Computer model of the airflow and thermal phenomena inside a large dome

The dome-covered house is an example of designing buildings by learning from the optimized biological forms from the nature in order to reduce the energy use for heating in cold climates. This paper presents the three-dimensional thermal and airflow (3D-TAF) model that predicts the impact of such dome on the heating load of the protected house. The emphasis is on the airflow model, the formulation of the system of equations, the calculation procedure, and the comparison with a CFD model. A case study of a dome located in Montreal (Canada) is presented. A linear correlation model is developed that predicts the variation of the dimensionless air temperature inside the dome with the dimensionless height.     

The multi-chamber theory reconsidered from the viewpoint of air quality studies

A general multichamber model is presented and explored from the viewpoint of air quality studies. The model involves the following key concepts: purging flow rate and age distribution of both air and contaminants. From the physical and mathematical properties of the model, are deduced estimates of the magnitude of, and the relations between, the key concepts. The practical use of the model is illustrated.     

A neural network evaluation model for individual thermal comfort

An evaluation model for individual thermal comfort is presented based on the BP neural network. The train data came from a thermal comfort survey. The evaluation results of the model showed a good match with the subject's real thermal sensation, which indicated that the model can be used to evaluate individual thermal comfort rightly. Taken a room air conditioner as an example, the application of the NNEM in creating a microenvironment for individual was discussed. The result showed that the NNEM can play an important role of connecting individual thermal comfort with the control on the air conditioner.     

Development and application of an updated whole-building coupled thermal,airflow and contaminant transport simulation program (TRNSYS/CONTAM)

The TRNSYS energy analysis tool has been capable of simulating whole-building coupled heat transfer and building airflow for about 10 years. The most recent implementation was based on two TRNSYS modules, Type 56 and Type 97. Type 97 is based on a subset of the airflow calculation capabilities of the CONTAM multizone airflow and contaminant transport program developed by the National Institute of Standards and Technology. This paper describes the development of new CONTAM capabilities in support of an updated combined, multizone building heat transfer, airflow and contaminant transport simulation approach using TRNSYS. It presents an illustrative case that highlights the new coupling capability and also presents the application of this coupled simulation approach to a practical design problem of the energy use related to airflow through entry doors in non-residential buildings.     

On the effect of turbulent intensity towards the accuracy of the zero-equation turbulence model for indoor airflow application

The zero-equation turbulence model for indoor airflow applications proposed by Chen and Xu [4] has obtained immense popularity amongst the CFD practitioners in HVAC industry. A uniform turbulent intensity of 10% has been assumed in their model. In this paper, following the analogy of Chen and Xu [4] in deriving the coefficient of their zero-equation turbulence model (0.03874) which is indeed expressed as a function of turbulent intensity, the effect of turbulent intensity value assumed in the model towards the solution accuracy is investigated in this paper. Three indoor airflow cases, i.e. forced convection, natural convection and mixed convection problems are studied. It has been discovered that as the assumed uniform turbulent intensity T_i is reduced, the solution accuracy is significantly improved and the prediction comes closer to those of the two-equation standard k-? model, LES model as well as the experimental data.     

玉路机选型的属性测度模型与应用

结合路基施工中振动压路机选型的实践，以属性数学理论建立振动压路机选型综合评价的属性测度模型。实例研究表明，该模型评价结果合理，计算过程简便，并且还可用于振动压路机的工程适用性、经济性和可靠性的综合评价中。     

压路机选型的属性测度模型与应用

结合路基施工中振动压路机选型的实践,以属性数学理论建立振动压路机选型综合评价的属性测度模型。实例研究表明,该模型评价结果合理,计算过程简便,并且还可用于振动压路机的工程适用性、经济性和可靠性的综合评价中。     

谈自动控制在热网调度系统中的应用

对热网调度系统进行了简述,探讨了热网调度系统自动控制的实现策略,并从自动化信息传输、热网监控系统、换热站自动控制系统等方面,介绍了自动控制在热网调度系统中的实际应用,以期为供热系统现代化发展提供参考。     

Development and identification of an integrated waterworks model for trihalomethanes simulation

To evaluate the impact that new trihalomethanes (THMs) regulations will have on the performance of conventional waterworks in China, we developed an integrated waterworks model to simulate the dynamic behavior of THMs and other associated components, e.g. organic matter, ammonia, and residual chlorine, throughout the conventional water treatment process, which included pre-chlorination, coagulation-flocculation, sedimentation, filtration and post-chlorination. A comprehensive kinetic scheme that takes into account both the physical and biological mechanisms involved in the water treatment processes and the chemical reactions that result from chlorination was proposed for model conceptualization. In addition, the Petersen matrix was designed to present the model and formulate the mass balance equations for the model variables. The model was then identified using the Hornberger-Spear-Young (HSY) algorithm and tested against field data from the Qingzhou Waterworks in Macao, China. Despite gross uncertainty associated with the field data, the model could generally provide good predictions of the simulated variables and meet the management purposes. Furthermore, the identified model parameters agreed well with values that were reported in the literature and could be reasonably interpreted.     

Verification of a CFD model for indoor airflow and heat transfer

The SST k–ω based model is applied to calculate air-flow velocities and temperatures in a model office room. Calculations are compared with experiments and with the results of the standard k–ε, the RNG k–ε model and the laminar model. It is concluded that (a) all the three tested turbulent models predict satisfactorily the main qualitative features of the flow and the layered type of temperature fields and (b) computations with the SST k–ω based model show the best agreement with measurements. The use of this model is proposed combined with a suitable grid.     

A passive scalar sub-grid scale model and its application to airflow simulation around a building

The airflow around a building is in high Reynolds number flow regime. It can be calculated by large eddy simulation method (LES). The air temperature around buildings is passive scalar. If the behavior of passive scalars is considered with sub-grid scale (SGS) model for LES, the calculation or the results will be improved greatly but it has not been implemented, till now. In this paper a passive scalar SGS model (PS-SGS) was derived based on the hypotheses about the sheet-like structure in Taylor scale. The kinetic-energy SGS model was improved with the derived PS-SGS. The validity of the model was checked out using the experimental data in reference. The field around a supposed two-dimensional building was estimated with the improved kinetic-energy SGS model. Karman vortex-street and some special behavior for passive scalars were distinguished with the derived model.     

Feasibility of wireless measurements for semi-empirical multizone airflow model tuning

The feasibility of wireless measurements for rapid tuning of a multizone airflow model was extensively investigated using a small-scale residential building as a test site. The main objective of the research was to provide fundamental information, such as measurement time and cost for various measurement techniques, needed for selecting an appropriate field measurement strategy. Potential advantages of the wireless measurement approach were evaluated. These include: portability and flexibility, fast equipment setup, time synchronized data collection, negligible interruption to the occupants’ activity during the measurement, and installation time and cost savings. Currently, the high equipment cost of the wireless approach, relative to more conventional techniques, may offset the noted advantages and be the highest barrier to the wide use of wireless sensors in field measurements. Consequently, conventional hand-held measurements can be more economical, but the stability of the building HVAC system operating status should be considered before selecting the hand-held measurement approach. System stability and the ambient and internal building load status to which it is responding have significant impact on the model tuning usefulness of this approach     

水压致裂法测量地应力理论与应用

针对水压致裂测量地应力理论与工程研究现状,对水压致裂测量地应力理论、方法、技术以及特点进行了分析,并对水压致裂测量地应力的测量结果进行了论述。     

Air leakage in Catalan dwellings: Developing an airtightness model and leakage airflow predictions

In this study we estimate the air leakage distribution of single-family dwellings in Catalonia and use a statistical analysis of an airtightness database for single-family dwellings in France to identify the building characteristics that have the greatest influence on airtightness. The most significant variables are found to be the structure type, the floor area, the age of the building, the number of stories and the insulation type. A multiple linear regression technique is then applied to establish a predictive model for deriving an estimated value of airtightness from these characteristics. To estimate the infiltration airflow, a stochastic simulation of the building characteristics was performed per census tract using real data on the distributions of building variables taken from the census information. The model is then applied to determine the power law coefficient and the airtightness distribution. The predicted flow coefficients are combined with the AIM-2 model and given meteorological conditions to determine the infiltration airflow. Two sets of meteorological conditions are considered: average conditions and extreme conditions for each season.     

无线网络通信在热力站控制中的应用

以太原市热力公司东山分公司的供热区域为例,介绍了无线移动通信系统的定义及其优缺点,阐述了其在热力站控制中的实现过程,并分析了其在热力站远程控制中的实际意义及优缺点,从而实现节能降耗。     

管网压力控制模型的建模检验与应用

依据宏观模型建立管网压力控制曲线模型,模型经仿真检验其远端服务压力精度为±0.002 MPa,年运行能耗预测精度为±1.5%;泵群沿管网压力控制曲线模型运行,调节流量压力满足管网需求又无多余扬程,千吨水电耗降低7.62%;可在线优化分配流量及自动调节,使少数区域阀门减漏效应放大至整个管网以降低漏损量。     

给水管网水力模型的建立及应用

介绍了给水管网水力模型的建立、校核标准及思路,并以天津市滨海新区某新建园区内给水管网为对象,建立了水力模型,模拟管网在不同水力工况条件下的运行情况,对给水管网优化运行决策具有指导意义.     

供水管网漏损预测模型的应用比较

管网漏损现象普遍存在于我国城市供水管网中,在造成经济损失的同时,也对城市公共安全形成隐患。本文以我国城市供水管网平均漏损率为研究对象,建立了时间序列分析方法的二次指数平滑模型和三次指数平滑模型,并分别进行预测。通过精度分析和比较发现,二次指数平滑模型能更好地反映出平均漏损率的变化趋势。该模型可以为供水行业管理水平评价提供参考,具有重要的指导意义。     

气流运动及其与热舒适关系研究的进展与评述

指出气流组织的研究对空调节能和保证人体舒适感有着重要的意义,综述了气流运动与热舒适关系及房间气流紊流特征的研究进展,评价了已有的研究成果,对该研究的发展提出了看法。     

灰色理论模型在桥梁领域的应用研究

介绍了灰色模型的表达方式及建模过程,以廊坊市的二姑院大桥为工程背景,运用大型软件MATLAB对所得的监测数据进行了处理,并与实测数据作了对比,进一步证实了灰色理论的有效性。