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.     

Heat loss to the ground from a building—II. Slab on the ground

The heat flow to the ground from a rectangular slab with an even thermal insulation is analysed. The steady-state heat loss factor is given in complete diagrams for any ratio between length and width of the slab and for any constant insulation of slab and ground surface. A two-dimensional edge approximation for time-dependent heat loss at the perimeter of the slab is introduced. New analytical solutions for the edge heat loss due to periodically variable outdoor temperature or a step change in the outdoor temperature are presented. The effect on the heat loss due to different variations of the outdoor temperature is easily analyzed with these solutions. For example, daily periodic variations can certainly be neglected. Based on this, simple design rules for the heat loss during a heating season and the peak effect are given.     

供热管网保温厚度的计算分析

建立了供热管网直埋、地沟敷设管道的二维数学模型,通过边界离散方法进行了求解。分析了保温管道的保温层及其邻域土壤的温度场和热流规律,计算了保温管道的热损失。运用经济学的相关理论,对供热管道的保温厚度进行了优化分析,讨论了影响保温管道经济厚度的因素。     

Modelling floor heating systems using a validated two-dimensional ground-coupled numerical model

This paper presents a two-dimensional simulation model of the heat losses and temperatures in a slab on grade floor with floor heating which is able to dynamically model the floor heating system. The aim of this work is to be able to model, in detail, the influence from the floor construction and foundation on the performance of the floor heating system. The ground-coupled floor heating model is validated against measurements from a single-family house. The simulation model is coupled to a whole-building energy simulation model with inclusion of heat losses and heat supply to the room above the floor. This model can be used to design energy efficient houses with floor heating focusing on the heat loss through the floor construction and foundation. It is found that it is important to model the dynamics of the floor heating system to find the correct heat loss to the ground, and further, that the foundation has a large impact on the energy consumption of buildings heated by floor heating. Consequently, this detail should be in focus when designing houses with floor heating.     

Transient simulation of a storage floor with a heating/cooling parallel pipe system

The exact 2-D transient solution of a slab with an embedded array of parallel circular pipes for heating/cooling is developed. The boundary and initial conditions are: constant temperature at the pipe surface, upper slab surface subjected to convection heat transfer, thermal insulation at the slab bottom, and constant initial temperature. The analytical solution of the transient bi-dimensional problem is obtained together with the fluid temperature. A calculation example is analysed at the end of the paper to enlighten practical issues appearing in the computation of the analytical solution.     

建筑隔声与地面辐射供暖

楼板传声是建筑噪声最主要来源之一,现有普通混凝土楼板的计权标准化声压级大多隔声性能不能满足国家标准,需要通过构造浮筑楼板等方式提高楼板隔绝撞击声性能,使其满足国家现行标准要求。地面辐射供暖系统因其特殊的结构形式,其内在具有提高楼板隔绝撞击声性能的优势。本文对建筑楼板隔声现状、地面辐射供暖对建筑隔声的作用以及地面辐射供暖隔声效应的测试方法进行了阐述。     

Validation of a FEM-program (frequency-domain) and a simplified RC-model (time-domain) for thermally activated building component systems (TABS) using measurement data

In an office building equipped with a thermally activated building component system (TABS) detailed in situ measurements have been performed. The measurements presented in this paper have been concentrated on the concrete core conditioning (CCC) system, which is used for heating and cooling the building. Plastic pipes with circulating water have been placed in the concrete slab. One coil of the thermally activated concrete slab has been measured in detail using 80 measurement points. The measurements include temperature measurements at different heights of the concrete slabs as well as in the suspended floor and in both adjacent rooms. Furthermore the supply and return water temperature, the volume flow for the coil as well as the heat flow at the surface of the concrete slab have been measured. The measurements have been analyzed in the frequency-domain with help of a Fourier-transform. The temperature measurements and the volume flow have been utilized to validate a FEM-program working in the frequency-domain and a simplified RC star network placed in the time-domain simulation environment TRNSYS. The simplified RC-network has been previously validated with help of the FEM-program working in frequency-domain. For the validation of the FEM-program the measured time series have been transformed into Fourier-series and then used as input to the FEM-program performing the calculation in frequency-domain.     

地表装饰材料和保温层性能对辐射地板热量损失影响的数值研究

建立了辐射地板供暖的传热模型，利用SIMPLER计算程序模拟计算了地表装饰材料和埋管保温层性能对辐射地板换热和地表温度分布的影响，得出了地板内部的温度场分布规律。研究结果表明，地表装饰材料对地板换热有很大的影响，埋管保温层对减少地板下层热量损失有十分重要的作用。     

地板辐射采暖电加热管传热过程影响分析

通过分析电加热地板辐射采暖传热过程,建立电加热管传热模型,进行方程离散和数值模拟,并分析电加热地板辐射的发热电缆间距、地板面材料等因素对电加热管传热影响.研究结果表明:满足室内热环境条件相同时,地板面热流密度按从大到小依次是大理石、瓷砖、软木板;随着发热电缆间距的增大,地板面温度分布开始出现波动,热流密度逐渐降低,地板...     

低温地板辐射供暖的动态仿真

建立了低温地板辐射供暖系统传热过程的数学模型,通过数值模拟,用有限差分法计算了地板内的温度场。利用动态仿真程序预测了不同的供回水温度,埋管层厚度,盘管间距对地板传热过程,地板表面温度的影响,并在典型工况下,通过对理论值与实验值进行分析,验证了本模拟程序是正确的,该研究为地板辐射供暖系统的推广应用奠定了基础。     

Prediction of yearly energy requirements of indoor ice rinks

A model of the transient heat transfer between the ground under and around the foundations of an indoor ice rink and the brine circulating in pipes embedded in the concrete slab under the ice has been coupled with a previously developed model calculating heat fluxes towards the ice by convection, radiation and phase changes. Subroutines calculating the energy consumption for heating and humidifying (or cooling and reheating) the ventilation air have also been added to the model. The resulting simulation tool has been used to calculate monthly refrigeration loads and energy consumption by the ventilation system, the lights, the brine pump, the radiant heating system of the stands and the underground electric heating used to prevent freezing and heaving for four North American cities with very different climates. Correlations expressing the energy consumption of the ventilation air stream in terms of the sol-air temperature are formulated.     

Insulation plan of aluminum curtain wall-fastening unit for high-rise residential complex

Aluminum curtain wall system is commonly used in high-rise residential complex. For the energy-efficient curtain wall system, the insulation performance of the fastening unit, which enjoins the curtain wall unit to the slab, should be improved because in Korea, hot water pipes for radiant heating are typically installed on the slab in residential buildings. However, this fastening unit composed of metals with high thermal conductivity, acts as a thermal bridge that increases heat loss. Therefore, in this study, we aim to develop a more effective insulation method for the fastening unit. Three alternative fasteners coated with urethane foam and insulation paint were selected (Case 1: using the existing fastener; Case 2: coating the upper part of fastener with urethane foam; Case 3: coating the entire surface of fastener with insulation paint; Case 4: coating the upper part of fastener with urethane foam and the lower part with insulation paint). The heat loss and economical efficiency of each case were analyzed through the three-dimensional annual transient heat transfer simulation and payback period method, respectively. Case 4, compared to Case 1, was found to show the best performance of reducing the annual heat loss by 8.14%. From an economical efficiency perspective, however, Case 2 was found to have the shortest payback period of 2.27years.     

相变通风屋顶的供热节能优化设计研究

提出太阳能相变屋顶系统(主要由太阳能空气集热系统、相变通风屋顶组成),将两种相变材料(PCM1、PCM2,PCM1用于供冷期蓄冷,相变温度在35℃左右。PCM2用于供暖期蓄热,相变温度在18℃左右)及风道(预制在钢筋混凝土板内,供冷期利用夜间低温空气冷却屋顶与PCM1,供暖期利用太阳能空气集热器出口热空气加热屋顶与PCM2)预制在屋顶内,形成相变通风屋顶(由上至下的基本结构为保护层、防水层、找坡层、保温层、找平层、PCM1、钢筋混凝土板),实现供冷期夜间蓄冷日间吸热、供暖期日间蓄热夜间放热。针对供暖工况,采用模拟方法,结合评价指标,对相变通风屋顶中相变材料(由于供暖工况PCM1不发生相变,因此研究对象为相变材料PCM2)的相变温度、结构(即相变材料位置)、相变材料厚度进行优化选取。A型相变通风屋顶将PCM2设置在PCM1与钢筋混凝土板之间,B型相变通风屋顶将PCM2设置在钢筋混凝土板下面,C型相变通风屋顶将PCM2设置在预制风道外圈。PCM2的最佳相变温度为18~20℃,最优结构为B型相变通风屋顶,PCM2最佳厚度为30 mm。与无相变通风屋顶(将B型相变通风屋顶中的30 mm厚PCM2相变材料替换成相同厚度的水泥砂浆,保留预制风道,其他各层材料及厚度均保持不变)相比,最佳相变通风屋顶(PCM2相变温度为18~20℃、厚度为30 mm的B型相变通风屋顶)的各项评价指标均更优。     

隧道地源热泵供热系统加热段隔热层厚度及热负荷计算

 为解决寒区隧道冻害问题,首次将地源热泵供热系统应用于内蒙古博牙高速林场隧道中。系统由取热段、加热段、热泵和分、集水管路组成。加热段位于隧道洞口处,由位于二衬和保温隔热层之间的供热管对隧道进行加热。将复杂的隧道加热段热传导问题转化为便于求解的圆形复合介质热传导问题,利用有限积分变换法获得其温度场解析解。利用考虑隔热层材料造价和耗能的经济计算模型,计算分析隧道全寿命周期30 a的隔热层厚度和供热负荷。计算结果表明：随着隔热层厚度的增加,隔热层材料费呈线性增加,供热消耗的电费呈递减趋势,材料费与电费之和呈递减趋势。建议林场隧道保温隔热层厚度取8 cm,年供热负荷取580 MJ/m2。     

内保温住宅的户间传热温差

以目前新建住宅中较为普遍的钢筋混凝土内保温外墙、陶粒混凝土内墙结构的居住建筑为对象，建立房间不稳态传热的数学模型，通过数值求解，得出了四种典型房间，在北京地区供暖室外设计温度下，采用分室调节最低值（即停止采暖）时，其室温和邻室的户间传热温差及房间围护结构温度分布的变化规律，为进行住宅按户计量供暖设计热负荷的确定，提供了户间传热计算的依据，也为按户计量收费和建筑保温及防结霜研究提供了参考依据。     

影响地板辐射采暖盘管散热的因素分析

建立了地板辐射采暖传热模型,分析了影响采暖盘管的散热因素。研究结果表明,管径增大导致地板表面温度增加趋势减小,管间距、热水温度增大导致供热区域地板表面温度分布呈周期性变化逐渐明显,且管间距变大导致其周期增加、热水温度变大导致其振幅增加,选择合适的地板层材料才能保证舒适的地面温度。     

大尺寸大开间页岩陶粒混凝土双向叠合板足尺试验研究

针对目前装配式建筑中常用的钢筋混凝土叠合楼板自重较大、工厂标准化生产的预制底板规格尺寸较小的问题,提出了一种由两块预制普通混凝土大板通过一条整体式接缝拼装,并后浇轻质页岩陶粒混凝土而成的大开间叠合楼板,页岩陶粒混凝土后浇层可有效减小楼板自重,提高楼板的保温、隔热和隔声性能。通过进行叠合板足尺试件的堆载试验,研究其在竖向荷载作用下的承载力、变形特征、破坏形态及整体式接缝的传力性能。结果表明,该大开间叠合板试件在正常使用极限状态下的跨中挠度和裂缝宽度均满足相关规范要求,且表现出明显的双向板裂缝分布特征,所采用的整体式接缝具有良好的传力性能,可以作为结构楼板使用。此外,有限元模型所选取的材料本构模型和接触面设定较为合理,计算结果与试验结果吻合良好,可用于轻质混凝土叠合楼板受力性能及影响参数分析。     

塑料埋管地板辐射采暖的试验研究

分析了塑料埋管地板辐射采暖的传热特点和铺设方式,通过热工性能的标准测试,指出地板辐射采暖是一种舒适节能的采暖方式,试验得出的热性能特征线为地板辐射采暖的设计计算提供了可靠的依据     

内嵌管式辐射地板传热简化模型研究

本文建立了考虑绝热层向下传热的内嵌管式辐射地板传热的简化计算模型,并获取了其解析解。同时对该地板辐射传热进行了数值模拟,计算结果可作为评价解析解准确性的参考标准。计算结果表明,不考虑绝热层向下传热的地板表面温度及热流解析解结果与数值模拟结果有很大的差异;考虑绝热层向下传热的地板表面温度及热流解析解结果与数值模拟结果比较吻合,温度平均误差为0.22℃,热流平均相对误差为3.2%。