严寒地区岩土热响应试验与地埋管地源热泵系统应用

结合严寒地区某工程,建立了两口120m深U形竖直埋管试验井并进行热响应试验,利用Kelvin无限长线热源理论模型计算了岩土层热物性参数及地埋管换热器的换热能力,分析了地埋管换热器的热阻特性,得出了夏季直接取冷条件下的单井取冷量与冷水温度的关系,并给出空调方案。依据土壤热平衡、初始土壤温度、地埋管换热器的换热能力及全年负荷等因素,确定了太阳能结合土壤蓄热的地埋管地源热泵系统供热供冷方案。     

地埋管群全年蓄热取热同步模式下岩土传热特性

结合内蒙古包头地区的地域特性,基于有限体积法,在实验验证的基础上,数值仿真研究了全年地埋管管群蓄热取热同步模式下的岩土传热特性,分析了蓄热取热同步过程中的蓄热地埋管流体温度、取热地埋管流体温度、岩土结构以及地埋管管群排列方式等因素对岩土温度场的影响规律。研究结果发现:地埋管群全年蓄热取热同步模式可使岩土温度得到快速恢复,进而可缓解岩土热失衡问题;取热流体温度不变的情况下,取热地埋管周围岩土温度随蓄热地埋管流体进口温度的增加而增加;岩土热扩散系数越大,取热地埋管与蓄热地埋管周围岩土温度分布越均匀越不易出现岩土热堆积现象;取热地埋管与蓄热地埋管叉排列时岩土温度分布较顺排列时均匀。     

广州与另两类地区埋地换热器换热性能的比较

本文将广州地区与另两类不同气候类型地区的埋地管换热器的换热性能进行了对比分析。结果表明,放热性能．广州地区比其它两类地区低;取热性能。广州处于中间位置。文中给出了取放热时,广州与另两类地区埋管换热器换热能力的相对大小数值．可为不同地区埋管换热器的设计提供参考。     

双回型辐射地板表面平均温度测量位置的模拟与分析

建立了辐射地板供冷／供暖系统传热过程的数学模型，分析了埋管上方结构热阻、室内负荷、供回水温差及埋管间距等因素对地板表面平均温度分布的影响，前三者的影响可以忽略。发现相同供回水平均温度条件下，不同供回水温差的两根供回水管间的地板表面平均温度是相同的；相邻两管间温差为0℃时，不同埋管间距地板表面平均温度的测量位置与埋管间距的比值均为0．22。     

地源热泵地埋管换热器实际换热性能评价方法研究

地埋管换热器换热效果良好与否关系着整个系统运行效率。本文提出了地埋管换热器换热效果评价方法。该方法以地埋管传热热阻为切入点,针对影响地埋管传热热阻的3个因素:地埋管施工质量、地埋管设计参数及地埋管累计换热量,明确地埋管换热器的评价应排除第3个因素,而着眼于前2个因素,提出了地埋管出水温度与最优热阻评价2种评估方法。     

定形相变贮能材料在暖通空调领域的应用研究

介绍了定形相变贮能材料制备方法,热物性、稳定性,定形相变贮能与太阳能、夜间通风、电加热地板供暖、蓄热槽贮换热等系统结合应用于建筑供暖空调方面的一些研究成果和动态,对进一步值得研究的问题提出了建议。     

主动式太阳房相变蓄热地板供暖实测研究

本实验考虑到建筑本身的节能,采用了保温、隔热性能良好的高性能围护结构搭建了主动式太阳房,以太阳能热水为热源,实验房的2个房间分别采用相变蓄热地板供暖系统与干式地埋管地板供暖系统,实测了2种地板供暖系统的蓄放热性能以及其对房间热性能的影响。运用相变蓄热地板供暖的房间,提高了室内最低温度的同时,温度波动减小了3.5℃,铺设的相变材料利用率较高。可根据需要进行自动调节的主动式太阳房供暖系统与相变蓄能地板的结合应用达到了节能降耗和提高房间舒适度的效果。     

建筑夜间通风降温研究进展

从夜间通风降温技术的原理入手,对其主要研究领域,包括气候潜力、降温影响因素分析、通风换气、对流换热、围护结构蓄热、夜间通风的建筑构造等进行了深入的文献研究,在此基础上归纳出了夜间通风的研究体系.对国内外的研究现状和存在问题进行了总结.     

综合管廊通风换热理论研究

将矩形结构综合管廊等效近似为圆筒形结构,综合考虑土壤导热热阻、壁面对流换热热阻及内热源对综合管廊通风降温的影响,建立了综合管廊一维稳态传热数学模型,求解得到管廊通风风速的解析表达式,辅以简单的Excel迭代计算可用于综合管廊实际工程换热通风量的计算.考虑壁面传热后机械通风量明显低于壁面绝热计算通风量.分析了综合管廊通风...     

桩基螺旋埋管换热器的沿程换热特性

建立了桩基螺旋埋管换热器的三维数值传热模型,研究了流体沿程换热特性和岩土温度分布特性。结果表明:桩基螺旋埋管换热器沿流动方向有进口、回填料热短路、小温差及出口4个换热阶段,每个换热阶段具有相应的换热特性;进行优化设计时,需控制小温差换热阶段的长度,增加其他换热阶段的长度,以提高螺旋埋管换热器的整体换热能力。     

热管技术在太阳能地板辐射采暖中的应用

针对北方冬季干燥少雪的季节特性,提出采用太阳能作为热管地板辐射采暖的热源,并建立了试验模型,对热管的敷设倾角、蒸发段长度、供水温度等一系列问题进行了试验分析,得出试验运行的较佳性能参数。     

Radiative and convective heat transfer coefficients of the human body in natural convection

The purpose of this study was to investigate the convective and radiative heat transfer coefficients of the human body, while focusing on the convective heat transfer area of the human body. Thermal sensors directly measuring the total heat flux and radiative heat flux were employed. The mannequin was placed in seven postures as follows: standing (exposed to the atmosphere, floor contact); chair sitting (exposed to the atmosphere, contact with seat, chair back, and floor); cross-legged sitting (floor contact); legs-out sitting (floor contact); and supine (floor contact). The radiative heat transfer coefficient was determined for each posture, and empirical formulas were proposed for the convective heat transfer coefficient of the entire human body under natural convection, driven by the difference between the air temperature and mean skin temperature corrected using the convective heat transfer area.     

地埋管地源热泵中长期数值模拟的土壤内热源法

在分析常规地埋管地源热泵中长期数值模拟方法——管群换热模拟法的基础上,提出了新的模拟方法——土壤内热源法.模拟结果表明,在内热源法网格数仅为管群换热模拟法网格数1/8的情况下,两者在中长期运行工况下的土壤温度场变化及埋管区域年温升变化基本相同,采用内热源法可以大大简化计算过程,缩短计算时间.     

A simple method for estimating transient heat transfer in slab-on-ground floors

The problem of calculating transient heat transfer in concrete floor slabs is complicated due to ground coupling, which can require the numerical solution of two or three-dimensional transient conduction equations. This paper presents a simplified method for calculating transient slab-on-ground heat transfer that can be incorporated within hourly simulation programs. The method assumes that there are two primary one-dimensional paths for heat transfer from a ground-coupled floor slab: (1) one-dimensional heat transfer from the perimeter of the slab to the ambient and (2) one-dimensional heat transfer between the slab interior surface and a portion of the soil beneath the slab. The perimeter heat transfer is assumed to occur at quasi-steady state and is characterized in terms of a perimeter heat loss factor (F_p). Transient heat transfer within the slab and ground are modeled using a simple thermal circuit employing three nodes with an adiabatic boundary condition at a specified depth within the soil underneath the slab. Although some simulation models consider this type of two-path model, there appears to be no validation of this approach and there is no guidance for specifying perimeter heat loss factors and underfloor soil depths and node locations for the thermal circuit. In the current paper, results from detailed two-dimensional finite-element models for typical floor constructions and soil properties were used to identify (1) locations for nodes within the slab and soil, (2) correlations for soil depth as a function of soil properties associated with the underfloor adiabatic boundary condition, and (3) correlations for perimeter heat loss factor as a function of soil properties and edge insulation levels for different constructions. Transient heat transfer results from the simple model compared well with results from the finite-element program for different floor constructions, edge insulation, soil properties, locations, and times of year.     

架空通风地板传热系数研究

采用稳态传热方法和等量传热原则得出了以架空层通风量为主要影响参数的地板传热系数计算公式,应用CFD软件模拟了通风口面积比与通风量的关系,给出了常用通风口设置情况下地板传热系数建议值.     

The effect of floor heat source area on the induced airflow in a room

We examine the role of heat source geometry in determining rates of airflow and thermal stratification in natural displacement ventilation flows. We modify existing models to account for heat sources of finite (non-zero) area, such as formed by a sun patch warming the floor of a room. Our model allows for predictions of the steady stratification and ventilation flow rates that develop in a room due to a circular heat source at floor level. We compare our theoretical predictions with predictions for the limiting cases of a point source of heat (yielding a stratified interior), and a uniformly heated floor (yielding a mixed interior). Our theory shows a smooth transition between these two limits, which themselves result in extremes of ventilation, as the ratio of the heat source radius to the room height increases. Our model for the transition from displacement to mixing ventilation is compared to previous work and demonstrates that the transition can occur for smaller sources than previously thought, particularly for rooms with large floor area compared to ceiling height.     

基于层换热理论的竖直地埋管换热器设计方法

建立了地源热泵竖直地埋管换热器的三维传热温度场数学模型,模拟计算了不同季节不同工况下地埋管换热器内的水温分布。提出了层换热理论,竖直地埋管换热器及其周围岩土可以分为三个换热层——饱和换热层、换热层、未换热层。通过实测验证了该层换热理论。介绍了地埋管换热器埋深的确定、出水管的保温及流量的确定等。     

地板送风对流热转移

针对下部有集中热源的地板送风空调小室,利用PHOENICS软件,对多种工况下室内气流流动的速度场和温度场进行了模拟,利用模拟结果计算对流热转移量,得出对流热转移量的变化规律。分析了影响对流热转移量的相关因素,主要是由于送风冷射流与热源的热射流在不同的影响因素下对室内气流流动及温度分布产生影响,从而造成对流热转移量的变化。结果表明:地板送风空调小室的对流热转移量与热源数目、送风口密度、热源强度、送风量4个因素有关;回风口数目对对流热转移量的影响很小,可以忽略不计。     

十八星旗花坛地源热泵供暖工程设计与施工

介绍了该工程的空调系统、地板辐射供暖系统和地埋管地源热泵系统的设计及地埋管换热器和地板辐射供暖系统的施工要点.     

污水换热器传热性能测试分析

以北京某宾馆污水源热泵系统中的污水换热器为研究对象,连续测试了污水、中间水以及热水流量、温度随时间的变化.根据测试数据计算得到了污水换热器换热效率的衰减情况,并拟合得到了传热系数的衰减公式,测试分析结果可为污水源热泵供热系统中的污水换热器设计和选型提供参考.