Increasing Air Flow Rate Research Articles

The impact of high biodegradable COD fraction in poultry processing wastewater to SBR performance

The present study investigates the impact of high biodegradable COD fraction in poultry processing wastewater on the performance of lab-scale SBR. The SBR’s reactor was operated under 3 phases with different airflow rates namely 2.5 L/min, 5.0L/min, and 7.0L/min; and each phase would have a constant 21days of Sludge Retention Time (SRT). The sample of poultry processing wastewater consists of 84.06% of biodegradable components and 15.94% of the non-biodegradable component. It was observed that high readily biodegradable soluble COD (rbsCOD) had caused a rapid bacteria’s metabolism to consume nutrient as fast as possible which consequently tuned the COD removal efficiency from 85.0% to 92.9% and increased the SVI from 51.66 mL/g to 66.96mL/g (2nd phase) and 110.1 mL/g (3rd Phase). The removal efficiency of Ammonia Nitrogen and Total Suspended Solid was observed in the range from 69.3% to 81.2%, and 61.8% to 81.7% respectively. The fluctuation of the biodegradable COD component in poultry processing wastewater was observed to affect the oxygen demand, where the oxygen transfer efficiency dropped from 3.82% to 0.63% as the airflow rate increase from 2.5L/min to 7.0L/min along with the increase of biodegradable COD fraction. Hence, this experiment provides a clear perspective of poultry processing wastewater behavior to SBR performance.

Performance Augmentation of Solar Air Heater for Space Heating Using a Flexible Flapping Guide Winglet

A new idea is presented in this paper for improving the performance of solar air heater (SAH) designed for space heating by employing a thin flexible guide winglet. In addition to the role of winglet in pushing the convective airflow toward the heated surface, it behaves as a vortex generator (VG) due to its vibration by fluid-solid interaction (FSI) that causes flow mixing and breaking thermal boundary layer. In flow simulation, the finite element method (FEM) is employed with considering a two-way strongly-coupled FSI approach at transient condition. Numerical solution of the governing equations, including the continuity, momentum and energy for convective flow and the equation of motion for VG are obtained by COMSOL multi-physics. The well-known model is employed for computation of turbulent stress and heat flux. The present numerical results are validated against the most recent relevant literature. To provide a clear and deep understanding of the proposed concept, extensive comparisons are made between different test cases. Results reveal considerable performance enhancement of SAH with elastic guide winglet compared with clean solar air heater (CSAH), such that 56% increase in the natural airflow rate and 9% decrease in the average absorber temperature is seen because of the flapping winglet. But, the air outlet temperature decreases about 14% due to flapping VG. This study aims to make the proposed SAH as an essential renewable thermal-solar system more efficient and attractive so that this improvement pushes the industrial society toward more sustainable infrastructure.

Fabrication of Poly(lactic acid) filter media via the meltblowing process and their filtration performances: A comparative study with polypropylene meltblown

Poly(Lactic acid) (PLA) is considered as a promising alternative for petroleum-based synthetic plastic under the rising concerns over the environmental sustainability of polypropylene (PP) filter materials. To adapt PLA for the meltblown filter media production, it is necessary to establish how PLA polymer properties affect the meltblown process, media structure and filtration performance. We investigated the processability and effects of processing parameters on PLA meltblown structures and filtration performances in an industrially relevant setting by utilizing a commercially available low molecular weight PLA resin and a Reicofil meltblowing production line. We were able to fabricate PLA meltblown media comparable with PP meltblown media both in structures and filtration performances. Increasing airflow rate and decrease throughput reduced fiber diameter of PLA meltblown, but at the given processing condition, PLA meltblown tends to have larger fiber diameters than PP meltblown. However, larger diameter did not deteriorate the filtration efficiency of PLA meltblown. Interestingly, the filtration efficiency of PLA meltblown is higher than those of PP meltblown with similar fiber diameters. We also found the solidity of PLA meltblown lower than that of PP meltblown. This further improved filtration performance by improving air permeability. The quality factors of PLA meltblowns were more than double of PP meltblowns’ quality factors when fiber sizes are similar. PLA also exhibited comparable chargeability and charge stability with PP when corona charged.

Physical parameters of the energy-carrying phase during crushing of a jet of slag melt

In this paper, the possibility of introducing slag in the fiery-liquid state into the metallurgical cycle with the production of different products depending on the processing technology (binders, slag, pumice, etc.) is considered. The scientific substantiation of the processing of slag melts by crushing a slag stream in order to obtain granules of a certain size is considered, and the process of deformation and crushing (decay) of a slag stream during interaction with the energy-carrying phase - high-speed gas (air) stream is analyzed. It has been established that under conditions of dynamic interaction with an air high-speed flow, the slag jet in the deformable section behaves like a quasi-elastic body, exhibiting properties characteristic of a solid, which explains the destruction of the jet under the action of a longitudinal tensile and deforming slag stream due to the pressure of the gas stream. Taking into account it the sizes of destroying pressure and corresponding for this purpose speed of current of air are set depending on a temperature and diameter of stream of slag fusion. It was found that the pressure and air flow rate increase with increasing diameter of the slag stream and decrease with increasing temperature of the slag. The got performances hired can be used for the choice of optimal parameters of slag fusion and energy-carrying phase at development of technological processes of processing of metallurgical slags with the forecast receipt of friction composition of eventual products. Mathematical models are neat for the got dependences with approximation of dependence of maximum pressure of current of air from the physical parameters of slag fusion and the quadratic is got and sedate to dependence with the high coefficient of determination, exceeding 0,98

CFD Analysis for The Effect of Personal Ventilation Combined with Mixing Ventilation on Performance Index (ADPI) and Thermal Human Comfort

Good indoor air quality and ideal thermal comfort are very important indicators for the comfort of occupant’s space. The Iraqi climate is hot dry in summer, so the use of air conditioners is indispensable. This work focuses on solving the IAQ problems in office room environments, and it evaluated a new principle of ventilation which is combined personal and mixing ventilation systems. Personal and mixing ventilation system can provide individual control of indoor climate. The airflow motion and distribution of temperature investigated numerically with the best flow rate from combined system. CFD study is used for simulation the indoor airflow and temperature distribution by using (AIRPAK3.0.16) for solving the turbulence equations, Naiver-Stocks, energy equations, and using (FVM). The Renormalization Group RNG K-Ɛ turbulence model was used for simulation this study cases, the airflow rate from ATD was 5 l/s and 10 l/s. For mixing ventilation supply temperature of 17°C and The temperature of the supplied air from the personal ventilation system ranges from (17 to 23) °C, it was found that if using personal ventilation system at airflow rate of 10 l / s it would improve the quality of the inhaled air present in the breathing zone. The personal and mixing ventilation system provides good human thermal comfort based on the values of effectiveness temperature (Ɛt) and air distribution performance index (ADPI) which give (1.241) and (63.226%) respectively. The increased airflow rate from (ATD) leads to a decrease in the temperature in the breathing zone, this increases the human thermal comfort of the occupants inside the room.

Simulation investigation on pre-cooled heat pipe (PCHP) for free cooling of high thermal density space

High thermal density space consumes massive energy, and cooling device accounts for large percentage of total consumption. To cut down energy consumption of cooling device, PCHP is proposed on the basis of heat pipe and evaporation technologies. Heat transfer and energy consumption models of PCHP are developed. The effects of geometric and operational parameters on the PCHP performance, including pad thickness, ambient temperature and ambient relative humidity (RH), air flow rate, are investigated. The results show that cooling capacity increases with the increase of pad thickness and airflow rate, and it decreases with the increase of ambient temperature and RH. With the increase of thickness, energy efficiency ratio (EER) increases at the start and then decreases under RH20%-40%, while it decreases continuously under RH70%-90%. EER increases with the decrease of ambient temperature, ambient RH and air flow rate. PCHP markedly enhances annual free cooling time compared with conventional heat pipe system (CHP), and the maximal enhanced free cooling time and increasing percentage occur at Urumchi and Guangzhou Cities, respectively.

Generation of a large-scale uniform plasma plume through the interactions between a pair of atmospheric pressure argon plasma jets

In this Letter, a uniform air plasma plume with a fairly large scale is generated downstream of an air flow through interactions between a pair of argon plasma jets excited by a direct current power supply. With increasing power voltage, two separated plumes are first generated downstream of the pair of jets, which transit to the uniform planar plume with a fairly large scale. The planar plume elongates with the increasing air flow rate or power voltage. Moreover, the temperature of the planar plume is comparatively low with a maximum of about 80 °C, which is symmetrically distributed perpendicular to the pair of jets. For the separated plumes, discharge current is intermittently pulsed under a time-invariant gap voltage. However, both gap voltage and discharge current are periodically pulsed for the planar plume. High-speed video images reveal that the planar plasma plume stems from two discrete plumes flushing out of the pair of jets, which are soon merged together by a cathode-directed streamer due to interactions between them, leading to the generation of an arc-shaped filament. Due to the air flow, the arc-shaped filament keeps moving away from the jet vicinity until it quenches at last, which belongs to a glow discharge regime. In addition, surface modification of polyethylene terephthalate (PET) is performed with our planar plasma plume, which reveals that the hydrophilicity of the PET surface can be improved greatly.

Evaluation of comfort levels in office space equipped with HVAC system based in personalized ventilation system using energy produced in DSF systems

In this study the numerical simulation of a Heating, Ventilating and Air Conditioning (HVAC) system, based in a personalized ventilation system, installed in an occupied office desk is made. The energy is produced in a Dual Skin Facades (DSF) system installed in the outdoor environment. The personalized ventilation system, placed above and below the writing area, installed in the desk central area. The office desk is occupied by eight virtual manikins. The numerical simulation is made in a winter typical day. This numerical study considers a coupling of a differential numerical model and an integral numerical model. The differential numerical model simulates the Computational Fluids Dynamics (CFD), evaluates the air velocity, air temperature, turbulence intensity and carbon dioxide concentration and calculates the indoor air quality. The integral numerical model simulates the Multi-Node Human Thermo-physiology Model, evaluates the tissue, blood and clothing temperatures distribution and calculates the thermal comfort level. The HVAC system, based on a DSF system, is built using three DSF unities, is equipped with internal venetian blinds. Each one, installed in a virtual chamber, is turned to south. The personalized ventilation system, made with eight upper and eight lower air terminal devices, is installed in the desk central area. On each table top two upper and two lower air terminal devices are considered in the left and right manikin area, while on each side of the table two upper and two lower air terminal devices are placed between the manikins. The office desk is occupied by eight virtual manikins, one sitting on each table top and three sitting on each side of the meeting table. In this numerical study, carried out in winter conditions, the occupants’ clothing level is 1 clo. In these situations a typical activity level of 1.2 met is considered. The evolution of indoor environmental conditions, in the DSF and in the office room, are calculated during a full winter typical day. The thermal comfort, the indoor air quality, the effectiveness for heat removal, the effectiveness for contaminant removal and the Air Distribution Index (ADI), are evaluated. In accordance with the obtained results the thermal comfort levels increase when the air renovation rate increases and the indoor air quality level increases when the air renovation rate increases. However, the ADI is quite constant when the inlet airflow rate increases, because the thermal comfort number decreases when the inlet airflow rate increases and the air quality number increases when the inlet airflow rate increases.

Experimental investigation of non-premixed and partially premixed methane lifted flames established on a lobed swirl injector

A lobed swirl injector was tested to examine its potential in combustion control for non-premixed and partially premixed flames. It was found in the experiment that the flame derived from the injector changed between attached and detached flames at different conditions, demonstrating a promising way to control combustion. When air is supplied through the external channel of the lobed swirl injector and fuel passes through the internal channel, a stable lifted flame that is partially premixed was established above the injector exit. With the increase of airflow rate, the flame lift-off height decreases gradually until it is reattached to the injector, forming a diffusion flame. When increasing the fuel flow rate, the lift-off height increases gradually until the flame is blown out. Flow fields of the partially premixed lifted flames were investigated using stereoscopic particle image velocimetry. Streamlines located in the near field of the injector exit do not expand but bend inward, which is quite different from the expansion motion at the exit of the traditional vane swirler. The trough structure on the lobed swirler leads to the outer air flowing inward. Although the crest structure should make the inside gas flow outward, the strong entrainment of the surrounding air would restrain the radial outward motion of the inner gas, thus causing a contracted motion. After the streamline develops to an axial position further away from the injector exit, the swirling jet begins to expand under effects of both the centrifugal force and the development of shear layer to form turbulence. This flow pattern affects both the flame stabilization position and the neighboring reaction zone structure significantly. The measurements also show that the lobed swirl injector is very capable of entraining the ambient air that is sucked into the mainstream from the downward direction.

Effect of Dry Eye Disease on the Kinetics of Lacrimal Gland Dendritic Cells as Visualized by Intravital Multi-Photon Microscopy

The lacrimal gland (LG) is the main source of the tear film aqueous layer and its dysfunction results in dry eye disease (DED), a chronic immune-mediated disorder of the ocular surface. The desiccating stress (DS) murine model that mimics human DED, results in LG dysfunction, immune cell infiltration, and consequently insufficient tear production. To date, the immune cell kinetics in DED are poorly understood. The purpose of this study was to develop a murine model of intravital multi-photon microscopy (IV-MPM) for the LG, and to investigate the migratory kinetics and 3D morphological properties of conventional dendritic cells (cDCs), the professional antigen presenting cells of the ocular surface, in DED. Mice were placed in a controlled environmental chamber with low humidity and increased airflow rate for 2 and 4 weeks to induce DED, while control naïve transgenic mice were housed under standard conditions. DED mice had significantly decreased tear secretion and increased fluorescein staining (p < 0.01) compared to naïve controls. Histological analysis of the LG exhibited infiltrating mononuclear and polymorphonuclear cells (p < 0.05), as well as increased LG swelling (p < 0.001) in DED mice compared to controls. Immunofluorescence staining revealed increased density of cDCs in DED mice (p < 0.001). IV-MPM of the LG demonstrated increased density of cDCs in the LGs of DED mice, compared with controls (p < 0.001). cDCs were more spherical in DED at both time points compared to controls (p < 0.001); however, differences in surface area were found at 2 weeks in DED compared with naïve controls (p < 0.001). Similarly, 3D cell volume was significantly lower at 2 weeks in DED vs. the naïve controls (p < 0.001). 3D instantaneous velocity and mean track speed were significantly higher in DED compared to naïve mice (p < 0.001). Finally, the meandering index, an index for directionality, was significant increased at 4 weeks after DED compared with controls and 2 weeks of DED (p < 0.001). Our IV-MPM study sheds light into the 3D morphological alterations and cDC kinetics in the LG during DED. While in naïve LGs, cDCs exhibit a more dendritic morphology and are less motile, they became more spherical with enhanced motility during DED. This study shows that IV-MPM represents a robust tool to study immune cell trafficking and kinetics in the LG, which might elucidate cellular alterations in immunological diseases, such as DED.

Degradation of chloramphenicol by pulsed discharge plasma with heterogeneous Fenton process using Fe3O4 nanocomposites

Pulsed discharge plasma (PDP) was coupled with Fe3O4 nanocomposites for promoting degradation of chloramphenicol (CAP) based on Fenton reaction. The prepared Fe3O4 nanocomposites were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and vibrating sample magnetometer. The results showed that Fe3O4 could be successfully prepared by hydrothermal method with reasonable composition. The magnetic intensity reached 71.99 emu/g, which could be easily separated from the solution when an external magnet was applied. Compared to PDP alone, the removal efficiency, kinetic constant and energy efficiency enhanced when Fe3O4 was added. Synergetic effect was achieved between PDP and Fe3O4. The optimal catalytic performance was obtained when the dosage was 0.26 g/L. CAP was beneficial to decomposition with higher peak voltage, lower initial solution concentration and lower initial pH value. With increasing air flow rate, the removal efficiency enhanced firstly and then declined. Although four times use, Fe3O4 still maintained a higher stability. The concentration of H2O2 and O3 generated by PDP were all declined when Fe3O4 was added. With the treatment time prolonged, the pH value declined but conductivity improved. The conjugate heterocyclic structures were destroyed during CAP degradation. The degradation pathway mainly related to the cleavage of phenyl-nitryl, COH, CCl and CN bonds, resulting in the formation of intermediates containing benzene ring. The benzene ring of intermediates were underwent rupture and transformed to small organic acids and inorganic acids, which were mineralized into Cl−, NO3−, CO2 and H2O finally. The toxicity of CAP was alleviated after plasma-catalytic treatment. The overall findings provided a new insight into wastewater treatment by PDP with heterogeneous Fenton catalyst.

Experimental observation of oil mist penetration ability in minimum quantity lubrication (MQL) spray

Minimum quantity lubrication (MQL) is an eco-friendly cooling and lubricating method that has its importance in machining sustainability. However, the behavior of the MQL droplets remains questionable. The present study is conducted to investigate the penetration performance of MQL with different combination of spray parameters and capillary sizes. An observation platform has been designed, which makes the overall penetration process controllable. The results have shown that the shortest penetration time was obtained with larger capillary size, higher air flow rate and the corresponding smaller droplet size. However, the increase of air flow rate has the optimal value when the objective is to penetrate to 1 mm deep from the entrance, whereas it has not shown the similar regulation when the droplet flowed deeper to the center due to the long transport distance has amplified the effects of multiple influence factors. The observation results were verified through simulation and cutting experiment.

Mitigation Strategies for Overheating and High Carbon Dioxide Concentration within Institutional Buildings: A Case Study in Toronto, Canada

Indoor air quality and thermal conditions are important considerations when designing indoor spaces to ensure occupant health, satisfaction, and productivity. Carbon dioxide (CO2) concentration and indoor air temperature are two measurable parameters to assess air quality and thermal conditions within a space. Occupants are progressively affected by the indoor environment as the time spent indoors prolongs. Specifically, there is an interest in carrying out investigations on the indoor environment through surveying existing Heating, Ventilation, Air Conditioning (HVAC) system operations in classrooms. Indoor air temperature and CO2 concentration in multiple lecture halls in Toronto, Canada were monitored; observations consistently show high indoor air temperature (overheating) and high CO2 concentration. One classroom is chosen as a representative case study for this paper. The results verify a strong correlation between the number of occupants and the increase in air temperature and CO2 concentration. Building Energy Simulation (BES) is used to investigate the causes of discomfort in the classroom, and to identify methods for regulating the temperature and CO2 concentration. This paper proposes retro-commissioning strategies that could be implemented in institutional buildings; specifically, the increase of outdoor airflow rate and the addition of occupancy-based pre-active HVAC system control. The proposed retrofit cases reduce the measured overheating in the classrooms by 2-3 °C (indoor temperature should be below 23 °C) and maintain CO2 concentration under 900 ppm (the CO2 threshold is 1000 ppm), showing promising improvements to a classroom’s thermal condition and indoor air quality.

Kinetic modeling of thermal reactor in Claus process using CHEMKIN-PRO software

We reported a kinetic modeling of thermal reactor in Claus process using CHEMKIN-PRO software. Five hypothetical acid gases with different H2S and NH3 contents were selected and analyzed with a focus on the reaction kinetics occurring in thermal reactor. Modeling results revealed that temperature in thermal reactor initially increased due to the facile oxidation of H2S and NH3, after which it maintained a constant value due to the competing pyrolysis and S2 formation reactions. These patterns lead to equilibrium temperature and gas composition at the reactor outlet. At this point, the reactor outlet temperature and gas composition were greatly affected by the ratio of H2S/NH3 in the acid gases. Accordingly, the ratio of H2S/SO2 in the outlet gas flowing into the subsequent catalytic reactor of the Claus process was changed, necessitating an appropriate process operation. Based on these results, we suggest that the Claus process can be properly controlled by adjusting the air flow rate according to H2S/NH3 ratio. The results indicated that the ratio of H2S/SO2 in the outlet gas decreased with increasing air flow rate. It is expected that the Claus process efficiency can be improved by appropriately controlling the air flow rate in correspondence with H2S/NH3 ratio.

Experimental investigation of imbert downdraft gasifier using rice straw briquettes

ABSTRACT The mechanized harvesting of rice crop has led to open-field burning of rice straw that liberates a large amount of greenhouse gases (GHGs), which have a negative effect on the environment. Gasification is an efficient technology for the conversion of biomass to producer gas with minimal greenhouse gas emissions. The present study was planned to convert the abundantly available rice straw into briquettes and its thermochemical conversion into producer gas for thermal energy utilization. The performance of imbert type gasifier was investigated using rice straw briquettes as fuel by studying the influence of airflow rate on fuel consumption rate and temperature profile inside the combustion zone. The augmentation of airflow rate from 0.0022 to 0.0042 m3/s led to a significant increase in feedstock consumption rate (63.3%). The time taken for boiling of water also increased with an increase in airflow rate which may be attributed to the corresponding decrease in calorific value of producer gas. Rice straw briquettes with cotton stalks as a binder (90:10) can act as a clean alternative fuel for gasification and the producer gas generated can be used for various thermal applications.

A new approach for air dehumidification at refrigerator temperatures: Electrolytic vapor dehumidifier with Proton Exchange Membrane (PEM)

Abstract Dehumidifier with Polymer electrolyte membrane (PEM) is suitable for high-accuracy, limited-space humidity control in refrigerators. This study experimentally investigated the performance of PEM-based dehumidifier under the temperature range of -10~10°C. Empirical equations of PEM water content at refrigerator temperatures were developed. Results showed that although the low-temperature performance of electrolytic dehumidifier is not as good as that of room temperature, the efficiency (~1.3 × 10−2 g·J−1·m−2) is still competitive to desiccant or electrochemical methods. The dehumidifier has a starting voltage, and the voltage is higher at lower air temperatures (i.e. 1.3V for 26.1°C and 2.3 V for -3.9°C). During dehumidification, the operating current first increases significantly and then drops as the applied voltage increases, leading to a first increase and then steady dehumidification rate. The peak of current occurs at a smaller voltage as the air temperature decreases, i.e. 1.8V for 0°C and 2.5V for 26°C. Furthermore, the dehumidification rate increases as the air temperature and flow rate increases, while the changing rate with operating conditions was lower at sub-zero temperatures. Dehumidification has little effect on the oxygen concentration or temperature increment of the supply air. Characterizations also indicated that there was no obvious physical change on the PEM surface after operating at low temperatures. However, there exists a starting temperature for the dehumidifier, i.e. -9.5°C for the 3V applied voltage, which is due to the possible icing and swelling problem within the membrane. This study provided a new method, and proved its feasibility for dehumidifying at refrigerator temperatures.

Empirical Thermal Performance Investigation of a Compact Lithium Ion Battery Module under Forced Convection Cooling

Lithium ion batteries (LiBs) are considered one of the most suitable power options for electric vehicle (EV) drivetrains, known for having low self-discharging properties which hence provide a long life-cycle operation. To obtain maximum power output from LiBs, it is necessary to critically monitor operating conditions which affect their performance and life span. This paper investigates the thermal performance of a battery thermal management system (BTMS) for a battery pack housing 100 NCR18650 lithium ion cells. Maximum cell temperature (Tmax) and maximum temperature difference (ΔTmax) between cells were the performance criteria for the battery pack. The battery pack is investigated for three levels of air flow rate combined with two current rate using a full factorial Design of Experiment (DoE) method. A worst case scenario of cell Tmax averaged at 36.1 °C was recorded during a 0.75 C charge experiment and 37.5 °C during a 0.75 C discharge under a 1.4 m/s flow rate. While a 54.28% reduction in ΔTmax between the cells was achieved by increasing the air flow rate in the 0.75 C charge experiment from 1.4 m/s to 3.4 m/s. Conclusively, increasing BTMS performance with increasing air flow rate was a common trend observed in the experimental data after analyzing various experiment results.

Heterogeneous electro–Fenton using three–dimension NZVI–BC electrodes for degradation of neonicotinoid wastewater

Neonicotinoids (NEOs), as the most widely used pesticides, pose a serious threat to water ecosystems, especially clothianidin (CLO). However, the degradation behavior of CLO, as a new type of persistent organic pollutant, is rarely studied in wastewater treatment. To bridge this gap, heterogeneous electro-Fenton system using three-dimension electrodes made of biochar-supported zero-valent iron nanoparticle hybrid material (NZVI–BC), abbreviated as 3D–ICE–EF system, is invented and initially applied in CLO wastewater degradation, without the addition of Fenton reagent. NZVI–BC in 3D–ICE–EF system can concentrate CLO on electrodes by excellent adsorption and effectively eliminate it to achieve self-cleaning effect. In addition, the deposition of iron mud (Fe(OH)3) and the circular utilization of Fe in Fenton system is effectively improved by the addition of hydroquinone (HQ) in 3D–ICE–EF system. The pH applicable scope of Fenton system is extended to alkaline condition by the applications of NZVI–BC electrodes. The increase in the acidity of electrolyte is considered the primary reason of the high degradation efficiency of CLO in 3D–ICE–EF system at an initial pH of 9.0. The degradation performance of 3D–ICE–EF system tends to be promoted by the increase of current intensity and air flow rate. Seven plausible mechanisms of CLO degradation were identified in 3D–ICE–EF system. The ecotoxicity evaluation of degradation products indicated that CLO degradation in 3D–ICE–EF system exhibits a remarkable tendency to reduce toxicity levels.

Flotation-based dye removal system: Sweet potato protein fabricated from agro-industrial waste as a collector and frother

Hazardous synthetic dyes have emerged as an imperative issue of water contamination. This investigation focused on the development of a green flotation-based dye removal (FBDR) system to remove trace crystal violet (CV). A natural protein derived from sweet potato waste which was a readily available and low-cost agro-industrial residual was utilized as the collector and frother, due to its biodegradability and nontoxicity. In the first-stage of FBDR, an inclined foam channel with hydrophobic surface was employed to continuously recover sweet potato protein (SPP). Its recovery percentage and volume ratio reached 84.7 ± 4.2% and 7.2 ± 0.4, respectively. Enriched SPP (10.4 ± 0.5 g/L) was then collected by isoelectric precipitation and freeze drying. Encouragingly, SPP induced the desirable foaming and stable bubbles of the solution. Analytical tests, including SEM, FTIR, UV–vis spectra, and fluorescence measurements, confirmed that the SPP-CV complex was formed mainly through the hydrophobic force. In the second-stage, an excellent CV removal was generated with the collection of SPP. The removal efficiency and enrichment ratio of CV were 95.8 ± 4.5% and 9.2 ± 0.4, respectively. The kinetic study indicated that the removal rate markedly increased with increasing air flowrate. In conclusion, this investigation demonstrated the waste protein could be an effective, inexpensive and eco-friendly alternative for classical collector and/or frother, and provided new insights into the disposal of dye wastewaters.

Experimental analysis of a new generation of membrane liquid desiccant air-conditioning (LDAC) system with free convection of desiccant for energy economic management

Abstract A new generation of membrane liquid desiccant air-conditioning (LDAC) system with free convection of desiccant is investigated experimentally. The free convection LDAC systems have benefits over conventional air conditioning (AC) systems with the added advantage of system operation with no circulating pump. The prototype system made up of mainly two externally cooled hollow fiber membrane (HFM) liquid-to-air energy exchangers worked as dehumidifiers and regenerators. The performance of the system studied under the standard summer air conditions, and a thorough study was done to reveal its behavior as an AC system in different airflow rates. The coefficient of performance (COP) of the system is 0.85 at the base condition, and the sensible heat factor (SHF) of the dehumidifier ranged between 0.24 and 0.4 for different operating conditions. The heat and moisture removal rate and sensible heat factor increased while the electrical and thermal coefficients of performance (ECOP and TCOP) decreased by the airflow rate increase. While the value of TCOP is approximately the same for all operating conditions, the ECOP is very sensitive to airflow rate, and its value reduced by 82% as the value of airflow rate tripled. It is inferred that unlike the forced energy transfer loops, it is mainly the solution side transfer coefficients that determine the system performance, and between the heat and moisture transfer coefficients, the latter is more effective on system performance.