Minimum Efficiency Research Articles

A dual‐excitation inductive power transfer system with decoupled transformer for high misalignment tolerance

AbstractThis study delves into the design and optimization of a 4 kW dual‐excitation inductive power transfer system designed to accommodate large misalignments. The system utilizes a bipolar‐solenoid inductive coupled transformer as its coupling mechanism. Detailed simulation and analysis of this coupling mechanism are conducted. Additionally, the system employs a control strategy aimed at optimizing the coordination between output power and efficiency. This control strategy dynamically adjusts the power of the two transmitters, aiming to enhance system efficiency to the maximum extent possible under favourable coupling conditions. Moreover, it ensures that the system's output power remains at or above the rated value even when coupling conditions deteriorate. During the experiment, the system can optimize the output power and efficiency at the same time by using a suitable control strategy when the coils are misaligned. Meanwhile, the system can achieve a minimum efficiency of 81.5% even when the misalignment distance reaches 300 mm (60% of per transmitting coil size). The system and control strategy proposed in this paper can effectively overcome the deterioration of the output characteristics of the wireless power transfer system when misalignment occurs.

Investigation of Chemical Composition and Biological Activity of Salix aegyptiaca L. Roots

The root of Salix aegyptiaca L. was extracted using their yield percentage, total condensed tannin concentration, antimicrobial, antioxidant activity and to determine chemical composition by LC-MS/MS. The root extraction was carried out together with water, ethanol and methanol. Accelerated solvent extraction (ASE), conventional extraction (CE), and microwave extraction (ME) were the extraction methods applied during the investigation. The LC-MS/MS methanol extract was used to detect phenolics. The antioxidant activities and total condensed tannin concentrations of root extracts have been done by UV-visible spectroscopy from 517 to 580 nm, severally. The disk diffusion method was used for antimicrobial activity. The maximum extraction yield (17.2%) was obtained in methanol by the ASE technique whereas, the conventional extraction technique obtained the minimum extraction efficiency (9.1%). By triplicate measurement, the total condensed tannin analysis result was found 35.14 mg/L. Using the ASE technique, the methanol extract was the maximum inhibitory zone (26 mm) against Candida albicans ATCC 10231. However, in water extract by conventional extraction, a minimum inhibitory zone (11 mm) was obtained against Staphylococcus aureus Cowan 1. The highest and lowest DPPH scavenging activity was determined in methanol (ASE) (98.8%) and ethanol (97.5%) extract respectively. The maximum amounts of quinic acid (63895 µg/g) were discovered using LC-MS/MS.

Energy-economic analysis and optimization of a shell and tube heat exchanger using a multi-objective heat transfer search algorithm

This study presents the energy-economic analysis and optimization of a shell and tube heat exchanger. A water-water, segmental baffled shell and tube heat exchanger was designed using the Kern method and analysed by performing energy and economic modelling. The analysis is carried out considering the design variables on the shell side i.e. baffle cut, baffle spacing, shell diameter and tube side variables i.e. tube layout, tube outside diameter, number of tube passes and number of tubes. The multi-objective heat transfer search algorithm was used to optimize the heat exchanger for minimum total cost and maximum heat exchanger efficiency. Multiple optimal solutions were presented using the Pareto optimal curve. TOPSIS selection criteria was used to identify the optimum operating condition. Within the given bounds of the variables, the shell and tube heat exchanger can be operated at a minimum cost of 72,000 $/year resulting in 16.4 % efficiency, or, it can be operated at a maximum efficiency of 81.6 % with a total cost of 275,000 $/year. The scattered distribution of shell diameter, baffle spacing, number of tube passes and number of tubes between the lower and upper bound represent their substantial role in optimizing the heat exchanger performance. The number of tubes and tube passes showed the maximum variation in efficiency, while significantly less impact was observed when the tube layout was altered.

Longevity of size-dependent particle removal performance of do-it-yourself box fan air filters.

Filtration performance of do-it-yourself (DIY) box fan filters deployed across a university campus was assessed over an academic year. Four DIY air filters were constructed from box fans and air filters with a minimum efficiency reporting value (MERV) of 13 and deployed in four spaces (two laboratories that include sources of particles and two offices). They were operated 9 hours daily with a programmable timer and were continuously monitored with power meters. Particle concentrations in the spaces were continuously monitored with low-cost nephelometers. The particle size dependent clean air delivery rate (CADR) and single pass filtration efficiency for each box was measured in a laboratory before deployment and every 10 weeks, for a total of five measurements over 40 weeks. We find that these DIY box fan filters maintain robust performance over time, with each air filter maintaining at least 60% of its initial CADR at the end of the 40 week study even with daily operation in environments with modest particle concentrations. CADR values for particles of 1.0-3.0 μm optical diameter averaged 34% higher than CADR values for 0.35-1.0 μm particles, aligning with MERV 13 filter size-dependent filtration expectations. Reductions in CADR over time were attributed to a reduction in filtration efficiency, likely due to a loss of filter electrostatic charge over time. There was no strong indication that increased resistance due to particle accumulation on filters appreciably decreased flow rates over time for any of the fans. The long-term robustness of DIY box fan air filters demonstrates their validity as a cost-effective, high performance, alternative to portable high efficiency particulate air (HEPA) filters.

Understanding public acceptability of climate policies in Europe

ABSTRACT Urgent and decisive government action to mitigate greenhouse gas emissions is more likely when the proposed measures are popular among the public. This paper compares the drivers of European public support for three alternative policies to combat climate change: carbon taxation, renewable energy subsidies, and minimum energy efficiency standards that apply to household appliances. We combine survey data with regional socio-economic and environmental indicators to provide a comprehensive, comparative analysis of policy acceptance that accounts for the geographic context in which these policies would be implemented. By comparing the drivers among three climate policies, we identify a rural-urban gap in predicting public perception of carbon taxation, which does not exist in the other policies. We also found a positive relationship between regional exposure to fine particular matter (PM2.5) and public support for climate policy, providing novel insights into the influence of environmental factors on public perceptions. This research highlights the importance of environmental and socio-economic context in predicting climate policy acceptance and offers valuable implications for policymakers seeking to garner public support for effective climate change mitigation strategies.

Understanding of the asymmetric twin-stroll radial turbine under steady and pulsating inlet conditions

Utilize asymmetrical twin-scroll turbines (ATSTs) to achieve high-pressure exhaust gas recirculation (EGR) with a single scroll while optimizing the other scroll’s design for engine scavenging optimization. ATST performance prediction relies heavily on understanding the turbine flow mechanism, which always faces the challenge posed by time-dependent non-uniform intake. This paper studied its performance and flow field under steady and unsteady intake conditions for a production ATST. Firstly, the steady performance of the ATST with different asymmetries (ASYs) under different scroll pressure ratios (SPRs) is investigated via the computational fluid dynamics (CFD) method. Results demonstrate that the distribution relationship between SPR and turbine flow parameter (MFP) has a certain symmetry based on SPR = 1. For efficiency, the imbalance of inlet conditions will lead to the reduction of turbine efficiency. Moreover, the ASY has little effect on the turbine’s efficiency under the condition of SPR = 1. Also, the unsteady CFD simulations are conducted under pulsating inlet conditions with different scroll averaged pressure ratios (SAPRs). The results show that the highest efficiency was achieved at an ASY of 0.5 under a SAPR of 1.2 conditions, and the maximum, minimum, and average efficiencies were 1.9%, 1.5%, and 0.9% higher than those at an ASY of 0.83. The turbine’s flow field at the optimal incidence angle point is analyzed. The secondary flow vortex in the volute of an ASY of 0.5 is more robust, and the volute outlet ‘s total pressure loss is more significant. However, a relatively good incidence angle is obtained at the rotor inlet, and the loss in the rotor flow field is more minor. Therefore, the turbine efficiency with an ASY of 0.5 is higher.

Waste tea as absorbent for removal of heavy metal present in contaminated water

The goal of this study is to investigate the efficacy of tea-derived absorbents for the removal of heavy metals from contaminated water. For this, absorbents were prepared from milk tea (MT) waste, Ilam tea (IT) waste, and various types of tea leaves, including Immature (IML), mature (ML), and old leaves (OL). The characterization of the absorbents revealed distinct physical and chemical properties from X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), with varying degrees of effectiveness observed across different absorbent types. Heavy metal removal efficiency was assessed using a chemical-free UV-spectrophotometer. The results show that the maximum removal efficiency for Cd using the IT absorbent reaches up to 82.14 % with 100 ppm cetyltrim ethylammonium bromide (CTAB), while the minimum removal efficiency is 32.14 % using the OL absorbent with 20 ppm CTAB. For Zn, the OL absorbent demonstrates a maximum removal efficiency of 52.59 % with 100 ppm CTAB, whereas the minimum efficiency is 3.70 % using the ML absorbent with 20 ppm CTAB. For Ni, the highest removal efficiency is achieved with the ML absorbent, reaching up to 97.73 % with 100 ppm CTAB, and the lowest is 31.82 % with the MT absorbent with 20 ppm CTAB. The addition of a catalyst further enhanced removal efficiencies in both absorbents and metals. Also, the removal of heavy metal ions using 0.05 g of tea absorbent combined with CTAB at varying concentrations. Results show that the addition of 20 ppm and 100 ppm CTAB significantly reduces metal ion concentrations from an initial 100 mg/L. The metal ion concentration decreases as CTAB concentration increases, demonstrating the effectiveness of CTAB in enhancing the absorption capacity of tea absorbent for heavy metal removal. The investigation of selective adsorption of Ni, Zn, and Cd by an adsorbent, revealing competitive adsorption behavior with Ni and Zn being adsorbed more rapidly than Cd, suggesting the impact of metal ion interference on adsorption efficiency. However, limitations were observed with certain absorbent types; for instance, immature leaves did not effectively remove Ni. Overall, this study underscores the potential of tea-derived absorbents as sustainable solutions for mitigating heavy metal pollution in industrial wastewater. Further research is needed to optimize absorbent formulations and explore their applicability in real-world environmental remediation scenarios.

Structure design and mechanism research of combined cyclone plate separator based on particle separation

Although there has been much research on the gas–solid separation equipment of cyclone plate, there is still a lot of research space for miniaturization, low resistance, and easy maintenance. In this paper, parallel gas–solid separation equipment is designed based on computational fluid dynamics and experimental verification methods to address the practical problems faced by the fresh air system of the enterprise plant. The internal flow field of the separator is studied by numerical simulation, and the structural parameters of the separator are optimized according to the performance indicators provided by the enterprise. The optimal structure that meets the performance requirements and has the best effect is determined. Subsequently, the actual performance of the optimal structure was verified by wind tunnel experiments, and the deviation between the experimental results and the numerical simulation results was compared. The results show that increasing the number of blades, adjusting the blade angle, and increasing the height of the outer cylinder are beneficial in improving the internal flow field of the separator. Among them, the blade angle significantly affects the tangential velocity and axial velocity of the separator. When these three parameters are increased, the filtration efficiency increases first and then decreases. Finally, when the number of blades is 8, the blade angle is 50°, and the height of the outer cylinder is 0.63 m, the separation efficiency is the highest, and the pressure drop is the lowest. This structure satisfies all performance indicators. The experimental results show that the minimum filtration efficiency is 92.4%, and the maximum pressure drop does not exceed 500 Pa. Compared with the numerical simulation results, the experimental value is 0.29% lower, which shows that the structure has good separation performance and has a significant reference value for the fresh air system of the industrial workshop.

Fast-airflow tumble clothes dryer with small thermoelectric heat pump: Experimental evaluation

Residential clothes drying accounts for about 5 % of the total residential-sector energy consumption in the United States. Most dryers use electric resistance heaters to dry clothes and have low efficiencies. Higher-efficiency dryers that use vapor compression heat pumps are expensive and complex and have not gained a large market share in the United States. A novel tumble clothes dryer using a small thermoelectric heat pump with faster airflow than typical dryers is presented in this work. The benchtop performance of the thermoelectric heat pump and high-speed blower are presented, and the development of the prototype dryer is described. The dryer was tested for efficiency and dry time for a range of airflow rates and applied currents to the thermoelectric heat pump. The combined efficiency factor was 5.09–6.29 lbBDW/kWh (specific moisture extraction rate of 1.23–1.53 kgw/kWh) with 100–138 min dry times for these tests. The measured efficiency was 36 %–68 % greater than the minimum efficiency standard in the United States, and compared with vapor compression heat pump–based clothes dryers, the prototype dryer had less expensive, less complex components and did not use refrigerants. The performance of this small thermoelectric heat pump clothes dryer is also compared with previous iterations of the thermoelectric tumble clothes dryer described in the literature.

Assessing the Impact of ASEAN’s Harmonised Minimum Efficiency Performance Standards on AC Manufacturers

Abstract The residential sector in ASEAN is highly dependent on cooling as a primary energy use along with cooking, making up about 82% of the sector’s demand in 2050. Air conditioner (AC) is one of the cooling appliances in ASEAN that will drive energy demand growth in ASEAN. Consequently, this surge in demand also contributes significantly to the region’s CO2 emissions. Recognizing the impact of AC utilisation, energy efficiency in AC is considered the most effective way to propose energy savings and environmental impacts. In order to improve energy efficiency in AC, ASEAN has committed to stringent Minimum Energy Performance Standards (MEPS) by achieving a target for a Cooling Seasonal Performance Factor (CSPF) of 3.7 by 2023 and 6.09 by 2025. However, an update of MEPS across the ASEAN region has key two challenges: Firstly, the financial investment required by manufacturers; and secondly, the development and evolution of AC technology. This study aims to utilise Techno-Economic Assessment (TEA) to evaluate the impact of increased MEPS on AC manufacturers in the ASEAN region, with MEPS levels forming the framework for the TEA. The findings from this study offer valuable insights to manufacturers and policymakers, particularly regarding the impact of increased MEPS on AC manufacturers.

Semiconductor production scheduling and industrial economic coordination based on deep learning and heat loss optimization

With the growing global focus on energy efficiency and environmental impact, the semiconductor industry faces the dual challenge of improving production efficiency and reducing energy consumption. Heat loss is an important source of energy consumption in semiconductor production, so optimizing heat loss is of great significance. This paper aims to explore the optimization method of semiconductor production scheduling based on deep learning technology, with special attention to the reduction of heat loss, so as to achieve the coordinated development of industrial economy. The source of thermal energy loss in semiconductor production is analyzed and a deep learning model is constructed to predict thermal energy loss under different production scheduling schemes. Through deep learning training of production data, the model can identify and optimize the thermal energy consumption patterns of each link in the production process. In order to achieve the balance between minimum heat loss and maximum production efficiency, a variety of production scheduling schemes are optimized using simulated annealing algorithms. The experimental results show that the production scheduling scheme based on deep learning can effectively reduce heat loss and optimize production efficiency. Compared with traditional scheduling methods, the optimized system has reduced thermal energy loss and increased production efficiency. These results demonstrate the potential of deep learning in semiconductor production scheduling, significantly optimizing heat loss and promoting the coordinated development of the industrial economy.

Analysis of Furnace Performance Efficiency 201-H-001 Prefractionation Unit PT Trans-Pacific Petrochemical Indotama Tuban-East Java

Petroleum processing generally begins with a heating process, so equipment is needed to heat the crude oil before entering the fractionation column. This heating is closely related to the separation of fractions based on differences in boiling points. Heating at a fairly high temperature is used by a furnace, where the heat source comes from gas fuel. Based on the discussion above, furnace efficiency is fascinating to calculate as an indication of whether or not the furnace is operational. This efficiency calculation is also a reference for PT. Trans-Pacific Petrochemical Indotama to shut down and repair equipment, especially furnaces. This research aims to understand the furnace's working principles, determine the parameters that influence furnace performance, and calculate the efficiency of Furnace 201-H-001 in the Prefractionation unit. The results obtained in this research are that there are variables used to calculate thermal furnace efficiency. These variables are air temperature, fuel gas temperature, fuel gas flow, flue gas temperature, theoretical air requirements, and excess air in terms of efficiency and combustion reactions. The results of the furnace efficiency calculations were 78.03%, 77.34%, and 77.75% respectively. The minimum thermal efficiency value ranges from 75 - 80%, so it can be said that the furnace in this research is still suitable for use.

Determination of the effects of size parameters and lean angle on Bovet-based Francis turbine runner performance

Abstract In global hydropower generation, the Francis turbine is widely used because of its ability to work efficiently in a wide range of conditions like varying head and flow rates. Turbine’s meridional profile can be developed using traditional design approaches, like the Bovet method which uses empirical relations based on hydrological factors, that can be refined through optimization. Runner performance evaluation considers factors such as efficiency, erosion resistance, resistance to cavitation, and many more. Adjusting design parameters can enhance a turbine’s performance at a particular site. In this paper, a Bovet-based Francis runner design was obtained for Damile Micro Hydro located at Pharping, Nepal and the effect of variation of size parameters and lean angle on the runner performance was investigated. Initially, In-house MATLAB codes were used to design 99 meridional profile of different sizes by changing the size parameters as indicated by Bovet method and numerical simulation was performed to select the best meridional profile based on efficiency. After obtaining best meridional profile, the effect of lean angle was studied by varying it from -10° to 10°. Among the 99 designs based on different sizes, the simulation results indicate that the maximum efficiency was found to be 92.3% whereas the minimum efficiency was found to be 87.84%. The corrected lean angle of -5° showed the maximum efficiency and better pressure distribution along the blade.

Investigating the filtration performance and service life of vehicle cabin air filters in China

To protect occupants in vehicle cabin environments from the health risks of high concentrations of particulate matter (PM), it is important to install vehicle cabin air filter (VCAF) to eliminate PM. In this study, we investigated the filtration performance of 22 VCAFs. Results showed that the minimum average filtration efficiency was 56.1 % for particles with a diameter of 0.1–0.3 μm, a pressure drop of 33.2–250 Pa at air velocity of 2.5 m/s, and the dust-holding capacity ranged from 5.8 to 19.4 g. In addition, as the filter area increased from 0.23 m2 to 0.50 m2, the filtration efficiency for particles with a diameter of 0.1–0.3 μm increased from 56.7 % to 77.5 %, the pressure drop decreased from 96.1 to 62.5 Pa, and the dust holding capacity increased 2.7 times. Furthermore, we compared the service life of VCAF from 31 major Chinese cities and found that the service life varied greatly from maximum of 1730 h for Haikou to minimum of 352 h for Shijiazhuang. Considering occupant health risks, Beijing requires that VCAFs have PM2.5 filtration efficiency at least 88.1 %, and Liaoning requires minimum of 97.5 %. Hence, choosing the appropriate VCAF based on the atmospheric environment of different cities deserves our attention.

Experimental investigation of earth-air heat exchanger using porous clay vessels for eco-friendly buildings

This study introduces an experimental investigation of a novel direct trend evaporative cooler based on a ground-air heat exchanger (GAHE) using porous clay vessels as an evaporation media under a variety of operational conditions, including air flow rate, inlet air temperature, temperature of inlet water, and in air humidity. The evaluation of the GAHE performance was based on the air-cooling effect, wet-bulb and dew-point efficiencies, energy efficiency ratio, water evaporation rate, specific water evaporation, specific cooling capacity, specific total cost, and CO2 emission rate. The influences of dry-bulb temperature, the incoming air's relative humidity (RH), and six air flow rates ranging from 11 to 25 L/s on the performance are investigated and discussed. Results indicated that increasing the air flow rate leads to an increase in the cooling capacity. Energy efficiency ratio (EER) reaches the highest value of about 25.5 recorded at 3:00 PM with air flow rate = 11 L/s. The lowest EER value is approximately 7.2 when the measured inlet and outlet temperatures are the closest at 7:00 PM, with a flow rate of 25 L/s. Increasing the air flow rate from 11 to 17 L/s increased the wet bulb efficiency, and the airflow rate was inversely proportional to wet-bulb efficiency. The maximum and minimum average dew-point efficiencies are 64% and 58% at 17 L/s and 22 L/s respectively. The water evaporation rate increases by 182.1%, increasing the air flow rate from 11 to 25 L/s.

Thermodynamic and Economic Analyses of a Novel Cooling, Heating and Power Tri-Generation System with Carbon Capture

The combined cooling, heating, and power (CCHP) system has attracted increasing attention due to its potential outstanding performance in thermodynamics, economics, and the environment. However, the conventional CCHP systems are carbon-intensive. To solve this issue, a low-carbon-emission CCHP system (LC-CCHP) is firstly proposed in this work by integrating a sorption-enhanced steam methane reforming (SE-SMR) process. In the LC-CCHP system, CO2 is continuously captured by the calcium loop so that low-carbon energy can be generated. Then, the LC-CCHP system thermodynamic model, mainly consisting of a dual fluidized bed reactor which includes the SE-SMR reactor and a CaCO3 calcination reactor, a hydrogen gas turbine, a CO2 reheater, and a lithium bromide absorption chiller, is built. To prove that the LC-CCHP model is reliable, the system major sub-unit model predictions are compared against data from the literature in terms of thermodynamics and economics. Finally, the effects of reforming temperature (Tref), the steam-to-carbon mole ratio (S/C), the calcium-to-carbon mole ratio (RCC), the equivalent ratio for gas turbine (RAE), and the hydrogen separation ratio (Sfg) on total energy efficiency (ηten), total exergy efficiency (ηtex), and carbon capture capability (Rcm) are detected. It is found that the minimum exergy efficiency of 64.5% exists at the calciner unit, while the maximum exergy efficiency of 78.7% appears at the gas turbine unit. The maximum energy efficiency and coefficient of performance of the absorption chiller are 0.52 and 1.33, respectively. When Tref=600 °C, S/C=4.0, RCC=7.62, RAE=1.20, and Sfg=0.27, the ηten, ηtex, and Rcm of the system can be ~61%, ~68%, and ~96%, and the average specific cost of the system is 0.024 USD/kWh, which is advanced compared with the parallel CCHP systems.

Experimental investigation of inclined solar still through localized interfacial evaporation using nano enhanced Bio wick under disparate flow rate

Water treatment is essential for obtaining potable water, and passive solar desalination offers a renewable and sustainable approach. However, productivity remains a key challenge for commercialization. Scaling up solar desalination systems while maintaining efficiency and cost-effectiveness is a significant challenge. The current state of research in solar desalination is focused on developing scalable and sustainable solutions to address challenges faced in productivity. To address this issue, ongoing efforts focus on improving productivity under localized interfacial evaporation. The present study aims to enhance productivity, particularly at higher mass flow rates, through a series of experiments conducted in three sets. In the first set of experiments, a bare Integrated Solar Still (ISS) was utilized with various mass flow rates (0.29, 0.42, 0.75, and 1.3 kg/min). The highest hourly yield of potable water was observed during peak solar intensity, typically between 13:00 and 14:00 Hrs for all mass flow rates. However, as the mass flow rate increased, the hourly yield of potable water decreased. For instance, at 14:00 Hrs, the maximum yield was 0.235, 0.15, 0.12, and 0.06 kg/m2 for mass flow rates of 0.29, 0.42, 0.75, and 1.3 kg/min, respectively, in the ISS without wick material. The highest cumulative yield achieved was 1.6 kg/m2 during 0.29 kg/min mass flow rate, while the minimum clean water yield of 0.4 kg/m2 was obtained at 1.3 kg/min. In the second set of experiments, the goal was to improve productivity at higher mass flow rates. The use of Fe2O3-impregnated jute cloth in comparison to the bare ISS resulted in an average absorber temperature increase of 4∘C, 4.8∘C, 4.8∘C, and 4.9∘C for mass flow rates of 0.29, 0.42, 0.75, and 1.3 kg/min, respectively. Interestingly, the trend showed an increasing rate of reduction mitigation at higher mass flow rates. Simultaneously, the average water temperature increased by 4.2∘C, 4.5∘C, 6.4∘C, and 7.1∘C for the corresponding mass flow rates with Fe2O3-impregnated jute cloth. The introduction of jute cloth enhanced energy harvesting at all mass flow rates compared to the bare ISS. The maximum energy efficiency, at 48.02 %, was achieved with Fe2O3-impregnated jute cloth during the 0.29 kg/min mass flow rate, while the minimum energy efficiency, at 9.14 %, was recorded at the highest mass flow rate of 1.3 kg/min. Notably, the energy efficiency of the jute cloth-covered ISS surpassed that of the bare ISS by 12.44 %, 9.14 %, 7.15 %, and 3.14 % for mass flow rates of 0.29, 0.42, 0.75, and 1.3 kg/min, respectively. Furthermore, the addition of Fe2O3-impregnated jute cloth further improved energy efficiency, with enhancements of 8.19 %, 1.14 %, 6.36 %, and 9.57 % over the jute cloth-covered ISS for the respective mass flow rates. During the 0.75 kg/min mass flow rate, energy efficiency reached 26.12 %, closely matching the 27.3 % efficiency achieved at 0.29 kg/min in the bare ISS. The study also demonstrated a 2.29 % improvement in exergy with Fe2O3-impregnated jute cloth at a mass flow rate of 0.29 kg/min. In conclusion, the results suggest that the implementation of jute cloth over the ISS absorber basin can enhance overall efficiency and mitigate the negative impacts of increased mass flow rates via localized interfacial evaporation. The combination of a jute cloth wick and Fe2O3 nanoparticles holds promise for improving energy efficiency in solar still desalination.

Thermodynamic analysis of a novel gas separator based on molecular exchange flow

An energy analysis model and several evaluation indexes are established for a novel gas separator employing molecular exchange flow as working principle. The influences of several important factors on energy consumption and thermal efficiency are investigated. As temperature difference increases, both energy consumption and thermal efficiency rise linearly. As Knudsen number increases, total work decreases while minimum separation work and thermal efficiency initially increase and subsequently decrease. When inlet velocity increases, total work increases but minimum separation work and thermal efficiency go down. Furthermore, both energy consumption and thermal efficiency initially rise and then decline with an increasing mole fraction of the lighter molecular weight component. The results indicate that energy consumption and separation performance should be taken into consideration when selecting temperature differences. In addition, it is preferable to choose the Knudsen number corresponding to optimal separation performance and the intermediate value for component mole fraction. Moreover, it had better employ a lower inlet velocity as long as the separation requirements are satisfied. This study presents a method to optimize the performance of the novel separator based on molecular exchange flow from the perspective of energy conversion and utilization.

Performance of anaerobic baffled reactor (ABR) and multi-staged UASB in anaerobic digestion process for treating leachate from refuse transfer stations under loading shocks

ABSTRACT This study compared an anaerobic baffled reactor (ABR) with a multi-staged UASB (MS-UASB) to investigate the effects of loading shocks on the anaerobic digestion in both reactors. Both reactors were subjected to five hydraulic/organic loading shocks, each lasting 3 days. During the hydraulic shock with the highest organic loading rate (OLR) (OLR of 24 g COD L−1 d−1), MS-UASB and ABR exhibited minimum effluent COD removal efficiency of 90.9 and 73.0%, with average methane concentrations decreasing to 62.4 ± 0.9% and 59.8 ± 3.0%. Under the highest organic shock (OLR of 12 g COD L−1 d−1), the minimum effluent COD removal efficiency of MS-UASB and ABR was 81.5 and 73.4%, with average methane concentrations decreasing to 60.4 ± 1.1% and 58.6 ± 0.8%. After the hydraulic and organic shock phase, the biomass concentration in the MS-UASB reached 159 and 130% of the ABR, respectively. The reason for the improved operational stability of the MS-UASB is due to the presence of the solid/liquid/gas separator, which promotes the formation of granular sludge and reduces biomass washout. In addition, MS-UASB exhibited a higher abundance of the syntrophic bacterium Candidatus cloacamonas, which plays a crucial role in maintaining the stability of anaerobic digestion systems.

Hydrodynamic performance of a pile-supported oscillating water column breakwater in front of a partially reflecting seawall

Integrating wave energy devices with breakwaters can offer an innovative and sustainable approach by combining wave power extraction with wave attenuation. The performance of this integrated system in offshore areas is influenced by the unique characteristics of the coastline. In this paper, a semi-analytical solution was developed using the matching eigenfunction method for the oscillating water column device integrated into a pile-supported breakwater in front of a partially reflective seawall. The model was validated through the energy conservation law, the Haskind relationship, and experimental data. Detailed examinations were conducted on the effects of the seawall's reflection coefficients, the distance between the system and the seawall, the wall draft, and the chamber breadth on hydrodynamic performance. Results show that the presence of the seawall significantly influences hydrodynamic coefficients (hydrodynamic efficiency, reflection coefficient, the relative transmitted amplitude, etc.), accompanied by the piston and sloshing mode resonances inside the chamber and the confined area between the system and the seawall. Due to energy dissipated by a partially reflective seawall, the magnitude of those hydrodynamic coefficients is mitigated, together with the piston and sloshing mode resonances inside the air chamber. The cancellation of the sloshing mode resonance inside the confined area is observed for the smaller seawall's reflection coefficient. The maximum and minimum hydrodynamic efficiency occur when the system is arranged at the wave nodes and antinodes of the formed standing wave field. Lower wave reflection and better wave power extraction can be achieved by properly adjusting the chamber drafts and breadths.