regions of Australia (north and south) without pre-cooling, with sole M−cycle pre-cooling and finally with an innovative hybrid pre-cooler. The hybrid pre-cooler consists of a Maisotsenko indirect evaporative cooler (M−cycle) and an absorption chiller (ABC). Briefly, the results indicate that power raise of the GT plant using the M−cycle IEC alone is about 2 % in temperate regions and 4 % in hot regions, while it would be about 4 % and 6 % respectively if the hybrid pre-cooler is used. Reducing the inlet air temperature by 8–10 °C increases the generated power of a GT with pre-cooler by 8–9 %.

Impact of Preheating on Flame Stabilization and NOx Emissions From a Dual Swirl Hydrogen Injector

Abstract Flame stabilization, flame structure, and pollutant emissions are investigated experimentally on a swirled injection system operating with globally lean air/hydrogen mixtures at atmospheric conditions and moderate Reynolds numbers. This injector consists of two coaxial ducts with separate injection of hydrogen into a central channel and of air into an annular channel. Both streams are swirled. The resulting flames exhibit two stabilization modes. In one case, the flame takes an M-shape and is anchored to the hydrogen injector lips. In the second case, the flame is aerodynamically stabilized above the injector and takes a V-shape. Regions of existence of each stabilization mode are determined according to the operating conditions. For low air flow rates, the flame can be either anchored or lifted above the hydrogen injector lips depending on the path followed to reach the operating condition. At high air flow rates, the flame is always lifted regardless of the trajectory followed. The impact of air inlet temperature on these stabilization regimes is then evaluated from T= 300 K up to 770 K. Flame re-attachment is shown to be controlled by edge flame propagation and the impact of preheating is well reproduced by the model. Unburnt hydrogen and NOx emissions are finally evaluated. Unburnt hydrogen is only observed for global equivalence ratios below 0.4 and at ambient inlet temperature. NOx emissions decrease when the global equivalence ratio is reduced. Furthermore, at fixed global equivalence ratio, NOx emissions decrease as the thermal power increases, regardless of air preheating and the flame stabilization regime. At high power, NOx emissions reach an asymptotic value that is independent of the thermal power. The impact of flame shape, air preheating, and combustion chamber wall heat losses on NOx production is also evaluated. NOx emissions are shown to scale with the adiabatic flame temperature Tad at the global equivalence ratio and the residence time inside the combustor.

Effects of cluster dextrin encapsulation on the properties and antioxidant stability of fractionated Riceberry protein hydrolysate powder prepared by bromelain

In this work, the biological properties of fractionated Riceberry bran protein hydrolysate obtained by ultrafiltration (URBPH) were evaluated and the possibility of using cluster dextrin to produce hydrolysate powder by spray-drying was investigated. Fractionation into peptides < 3 kDa was observed to improve antioxidant activity. URBPH < 3 kDa was then freeze-dried (FD-URBPH) and spray-dried (SD-URBPH) at different inlet air temperatures of 100–160 °C. The water solubility and antioxidant activity of FD-URBPH were higher than those of SD-URBPH. Nevertheless, encapsulation of hydrolysate with 10% cluster dextrin and an inlet temperature of 120 °C was also successful in maintaining protein qualities, which showed high 2,2′-azino-bis 3-ethylbenzthiazoline-6-sulfonic (ABTS•+) scavenging activity (89.14%) and water solubility index (92.49%) and low water activity (aw = 0.53). Moreover, encapsulation preserved the antioxidant activity of peptides during gastrointestinal digestion better than the free form. URBPH and its spray-dried microcapsules could be used as bioactive ingredients in functional drinks or foods.

Modeling and optimization of spray drying process parameters using artificial neural network and genetic algorithm for the production of probiotic (Lactiplantibacillus plantarum) finger millet milk powder

AbstractConsumers have been more inclined towards functional food due to various health issues. Non‐dairy‐based probiotic milk could be the potential alternative to fulfill consumer demand. Spray drying of functional health drinks could enhance the shelf life and reduce the transportation cost of developed food powder. The current study was focused on the modeling and optimization of spray‐drying process parameters using an artificial neural network (ANN) coupled with a genetic algorithm (GA). The data so obtained using ANN‐GA was also compared with the data obtained using response surface methodology (RSM) coupled with desirability function (DF). The results indicated that the ANN model was better at predicting the response parameters compared to the RSM model with a higher correlation coefficient (R) of .9997, .9994, .9964, and .9992 for training, testing, validation, and all datasets, respectively. The optimum conditions obtained using RSM‐DF were 160.41°C of inlet air temperature, 33.77% of maltodextrin content, and 138.79 mL/h of feed rate while that for ANN‐GA were 160.87°C, 20%, and 200 mL/h. The RSM‐DF method proved to be better for the optimization of response parameters. Therefore method selection for modeling and optimization of process and response parameters must be based on fulfilling the specific criteria.Practical ApplicationsNon‐dairy milk production has gained popularity in the area of research and product development. Various process protocols have been reported to produce high‐quality non‐dairy milk to fulfill the demand for a vegan diet. However, nutrient bioavailability, longer shelf life, product stability, and consumer acceptability are hard to obtain from cereal‐based non‐dairy milk. The current study contributes to produce spray‐dried milk powder followed by fermentation at optimum drying conditions with good quality and stability. The process has been modeled and optimized in the study using advanced statistical tools such as ANN‐GA and RSM‐DF. They can effectively predict the quality parameters and determine the optimal conditions for new experimental data.