Buffer Tank Research Articles

A Turbidity Module to Measure Spray Mixture Concentration for Premixing In-Line Injection System

Highlights A turbidity sensor module was investigated to monitor concentrations of pesticide mixtures in real time. A flow-through measurement platform was built to calibrate the turbidity sensor and determine its accuracy. Optimal location of the turbidity sensor was determined for monitoring in-line mixture concentrations. Spray mixture uniformity reached acceptable level for the premixing in-line injection system. Abstract. Monitoring mixture concentrations for precision pesticide spray systems in real time can assure the desired amount of chemicals distributed uniformly to target areas. An in-line turbidity sensor module was investigated to monitor concentrations of spray mixtures produced with a premixing in-line injection system developed for precision variable-rate orchard sprayers. The turbidity sensor was calibrated with simulated pesticides at concentrations ranging from 0% to 30.0%. A cubic polynomial regression model was established for the relationship between sensor output voltages and mixture concentrations. Sensors were mounted at three in-line locations to detect the mixture uniformity differences in the premixing in-line injection system. The module was found to have adequate precision and accuracy to measure concentrations of spray mixtures with simulated pesticides. Relative errors of the sensor were less than 4.70% and the sensor accuracy did not vary with mixture flow rates. Mounting the turbidity sensor downstream of the buffer tank in the premixing in-line injection system would be the optimal location to monitor spray mixture uniformity for variable-rate spray applications. At this location, the relative errors of measured mixture concentrations were between 0.12% and 3.70% which agreed with previous manual measurements. Therefore, there would be a great potential to integrate the in-line turbidity sensor into the variable-rate and even conventional constant-rate sprayers to achieve uniform spray applications in the target field. Keywords: Agitation, Mixture uniformity, Pesticide concentration, Sensor calibration, Variable-rate sprayer.

Numerical investigation of the dispersion features of hydrogen gas under various leakage source conditions in a mobile hydrogen refueling station

The leakage and dispersion of hydrogen gas in a mobile hydrogen refueling station is being numerically investigated in this paper. The investigated geometry is derived from the mobile hydrogen refueling station in China. The numerical models are verified by experimental data. The hydrogen gas leaks from the hydrogen buffer tank in the form of momentum-dominated jet. The combustible danger region, the hydrogen concentration distribution, and the volume of hydrogen gas cloud are investigated. The effects of leakage positions and leakage flow rates on the characteristics and evolution of hydrogen diffusion in the mobile hydrogen refueling station and the open space are analyzed. The results show that the hydrogen concentration in the 3-way corner of the ceiling opposite the leakage orifice first reaches 0.4% and 4%. When the leakage orifice faces the sidewall of the truck container, the liquid hydrogen storage is completely surrounded by hydrogen gas clouds in the flammability limit. The maximum diffusion height of hydrogen at the lower flammable limit increased as the leakage flow rate increased, and the volume of hydrogen in the flammability limit increased virtually exponentially in the open space. The research findings provide a significant reference for potential explosion and risk assessment studies of mobile hydrogen refueling station.

Buffer Tank Discharge Strategies in the Case of a Centrifugal Water Chiller

In this article, energy optimization of the cooling system of IKEA Budaörs is carried out. The cooling system is served by a centrifugal water chiller and includes a large-volume cooling buffer tank. The facility operates the hydraulic system of the buffer storage tank only during the transitional period. The main goal is to reduce energy consumption by changing the operating strategy of the existing system. To test the operating strategies, the operation and the thermal load of the shopping center during the summer season had to be simulated to find the best operation strategy. A hybrid method (real data and calculated values) was used in the simulation. The three operating scenarios examined show that the annual energy consumption and the number of operating hours of the chiller can be reduced by using the buffer tank with the right strategy. In the examined scenarios, a 30% energy improvement was achieved. The possibility of using a buffer tank is significantly limited by the fact that the heat exchangers were sized for low forward water temperatures. By re-sizing the heat exchangers, the utilization of the buffer tank could be considerably improved in conditions close to peak heat load.

Small-scale ORC-based unit for domestic micro-cogeneration operating in the temperature range of the solar thermal flat panels

CO2 emissions related to the energy demand in commercial and residential buildings account for over 15% of worldwide greenhouse gases emissions. This issue requires the development of new solutions, technologies, and energy management strategies to reduce the environmental impact of this sector. Simultaneous heat and power production, namely cogeneration, is a proven method for this purpose. Among the different power systems, Organic Rankine Cycle (ORC) plants allow the production of mechanical and electric energy using hot sources at low temperature levels. This feature allows to combine this technology with solar collectors, making it possible to exploit the thermal energy exceeding the thermal needs when the solar irradiation is high. In this paper, an experimental characterization of a Solar Organic Rankine Cycle (SORC) is presented. The hot source of the power plant is reproduced by water heated up to 120 °C by two 12 kW electric resistances and stored in a buffer tank with a capacity of 200 L. The 1 kW ORC unit is equipped with a scroll volumetric expander operating off-grid. The main control variable of the unit is the pump speed which is varied in each operating condition to guarantee a superheating degree at the expander inlet. Since the variability of the solar source is a critical issue in these applications, off-design operating conditions have been tested, showing the capability of the plant to be also operated far from the design point. The maximum efficiency of the unit reached 4.7 % while the highest net power was 400 W. A further test conducted to evaluate the transient performances of the unit demonstrated its small inertia and the capability of the expander to produce power right after the unit activation.

Validations of a double U-tube borehole model and a seasonal solar thermal energy storage system model

In order to predict the performance of seasonal thermal energy storage systems reliably, a validated simulation model is required. In this article, an experimental investigation of a seasonal solar thermal energy storage system was used for the validation of the simulation model. Details of the system components, validation procedures, operating modes and schedules, data acquisition system, and measuring instruments are described. Three TRNSYS project files are developed for validations of the double U-tube borehole model, and different modes of operation. The operational and performance data, as well as relevant weather data, are collected. Mean bias error, root mean square error and correlation coefficient (CC) are used to quantify the agreement between each simulated and measured temperature of interest. The CCs for the double U-tube borehole outlet temperatures are 0.99 and 0.91 for solar heat charging and space heating modes, respectively. The CCs for the outlet temperatures of the solar collector and buffer tank are 0.91 and 0.88 in the solar heat charging mode, respectively. The CCs for the leaving water temperature, leaving air temperature, and room temperature are 0.95, 0.97 and 0.83 in space heating mode, respectively. The simulated absolute temperatures are found to be within ±4% of those measured.

Scheduling and batching with evolutionary algorithms in simulation–optimization of an industrial formulation plant

Industrial scheduling problems are usually characterized by a high complexity and in many, if not all cases, a detailed representation of many specific features of the production process and of the constraints is necessary to ensure that the resulting schedules are feasible when they are executed. Such detailed representations are provided by commercial discrete-event simulation programs which are often employed in the planning phase to detect bottlenecks and to validate design decisions, but usually do not provide optimized schedules. In this paper, we combine a tailored Evolutionary Algorithm with a high-fidelity simulation model in a Simulation–Optimization approach in order to obtain optimized executable production schedules.The industrial production process considered here is a formulation plant that consists of a formulation stage and a filling stage with optional intermediate storage in a set of buffer tanks. The operational constraints include limited operator availability and shift constraints, sequence-dependent changeover times in both stages, product- and line-dependent processing rates, and the need for synchronization of operations. The objective is to minimize the tardiness of a set of orders some of which have long operation times and small slack between the earliest possible end times and the due dates.The orders consist of a certain number of batches, but if all the batches of an order are processed on the same equipment, meeting the due dates is not possible. Therefore the orders have to be decomposed into sub-orders (production orders) to realize parallel processing of urgent orders on several units with the goal to meet due dates. The decision to distribute the total demand of the individual customer orders to production orders is also called batching decision in the literature.A distinctive feature of our approach is that three independent encodings of the batching, allocation and sequencing decisions are used. The batching decisions lead to variable-length chromosomes for the allocation and sequencing encodings. For the treatment of variable-length chromosomes, new crossover and mutation operators, as well as repair algorithms are presented.The results for three test cases show that the introduction of the batching decisions significantly improves the tardiness of the production schedules. A thorough tuning of the categorical parameters of the Evolutionary Algorithm has been performed and it is shown that the resulting parameter setting yields reproducible results, while outperforming simpler approaches.

Intelligent HAZOP analysis method based on data mining

Accidents in production equipment are occurring with increasing frequency, which has caused serious negative impacts on society and petrochemical enterprises. It is important to learn prevention and control rules and lessons from accident cases to prevent accidents and improve intrinsic safety levels of enterprises. The hazard and operability (HAZOP) analysis method has been widely used for risk identification and accident prevention in petrochemical enterprises. However, the rules contained in many completed HAZOP analysis reports have not been deeply studied, inherited, or extensively applied. The analysis of a new process, however, relies on expert experience, which is usually subjective and time-consuming. This paper proposes an intelligent HAZOP analysis method based on data mining to explore the law of accident cause mechanisms, help promote intelligent analysis, and improve the accuracy of analysis results. A HAZOP analysis data table structure is proposed. The frequencies of all words in the process parameter, guide word, cause, and consequence were calculated, and the words were sorted based on the word frequency statistics method. Words with high word frequencies were considered key in formulating the safety inspection checklists. The latent Dirichlet allocation (LDA) model and contingency table were used to explain the correlation between the process parameters, guide words, causes, and consequences. The co-occurrence probability sequence of the elements can then be acquired. Using the naive Bayes algorithm, a method for calculating the likelihoods, severities, and risk levels of accidents is proposed. The accident risk ranks can be intelligently predicted to realize an intelligent HAZOP analysis. This study developed a software to help execute the method. The intelligent HAZOP analysis method was applied based on data from 14 petrochemical units; the raw oil buffer tank in the wax oil hydrocracking unit was taken as an example to illustrate the application of the method. The method provides a technical basis and basic guarantee for risk identification, accident prevention, and rescue of petrochemical plants.

Review of Hydrogen Based Fuel Cells Energy Storage Systems

This paper presents a review of the hydrogen energy storage systems. Most developed countries have turned to search for other sources of renewable energy, especially solar energy, and hydrogen energy, because they are clean, environmentally friendly, and renewable energy. Therefore, many countries of the world began to accept the inevitability of shifting to an economy based on hydrogen as a future fuel. Among the difficult challenges in this transformation are the methods of storing electrical energy in fuel cells and storing hydrogen, as the race of large energy companies has begun to provide solutions to develop many types of fuel cells, given that they are the biggest challenge to energy generation and storage. This paper presents a review of fuel cells including Energy Storage Using Hydrogen Produced from Excess Renewable Electricity, as well as to cover the storage system includes three main components: electrolysis, fuel cell, and a hydrogen buffer tank. We will discuss the different types of fuel cells, such as: Alkaline Fuel Cells (AFC), Polymer Exchange Membrane Fuel Cell (PEMFC)...etc.) along with the different application of fuel cell hydrogen energy storage, we will also investigate some case studies of the hydrogen energy storage and main opportunities and challenges of the implementation.

Research on the hydrogen consumption of fuel cell electric vehicles based on the flowmeter and short-cut method

Energy consumption is essential for evaluating the competitiveness of fuel cell electric vehicles. A critical step in energy consumption measurement is measuring hydrogen consumption, including the mass method, the P/T method, and the flowmeter method. The flowmeter method has always been a research focus because of its simple operation, low cost, and solid real-time performance. Current research has shown the accuracy of the flowmeter method under specific conditions. However, many factors in the real scenario will influence the test result, such as unintended vibration, environment temperature, and onboard hydrogen capacity calibration. On the other hand, the short-cut method is also researched to replace the run-out method to improve test efficiency. To evaluate whether the flowmeter method basing on the short-cut method can genuinely reflect the hydrogen consumption of an actual vehicle, we research and test for New European Driving Cycle (NEDC) and China Light-Duty Vehicle Test Cycle (CLTC) using the same vehicle. The results show that the short-cut method can save at least 50% of the test time compared with the run-out method. The error of the short-cut method based on the flowmeter for the NEDC working condition is less than 0.1%, and for the CLTC working conditions is 8.12%. After adding a throttle valve and a 4L buffer tank, the error is reduced to 4.76% from 8.12%. The test results show that hydrogen consumption measurement based on the flowmeter and short-cut method should adopt corresponding solutions according to the scenarios.

DYNAMIC MODELLING OF AMMONIA CRACKERS AND HYDROGEN PEM FUEL CELLS FOR SHIPPING APPLICATIONS

The pathway towards sustainable maritime propulsion is unclear. One concept is using ammonia as a fuel. This study investigated using an ammonia cracker (a device to convert ammonia to hydrogen) and a Proton Exchange Membrane fuel cell. This requires a hydrogen buffer tank and purification, each process has been dynamically modelled. Simulations show the power demand for different vessel types (cargo and survey) for several routes. This enabled analysis of ammonia demand and system requirements during: in port; manoeuvring; cruising; surveying. The same simulations ran for other potential setups to facilitate a fair comparison of the technical challenges, storage requirements, and support system requirements (e.g. batteries). Results showed that the total system plus fuel for this concept for a case study cargo voyage would weigh 150 tonnes and require 586 m3 of volume. For comparison, a liquid hydrogen system for the same voyage weighed 35 tonnes and required 222 m3 .

Economic, technical, and environmental evaluation of retrofitting scenarios in a full-scale industrial wastewater treatment system

The use of mathematical models is a well-established procedure in the field of (waste) water engineering to “virtually” evaluate the feasibility of novel process modifications. In this way, only options with the highest chance of success are further developed to be implemented at full-scale, while less interesting proposals can be disregarded at an early stage. Nevertheless, there is still lack of studies, where different plant-wide model predictions (effluent quality, process economics, and technical aspects) are comprehensibly verified in the field with full-scale data. In this work, a set of analysis/evaluation tools are used to assess alternative retrofitting options in the largest industrial wastewater treatment plant in Northern Europe. A mechanistic mathematical model is simulated to reproduce process behavior (deviation < 11%). Multiple criteria are defined and verified with plant data (deviation < 5%). The feasibility of three types of scenarios is tested: (1) stream refluxing, (2) change of operational conditions and (3) the implementation of new technologies. Experimental measurements and computer simulations show that the current plant´s main revenues are obtained from the electricity produced by the biogas engine (54%) and sales of the inactivated bio-solids for off-site biogas production (33%). The main expenditures are the discharge fee (39%), and transportation and handling of bio-solids (30%). Selective treatment of bio-solid streams strongly modifies the fate of COD and N compounds within the plant. In addition, it increases revenues (+3%), reduces cost (-9%) and liberates capacity in both activated sludge (+25%) and inactivation reactors (+50%). Better management of the buffer tank promotes heterotrophic denitrification instead of dissimilatory nitrate conversion to ammonia. In this way, 11% of the incoming nitrogen is removed within the anaerobic water line and does not overload the activated sludge reactors. Only a marginal increase in process performance is achieved when the anaerobic granular sludge reactor operates at full capacity. The latter reveals that influent biodegradability is the main limiting factor rather than volume. Usage of either NaOH or heat (instead of CaO) as inactivation agents allows anaerobic treatment of the reject water, which substantially benefits revenues derived from higher electricity recovery (+44%). However, there is a high toll paid on chemicals (+73%) or heat recovery (-19%) depending on the inactivation technology. In addition, partial nitration/Anammox and a better poly-aluminum chloride (PAC) dosage strategy is necessary to achieve acceptable (< 2%) N and P levels in the effluent. The scenarios are evaluated from a sustainability angle by using life cycle impact assessment (LCIA) in form of damage stressors grouped into three categories: human health, ecosystems quality, and resource scarcity. The presented decision support tool has been used by the biotech company involved in the study to support decision-making on how to handle future expansions.

How does a resilient, flexible ammonia process look? Robust design optimization of a Haber-Bosch process with optimal dynamic control powered by wind

Ammonia can be an essential energy vector for storing excess renewable energy during the year and release this energy when demand is high. This storage during the year provides an essential part in the energy sector for moments when there is not enough wind and sun to cover the demand. Although the Haber-Bosch is a very mature process to synthesize hydrogen and nitrogen to ammonia, it is not flexible enough to match the erratic nature of renewables. This mismatch creates the need for large intermediate hydrogen buffer tanks. To reduce the capacity of the hydrogen storage tank, we need to optimize the dynamic power-to-ammonia process in a minute time scale while considering the uncertainties linked to renewables. Therefore, we coupled a stochastic wind power process to a dynamic Power-to-Ammonia process and performed a design optimization under uncertainties, i.e. a robust design optimization, for a three-hour wind scenario while considering optimal dynamic control. The robust design optimization showed significant trade-offs between the most productive, the most flexible, the most resilient, and robust power-to-ammonia plant designs. For the flexible and productive designs, the bypass fraction and buffer feed have essential roles in achieving these designs. In the future, we will use a stochastic process to consider the uncertainty of renewable power over more extended periods (days, weeks and months) coupled with the robust design optimization of the dynamic power-to-ammonia process and investigate its effect on the intermediate hydrogen buffer size and the plant’s cost.

Development and research of a digital control system for juice consumption after the diffusion apparatus in sugar production

The article is devoted to solving the problem of stabilizing the flow rate of diffusion juice at the outlet from the buffer tank under conditions of an unstable hydrodynamic mode of operation of the diffusion apparatus in sugar production. The existing system does not provide effective stabilization of the juice consumption in case of significant fluctuations in the level and situations arise when the buffer tank is empty or overflowed. A digital control system is proposed that improves the dynamic accuracy of juice flow stabilization due to digital correction according to the integral law of setting the flow regulator according to filtered (smoothed) level values and including proportional, differential components in the correction algorithm when the level leaves the “smooth” control area. The effectiveness of the digital control system is confirmed by mathematical modeling in various modes.

Purification of biodiesel from crude palm oil using multistage portable fixed bed adsorber

Crude biodiesel needs to go through purification process, to meet international biodiesel specifications.. The widely used adsorption column is in the form of a fixed bed column, where the contents of the column are stacked in a mess. This makes the adsorbent difficult to clean and fill, and irregular adsorbent accumulation can hinder the flow of the fluid to be purified. In this study, an adsorption column with a portable circulation system used to observe the influence of circulation and adsorption level on the purity of biodiesel. Main equipment of this research is a portable adsorption biodiesel purification device. The column consists of: top distributor, packed bed and bottom collector. The tool is made of 3D printed polymer material. At the bottom of the tower there is a buffer tank and a pump for circulating the biodiesel to be purified. The results showed that some analytical parameters based on the results of t-test, namely: density, acid value, saponification and yellowish-blue tendency, there are significant differences between the results before and after purification. For all the parameters analyzed in this study, the number of stages and fluid circulation gave significantly different results. The results of methyl ester analysis confirmed this, where the more cycles in the column, the higher the methyl ester peak produced. As number of cycles in the adsorption column increases, peak area of the methyl ester produced becomes wider, which can be explained by the ability of column and its packing materials to filter impurities present in column.

Optimization of the South Coast Seawater Purification Process by Using a Circulating Adsorption Column

Seawater which contains salt, metal components and mycobacteria is part of Indonesia's natural resources. Behind its abundance, not many benefits can be used, such as clean water to drinking water. Therefore, various technologies are needed to reduce the salt content and other components. In this study, a portable seawater purifier based on the adsorption function was used. The purification apparatus is in the form of a column, and has a series of plates that are placed as a support for the filling material in order to increase residence time and complete the purification process. Materials used as adsorbents in this study include ceramic biological balls, ammonite, volcanic rock, activated carbon and zeolite. Each material is organized in a filter bag for easy installation and cleaning. The equipment construction is arranged where in addition to the column there is also a circulation flow system for seawater to ensure the purification process can run optimally. The circulation process uses a buffer tank and a booster pump back to the column input line. The variable in this study, namely the location of the water sample at Ngobaran Beach, Gunungkidul. Another variable is the filtration rate. Based on the pH value of the TDS analysis and the adsorption results of seawater samples, it can be seen that the 2-stage adsorption process is the most optimal process configuration compared to other levels. This is because the 2-stage adsorption process obtained the smallest TDS value and the most suitable pH value for clean water. The results of this study can be an alternative for an easy and portable seawater purification method. This research can continue to be developed with innovations from the type of filling material and the configuration of the adsorption column used.

Transient performance study of high pressure fuel gas supply system for LNG fueled ships

The transient performance of the fuel system is a critical issue for the operation of liquefied natural gas (LNG) fueled ships. In this paper, experiments and simulations of a high pressure fuel gas supply system (HP-FGSS) were conducted to investigate the system transient responses during load variations and environmental disturbances. A prototype of the HP-FGSS was tested at different running loads from 0% to 110% in combination with a MAN high pressure two-stroke dual fuel engine. A dynamic model of the HP-FGSS was developed and validated by the test data. The effects of the operating parameters and equipment sizes on the system performances were simulated and analyzed. The results show that during the load variations from 75% to 100% the fuel gas pressure fluctuation is nearly 10 bar and lasts for 5 min. The HP-FGSS control system has a high robustness to the LNG composition, but the pressure overshoot increases as the methane content decreases. The LNG composition will also affect the steady state value of the gas temperature. The buffer tank volume has a significant impact on the pressure response. The pressure disturbance in the LNG tank induced by violent sloshing will be transmitted to the suction port of the high pressure pump, causing a cavitation risk.

Exploration of efficient water, energy and nutrient use in aquaponics systems in northern latitudes

Efficient energy and resource management are essential for a more sustainable food production system. On-demand coupled multi-loop aquaponics, containing at least a fish, plant and anaerobic digester unit, has shown great potential for optimizing nutrient use. However, balancing the nutrients for both fish and crop production becomes increasingly complex at higher latitudes. In these areas also significant reductions in energy use are required. Hitherto, the effects of energy-saving strategies on the dynamics of an aquaponics system have not been explored.The objective of the study was to investigate and mathematically model an aquaculture-hydroponic (aquaponics) system with Nile tilapia (Oreochromis niloticus L.) and lettuce (Lactuca sativa L.) or tomato (Solanum lycopersicum L.), and to verify it for the Netherlands.In the mathematical model several physical and operational parameters were varied to find their influence on water and nutrient use efficiency, energy use and the growing environment, in particular in the greenhouse.The variation in crop transpiration was found to be a simple, yet effective, indicator for the influence of greenhouse settings on the performance of on-demand coupled multi-loop aquaponics systems. The correlation between water or nutrient use efficiencies and transpiration variation (0.98) is stronger than the correlation with energy use (0.78). The maximum allowed humidity (70% to 90%) and use of artificial lighting (0 – 200 W/m2) has the largest effect on both performance and energy use. Other settings, such as inclusion of thermal insulation of the cover, minimum temperature, addition of heat storage, and use of screens, have effect on the energy efficiency, but have little effect on the nutrient dynamics. To counter the negative effects of variation caused by other energy-saving strategies or climatic variations, the use of a buffer tank, placed between anaerobic digester and hydroponic system, was found a feasible option.Aquaponics is an emerging technology in sustainable food production and this research supports the introduction of on-demand coupled aquaponics systems in northern latitudes.

Optimization of electrolytic system type for industrial reverse osmosis concentrate treatment to achieve effluent quality and energy savings

This study demonstrated the remarkable potential of electrolytic system type for industrial reverse osmosis concentrate (ROC) treatment on effluent quality and energy requirements. Following their individual system optimization, the required current density decreased from 20 mA cm−2 for the batch system during 4 h of electrolysis, to 5 mA cm−2 for a continuous-flow system (CFS) without effluent recirculation (CFS-A), and 3 mA cm−2 for a CFS system with a rear (CFS-B) or front (CFS-C) buffer tank for effluent recirculation (R = 1). The final or effluent chemical oxygen demand (COD) and NH4+−N levels were 31 and 0.4 mg L−1 (Batch), 24 and 0.56 mg L−1 (CFS-A) and 5.7–8.1 and 0.24–0.34 mg L−1 (CFS-B or -C), respectively. Besides the highest pollutant removal, the optimized CFS-B and -C systems also achieved the highest treatment capacity and energy efficiency, and the lowest effluent toxic organic byproduct levels due to the homogeneous diffusion characteristic of CFS systems, and the reutilization of long-lived active chlorine species (ACS) oxidants in CFS-B/C electrolytic effluent. As compared with the optimized CFS-B system, the optimized CFS-C system at an identical recirculation ratio further achieved the lowest effluent ACS level due to the ACS consumption in the front buffer tank (rather than direct discharge in the CFS-B system) and lower flow rate into the electrochemical cell (than that in the CFS-B system), and was finally recommended for future engineering implementation.

Novel thermal treatment model to decontaminate airborne SARS Cov‐2 virus for residential and commercial buildings

In the COVID‐19 pandemic, control of airborne virus transmission is exceptionally challenging as it is attached to suspended particles in the air and stays for an extended time. Air contaminated with airborne viruses holds a substantial risk for household transmission. In this study, a novel thermal treatment system is modeled based on porous heating for the decontamination of airborne SARS‐Cov‐2. The model includes an air heating domain, insulated chamber, buffer tank and heat exchanger. The airborne SARS‐Cov‐2 is decontaminated when passing through a porous heat pipe and the insulated chamber for an anticipated dwelling period of more than 5 min at 105°C and further stored in a buffer tank for natural cooling. The obligatory decontaminated air is allowed in the residential space under ambient conditions passing through a heat exchanger. The numerical investigation of the porous pipe model at different L/D ratios with altered porosities aims to establish the best‐performing porous domain. Besides this, the buffer tank is intended to maintain buffer storage of the treated air and significant natural cooling before passing to the heat exchanger. A solar PV module is proposed to meet the prerequisite energy requirements of the equipped devices.

Prediction of mass and volumetric flows in a full-scale industrial waste treatment plant

In this paper a set of mathematical tools are developed and assembled together to assess and predict mass and volumetric flows in waste treatment systems (WTS). The proposed approach is constructed upon a set of data reconciliation methods, influent fractionation routines and process simulations models (and model interfaces) to balance, analyze, reproduce and forecast the behavior of different compounds within treatment facilities. The proposed approach is tested on full-scale data collected after two five-week measuring campaigns at the largest industrial WTS in Northern Europe. Results show that the proposed reconciliation methodology based on the definition of the identity matrix, data curation, the estimation of missing fluxes and the calculation of Lagrange multipliers allowed to close flow and COD, N, P, S and multiple metals (Na, K, Ca, Mg and Al) mass balances. Plant-wide overall mass balance reveals that that: 1) 32% of the incoming COD is recovered mostly as methane, 2) 23% and 65% of COD and N are biologically removed and leave the system via the gas phase, 3) 32 % and 33% of COD and N are stored in the activated sludge, 4) > 70% of P, Ca, Mg and Al are accumulated in the bio-solids stream as precipitates and 5) > 70% of Na, K and S remain soluble and leave the plant via effluent. Plant measurements were allocated into the model states describing soluble/particulate and organic/inorganic loads arriving to the WTS under study. The average deviation between computer simulations and the result of the measuring campaign is 10.5%. This study also shows that the proposed approach is capable to reproduce main streams neutralization, volatile fatty acid production, particulate removal and nitrate denitrification in the anaerobic water line (buffer tank, primary clarifier, pre-acidification tank). It also correctly predicts organics transformation into biogas in the anaerobic granular sludge reactor. Lastly, it is possible to describe biological and chemical N and P removal processes in the activated sludge and the quality of bio-solids after inactivation/dewatering (reject water /cake). A scenario analysis is included showing the potential use of the presented tools under dynamic conditions. This is the first study where both tracking and prediction of multiple compounds in large industrial sites has been done at this level of detail. The tool resulting from this study can serve as starting point for a variety of applications, for instance: holistic evaluation of retrofitting scenarios, advanced plant-wide control strategie and environmental assessment.