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Predicting moisture condensation risk on the radiant cooling floor of an office using integration of a genetic algorithm-back-propagation neural network with sensitivity analysis

Energy and Built Environment

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Energy and Built Environment 2024年第1期5卷 110-129页

作者： Meng Su Jiying Liu Moon Keun Kim Xiaozhou Wu School of Thermal Engineering Shandong Jianzhu UniversityJinan 250101China Department of Civil Engineering and Energy Technology Oslo Metropolitan UniversityOslo N-0130Norway School of Civil Engineering Dalian University of TechnologyDalianChina

Pre-dehumidification time(τ_(pre))and pre-dehumidification energy consumption(E_(pre))play important roles in preventing the condensation of moisture on the floors of rooms that use a radiant floor cooling(RFC)system.However,there are few theoretical or experimental studies that focus on these two important quantities.In this study,an artificial neural network(ANN)was used to predict condensation risk for the integration of RFC systems with mixed ventilation(MV),stratum ventilation(SV),and displacement ventilation(DV)systems.A genetic algorithm-back-propagation(GA-BP)neural network model was established to predict τ_(pre) and E_(pre).Both training data and validation data were obtained from tests in a computational fluid dynamics(CFD)simulation.The results show that the established GA-BP model can predict τ_(pre) and E_(pre) well.The coefficient of determination(R^(2))of τ_(pre) and of E_(pre) were,respectively,0.973 and 0.956.For an RFC system integrated with an MV,SV,or DV system,the lowest values of τ_(pre) and E_(pre) were with the DV system,23.1 s and 0.237 kWh,respectively,for a 67.5 m^(3) room.Therefore,the best pre-dehumidification effect was with integration of the DV and RFC systems.This study showed that an ANN-based method can be used for predictive control for condensation prevention in RFC systems.It also provides a novel and effective method by which to assess the pre-dehumidification control of radiant floor surfaces.

关键词： Condensation prevention Radiant floor cooling ventilation system genetic algorithm BP neural network

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Monitoring and evaluation of building ventilation system fans operation using performance curves

能源与人工环境(英文)

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能源与人工环境(英文) 2020年第3期1卷 307-318页

作者： Mahendra Singh Muhyiddine Jradi Hamid Reza Shaker Center for Energy Informatics University of Southern DenmarkCampusvej 555230Denmark

ventilation fans are an important component of any mechanically ventilated building.Poor fan performance could significantly affect the whole building performance metrics.There are several issues such as dirty blades,mechanical wear,aging of fans could impact the fan’s performance.In present work,a novel,indirect and data-driven methodology is introduced to monitor the ventilation fan unit performance.The proposed method is able to perform continuous monitoring of ventilation fan unit in real-time.The real-time performance of 3 Air handling unit(AHU)fans is examined in an academic building.Expected fan performance is modeled with the help of manufacturer data and compared against the real-time performance.Two data-driven models are developed and implemented.The first model is used to compute expected total fan pressure at a given airflow rate while second is a Support Vector Regression(SVR)model,to predict the fan efficiency.The performance monitoring of the ventilation fan unit is determined in terms of expected and actual fan energy consumption.Findings indicated a significant performance gap in three ventilation fan unit in a case building known as OU44,located in city Odense,Denmark.The advantage of this method comprises simplicity,no direct human intervention and scalability to the series of ventilation units.

关键词： Buildings ventilation system Fan unit Performance curve Modeling Fan efficiency Energy consumption HVAC Performance testing Support vector regression(SVR) Polynomial regression

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Simulation study of the purification system for indoor oil mist control in machining factories

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建筑模拟(英文) 2023年第8期16卷 1361-1374页

作者： Yukun Wang Yu Guo Wenjia Hao Wei Liu Zhengwei Long Tianjin Key Laboratory of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityWeijin Road 92Tianjin 300072China Division of Sustainable Buildings Department of Civil and ArchitecturalEngineeringKTH Royal Institute of TechnologyBrinellvägen 23Stockholm10044Sweden

High-concentration oil mists can cause serious health problems to workers,which are generally mitigated by ventilation and purification systems.However,the coupling relationship between these systems is not clear.In this study,the effects of purifier outlet direction,purification air volume,installation height,and purification efficiency on indoor oil mist distribution were investigated by numerical simulation using an actual machining factory.The mitigation of oil mist in various combinations of ventilation and purification systems was also discussed.The results show that the outlet direction of the purifier has a great influence on the distribution of oil mist in the factory,and the maximum difference of oil mist concentration in the breathing zone under different orientations is 17%.The best purifier outlet direction is vertically upward.When the purifier outlet direction is upward,a larger purification air volume is beneficial for contaminant removal,and a lower purifier exhaust installation height is helpful for oil mist discharge from the bottom of the factory and reducing the concentration of oil mist in the breathing area.The oil mist concentration of purifier exhaust increases from 0 to 2 mg/m^(3) and the oil mist concentration in the breathing zone increases by 67%.The combined system of purification system with the roof exhaust system and displacement ventilation system has the optimal pollution removal efficiency and the lowest concentration of oil mist in the breathing zone compared to other systems.The research results can provide a reference for the design,installation,and operation of ventilation and purification systems in machining factories.

关键词： oil particulate matter purification system ventilation system indoor air quality CFD

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Assessment Index Structure of Mine ventilation system and Application

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International Journal of Mining Science and Technology 2005年第2期15卷 135-140页

作者： CHENG Lei, YANG Yun-liang, Xiong Ya-xuan Department of Resources and Materials Engineering, Henan Polytechnic University, Jiaozuo,Henan 454003 China Department of Resources and Materials Engineering Henan Polytechnic University JiaozuoHenan 454003 China

Based on the basic content of advanced technology,safety and reliability, and economic reasonability and the definition of mine ventilation system, 16 assessment indexes of ventilation system are put forward from the point of 8 aspects such as mine ventilation power, ventilation network, ventilation equipments, ventilation quality, ventilation monitoring, capacity of preventing and fighting disaster, ventilation consumption of power, and the capacity of ventila- tion system. A new assessment index system is put forward and has a good effect after being applied in coal mines.

关键词： ventilation system assessment index system safety and reliability economic reasonability

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Dust pollution during shotcrete process in high-altitude tunnel based on numerical simulation

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Particuology 2023年第4期75卷 82-95页

作者： Cong Li Zhongan Jiang Guoliang Zhang Xue Feng Fabin Zeng College of Civil and Resource Engineering University of Science and Technology BeijingBeijing100083China NHC Key Laboratory for Engineering Control of Dust Hazard University of Science and Technology BeijingBeijing100083China

The surrounding rock needs shotcrete support after drilling and blasting excavation in the tunnel;the high concentration of dust generated in the process will endanger workers'occupational health.Therefore,to ensure the cleanness and safety of the tunnel construction process,a full-scale model of the tunnel was established based on field data of a high-altitude tunnel of the Sichuan-Tibet railway.The dust production mechanism is summarized by combing the whole process of shotcrete.The Computa-tional Fluid Dynamics(CFD)method was used to study the diffusion and transport of dust under different conditions.The grey relational analysis was applied to investigate the correlation values of the influ-encing factors on dust diffusion in the shotcrete operation area.The results show that the dust gener-ation mechanism of shotcrete includes the sudden change of particle velocity in the jet area leading to escape and particle impact dust generation,where fine dust is easily dispersed in the tunnel.During continuous dust production,the dust concentration is higher near the wet spraying machine and on the backflow side of the working face.Increasing the air supply volume and shortening the distance between the air duct and the working face is conducive to diluting the dust concentration in the tunnel.In the high-altitude environment,the dust concentration in the tunnel decreases,the diffusion distance be-comes smaller,the settlement proportion of dust particles increases,and the risk of secondary pollution increases.The simulation results and the field measurement data are consistent,which can provide theoretical support for the construction site dust control.

关键词： High-altitude tunnel Shotcrete Dust diffusion Numerical simulation ventilation system

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Localization and characterization of intermittent pollutant source in buildings with ventilation systems:Development and validation of an inverse model

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Building Simulation 2021年第3期14卷 841-855页

作者： Lingjie Zeng Jun Gao Lipeng Lv Bowen Du Yalei Zhang Ruiyan Zhang Wei Ye Xu Zhang College of Environmental Science and Engineering Tongji UniversityShanghai200092China School of Mechanical Engineering Tongji UniversityShanghai 200092China Department of Civil and Mineral Engineering University of TorontoTorontoCanada

Terrorist attacks through building ventilation systems are becoming an increasing concern.In case pollutants are intentionally released in a building with mechanical ventilation systems,it is critical to localize the source and characterize its releasing curve.Previous inverse modeling studies have adopted the adjoint probability method to identify the source location and used the Tikhonov regularization method to determine the source releasing profile,but the selection of the prediction model and determination of the regularization parameter remain challenging.These limitations can affect the identification accuracy and prolong the computational time required.To address the difficulties in solving the inverse problems,this work proposed a Markov-chain-oriented inverse approach to identify the temporal release rate and location of a pollutant source in buildings with ventilation systems and validated it in an experimental chamber.In the modified Markov chain,the source term was discrete by each time step,and the pollutant distribution was directly calculated with no iterations.The forward Markov chain was reversed to characterize the intermittently releasing profile by introducing the Tikhonov regularization method,while the regularized parameter was determined by an automatic iterative discrepancy method.The source location was further estimated by adopting the Bayes inference.With chamber experiments,the effectiveness of the proposed inverse model was validated,and the impact of the sensor performance,quantity and placement,as well as pollutant releasing curves on the identification accuracy of the source intensity was explicitly discussed.Results showed that the inverse model can identify the intermittent releasing rate efficiently and promptly,and the identification error for pollutant releasing curves with complex waveforms is about 20%.

关键词： intermittent source inverse identification Markov chain regularization parameter ventilation system

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Applying multi-criteria analysis to select the most appropriate broiler rearing environment

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Information Processing in Agriculture 2021年第2期8卷 205-218页

作者： Karla A.O.Lima Irenilza A.Nääs Daniella J.Moura Rodrigo G.Garcia Angélica S.Mendes College of Agricultural Engineering The State University of CampinasAve.Cândido Rondon501Barão Geraldo13083-875 CampinasSPBrazil College of Agrarian Sciences The Federal University of Grande DouradosRod Dourados-Itahumkm 1279804-970 DouradosMSBrazil College of Animal Sciences The Technological Federal University of ParanáRod Boa Esperançakm 0485660-000 Dois VizinhosPRBrazil

The present study aimed to assess the most appropriate rearing system for broiler housing in tropical regions using the Analytical Hierarchy Process(AHP).The research was done using data sampling from a field study carried out in eight mechanically-ventilated commercial broiler houses.Four had positive ventilation(open-sided conventional system),and the other four had negative pressure systems,which were named according to the curtains color and light management(blue-house with blue curtains,and dark-house with black side curtains).The data from the field research(rearing dry-bulb temperature and relative humidity;ammonia and carbon dioxide concentrations;energy use;litter type and quality;and broiler performance)were organized,and the multi-criteria analysis AHP was applied.In the process,the decision-maker must define the problem and chose the criteria to evaluate the alternatives to make a suitable decision.The alternative selected needs to be according to the stakeholders’expectations.The alternatives consisted of houses using three ventilation systems(conventional,blue-house,and dark-house).The different chosen criteria were the thermal and aerial environment,broiler productivity,energy consumption,and litter quality.We selected data collected from the field experiment and from current literature to subsidize the selection of the criteria.The computation was done using field data results,knowledge from existing literature,and the expertise of three specialists.For the first time,the AHP technique is applied to select the most suitable broiler housing,considering the complex variables involved in the process.Results indicated the conventional system as the most appropriate alternative.Results of the conventional system showed the highest scores on most criteria in the pairwise comparison.Which considered broiler performance,gasses concentration,and electricity cost,providing natural ventilation open-sided conventional house as the most appropriate rearing system for broiler production in tropical countries.

关键词： AHP Energy use Litter Noxious gasses Poultry production ventilation system

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