隔断式工位空调系统气流组织与人体热舒适评价

采用K-ε湍流模型对采用隔断式工位空调的典型办公室工作微环境进行数值模拟,分析工位空调在人体周围所形成的非均一环境参数场,并进一步研究非均匀环境对人体热舒适的影响.在不同工位送风参数下对房间和人体周围环境参数的分布状况及吹风感和热舒适性进行研究.模拟结果发现:工位空调送风可以使室内温度呈现分区分布,工位送风效率高,可以...     

纤维风管送风系统对室内气溶胶分布影响研究

为了研究办公场所纤维风管系统送风时的气溶胶分布情况，采用Fluent软件，针对风机盘管送风系统和纤维风管送风系统在不同的运行工况下，对办公场所室内速度场和气溶胶浓度分布情况进行数值模拟，并进行实验验证。通过分析速度场和气溶胶浓度场的分布特点，比较得出纤维风管送风系统下气溶胶分布效果优于风机盘管送风系统，且送风速度的增加能有效降低气溶胶质量浓度。采用纤维风管送风系统时，在一定范围内增加送风量可降低室内气溶胶质量浓度，进而可改善室内空气品质。结果表明，相比于风机盘管送风系统，将纤维风管送风系统应用在办公场所具有“独特”的优势。     

多孔射流相互作用特性及对空调送风的影响

多孔射流相互作用特性及对空调送风的影响一直是国内外流体力学界和工程技术界关注的问题。本文以FLUENT软件为计算平台,研究二维平面射流及三维空调房间内通风空调气流的流动。采用k-ε两方程湍流模型及SIMPLE算法对二维平面射流和三维空调房间内的非等温浮力射流进行数值模拟。通过对速度场和温度场详细的对比分析,为空调室内的气流组织的优化设计及舒适性提供了研究依据。     

用于热泵采暖的强制对流散热器多参数耦合优化

为了提升热泵采暖系统的运行能效,提出一种强制对流散热器作为热泵的室内末端。以某典型办公室为例,在实测研究的基础上,采用CFD模拟该散热器营造的室内热环境状况,并在考虑热舒适性约束的前提下,以最大化节能潜力为优化目标,对强制送风速度和散热器表面温度进行同步优化。研究发现,送风速度和表面温度对室内热环境的影响具有耦合性。为避免人体吹风感,可在散热器出风口处安装导流罩。优化获得的送风速度为1.2～1.9 m/s,对应的散热器表面温度为41～45℃,表明该技术可带来较为显著的节能效益。     

空调房间送风射流与回风气流相互作用的数值模拟

以工程中广泛采用的k-ε二方程湍流模型为基础,运用计算流体力学的有限容积法对空调房间送风射流与回风气流相互作用对室内气流组织的影响进行数值模拟,给出不同的送风形式在不同场所的适用性及特点,为室内气流组织的设计与研究提供一定的理论依据。     

空调房间气流组织的数值模拟研究

利用Fluent软件,从室内的速度场、温度场及室内CO_2浓度场分布出发,模拟研究了某一空调房间内置换通风和侧送风两种空调方式的差异性。结果表明:置换通风方式在提高人体热舒适性、改善工作区空气品质及节能等方面要优于侧送风方式。     

环形进出口旋流燃烧室内有回流的湍流旋流流动的数值模拟

对环形进出口旋流燃烧室内有较强回流的湍流旋流流动进行了数值模拟。计算中分别采用了完整形式与简化形式的新的代数Reynolds应力模型及κ－ε模型。模拟结果与实验测量数据在气体轴向与切向时均速度和轴向、切向与径向湍流脉动速度均方根值分布上的对比表明，新的代数应力模型可预报出旋流燃烧室内范围较大的中心回流区，气体切向速度分布的Rankine涡结构，以及湍流脉动的各向异性。     

SPF级实验动物房空气幕送风气流组织研究

为了研究SPF级实验动物房空气幕送风的气流组织,建立数值模型,模拟实验动物房内部的空气流动情况。研究送风换气次数对室内气流组织的影响,并对空气幕送风和方形送风形式进行对比分析。结果显示：相同换气次数下,空气幕送风的室内温度比方形送风的室内温度低,空气幕送风能够更有效地控制污染物。     

琅琊山水电站发电机层气流组织试验研究

以琅琊山水电站为例,对发电机层顶拱送风方式进行了热态相似模型试验,采用相似理论与热量阿基米德相似准则数,构建试验模型相似比例尺,探讨了同一风量下不同风口个数、送风温度、送风方式及排风方式对发电机层工作区速度场与温度场的影响程度.结果表明,在空调送风、机械排风时发电机层工作区气流组织均匀,风速满足要求,能有效消除工作区热负荷.     

上海某游乐项目剧院的暖通设计技术

在剧院的暖通设计中,采用了FLUENT流体力学分析软件对剧场内的空气速度场、温度场分布进行模拟,预测出不同空调方案的气流组织的效果并对设计提出优化建议。通过对舞台特效排烟及补风系统气流组织模拟及调整,确定了最经济排烟换气次数及送排风口位置;并对观众厅座椅送风进行了空气速度场、温度场分布进行模拟,优化分析出座椅送风最经济舒适性的运行条件。考虑到剧场观众厅池座和楼座的温度分层现象,采用了多区域空调箱送风方式,实现了根据负荷需求供给不同温湿度条件下送风的优化运行策略控制。\本工程采用了BIM(Building Information Modeling)技术,对管线碰撞进行检测,并对机电管线进行优化调整,最终实现了目标吊顶净空内的管线排布。     

置换通风与混合通风室内舒适性对比研究

针对一个典型办公室,建立了置换通风系统和混合通风系统的物理模型及数学模型.利用AirPak软件对室内温度场、速度场进行了模拟计算,对比分析了置换通风和混合通风两种通风方式的舒适性.     

基于CFD技术的太阳能污泥干燥室内热湿环境研究

基于传热传质理论,建立一种太阳能污泥干燥室内热湿耦合传递的数学模型。综合考虑空气流动以及对流和辐射传热,利用CFD软件Fluent的k~ε湍流模型、组分输运模型及辐射模型,初步分析了在太阳辐射条件下不同干燥室结构、排风形式以及通风量对太阳能污泥干燥室内干燥区域的温度、相对湿度以及速度分布的影响。模拟结果表明:干燥室内温、湿度模拟值与实测值吻合较好,平均相对误差分别为3.55%和5.39%。对比分析不同结构下干燥室内的流场分布,两出口排风形式的太阳能污泥干燥室可以形成良好的干燥微环境。当两出口排风风速≥5 m/s时,室内干燥区域温度高于室外环境温度,同时相对湿度低于室外环境相对湿度,且增大出流风速,在干燥区域内空气扰流强度增强,有利于干燥室内污泥水分的蒸发。     

Correlation of spherical thermistor for the measurement of low velocity air flow

A spherical thermistor, an accurate temperature sensor, is employed as an air velocity sensor in this work. The measuring principle is derived and the effects of the insulation layer, air temperature, natural convection and thermal radiation are discussed. Two different correlation relations for velocity measurements are proposed based on theoretical analyses and experimental calibrations. Experiments have shown that spherical thermistor is a good velocity sensor for speed between 0.1–2.5 m/s at room temperature and the insulation layer hardly influences the accuracy of the thermistor used in the present work. Modification on correlation can even further improve measurement accuracy. Since the thermistor is small and cheap, it is possible to apply this method to multi-point velocity measurement with a low disturbance to the flow field.     

Combined heat transfer of radiation and natural convection in a square cavity containing participating gases

This article deals with analyzing the effect of radiative heat transfer on natural convection heat transfer in a square cavity under normal room conditions. The governing equations of natural convection and radiative transfer are solved simultaneously to obtain the temperature, velocity and heat flux distributions inside the participating medium. The finite volume method has been adopted to solve the governing equations and the discrete ordinates method (DOM) is used to model the radiative transfer in absorbing-emitting media. The radiative–convective model is validated by comparison with test cases solutions from the literature. Then, the effects of Rayleigh number from 10² to 10⁶ and optical thickness in a broad range from 0 to 100 on temperature and velocity distributions and Nusselt numbers are investigated. The results show that even under normal room conditions with a low temperature difference, the radiation plays a significant role on temperature distribution and flow pattern in the cavity. Also, several interesting effects of radiation are observed such as a sweep behavior on the isotherms, streamlines and velocity distributions of the cavity along the optical thickness and a reverse behavior on maximum stream function and convective Nusselt number at different Rayleigh numbers.     

低速高温风洞设计及性能测试

设计了用于高温部件实验以及气膜冷却实验的低速直流回热风洞。该风洞由动力段、扩散段、稳定段、收缩段、实验段以及加热和回热设备构成,校核并测试了风洞的流场。利用实验段搭载的热电偶在常温工况下测定了风洞出口中心处1 h内的温升。在热态实验中将主流温度提高并利用热电偶测定实验段中心温度,建立校正关系。利用毕托管测定了风洞实验段常温工作的动压分布,计算了平均流速、平均动压以及流速和动压不稳定度。流场校验结果显示,风洞的流速以及动压稳定,常温工作下主流温升不明显,高温工况下温控性能卓越,适用于模拟高温流场、测量高温部件以及气膜冷却实验。     

多孔介质中高温气体非稳态渗流传热数值计算

针对水平导管中填充颗粒物料层内的高温气体参流传热现象，考虑渗流与传热的相互作用并采用局部非平衡假设建立多孔介质中的瞬态渗流传热物理数学模型。研究不同情况下填充物料中的渗流速度和气固温度分布。计算结果表明，高温热气体对水平导管中移动颗粒料层的热渗透主要发生在渗流入口端区域，随着渗流时间延长，热渗透深度沿导管推进。增大入口渗流速度以及减小出料速度，将导致物料温度沿导管慢速下降，热渗透深度扩大，热渗透作用区域内的物料温度水平提高。在热渗透作用区域，孔隙率对流场和温度场有很大的影响。研究对于高温反应器的颗粒输运和给料器的设计与运行有一定的参考作用。     

某游泳馆空调三维紊流流场的CFD模拟与研究

为评价游泳馆空调方案的气流组织设计,用k-ε模型对某游泳馆空调室内空气三维紊流流场进行了模拟,预测了游泳馆内的速度场、温度场。对模拟结果进行了分析与研究,表明CFD模拟可以为游泳馆空调系统的节能设计提供依据。     

Model of a porous regenerator used for magnetic refrigeration at room temperature

A transient three-dimensional model of a porous regenerator operating at room temperature is presented. The solid magnetic material and the regeneration fluid are modeled separately. The fluid flows through interstitial channels formed by a regular matrix of solid particles. The velocity, pressure and temperature fields are obtained from the simultaneous solution of the Navier–Stokes and energy equations with variable properties in the solid and the Boussinesq approximation for the fluid. The magnetocaloric effect (MCE) is taken into account by the inclusion of a source term in the energy equation for the magnetic solid. Special numerical schemes are used to avoid unrealistic computation time and memory requirements. Typical velocity fields and transient temperature profiles are presented.     

Modélisation d'un panache d'émetteur de chaleur pour le logiciel de simulation énergétique des bâtiments SPARK

Plume's convector modeling for object-oriented thermal building simulation software SPARK. In this paper, a zonal model used to predict air movement and temperature distribution in a room is presented. This model is based on a rough partitioning of the room: it is an intermediate approach between one-node models (that consider a homogeneous temperature in each room) and CFD models. Flow rates are calculated in respect to the pressure distribution in low velocity domains and specific laws describe plumes and jets. The airflow model is coupled with a building envelope model. They are implemented in an object-oriented environment called SPARK. The modularity of SPARK allows the creation of very flexible tools, and its strict syntax permits having the simulations automatically generated.     

Non-axisymmetric forced and free flow in a vertical circular duct

The fully developed laminar mixed convection in a vertical circular duct is studied analytically, with reference to non-axisymmetric boundary conditions such that the fluid temperature does not change along the axial direction. The Boussinesq approximation is applied by taking the average temperature in a duct section as the reference fluid temperature. The dimensionless momentum and energy balance equations are solved by employing Fourier series expansions of the temperature and the velocity fields. The solution shows that the temperature field is not influenced by the velocity distribution and that the Fanning friction factor is not affected by buoyancy. On the other hand, the velocity field is strongly influenced by the buoyancy forces and may display flow reversal phenomena. Two special cases are studied in detail: a duct with a sinusoidal wall temperature distribution; a duct subjected to an external convection heat transfer with two environments having different reference temperatures.