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Showing records 101 to 125 of 330. [First] Page: 1 2 3 4 5 6 7 8 9 Last
Performance Investigation of a Two-Bed Type Adsorption Chiller with Various Adsorbents
Jung-Gil Lee, Kyung Jin Bae, Oh Kyung Kwon
March 27, 2023 (v1)
Keywords: adsorbent, adsorption chiller, coefficient of performance, cooling capacity, isotherm characteristics, low quality waste heat, metal organic frameworks, Renewable and Sustainable Energy, Simulation
In this study, the performance evaluation of an adsorption chiller (AD) system with three different adsorbents—silica-gel, aluminum fumarate, and FAM-Z01—was conducted to investigate the effects of adsorption isotherms and physical properties on the system’s performance. In addition, the performance evaluation of the AD system for a low inlet hot-water temperature of 60 °C was performed to estimate the performance of the system when operated by low quality waste heat or sustainable energy sources. For the simulation work, a two-bed type AD system is considered, and silica-gel, metal organic frameworks (MOFs), and ferro-aluminophosphate (FAPO, FAM-Z01) were employed as adsorbents. The simulation results were well matched with the laboratory-scale experimental results and the maximum coefficient of performance (COP) difference was 7%. The cooling capacity and COP of the AD system were investigated at different operating conditions to discuss the influences of the adsorbents on the system... [more]
Non-Isothermal Treatment of Oily Waters Using Ceramic Membrane: A Numerical Investigation
Hortência L. F. Magalhães, Gicelia Moreira, Ricardo S. Gomez, Túlio R. N. Porto, Balbina R. B. Correia, Anderson M. V. Silva, Severino R. Farias Neto, Antonio G. B. Lima
March 24, 2023 (v1)
Keywords: ceramic membrane, CFX, Simulation
Currently, the oil industry deals with the challenge of produced-water proper disposal, and the membrane-separation technology appears as an important tool on the treatment of these waters. In this sense, this work developed a mathematical model for simulating the oil/water separation by a ceramic membrane. The aim was to investigate the thermal aspects of the separation process via computational fluid dynamic, using the Ansys CFX® 15 software (15, Ansys, Inc., Canonsburg, PA, USA). Oil concentration, pressure, and velocity distributions, as well as permeation velocity, are presented and analyzed. It was verified that the mathematical model was capable of accurately representing the studied phenomena and that temperature strongly influences the flow behavior.
Optimal Design of a Stand-Alone Residential Hybrid Microgrid System for Enhancing Renewable Energy Deployment in Japan
Yuichiro Yoshida, Hooman Farzaneh
March 24, 2023 (v1)
This paper aims at the optimal designing of a stand-alone microgrid (PV/wind/battery/diesel) system, which can be utilized to meet the demand load requirements of a small residential area in Kasuga City, Fukuoka. The simulation part is developed to estimate the electrical power generated by each component, taking into account the variation of the weather parameters, such as wind, solar irradiation, and ambient temperature. The optimal system design is then based on the Particle Swarm Optimization (PSO) method to find the optimal configuration of the proposed system, using the least-cost perspective approach.
A Building Energy Management System Based on an Equivalent Electric Circuit Model
Giovanni Bianco, Stefano Bracco, Federico Delfino, Lorenzo Gambelli, Michela Robba, Mansueto Rossi
March 24, 2023 (v1)
Keywords: building energy management system, equivalent electric circuit, Optimization, Simulation
In recent decades, many EU and national regulations have been issued in order to increase the energy efficiency in different sectors and, consequently, to reduce environmental pollution. In the building sector, energy efficiency interventions are usually based on the use of innovative insulated materials and on the installation of cogeneration and tri-generation units, as well as solar technologies. New and retrofitted buildings are more and more commonly being called “smart buildings”, since they are characterized by the installation of electric and thermal power generation units, energy storage systems, and flexible loads; the presence of such technologies determines the necessity of installing Building Energy Management Systems (BEMSs), which are used to optimally manage their operation. The present paper proposes a BEMS for a smart building, equipped with plants based on renewables (photovoltaics, solar thermal panels, and geothermal heat pump), where the heating and cooling demand... [more]
Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load
Xuewei Pan, Yinghua Zhao, Diming Lou, Liang Fang
March 23, 2023 (v1)
Keywords: efficiency, experiment, gasoline engine, Miller cycle, Simulation
This contribution is focused on the fuel economy improvement of the Miller cycle under part-load characteristics on a supercharged DI (Direct Injection) gasoline engine. Firstly, based on the engine bench test, the effects with the Miller cycle application under 3000 rpm were studied. The results show that the Miller cycle has different extents of improvement on pumping loss, combustion and friction loss. For low, medium and high loads, the brake thermal efficiency of the baseline engine is increased by 2.8%, 2.5% and 2.6%, respectively. Besides, the baseline variable valve timing (VVT) is optimized by the test. Subsequently, the 1D CFD (Computational Fluid Dynamics) model of the Miller cycle engine after the test optimization at the working condition of 3000 rpm and BMEP (Brake Mean Effective Pressure) = 10 bar was established, and the influence of the combined change of intake and exhaust valve timing on Miller cycle was studied by simulation. The results show that as the effect of t... [more]
Analyzing the Validity of Brazilian Testing Using Digital Image Correlation and Numerical Simulation Techniques
He Zhang, Fatick Nath, Prathmesh Naik Parrikar, Mehdi Mokhtari
March 23, 2023 (v1)
Keywords: Brazilian test, Digital Image Correlation, MAPE, Simulation, Spider Berea sandstone, stress distribution
Characterizing the mechanical behavior of rocks plays a crucial role to optimize the fracturing process in unconventional reservoirs. However, due to the intrinsic anisotropy and heterogeneity in unconventional resources, fracture process prediction remains the most significant challenge for sustainable and economic hydrocarbon production. During the deformation tracking under compression, deploying conventional methods (strain gauge, extensometer, etc.) is insufficient to measure the deformation since the physical attachment of the device is restricted to the size of the sample, monitoring limited point-wise deformation, producing difficulties in data retrieval, and a tendency to lose track in failure points, etc. Where conventional methods are limited, the application of digital image correlation (DIC) provides detailed and additional information of strain evolution and fracture patterns under loading. DIC is an image-based optical method that records an object with a camera and moni... [more]
Techno-Economic and Environmental Evaluations of Decarbonized Fossil-Intensive Industrial Processes by Reactive Absorption & Adsorption CO2 Capture Systems
Ana-Maria Cormos, Simion Dragan, Letitia Petrescu, Vlad Sandu, Calin-Cristian Cormos
March 23, 2023 (v1)
Subject: Environment
Keywords: and process integration, decarbonization technologies, fossil-intensive industrial processes, Modelling, reactive absorption/adsorption CO2 capture systems, Simulation, techno-economic and environmental assessments
Decarbonization of energy-intensive systems (e.g., heat and power generation, iron, and steel production, petrochemical processes, cement production, etc.) is an important task for the development of a low carbon economy. In this respect, carbon capture technologies will play an important role in the decarbonization of fossil-based industrial processes. The most significant techno-economic and environmental performance indicators of various fossil-based industrial applications decarbonized by two reactive gas-liquid (chemical scrubbing) and gas-solid CO2 capture systems are calculated, compared, and discussed in the present work. As decarbonization technologies, the gas-liquid chemical absorption and more innovative calcium looping systems were employed. The integrated assessment uses various elements, e.g., conceptual design of decarbonized plants, computer-aided tools for process design and integration, evaluation of main plant performance indexes based on industrial and simulation r... [more]
A Cloud-Based In-Field Fleet Coordination System for Multiple Operations
Caicong Wu, Zhibo Chen, Dongxu Wang, Bingbing Song, Yajie Liang, Lili Yang, Dionysis D. Bochtis
March 22, 2023 (v1)
Keywords: agricultural machinery, auto-steering system, collaborative operating system, field experiment, fleet management, flow-shop, Simulation
In large-scale arable farming, multiple sequential operations involving multiple machines must be carried out simultaneously due to restrictions of short time windows. However, the coordination and planning of multiple sequential operations is a nontrivial task for farmers, since each operation may have its own set of operational features, e.g., operating width and turning radius. Taking the two sequential operations—hoeing cultivation and seeding—as an example, the seeder has double the width of the hoeing cultivator, and the seeder must remain idle while waiting for the hoeing cultivator to finish two rows before it can commence its seeding operation. A flow-shop working mode can coordinate multiple machines in multiple operations within a field when different operations have different implement widths. To this end, an auto-steering-based collaborative operating system for fleet management (FMCOS) was developed to realize an in-field flow-shop working mode, which is often adopted by... [more]
Simulation Study to Investigate the Effects of Operational Conditions on Methylcyclohexane Dehydrogenation for Hydrogen Production
Muhammad Haris Hamayun, Ibrahim M. Maafa, Murid Hussain, Rabya Aslam
March 22, 2023 (v1)
Keywords: Aspen HYSYS, dehydrogenation, Energy, LOHC, methylcyclohexane, Simulation
In the recent era, hydrogen has gained immense consideration as a clean-energy carrier. Its storage is, however, still the main hurdle in the implementation of a hydrogen-based clean economy. Liquid organic hydrogen carriers (LOHCs) are a potential option for hydrogen storage in ambient conditions, and can contribute to the clean-fuel concept in the future. In the present work, a parametric and simulation study was carried out for the storage and release of hydrogen for the methylcyclohexane toluene system. In particular, the methylcyclohexane dehydrogenation reaction is investigated over six potential catalysts for the temperature range of 300−450 °C and a pressure range of 1−3 bar to select the best catalyst under optimum operating conditions. Moreover, the effects of hydrogen addition in the feed mixture, and byproduct yield, are also studied as functions of operating conditions. The best catalyst selected for the process is 1 wt. % Pt/γ-Al2O3. The optimum operating conditions selec... [more]
Long-Term Temperature Evaluation of a Ground-Coupled Heat Pump System Subject to Groundwater Flow
Nehed Jaziri, Jasmin Raymond, Nicoló Giordano, John Molson
March 22, 2023 (v1)
Keywords: building, FEFLOW, geothermal, ground-coupled heat pump, groundwater, numerical modelling, Simulation
The performance of ground-coupled heat pump systems (GCHPs) operating under significant groundwater flow can be difficult to predict due to advective heat transfer in the subsurface. This is the case of the Carignan-Salières elementary school located on the south shore of the St. Lawrence River near Montréal, Canada. The building is heated and cooled with a GCHP system including 31 boreholes subject to varying groundwater flow conditions due to the proximity of an active quarry being irregularly dewatered. A study with the objective of predicting the borehole temperatures in order to anticipate potential operational problems was conducted, which provided an opportunity to evaluate the impact of groundwater flow. For this purpose, a numerical model was calibrated using a full-scale heat injection test and then run under different scenarios for a period of twenty years. The heat exchange capacity of the GCHP system is clearly enhanced by advection when the Darcy flux changes from 6 × 10−... [more]
Novel Adsorption Cycle for High-Efficiency Adsorption Heat Pumps and Chillers: Modeling and Simulation Results
Valentin Schwamberger, Aditya Desai, Ferdinand P. Schmidt
March 22, 2023 (v1)
Keywords: adsorption cycle, adsorption system, heat recovery, Modelling, Simulation, stratified thermal storage, thermodynamic cycle
A novel thermodynamic cycle for adsorption heat pumps and chillers is presented. It shows a significant improvement of the internal heat recovery between the adsorption and the desorption half cycle. A stratified thermal storage, which allows for a temperature-based extraction and insertion of storage fluid, is hydraulically coupled with a single adsorber. The benefit is an increased efficiency by reusing the released heat of adsorption for regeneration of the adsorber and by rendering possible low driving temperature differences. For investigating the second law of this cycle, a dynamic model is employed. The transient behavior of the system and the respective losses because of driving temperature differences at the heat exchangers and losses due to mixing within the storage and to the surroundings are depicted in this one-dimensional model. The model is suitable both for analyzing this advanced cycle as well as for comparisons with other cycles.
Parametrization of a Modified Friedman Kinetic Method to Assess Vine Wood Pyrolysis Using Thermogravimetric Analysis
Sergio Suárez, Jose Guillermo Rosas, Marta Elena Sánchez, Roberto López, Natalia Gómez, Jorge Cara-Jiménez
March 21, 2023 (v1)
Keywords: Biomass, Fraser–Suzuki function, isoconversional method, kinetic, Simulation, thermogravimetric analysis
Common kinetic parameters were obtained for leached and non-leached samples of vine wood biomass. Both samples were considered to have different proportions of cellulose, hemicellulose, and lignin compositions as a result of the leaching process. The two samples were analyzed in terms of pyrolysis kinetic parameters using non-isothermal thermogravimetric analysis. Furthermore, the classic Friedman isoconversional method, a deconvolution procedure using the Fraser−Suzuki function, and a modified Friedman method from a previous study on the delay in conversion degree were satisfactorily applied. The observed difference when the deconvolution technique was applied suggests that the classic Friedman method is not adequate for studying the pyrolysis of individual vine wood biomass components. However, this issue was solved by studying the delay in conversion degree of both biomasses and calculating the kinetic parameters using the resulting information. This procedure was found to be useful... [more]
A Review of Gerotor Technology in Hydraulic Machines
Pedro Javier Gamez-Montero, Esteve Codina, Robert Castilla
March 21, 2023 (v1)
Keywords: design, flow, gerotor, leakage, motor, pump, review, Simulation, stress, trochoidal
Over the years, numerous investigations have established the gerotor fundamentals. This work aims to provide a complete review of the literature from the last decade, focusing on the articles published in the past five years on gerotor technology in hydraulic machines. The report gives a catalogue of guidelines based on the trochoidal-envelope definition, a background analysis, the worldwide distribution of articles in each continent and country and the most frequently used keywords in the field. The paper identifies state-of-the-art research, and reports on current mainstream ideas. From the historical background, this literature review reports the current approaches in gerotor pumps (geometry and performance approaches, modeling and numerical simulations), orbital motors and new concepts. The report will serve as a guide and a directory for novel engineers working with gerotor technology in hydraulic machines. Another intention of this paper is to disseminate the works of the researc... [more]
Numerical Investigation of the Aeroelastic Behavior of a Wind Turbine with Iced Blades
Sudhakar Gantasala, Narges Tabatabaei, Michel Cervantes, Jan-Olov Aidanpää
March 21, 2023 (v1)
Keywords: aeroelastic behavior, Computational Fluid Dynamics, icing, Simulation, wind turbine
Wind turbines installed in cold-climate regions are prone to the risks of ice accumulation which affects their aeroelastic behavior. The studies carried out on this topic so far considered icing in a few sections of the blade, mostly located in the outer part of the blade, and their influence on the loads and power production of the turbine are only analyzed. The knowledge about the influence of icing in different locations of the blade and asymmetrical icing of the blades on loads, power, and vibration behavior of the turbine is still not matured. To improve this knowledge, multiple simulation cases are needed to run with different ice accumulations on the blade considering structural and aerodynamic property changes due to ice. Such simulations can be easily run by automating the ice shape creation on aerofoil sections and two-dimensional (2-D) Computational Fluid Dynamics (CFD) analysis of those sections. The current work proposes such methodology and it is illustrated on the Nation... [more]
A Fault Diagnosis Method of the Shearer Hydraulic Heightening System Based on a Rough Set and RBF Neural Network
Min Liu, Zhiqi Liu, Jinyuan Cui, Yigang Kong
March 20, 2023 (v1)
Keywords: accuracy, fault diagnosis, hydraulic heightening system, RS-RBFNN, Simulation
The hydraulic heightening system is the core component of the shearer, and its stable operation directly affects the safety and reliability of the equipment, so it is of great significance to realize an efficient and accurate fault diagnosis. This paper proposes a fault diagnosis method combining a rough set and radial basis function neural network (RS-RBFNN). Firstly, the RS is used to discretize the original fault data set and attribute reduction, remove the redundant information, and mine the implicit knowledge and potential rules. Then, the topology structure of the RBFNN is determined. The mapping relationship is established between the fault symptom and category. The fault diagnosis is carried out with Python language. Finally, the method is compared with two diagnostic methods including a back propagation neural network (BPNN) and RBFNN. The research results show that the RS-RBFNN has the highest fault diagnosis accuracy, with an average of 98.68%, which verifies the effectivene... [more]
A Novel Data-Driven Tool Based on Non-Linear Optimization for Offshore Wind Farm Siting
Marina Polykarpou, Flora Karathanasi, Takvor Soukissian, Vasiliki Loukaidi, Ioannis Kyriakides
March 17, 2023 (v1)
Keywords: Aegean Sea, floating installations, K-means clustering, sequential Monte Carlo method, Simulation, site selection
One preliminary key step for developing an offshore wind farm is identifying favorable sites. The process of sitting involves multiple requirements and constraints, and therefore, its feasible implementation requires either approximating assumptions or an optimization method that is capable of handling non-linear relationships and heterogeneous factors. A new optimization method is proposed to address this problem that efficiently and accurately combines essential technical criteria, such as wind speed, water depth, and distance from shore, to identify favorable areas for offshore wind farm development through a user-friendly data-driven tool. Appropriate ranks and weighting factors are carefully selected to obtain realistic results. The proposed methodology is applied in the central Aegean Sea, which has a high offshore wind energy potential. The application of the proposed optimization method reveals large areas suitable for developing floating wind energy structures. The algorithm m... [more]
Methodology Presentation for the Configuration Optimization of Hybrid Electrical Energy Systems
Dubravko Žigman, Tomislav Tomiša, Krešimir Osman
March 17, 2023 (v1)
Keywords: electrical hybrid system, hybrid power system configuration, methodology, microgrid, Optimization, Simulation
The paper presents the methodology that should be used to optimize hybrid power system configurations, i.e., the chosen microgrid scenario. The methodology was developed with the aim of evaluating the different production capacities of a system and comparing them with alternative connections to the main grid. It has a step-by-step structure and includes part of the steps performed by simulations in a computer program. It provides us with not only a basic but also a representative idea of an actual microgrid configuration, which is further used as support in the system’s design. An algorithm has been developed to check the energy flows and correct the selling price. The program HOMER Pro is used as the program support in performing the hybrid optimization simulation. In the analysis, it was found that the maximum share of generation from renewable energy sources in relation to the power grid is 143%, while the share of renewable energy sources in the generated energy is 65.3%. Greenhous... [more]
A Simulation Environment for Training a Reinforcement Learning Agent Trading a Battery Storage
Harri Aaltonen, Seppo Sierla, Rakshith Subramanya, Valeriy Vyatkin
March 10, 2023 (v1)
Subject: Environment
Keywords: Artificial Intelligence, battery, electricity market, frequency containment reserve, frequency reserve, real-time, reinforcement learning, Simulation, timescale
Battery storages are an essential element of the emerging smart grid. Compared to other distributed intelligent energy resources, batteries have the advantage of being able to rapidly react to events such as renewable generation fluctuations or grid disturbances. There is a lack of research on ways to profitably exploit this ability. Any solution needs to consider rapid electrical phenomena as well as the much slower dynamics of relevant electricity markets. Reinforcement learning is a branch of artificial intelligence that has shown promise in optimizing complex problems involving uncertainty. This article applies reinforcement learning to the problem of trading batteries. The problem involves two timescales, both of which are important for profitability. Firstly, trading the battery capacity must occur on the timescale of the chosen electricity markets. Secondly, the real-time operation of the battery must ensure that no financial penalties are incurred from failing to meet the techn... [more]
Simulation Modeling of a Photovoltaic-Green Roof System for Energy Cost Reduction of a Building: Texas Case Study
Sojung Kim, Burchan Aydin, Sumin Kim
March 9, 2023 (v1)
Keywords: condensate water, green roof, photovoltaic, Renewable and Sustainable Energy, Simulation, urban agriculture
This study aims at introducing a modeling and simulation approach for a green roof system which can reduce energy cost of a building exposed to high temperatures throughout the summer season. First, to understand thermal impact of a green roof system on a building surface, a field-based study has been conducted in Commerce, Texas, U.S., where the average maximum temperature in summer is 104 °F (40 °C). Two types of analyses were conducted: (1) comparison of temperature between different plant type via Analysis of variance (ANOVA) and (2) polynomial regression analysis to develop thermal impact estimation model based on air temperature and presence of a green roof. In addition, an agent-based simulation (ABS) model was developed via AnyLogic® University 8.6.0 simulation software, Chicago, IL, U.S., in order to accurately estimate energy cost and benefits of a building with a photovoltaic-green roof system. The proposed approach was applied to estimate energy reduction cost of the Keith... [more]
Improving the Energy Efficiency of Buildings Based on Fluid Dynamics Models: A Critical Review
Xiaoshu Lü, Tao Lu, Tong Yang, Heidi Salonen, Zhenxue Dai, Peter Droege, Hongbing Chen
March 9, 2023 (v1)
Subject: Environment
Keywords: buildings, Energy Efficiency, fluid dynamics models, indoor environment, Simulation, ventilation
The built environment is the global sector with the greatest energy use and greenhouse gas emissions. As a result, building energy savings can make a major contribution to tackling the current energy and climate change crises. Fluid dynamics models have long supported the understanding and optimization of building energy systems and have been responsible for many important technological breakthroughs. As Covid-19 is continuing to spread around the world, fluid dynamics models are proving to be more essential than ever for exploring airborne transmission of the coronavirus indoors in order to develop energy-efficient and healthy ventilation actions against Covid-19 risks. The purpose of this paper is to review the most important and influential fluid dynamics models that have contributed to improving building energy efficiency. A detailed, yet understandable description of each model’s background, physical setup, and equations is provided. The main ingredients, theoretical interpretatio... [more]
Effects of Water Injection Strategies on Oxy-Fuel Combustion Characteristics of a Dual-Injection Spark Ignition Engine
Xiang Li, Yiqiang Pei, Dayou Li, Tahmina Ajmal, Khaqan-Jim Rana, Abdel Aitouche, Raouf Mobasheri, Zhijun Peng
March 9, 2023 (v1)
Keywords: dual-injection spark ignition (SI) engine, oxy-fuel combustion (OFC), Simulation, water injection (WI) strategies
Currently, global warming has been a serious issue, which is closely related to anthropogenic emission of Greenhouse Gas (GHG) in the atmosphere, particularly Carbon Dioxide (CO2). To help achieve carbon neutrality by decreasing CO2 emissions, Oxy-Fuel Combustion (OFC) technology is becoming a hot topic in recent years. However, few findings have been reported about the implementation of OFC in dual-injection Spark Ignition (SI) engines. This work numerically explores the effects of Water Injection (WI) strategies on OFC characteristics in a practical dual-injection engine, including GDI (only using GDI), P50-G50 (50% PFI and 50% GDI) and PFI (only using PFI). The findings will help build a conceptual and theoretical foundation for the implementation of OFC technology in dual-injection SI engines, as well as exploring a solution to increase engine efficiency. The results show that compared to Conventional Air Combustion (CAC), there is a significant increase in BSFC under OFC. Ignition... [more]
Influence of Fuel Type and Water Content Variation on Pollutant Emission Characteristics of a Biomass Circulating Fluidized Bed Boiler
Jianjie He, Shanjian Liu, Di Yao, Ranran Kong, Yaya Liu
March 9, 2023 (v1)
Subject: Environment
Keywords: Biomass, circulating fluidized bed, fuel type, pollutant emission, Simulation, water content
In general, the biomass raw materials burned by biomass power plants generally have the characteristics of variable fuel types, high moisture content, and high volatile content. In this paper, a 130 t/h biomass circulating fluidized bed (BCFB) model was established on the MWorks platform with Modelica language. The influence of biomass type changes on operation parameters, the corresponding steady-state characteristics, and the dynamic characteristics of the BCFB were carried out. The temperature corresponding to the combustion of pine was overall higher than that of the other fuels, and the flue gas from the combustion of pine had the highest concentration of SO2, up to 520.49 mg/Nm3. The flue gas from the combustion of pure cotton sticks had the highest concentration of NO, up to 254.34 mg/Nm3. The changes of fuel type and moisture content all have a great influence on the operation of BCFBs. The emission of pollutants was not only related to the element content of fuel, but also clo... [more]
Linearization of Thermal Equivalent Temperature Calculation for Fast Thermal Comfort Prediction
Christian Rommelfanger, Louis Fischer, Jérôme Frisch, Christoph Van Treeck
March 9, 2023 (v1)
Keywords: heat transfer, numerical fluid simulation, Simulation, thermal comfort
Virtual simulations and calculations are a key technology for future development methods. A variety of tools and methods for calculating thermal comfort have not gained sufficient acceptance in practice due to their inherent complexity. This article investigates alternative means of determining thermal comfort, namely, the linearization of the equivalent temperature calculation. This enables a wide range of users to evaluate thermal comfort in a fast and easy manner, for example, for energy efficiency simulation. A flow and thermal model were created according to the requirements of DIN EN ISO 14505 to determine heat transfer coefficients under calibration conditions. The model to simulate the equivalent temperature in calibration conditions comprises a geometrically realistic 3D model of a human test person according to the standard. The influence of the turbulence model, as well as the influence of the equivalent temperature on the heat transfer coefficient in calibration conditions,... [more]
Modelling to Lower Energy Consumption in a Large WWTP in China While Optimising Nitrogen Removal
Mónica Vergara-Araya, Verena Hilgenfeldt, Di Peng, Heidrun Steinmetz, Jürgen Wiese
March 9, 2023 (v1)
Keywords: Energy Efficiency, Modelling, nitrogen removal, optimisation, Simulation, wastewater treatment
In the last decade, China has sharply tightened the monitoring values for wastewater treatment plants (WWTPs). In some regions with sensitive discharge water bodies, the values (24 h composite sample) must be 1.5 mg/L for NH4-N and 10 mg/L for total nitrogen since 2021. Even with the previously less strict monitoring values, around 50% of the wastewater treatment plants in China were permanently unable to comply with the nitrogen monitoring values. Due to the rapid changes on-site to meet the threshold values and the strong relation to energy-intensive aeration strategies to sufficiently remove nitrogen, WWTPs do not always work energy-efficiently. A Chinese WWTP (450,000 Population equivalents or PE) with upstream denitrification, a tertiary treatment stage for phosphorus removal and disinfection, and aerobic sludge stabilisation was modelled in order to test various concepts for operation optimisation to lower energy consumption while meeting and undercutting effluent requirements. F... [more]
Simulation Study on Active Air Flow Distribution Characteristics of Closed Heat Pump Drying System with Waste Heat Recovery
Hai-Bo Zhao, Kun Wu, Jing-Feng Zhang
March 9, 2023 (v1)
Keywords: flow distribution, flow field, heat pump drying, Simulation
A tridimensional turbulent flow model is established for a closed heat pump drying system with waste heat recovery to improve the drying air flow characteristics and reduce the energy consumption of air circulation. The active flow distribution mode is introduced to guide air flowing in the system’s drying cabinet, top air duct, mixing zone, and heat pump. It is found that the wind velocity in the cabinet’s supply channel is greater than that in the return channel, the velocity distribution in the top duct is uneven, and the outlet velocity of the bypass fan is high and a vortex forms. A partition panel added in the top duct and modulating fans in the drying cabinet are proposed to solve these problems. The simulation results show that removing the circulating fan, changing the volume flow of the bypass fan, adopting the alternative operation mode of the bypass fans, reducing the air volume flow of the supply fan, and reducing the total pressure of the fans can improve the dry air velo... [more]
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