Higher Inlet Air Temperature Research Articles

Enhancement of the precooling system performance for aviation engines by volatile liquid injection

Water injection precooling in aviation engines is a promising technique that can enhance performance, improve efficiency, and reduce emissions, especially at high altitudes and Mach numbers. However, its implementation in aviation engines requires careful engineering and design considerations due to the restricted space available for installation and operation, as well as the challenges posed by high inlet air velocities. Therefore, the present study experimentally and numerically evaluates the effectiveness of spray precooling for jet engines and introduces novel insights into optimizing droplet dynamics and nozzle configurations in short, narrow spray ducts under high inlet air temperature and velocity. The impact of water spray cooling on the uniformity of inlet air is also investigated for nonuniform air temperature conditions, which has yet to be mentioned in previous research. An experimental configuration has been devised and implemented to investigate water injection precooling within a rectangular spray duct. The evaporative cooling process through the spray duct and the injected droplet trajectories were predicted using an Eulerian-Lagrangian computational fluid dynamics (CFD) model. The CFD model was verified using the present experiments, and there is a strong correlation between the experimental data and simulation findings, with an average discrepancy of less than 7%. The effectiveness of the water injection system is investigated at different operating parameters such as nozzle arrangements, coolant type, droplet size, and variable velocities. The results showed that sprays characterized by small mean diameters and high initial droplet velocity significantly enhance spray cooling performance. Changing the nozzle configurations impacts spray cooling performance considerably, with the cross-outside case providing the best results. Notwithstanding its advantageous evaporation rate, introducing methanol via injection does not yield significant enhancements. Water injection is crucial in achieving a more homogeneous temperature distribution by reducing temperature disparities and promoting mixing and evaporation.

Analysis of melting behavior of layered different phase change materials for a cylinder insert into a channel

Phase change materials (PCMs) have diverse fields of application due to higher thermal inertia. The present study explores the melting behavior in dual-layered different PCMs in a cylindrical lithium-ion battery module placed in a long channel under the hot air stream. The main cylinder is packed with paraffin wax and covered PCM is chosen as calcium chloridehexahydrate (CaCl2-6H2O). The material between two PCMs is considered highly conductive and impermeable. The involved mathematical equations in two-dimensional forms are numerically simulated the applying the finite volume technique. The primary important parameters of melting behavior are the difference in temperature and inlet air velocity. The analysis is carried out for the effective parameters such as the inlet air temperature (Thot = 100 °C and 120 °C) and air velocity (սair = 2.5 and 5.0 m/s). The results revealed that an increase in air velocity reduces the highest and average temperature of the PCM. The changes in melting time of PCMs decline with time. Higher inlet air temperature also causes fast melting of the PCMs over time. The analysis revealed that the application of PCMs is undue when there is no phase change process. The analysis also revealed that an increment in the inlet air velocity causes a decrease in the average temperature. For the same air inlet temperature (Thot) higher air velocity leads to a slower rate of the melting process Therefore, melting time is less by ∼ 30 % (for the inner layer) and 32 % (for the outer layer) with decreasing air velocity. The findings of this study will help the designer to improve the battery thermal management system by modulating the temperature.

Theoretical design and drainage characteristic of a C-type heat exchanger in duct air conditioner

The conventional duct air conditioner typically uses an A-type heat exchanger for indoor units, which has poor drainage behavior under wet conditions. In this research, a C-type heat exchanger is developed for drainage improvement. The innovative design employs a unitary fin and a curved profile instead of the sectional fin and linear profile. Theoretical calculations are conducted, determining that the droplet sliding time on the cycloid is the shortest among the curves. The C-type is then produced and subjected to dynamic dip testing to assess its drainage performance. Results reveal that it achieves steady drainage within 3 s and reduces residual water by 10.9% compared to the A-type. A CFD model is generated to simulate the drainage process, with a calculated deviation of less than 10% for residual water. Finally, the C-type prototype is installed in the duct unit for performance measurement under wet conditions. It exhibits a 7.12% increase in heat transfer capacity and a 12.74% increase in drainage rate under the basic condition. The lower evaporating temperature, higher inlet air temperature, higher relative humidity, and larger air volume flow rate contribute to the more apparent drainage enhancement of the C-type.

Comparative Analysis of Concurrent (CC), Mixed Flow (MX), and Combined Spray Drying Configurations on the Physicochemical Characteristics of Satsuma Mandarin (Citrus unshiu) Juice Powders.

Satsuma mandarins are good sources of vitamin C and can be used as raw materials to produce novel plant-based food ingredients including satsuma mandarin juice powders (SJP). Food powders produced via spray drying often show thermal degradation due to the drying conditions and high drying air temperatures. The aim of this study was to evaluate the effect of using different spray drying configurations, including concurrent (CC), mixed flow (MX), and combined (CC + MX), at two inlet air temperatures (160 and 180 °C) on the physicochemical properties of SJP. Remarkably, SJP produced using the CC spray drying configuration exhibited a higher vitamin C content (3.56-4.01 mg/g) and lower moisture levels (15.18-16.35 g/100 g) than powders produced via MX or CC + MX. The vitamin C content of MX and CC + MX powders ranged from 2.88 to 3.33 mg/g. Meanwhile, all SJP had water activity values below 0.19. Furthermore, MX powders displayed the largest mean particle sizes (D50) (8.69-8.83 µm), higher agglomeration, and a rapid dissolution. Despite these differences, all SJP variants exhibited consistent color, surface area, and pore volumes. Notably, powders dried at higher inlet air temperatures (180 °C) showed less vitamin C content and increased thermal damage when compared with powders dried at 160 °C inlet air temperature. This study demonstrated the feasibility of producing high-quality SJP with an extended shelf life. SJP can be used as a novel plant-based ingredient in different food applications.

Theoretical study on the wetting rate in wet channel of dew-point evaporative cooler based on Marangoni effect

Dew-point evaporative cooler is widely concerned as a fresh air precooling system, for its high efficiency, energy saving and environmental protection. A mathematical model for a plate-type counter flow dew-point evaporative cooler is developed in the paper, in which the film shrinkage induced by the Marangoni effect is taken in account. The results show that the model based on Marangoni effect has a higher accuracy compared to the model with wetting rate σ = 100%, in which the Average Relative Deviation from the experiment decreases by 15.8%. The wettability distribution characteristics are investigated. Along the air flow, the transverse contraction distance of film is varied, which mostly depends on the evaporation process. The higher inlet air temperature, the lower inlet air humidity, the higher velocity of inlet air, the larger channel gap, and the higher ratio of working air to inlet air would cause the higher Marangoni number and lower wetting rate. Further, a constant value of wetting rate 96.2% is recommended to simplify the calculation, while the Average Relative Deviation of the simulated results compared to the actual process is only 0.47%.

Effect of spray-drying conditions on the physical and antioxidant properties of a hydrolysate from red tilapia (Oreochromis spp.) viscera

Fish hydrolysates have become one of the most remarkable sources of bioactive peptides. However, the processing conditions for incorporating hydrolysates into food matrices can affect their bioactive performance. The effect of temperature and pH on the radical scavenging activity of tilapia hydrolysate was determined in the wet hydrolysate. Also, a central composite design was used to study the effect of the drying conditions on moisture, drying ratio, productivity, drying rate, and antioxidant activity in the tilapia hydrolysate. The results showed that the hydrolysate has high activity at acidic and neutral pH; but at pH 10, the activity decreases significantly. In the spray-drying process, the antioxidant activity was higher at 115 °C. Moreover, inlet air temperature and feed flow had a statistically significant effect (p < 0.05) on response variables. High inlet air temperature and fast feed flow decrease the moisture of the powder hydrolysate and increase the drying rate and antioxidant activity. Scanning electron microscopy showed liquid bridges between particles with irregular concavities or pores on the surface and the presence of particle agglomerations due to the hygroscopicity of the hydrolysate.

The Characteristics of a Novel After-Burner Used for Metal-Supported Planar SOFC System

Abstract A novel after-burner used for the heat-up and normal operating conditions of a metal-supported planar solid oxide fuel cell (SOFC) system, is designed and experimentally studied in this paper. The burner construction and the calculation of maximum burner power are shown in detail. Meanwhile, its static characteristics are researched through the influence of excess air ratio (ER), air velocity, inlet air temperature, and fuel utilization rate (Uf) and its transient characteristics are researched through the processes of burner start-up, burner operating state switch, and stack start-up. The results suggest that the best ER value gets larger with the increased burner power. The air velocity is better controlled within 3 m/s to prevent the influence of a lifted flame. High inlet air temperature can extend the lean combustion range and reduces incomplete combustion products, but large ER mutations should still be avoided. In the case of anode off-gas combusting with cathode off-gas, there are nearly zero emissions. Meanwhile, the flue gas temperature decreases to about 760 °C because of enlarged heat loss, but it is minimally influenced by Uf. Under the static condition, the optimal point with both controlled temperature and lowest emissions can be obtained in a wide range, and the after-burner can well adapt to various operating states of the stack. Under the transient condition, the after-burner has good response performance with much shorter time in burner start-up and burner operating state switch than conventional porous media ones. It can start up the stack in 1715 s.

Experimental Investigations on Detonation Initiation Characteristics of a Liquid-Fueled Pulse Detonation Combustor at Different Inlet Air Temperatures

The detonation initiation characteristics of a single tube liquid-fueled pulse detonation combustor (PDC) is investigated at different inlet air temperatures in this paper. The inner diameter of the PDC is 62 mm. Gasoline and air are used as fuel and oxidant, respectively. The inlet air temperature is 288–523 K and the operating frequency of the PDC is 10~30 Hz. The experimental results show that the deflagration to detonation transition (DDT) distance, detonation initiation time, DDT time and jet ignition time decrease with the increasing operating frequency at the same inlet temperature. When the inlet temperature is 288 K, the DDT distance is shortened from 860.5 mm to 787.7 mm as the operating frequency increases from 10 Hz to 30 Hz. The detonation initiation time, the jet ignition time and the DDT time are reduced from 10.01 ms, 7.66 ms and 2.35 ms to 6.55 ms, 4.99 ms and 1.56 ms, respectively. When the inlet air temperature increases, the atomization and evaporation of the gasoline is improved, which also leads to the decrease in the DDT distance, the detonation initiation time, the jet ignition time and the DDT time. For example, when the inlet air temperature increases from 288 K to 523 K at the frequency of 10 Hz, the DDT distance is shortened from 860.5 mm to 747.2 mm and the detonation initiation time, the jet ignition time and the DDT time is reduced to 5.867 ms, 2.51 ms and 1.11 ms, respectively. Additionally, the self-ignition caused by high inner wall temperature occurs when PDC is operating at high frequency under high inlet air temperature.

Thermal performance analysis of a mixed-flow indirect evaporative cooler

This study experimentally investigates the performance of an indirect evaporative cooler based on the Maisotsenko cycle. It consists of a heat and mass exchanger (HMX) with a novel mixed-flow configuration. The de-sized cellulose rich cotton fabric is used as water-absorbing material, and aluminum sheets are used to fabricate the heat mass exchanger unit. The cooling performance indices of the system, namely dew point effectiveness (DPE), wet bulb effectiveness (WBE), and the coefficient of performance (COP), are evaluated at different inlet air temperatures (24 to 35 °C), volumetric flow rates (600 to 1050 m 3 /h), relative humidity (35 to 65%) and the extraction ratio (0.1 to 0.6). The results of the experimental study show that at a relative humidity of 35%, and inlet air temperature of 35 °C, the magnitude of the wet bulb and dew point effectiveness are highest and higher dew point and wet bulb effectiveness are observed at lower mass flow rates. The best cooling capacity and COP were obtained at an extraction ratio of 0.3 and are found to be highest at DBT of 35 °C. The maximum magnitude of CC was 2 kW with a COP of 16. Additionally, the convective heat transfer coefficient is calculated theoretically and compared with the experimental value. Further, a comparison of the obtained results for the mixed flow configuration considered in this study with those for other configurations reported in the literature reveals that the indirect evaporative cooler with mixed-flow configuration yields comparably good effectiveness. • Performance of indirect mixed flow evaporative cooler evaluated experimentally. • Effect of temperature, flow rate, relative humidity and extraction ratio are studied. • The optimum extraction ratio is observed to be 0.30. • Better performance is at higher inlet air temperature with lower humidity. • The maximum COP of 16 was observed at 35 °C with 35% relative humidity.

Evaluation of the microencapsulation process of conidia of Trichoderma asperellum by spray drying.

Microencapsulation of microorganisms has been studied to increase product shelf life and stability to enable the application in sustainable agriculture. In this study, the microencapsulation of Trichoderma asperellum conidia by spray drying (SD) was evaluated. The objective was to assess the effect of drying air temperature and wall material (maltodextrin DE20, MD20) concentration on the microencapsulation and to identify the optimum conditions to produce, in high yield, microparticles with low moisture, high conidial viability and conidial survival. Microparticles were characterized in terms of morphology, particle size, and shelf life. A central composite rotatable design (CCRD) was used to evaluate the effect of operating parameters on drying yield (DY), moisture content, conidial viability (CV), and conidial survival (SP). Microencapsulation experiments were carried out under optimum conditions to validate the obtained model. The optimum temperature and MD20/conidia dry weight ratios were 80°C and 1:4.5, respectively, which afforded a drying yield of 63.85 ± 0.86%, moisture content of 4.92 ± 0.07%, conidial viability of 87.10 ± 1.16%, and conidial survival of 85.78 ± 2.88%. Microencapsulation by spray drying using MD20 as wall material extended the viability of conidia stored at 29°C compared with the control. The mathematical models accurately predicted all the variables studied, and the association of the microencapsulation technique using DE20 maltodextrin was able to optimize the process and increase the product's shelf life. It was also concluded that high inlet air temperatures negatively affected conidia survival, especially above 100°C.

Study on the Performance of the Low-Cost Cooling System for Transmit/Receive Module and Broadening the Exploitative Capabilities of the System Using Gravity Heat Pipes

Abstract The authors use computer simulation and experiment to study thermal characteristics of a less expensive design of the air cooling system for transmit/receive modules based on the heat sink with the dimensions of 25 × 324 × 500 mm made of mass-produced heat sink profile. The total power of the 8 transistors in the transmit/receive module is 224 W. It is shown that the increase in air velocity in the heat sink channels from 1 to 30 m/s causes an approximately twofold drop in the maximum temperature of the mounting surface (from 78.45 to 38.70 °C) and a decrease in thermal resistance of the cooling system by 3.16 (from 0.262 to 0.083 °C/W). The air velocity range from 5 to 10 m/s proves to be the most rational option. For the inlet air temperature of 20 °C, the temperature in the spots where the transistors are mounted remains below 56.3 °C for the air velocity of 5.5 m/s in the heat sink channels and below 51.8 °C for 10.5 m/s. A new original technical solution based on low-cost flat gravity heat pipes with a threaded evaporator will provide the efficiency of the cooling system at higher inlet air temperatures.

Computational study on the flame and extinction behavior of a high enthalpy air slab

A solid fuel ramjet has been recognized as a viable contender for atmospheric supersonic flight due to its performance and simple construction. However, the static temperature increases due to shock compression at the inlet that results in high temperature air entering the combustor. As such, the goal of this study is to analyze how the kinetics and flame sustainment properties are altered with this higher enthalpy air exposure. To examine these effects, a slab burner is modeled with gaseous using OpenFOAM© software. The reaction processes are modeled using complete University of California San Diego chemical-kinetic mechanism for burning in a hydrogen–air environment. Temperatures in the air intake range from 300 to 1000 K in 100 K increments, with the hydrogen fuel temperature kept at 300 K. In examining the conductive and convective heat flux data at the fuel surface, two distinct temperature regimes appeared for each respective heat flux mechanism. The results showed a large drop in conductive heat flux seen only between inlet temperatures of 300 and 500 K. Conversely, convective heat flux saw an increase in heat flux as a fully turbulent flow was approached for temperatures between 600 and 1000 K. In analyzing the Damköhler numbers of involved reactions, it was found that higher temperatures activated an endothermic chain branching reaction, which contributed significantly to the OH radical pool. This activation prevented a large drop in conductive heat flux for high inlet air temperatures. The results showed the impact of inlet temperatures on reaction pathways, which allows improved flame holding at higher air velocities.

Analysis of Inlet Temperature and Airflow Rate on Drying Process in a Spray Dryer Using Computational Fluid Dynamics Method

Spray drying is a method of producing a dry powder from liquid or slurry by rapid drying with a hot air. The spray drying process consists of atomizing the liquid into fine droplet, contacting the hot air with the droplets, drying droplets by the formation of solid particle agglomerates and separating solid products. This research was carried out to analyse the drying process parameter of spray dryer to reach the fluid drying temperature of around 100°C in which the drying process is assumed to be successful. Simulation using computational fluid dynamics method was performed. Air and water were employed as the working two phase fluids injected into the drying chamber at various inlet temperatures and airflow velocities. RNG k-ɛ and k-ω were used to solve drying process phenomenon in the drying chamber. In this work, the inlet air temperatures and the airflow velocities were varied from 175°C to 225°C and 1.5 m/s to 3 m/s, respectively. The results showed that the higher inlet air temperature, the greater the outlet temperature. In addition, the outlet temperature also increased with the increase of airflow velocity. Under the condition investigated, the optimal parameter was found at inlet temperature of 225°C and airflow velocity of 3 m/s. This condition is expected in avoiding the failure of spray drying process.

Experimental Study on the Performance of a Dew-Point Evaporative Cooling System with a Nanoporous Membrane

In this paper, a plate counter-flow dew-point evaporative cooling system was designed with a nanoporous membrane covered on the surface of the wet channel for enhancement of heat and mass transfer. First, the operating principle of this device and theoretical analysis of nanoporous membrane evaporation were discussed in detail. Then, the impacts of several operating parameters on cooling performance, mainly including inlet air temperature, humidity, velocity, and the effect of utilizing the membrane, were investigated in trials. It was found that the cooling performance can be improved by using membrane significantly. In the dry channel, the maximum temperature decrease can reach 12.5 °C. At a high inlet air temperature, the product air can be dropped to a lower temperature, contributing to a more significant heat transfer process. Lower humidity, on the other hand, resulted in a reduced product air temperature and a lower cooling efficiency. Under the condition of 50% humidity, the wet-bulb efficiency and dew-point efficiency were 1.09 and 0.79, respectively. With the inlet air velocity increasing from 1.5 m/s to 2 m/s, the outlet air temperature would rise, and the wet-bulb efficiency and dew-point efficiency would decrease. To achieve better cooling performance, inlet air velocity ought to be limited to a low speed.

Application of Artificial Neural Networks, Support Vector, Adaptive Neuro-Fuzzy Inference Systems for the Moisture Ratio of Parboiled Hulls

Drying as an effective method for preservation of crop products is affected by various conditions and to obtain optimum drying conditions it is needed to be evaluated using modeling techniques. In this study, an adaptive neuro-fuzzy inference system (ANFIS), artificial neural network (ANN), and support vector regression (SVR) was used for modeling the infrared-hot air (IR-HA) drying kinetics of parboiled hull. The ANFIS, ANN, and SVR were fed with 3 inputs of drying time (0–80 min), drying temperature (40, 50, and 60 °C), and two levels of IR power (0.32 and 0.49 W/cm2) for the prediction of moisture ratio (MR). After applying different models, several performance prediction indices, i.e., correlation coefficient (R2), mean square error index (MSE), and mean absolute error (MAE) were examined to select the best prediction and evaluation model. The results disclosed that higher inlet air temperature and IR power reduced the drying time. MSE values for the ANN, ANFIS tests, and SVR training were 0.0059, 0.0036, and 0.0004, respectively. These results indicate the high-performance capacity of machine learning methods and artificial intelligence to predict the MR in the drying process. According to the results obtained from the comparison of the three models, the SVR method showed better performance than the ANN and ANFIS methods due to its higher R2 and lower MSE.

Numerical study on the impact of mucus layer and inlet air-temperatures on the particle deposition in a highly idealized mouth-throat model using LES

Presence of mucus layer and inlet air temperature variations can significantly affect the extent of particle transport and deposition in the mouth-throat airway for aerosol drug delivery applications. In addition, higher inlet air temperature can lead to thermal injuries as well. The main goal of the present paper is to investigate these effects in a highly idealized mouth-throat geometry in detail. Large eddy simulation was performed to accurately predict the air flow-fields and a Lagrangian particle tracking model has been employed to capture the particle deposition efficiencies and patterns. The effects of three different inlet air temperatures (15 °C, 26.7 °C and 45 °C) and three different particle sizes (3 μm, 5 μm and 6 μm) have been studied for inlet flow rates of 15 L/min and 30 L/min with and without mucus layer in the present investigation. Detailed velocity and temperature fields, as well as, particle deposition efficiencies and patterns were analyzed and it has been found out that (a) the particle deposition efficiencies varied significantly with changes in inlet air temperature and flow rates, particle diameters and in the presence of mucus layer, (b) the presence of recirculation zones and secondary vortices determined the rate of particle deposition at different inhalation flow rates and inlet air temperatures, and (c) the changes in temperature distribution near the mouth-throat wall in the presence of mucus layer have a dominant effect on particle deposition as compared to inertial deposition. The findings of the present work will provide useful information in understanding the heat transfer effects on particle transport and deposition for the design of pulmonary drug delivery devices under the influence of various environmental and human factors.

Drying of granular cellulosic fibers by-products: Material characterization, kinetics modeling, and costs analysis towards process optimization

The objective of this work was to study the drying kinetics of granular cellulosic fibers to provide qualitative and quantitative results for preliminary analysis of dryer design and capital costs estimation towards process optimization and feasibility. The drying curves were predicted by a mathematical model that considers the combination of both internal and external resistances to moisture movement to estimate the drying time for design calculations. Discussions regarding the drying kinetics and dryer selection and design were strengthened by the materials characterization, which consisted of determining physical properties, geometric and shape factors, morphology and microstructure, and thermal properties of the GCF particles. A reduction of at least 39% in the conveyor-belt dryer area for higher throughput conditions showed an effective reduction of capital costs. It was verified that the combination with thicker material layers with high inlet air temperatures yields higher dryer throughput, indicating significant possibilities for capital cost savings.

Physicochemical and nutritional properties of pomegranate juice powder produced by spray drying

Pomegranate juice powder could be applied as a valuable ingredient in other food and pharmaceutical products and be accessible throughout the year. In this research, pomegranate juice was spray dried at three maltodextrin levels (25, 35 and 45% w/w) and two inlet air temperatures (124 and 143 °C) and physicochemical and nutritional characteristics of the powder in terms of moisture content, pH value, ash content, color values, total phenolic compounds, along with microstructural properties of the pomegranate juice powders were analyzed. Inlet air temperature just could affect ash content of the powder while maltodextrin level could influence all properties of the final powder. SEM analysis revealed that lower maltodextrin levels and higher inlet air temperatures resulted in smaller but smoother particles. In conclusion, pomegranate juice powders produced at 25% maltodextrin level and 143 °C, with a low moisture content of 3.19%, high ash content of 0.58%, safe pH value of 3.4 and considerable total phenolic compounds of around 903 mg gallic acid/g db, are suitable and nutritionally-rich choices for industrial production.

Effects of n-heptane/toluene/ethanol ternary fuel blends on combustion, operating range and emissions in premixed low temperature combustion

Low temperature combustion engines are a new combustion model that the reduction of nitrogen oxide emissions and the increasing of the thermal efficiency can be observed simultaneously. In addition, the problem of misfire at low engine loads and knocking at high engine loads occurs. The fuels have low octane number can be used to eliminate the misfire problem at low engine loads, and the fuels have high octane number can be used to eliminate knocking problem at high engine loads. In this study, the operating ranges of low and high reactivity fuel mixtures with different chemical properties were experimentally investigated in a low temperature combustion engine. While high reactivity n-heptane, T10 and E10 fuels were used, it was seen to be suitable for HCCI strategy in wider and leaner mixing conditions, while low reactivity E20 and E30 showed good performance at high engine loads close to the knocking zone. The highest brake thermal efficiency was obtained as 44.5% with E30 fuel under extremely lean mixture conditions (ʎ = 2.95). While E20 fuel shows a good performance like E30, the fact that most of the combustion takes place before TDC in the use of high reactivity fuel caused low efficiency due to knock and heat losses. It can be stated that ethanol has low reactivity needs high inlet air temperature, high compression ratio or combustion improving additives such as n-heptane and toluene to be used in HCCl applications. The results obtained support the idea of fuel flex vehicles for the current engine.

Effect of Spray Drying Conditions on Physical Properties of Panax notoginseng Saponin (PNS) Powder and the Intra-Batch Dissolution Variability of PNS Hydrophilic Matrix Tablet.

PurposeUnderstanding raw material variability and its impact on product quality are crucial for developing robust pharmaceutical processes. This work aimed to study the effects of spray drying conditions on properties of the spray dried Panax notoginseng saponin (PNS) powders as well as the subsequent intra-batch dissolution variability of PNS hydrophilic matrix tablets.MethodsThe Plackett-Burman design was applied to screen the critical process parameters (CPPs). Then, the Box-Behnken design was used to investigate the relationship between the CPPs and the physiochemical properties of spray dried PNS powders. The PNS hydrophilic matrix tablets containing 57% spray dried PNS powders were directly compressed. The partial least squares (PLS) regression was used to uncover the hidden multivariate relationships among the CPPs, intermediate powder properties, and tablet quality attributes.ResultsThe identified CPPs were the feed concentration, the inlet air temperature, and the atomization pressure. It was found that the CPPs exerted little impact on chemical properties of spray dried PNS powders, but had significant impact on physical properties, such as particle size, specific surface area, bulk density, hygroscopicity, and inter-particle porosity, etc. Latent variable modeling results revealed that the high inlet air temperature of spray drying process could produce PNS powders with low moisture content and high hygroscopicity, which were beneficial to reduce the intra-batch dissolution variability of PNS hydrophilic matrix tablets. Finally, a design space of the spray drying process was built in order to ensure the dissolution consistency.ConclusionOur research provided a reference for improving the spray drying conditions in order to ensure the dissolution consistency of the PNS hydrophilic matrix tablet.