Comprehensive assessment of a greenhouse solar dryer for handmade paper drying: economic, environmental, drying kinetics and post-drying analysis

Investigation of soil thermal saturation and recovery under intermittent and continuous operation of EATHE

Challenges in Start-up Control of a Heat Exchange Reactor With Exothermic Reactions; A Hybrid Approach

Sensitivity analysis of a vertical geothermal heat pump system

Comparative utilization of a limited amount of energy for continuous and pulse operations was investigated. Under a restriction that the amount of available energy was limited, general equations for operational hours of the energy source for given power output were derived for both continuous and pulse mode operations. This paper points out that due to various adjustable parameters available for pulse mode operation, if properly designed pulse mode operation produces longer utilization of available energy for required output power than continuous mode operation.

A walk in type semicylindrical solar tunnel dryer for drying 1500 handmade papers per batch has been commissioned at M/s Cellulosic Waste Recycling Education Project, Vidhya Bhawan Society, Udaipur, Rajasthan, India. A solar tunnel dryer with 122.95 m2 solar collector area was sufficient for drying handmade paper from 53.85% to 9.96% moisture content (dry basis) in 4–5 h. In this paper the results are shown in terms of the variation of air temperature, solar flux density, relative humidity, air flow rate, moisture content, etc., which indicate that the performance of solar tunnel dryer was quite satisfactory. The performance of the dryer for drying handmade papers has been analyzed through no load and full load test. Technoeconomic analysis of solar tunnel dryers was also carried out by using different economic indicators.

Based on fractional calculus and the fact that the capacitor and the inductor are fractional in nature, the fractional mathematical model and the fractional state averaged model of the Boost converter in continuous conduction mode operation are built and analyzed. Also, the condition for the continuous conduction mode operation of the Boost converter is given. Finally, in order to verify the theoretical analysis, the simulation model of the Boost converter in continuous conduction mode operation is established by using the software of Matlab/Simulink.

Unburnt coal in a boiler gets converted to fly ash and bottom ash. Fly ash particles travel along with flue gas and get deposited on heat transfer surfaces along the way. Fouling and slagging are phenomena associated with fly ash deposits which could potentially damage the heat transfer surface, if left unattended. Sodium and potassium are directly linked to the deposition of fly ash, as they form a molten salt film which aids in sticking of fly ash particles. Ultrasound is one of the mitigation techniques used to prevent ash deposition. This study aims at reducing the concentrations of alkali metals in coal as a pretreatment method, using ultrasound. Two modes of operation are chosen: continuous and pulsed. A solvent has been used to enhance the leaching process. In the pulsed mode, the sample is alternated between periods of exposure and nonexposure. A maximum leaching rate of 62% for potassium and 24.5% for sodium was observed in the continuous mode at 360 kHz of operation while pulsed mode of operation showed a maximum leaching rate of 91.3% and 54.4% for potassium and sodium operated at 360 kHz, respectively. The experimental data have been fit to the shrinking core model, and the rate-controlling step has been found to be surface diffusion of reactants into the core. The effect of various parameters is analyzed and compared for pulsed and continuous modes of operation. Order of the reaction, activation energy, and leaching kinetics are obtained by fitting the data into the shrinking core model.

Performance comparison of mesophilic and thermophilic aerobic sidestream membrane bioreactors treating high strength wastewater

基于实际电容和电感本质上是分数阶的事实，针对以往开关变换器建模过程中一些理想化假设会引起较大误差的问题，建立了电感电流连续模式下Buck变换器的非理想状态分数阶模型及状态平均模型，提出了一种用于分数阶模型阶次辨识的改进随机数辨识方法，通过仿真验证了运行非理想状态下Buck变换器的分数阶仿真模型的合理性和可行性，并对Buck变换器分数阶阶次进行辨识，与一般传统的算法对比，结果表明改进的方法具有更高的准确性。 Based on the fact that the capacitor and the inductor are fractional in nature, and some ideal as-sumptions could bring errors during the modeling of the switching converters, the fractional mathematical and the fractional state averaged model of the not ideal buck converter in continu-ous mode operation are built and analyzed, a parameter identification method that can be applied in fractional model is proposed. Finally, to verify the theoretical analysis the simulation model of the buck converter in continuous conduction mode operation is established by using the software of Matlab/Simulink, the validated of the new identified method is validated by compared with traditional methods.

Paper analyticaldevices (PADs) are a class of low-cost, portable,and easy-to-use platform for several analytical tests in clinicaldiagnostics, environmental pollution monitoring, and food and drugsafety screening. These devices are primarily made from cellulosicpaper. Considering the importance of eco-friendly and local or distributedmanufacturing of devices realized during the COVID-19 pandemic, wesystematically studied the potential of handmade Nepali paper to beused in fabricating PADs in this work. We characterized five differenthandmade papers made from locally available plant fibers using aneco-friendly method and used them to fabricate PADs for determiningthe drug quality. The thickness, grammage, and apparent density ofthe paper samples ranged from 198.6 to 314.8 μm, 49.1 to 117.8g/m2, and 0.23 to 0.43 g/cm3, respectively.The moisture content, water filtration, and wicking speed ranged from5.8 to 7.1%, 35.7 to 156.7, and 0.062 to 0.124 mms–1, respectively. Furthermore, the water contact angle and porosityranged from 76.6 to 112.1° and 79 to 83%, respectively. The bestpaper sample (P5) was chosen to fabricate PADs for the determinationof metformin, an antidiabetic drug. The metformin assay on PADs followeda linear range from 0.0625 to 0.5 mg/mL. The assay had a limit ofdetection and limit of quantitation of 0.05 and 0.18 mg/mL, respectively.The average amount of metformin concentration in samples collectedfrom local pharmacies (n = 20) was 465.6 ± 15.1mg/tablet. When compared with the spectrophotometric method, PAD assaycorrectly predicted the concentration of 90% samples. The PAD assayon handmade paper may provide a low-cost and easy-to-use system forscreening the quality of drugs and other point-of-need applications.

Purpose: The purpose of this study was to assess the drying performance and economic feasibility of a Greenhouse Solar Dryer for Tomatoes. With a focus on small-scale tomato drying, the study aimed to evaluate the effectiveness of the greenhouse in comparison to traditional sun drying methods. Additionally, the economic analysis sought to determine the investment attractiveness of the greenhouse dryer by considering the initial investment, operational costs, and potential revenue generation. Methodology: The methodology involved conducting drying experiments using the Greenhouse Solar Dryer for Tomatoes under existing weather conditions. The dryer's components include the steel frame, greenhouse plastic cover, and concrete floor. The temperature and relative humidity contributed to the environment inside the greenhouse that facilitated the drying process. Moisture content measurements were taken at regular intervals to assess the drying kinetics and effectiveness of the greenhouse. Economic analysis was conducted to evaluate the project's financial viability, considering initial investment, revenue generation, and operational costs. Findings: The findings revealed that the Greenhouse Solar Dryer outperformed sun drying methods, achieving higher temperatures and faster drying times for tomatoes. Specifically, the greenhouse reached maximum temperatures of 38.4 °C and 45.5 °C on the first and second days, respectively, leading to a moisture content of 14.9% wet basis within 11 hours on the second day. In contrast, sun drying resulted in a significantly higher moisture content of 37.9% at the same time, highlighting the effectiveness of the greenhouse. Economic analysis demonstrated that the project had a payback period of 1.6 years, indicating its attractiveness as an investment opportunity for farmers. Unique Contribution to theory, practice and policy: This study makes a unique contribution to knowledge by providing empirical evidence of the drying performance and economic viability of a Greenhouse Solar Dryer for Tomatoes. By demonstrating the effectiveness of the greenhouse in achieving faster drying times and lower moisture content compared to sun drying methods, the study underscores the potential of solar drying technologies in small-scale agricultural settings. Additionally, the economic analysis offers valuable insights into the financial feasibility of adopting greenhouse dryers, particularly for farmers seeking to enhance their income through value-added tomato products.

The study evaluates the ability of extrudates to deliver coumarin particles micronized by the rapid expansion of supercritical solutions (RESS). The RESS parameters were drug load (2-50g), pressure (15-42MPa) and temperature (40-60°C) in the extraction and pressure in the expansion (0.1-5MPa) chambers in batch or continuous and CO2 flow rate in the continuous mode of operation. Particles were characterized for size (laser diffractometry, optical and electronic microscopies-19-61μm), surface area (BET-0.282-0.423m2/g), density (pycnometry-1.273-1.358g/cm3) and yield (2-70%). Extrudates were characterized for the force of extrusion (4kN), release of coumarin (100%/24h) and mechanical properties (bending strength and stiffness increased, whereas elasticity decreased in storage) and X-ray diffractometry (micronized particles and extrudates have shown identical patterns) and calorimetry (DSC, enthalpies increased on storage). In the discontinuous mode of operation, increased loads in the extraction or increased pressure in the expansion chambers led to larger particles, whereas increased temperature and pressure in the extraction chamber led to smaller particles. In the continuous mode of operation, a decrease on the expansion pressure, load and CO2 flow rate led to increased yields. An increase on the flow rate led to a decrease on the particles' diameter, but an increase on coumarin load in the extraction chamber led to an increase in diameter. The study has identified the key parameters in RESS continuous and discontinuous modes of operation affecting the properties of the micronized coumarin particles and has proved the ability of extrudates with a laminar shape on delivering micronized particles.

Core Ideas Quantifying intra‐seasonal fluctuations allows for simulating productivity trade‐offs. Biomass yields peaked August–September when N and K and moisture contents were elevated. Delaying harvests to late fall reduces fertilizer replacement needs. Temporal patterns of plant growth, composition, and nutrient removal impact development of models for predicting optimal switchgrass (Panicum virgatum L.) harvest times for bioenergy. Original time‐course data are needed to construct useful models. Objectives were to characterize seasonal trends in yield, tissue moisture, ash content, leaf area index (LAI), interception of photosynthetically active radiation (PAR), and macronutrient accumulation and losses. Plots were subjected to 12 single harvests May to February in 2009–2010 and 2010–2011. Biomass accumulation into late summer followed a sigmoidal function, reaching an asymptote at 14 Mg ha−1, concurrent with early seed filling. During both seasons, yields decreased 26 to 32% from September to February. Moisture content declined to levels appropriate for storage (≤200 g kg−1, wet basis) by 15 December. Interception of PAR plateaued at 96% in late July 2009 and mid‐June 2010, whereas LAI declined in early July both years. Peak N uptake occurred in August 2009 and July 2010 (80 and 141 kg N ha−1, respectively). Potassium uptake peaked in July 2009 (136 kg ha−1) and in June 2010 (180 kg ha−1). Phosphorus peaked in July and August 2009 and 2010 at 16 and 17 kg ha−1, respectively. Peak biomass yields occurred in August–September when N and K uptake and moisture contents were still elevated. Delaying harvests until late fall or winter reduced fertilizer replacement needs and moisture content, but a trade‐off in yield occurred. Quantifying these intra‐seasonal changes allows for simulating productivity trade‐offs and applying those to economic and environmental analyses.

Performance of an electrocoagulation (EC) process in batch and continuous operating modes was thoroughly investigated and evaluated for enhancing wastewater phosphorus removal under various operating conditions, individually or combined with initial phosphorus concentration, wastewater conductivity, current density, and electrolysis times. The results revealed excellent phosphorus removal (72.7-100%) for both processes within 3-6min of electrolysis, with relatively low energy requirements, i.e., less than 0.5kWh/m3 for treated wastewater. However, the removal efficiency of phosphorus in the continuous EC operation mode was better than that in batch mode within the scope of the study. Additionally, the rate and efficiency of phosphorus removal strongly depended on operational parameters, including wastewater conductivity, initial phosphorus concentration, current density, and electrolysis time. Based on experimental data, statistical model verification of the response surface methodology (RSM) (multiple factor optimization) was also established to provide further insights and accurately describe the interactive relationship between the process variables, thus optimizing the EC process performance. The EC process using iron electrodes is promising for improving wastewater phosphorus removal efficiency, and RSM can be a sustainable tool for predicting the performance of the EC process and explaining the influence of the process variables.

The microwave enhanced advanced oxidation process (MW/H2O2-AOP) was used to treat dairy manure for solubilization of nutrients and organic matters. This study investigated the effectiveness of the MW/H2O2-AOP under a continuous mode of operation, and compared the results to those of batch operations. The main factors affecting solubilization by the MW/H2O2-AOP were heating temperature and hydrogen peroxide dosage. Soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFA) increased with an increase of microwave (MW) heating temperature; very high concentrations were obtained at 90°C. Insignificant amounts of ammonia and reducing sugars were released in all runs. An acidic pH condition was required for phosphorus solubilisation from dairy manure. The best yield was obtained at 90°C with an acid dosage of 1.0 %; about 92 % of total phosphorus and 90 % of total chemical oxygen demand were in the soluble forms. The MW/H2O2-AOP operated in a continuous operation mode showed pronounced synergistic effects between hydrogen peroxide and microwave irradiation when compared to a batch system under similar operating conditions, resulting in much better yields.