车站高大空间空调系统气流组织与热舒适性分析

兼顾人体热舒适和建筑节能的要求,对目前车站高大空间空调气流组织的数值模拟研究报道进行对比分析。分析结果显示,人们对高大空间建筑室内热舒适要求高于居住建筑和办公建筑;从满足人体热舒适角度出发,空调送风加地板辐射供冷方案适于夏季满员工况,地板辐射供热加空调加湿方案适用于冬季满员工况;高大空间的空调系统适宜采用上送上回的送风方式,其温度场和速度场均优于上送下回的空调送风方式;在高大空间内设置分层空调系统将在一定程度上降低空调能耗,且分层空调中送风速度对分层界面的位置影响较大,送风温差对高大空间分层空调的温度分布和流场分布有较大影响。     

冷却顶板空调系统中热环境分析

采用CFD软件,探讨了某通透大型玻璃幕墙建筑顶板冷辐射空调系统中的空调方案对室内热环境的影响,并进行了热舒适评价,研究表明：在不能安装辐射换热管系统的部分空间内,可以采用安装地板辐射管,并采取适当的通风方式带走室内余热以达到设计要求。     

Radiant floors integrated with PCM for indoor temperature control

The control of indoor thermal comfort in buildings through thermal inertia during the summer season plays a fundamental role in the design of energy efficient buildings, especially in the Mediterranean climate. In fact, lightweight, highly insulated buildings cannot provide the necessary mass to buffer thermal gains. Phase change materials (PCM) have been used to provide lightweight building components with the required thermal inertia without increasing their overall mass. So far the integration of PCM into lightweight piped radiant floors for the control of thermal comfort during summer cooling regimes has not been investigated. This paper reports the development of a lightweight piped radiant floor prototype with an integrated PCM layer aimed at buffering internal gains at constant temperature during summer cooling regimes without affecting its winter warming capacity. Both the construction of the laboratory specimens and the development of the optimized finite element models are detailed and the assessment of the floor performance in a simulated room is discussed.     

Model validation of a dynamic embedded water base surface heat emitting system for buildings

A numerical model is developed to assess the static and dynamic operations of a new kind of floor heat emitter. Surface floor heating systems are widely used to achieve better comfort conditions in residential and tertiary building sector. Classical floor heating systems have a low thermal response while the emitting device studied in this paper is highly reactive. It allows comfort enhancement and energy savings. A finite element method based software COMSOL Multiphysics is applied to solve the heat equation. This work focuses on the thermal behaviour of the emitter itself, but does not include a building model. A test bench has been built for this application to verify the numerical model. Both computational and experimental results demonstrate the benefits of this new heating and cooling device.     

Inter-model comparison of embedded-tube radiant floor models in BPS tools

Hydronic radiant floor heating and cooling can potentially reduce energy consumption in buildings. Numerous building performance simulation (BPS) tools contain models for predicting the heat transfer between embedded-tube radiant floor systems and building thermal zones. However, the accuracy, limitations, and methodologies of these models, and their implementations into BPS tools, have never been contrasted in the literature. This paper describes the approaches employed by TRNSYS, ESP-r, and EnergyPlus for modelling embedded-tube radiant floors. An inter-model comparison is then presented for test cases designed to explore model performance. The predictions from the three BPS tools are compared to each other as well as to predictions made with a transient stand-alone finite element analysis tool. Significant issues are identified with the embedded-tube radiant floor models in all three BPS tools.     

Thermal comfort and energy consumption of the radiant ceiling panel system.: Comparison with the conventional all-air system

The purpose of this study is to investigate the various characteristics of a radiant ceiling panel system and their practical application to office buildings. The radiant ceiling panel system and conventional air-conditioning system were compared in terms of thermal comfort, energy consumption, and cost. Thermal environment, along with human response, was tested by using a small meeting room equipped with radiant ceiling panels. The responses were collected by questionnaires given to the male subjects in the room. The experiment for the female subjects was conducted separately. Results show that the radiant ceiling panel system is capable of creating smaller vertical variation of air temperature and a more comfortable environment than conventional systems. When using a cooled ceiling, a small volume of supplied air creates a less draught environment, which reduced the discomfort of feeling cold in the lower part of the body. Numerical simulation of yearly energy consumption and cost estimation were conducted. Typical office rooms located on the 3rd, 4th, and 5th floor of a six-floor building in the Tokyo area were simulated. Since part of the sensible heat load is handled by radiant ceiling panels, the volume of supplied air can be reduced, leading to lower energy consumption for air transport. By using the radiant ceiling panel system in one of the three floors of the simulated building, energy consumption can be reduced by 10%. Estimated pay back time was from 1 to 17 years depending on the market price of the radiant ceiling panel.     

Numerical simulation of radiant floor cooling system: The effects of thermal resistance of pipe and water velocity on the performance

Using the existing floor heating system, the radiant floor cooling system can be used as an alternative to the conventional all-air cooling systems. In this paper, a numerical model for the radiant floor cooling system is built using finite volume method. The objective of this study is to research the effects of the thermal resistance of pipe and water velocity on the performance of the radiant floor cooling system. In order to provide better heat transfer simulation in the pipe, composite grids are used in the model. The numerical floor surface temperature and the heat flux are in agreement with the measured results. The results illustrate that the pipe has effect on the performance of the radiant floor cooling system when the thermal conductivity of the pipe is low. However, the effect of the water velocity on the performance of the cooling system is not great. The model is helpful to calculate and design such kind of radiant floor cooling systems.     

Kühldeckensystem mit Aktivierung der Speichermasse der Betondecke

Büro‐ und Verwaltungsgebäude werden seit vielen Jahren zur allgemeinen Nutzerzufriedenheit mit Flächensystemen beheizt und gekühlt. Am Anfang dieser Entwicklung stand die abgehängte Kühldecke, die sich wegen ihrer hohen Kundenakzeptanz in ganz Europa verbreitet hat. Eine weitere, inzwischen ebenfalls weitverbreitete Anwendungsform von Strahlungssystemen ist die thermische Aktivierung von Betondecken, auch als Betonkerntemperierung bezeichnet. Dass diese nach dem Strahlungsprinzip funktionierenden Systeme auch zur Beheizung von Gebäuden geeignet sind, stellen viele erfolgreich ausgeführte Bauprojekte eindrucksvoll unter Beweis, [9] und [10]. Obwohl beide Systemvarianten nach demselben Strahlungsprinzip arbeiten, bestehen signifikante Unterschiede. Vor der Entscheidung für die eine oder andere Systemvariante müssen die typischen Merkmale sorgfältig geprüft und gegeneinander abgewogen werden. Dieser Fachbericht beschreibt eine Mischform, die aus beiden Systemvarianten heraus entwickelt wurde und immer häufiger Anwendung findet. Messungen in einem thermisch schweren Versuchsraum belegen die Leistungsfähigkeit von beidseitig aktivierten Kühlsegeln in Kombination mit der Betondecke. Suspended radiant cooling system with thermally activated concrete ceiling. Office buildings are heated and cooled by thermoactive building systems for many years. These energy efficient heating and cooling concepts provide excellent thermal comfort. The first systems were installed as suspended cooling ceilings which are applied all‐over Europe and go along with a high user satisfaction. Another widely adopted construction principle is the concrete conditioning. Monitoring campaigns in energy efficient office buildings show clearly that radiant systems can be successfully operated for both cooling and heating. Although both the radiant ceiling and the concrete core conditioning use the same long‐wave radiative heat transfer the operation is different due to the thermal storage effect. Architects and HVAC planners have to decide for one of these solutions based on the pros and cons for each system. This article presents a hybrid form which can be used for new buildings and refurbishment projects. Laboratory measurements in a thermally heavy test chamber prove the thermal performance of a double‐sided suspended radiant panel in interaction with the concrete ceiling.     

地板辐射与置换通风空调系统运行参数

建立了基于EnergyPlus的地板辐射供冷加置换通风空调系统模型,模拟得到的室内温度和辐射地板所承担冷量与实验结果的误差小于±7%。在此模型基础上,改变送风参数和供水参数,得到置换通风供冷量、辐射地板供冷量、地板表面温度、室内空气平均温度、AUST温度等参数的变化规律。结合热舒适性模型,得到满足室内热舒适性(-0.5≤PMV≤0.5)条件下,置换通风的送风参数和辐射地板的供水参数范围,为复合系统设计和应用提供依据。     

Energy performance optimization of radiant slab cooling using building simulation and field measurements

Few field studies of energy performance of radiant cooling systems have been undertaken. A recently constructed 17,500 m² building with a multi-floor radiant slab cooling system in the tower was investigated through simulation calibrated with measured building energy use and meteorological data. For the very cold, dry region where the building was located, it was found that a typical floor of the tower would have had 30% lower annual energy use with a conventional variable air volume system than with the as-built radiant cooling-variable air volume combination. This was due to (1) simultaneous heating and cooling by the existing radiant cooling and air systems, (2) the large amount of free cooling possible in this climate, and (3) suboptimal control settings. If these issues were remedied and combined with improved envelope and a dedicated outdoor air system with exhaust air heat recovery, a typical floor could achieve annual energy use 80% lower than a typical floor of the existing building HVAC system. This shows that radiant thermal control can make a significant contribution to energy-efficiency, but only if the building design and operating practices complement the strengths of the radiant system.     

Experimentally-determined characteristics of radiant systems for office buildings

Radiant heating and cooling systems have significant energy-saving potential and are gaining popularity in commercial buildings. The main aim of the experimental study reported here was to characterize the behavior of radiant cooling systems in a typical office environment,including the effect of ceiling fans on stratification,the variation in comfort conditions from perimeter to core,control on operative temperature vs. air temperature and the effect of carpet on cooling capacity. The goal was to limit both the first cost and the perceived risk associated with such systems. Two types of radiant systems,the radiant ceiling panel( RCP) system and the radiant slab( RS) system,were investigated. The experiments were carried out in one of the test cells that constitute the FLEXLAB test facility at the Law rence Berkeley National Laboratory in March and April 2016. In total,tentest cases( five for RCP and five for RS) were performed,covering a range of operational conditions. In cooling mode,the air temperature stratification is relatively small in the RCP,with a maximum value of 1. 6 K. The observed stratification effect was significantly greater in the RS,tw ice as much as that in the RCP.The maximum increase in dry bulb temperature in the perimeter zone due to solar radiation was 1. 2 K for RCP and 0. 9 K for RS-too small to have a significant impact on thermal comfort. The use of ceiling fans was able to reduce any excess stratification and provide better indoor comfort,if required. The use of thin carpet requires a 1 K low er supply chilled water temperature to compensate for the added thermal resistance,somew hat reducing the opportunities for water-side free cooling and increasing the risk of condensation. In both systems,the difference betw een the room operative temperature and the room air temperature is small when the cooling loads are met by the radiant systems. This makes it possible to use the air temperature to control the radiant systems in lieu of the operative temperature,reducing both first cost and maintenance costs.     

A combined system of chilled ceiling,displacement ventilation and desiccant dehumidification

Different types of heating, ventilation, and air-conditioning (HVAC) systems consume different amounts of energy yet they deliver similar levels of acceptable indoor air quality (IAQ) and thermal comfort. It is desirable to provide buildings with an optimal HVAC system to create the best IAQ and thermal comfort with minimum energy consumption. In this paper, a combined system of chilled ceiling, displacement ventilation and desiccant dehumidification is designed and applied for space conditioning in a hot and humid climate. IAQ, thermal comfort, and energy saving potential of the combined system are estimated using a mathematical model of the system described in this paper. To confirm the feasibility of the combined system in a hot and humid climate, like China, and to evaluate the system performance, the mathematical model simulates an office building in Beijing and estimates IAQ, thermal comfort and energy consumption. We conclude that in comparison with a conventional all-air system the combined system saves 8.2% of total primary energy consumption in addition to achieving better IAQ and thermal comfort. Chilled ceiling, displacement ventilation and desiccant dehumidification respond consistently to cooling source demand and complement each other on indoor comfort and air quality. It is feasible to combine the three technologies for space conditioning of office building in a hot and humid climate.     

顶板辐射供冷加置换通风系统广州地区适用性分析

顶板辐射供冷加置换通风系统以其独有的舒适性好、能耗低等特点逐步被国内用户接受,并在民用建筑项目中被采用.本文以等效辐射换热系数方法对盘管式辐射顶板单位面积的供冷量进行了数值模拟分析,并以广州地区为例,对该系统的适用性及影响因素进行了讨论:顶板辐射供冷加置换通风系统更适用于围护结构冷负荷指标低的节能建筑;当围护结构冷负荷指标低于20 W/m2时,采用较高供回水温度的冷水机组可满足室内设计要求且有明显的节能效果;顶板承担的冷负荷随人员密度的增大而减小,降低送风温度、采取大温差送风,可降低顶板承担的冷负荷.     

Application of latent heat thermal energy storage in buildings: State-of-the-art and outlook

Latent heat thermal energy storage (LHTES) is becoming more and more attractive for space heating and cooling of buildings. The application of LHTES in buildings has the following advantages: (1) the ability to narrow the gap between the peak and off-peak loads of electricity demand; (2) the ability to save operative fees by shifting the electrical consumption from peak periods to off-peak periods since the cost of electricity at night is 1/3–1/5 of that during the day; (3) the ability to utilize solar energy continuously, storing solar energy during the day, and releasing it at night, particularly for space heating in winter by reducing diurnal temperature fluctuation thus improving the degree of thermal comfort; (4) the ability to store the natural cooling by ventilation at night in summer and to release it to decrease the room temperature during the day, thus reducing the cooling load of air conditioning. This paper investigates previous work on thermal energy storage by incorporating phase change materials (PCMs) in the building envelope. The basic principle, candidate PCMs and their thermophysical properties, incorporation methods, thermal analyses of the use of PCMs in walls, floor, ceiling and window etc. and heat transfer enhancement are discussed. We show that with suitable PCMs and a suitable incorporation method with building material, LHTES can be economically efficient for heating and cooling buildings. However, several problems need to be tackled before LHTES can reliably and practically be applied. We conclude with some suggestions for future work.     

DALEC – a novel web tool for integrated day- and artificial light and energy calculation

DALEC is a novel, combined lighting and thermal simulation web tool. This tool allows building designers to evaluate their individual façade concepts in terms of thermal and visual performance and ultimately their impact on overall building energy use. Although easy to use, the software accounts for the complex thermal and light processes in buildings, by way of sophisticated and time-saving pre-calculations. Based on climatic data a calculation of heating, cooling and electric lighting loads can be obtained within a simulation time shorter than one second. The model has been validated by comparison with experimental data and other state-of-the-art software and shows deviations less than 15%. Not only energy demand is considered, but also user behaviour (e.g. glare protection), as well as visual and thermal comfort. This innovative, holistic approach facilitates and accelerates the design of sustainable and energy-efficient building for new, as well as for refurbished buildings.     

下送上回通风方式供冷与供暖运行性能比较

下送上回通风方式目前得到了广泛的研究应用,其供冷运行时就是置换通风,但同样一套通风系统在一些地区的寒冷季节则有可能需要作供暖运行.为了获得下送上回通风系统在分别作供冷与供暖运行时的具体性能参数,本文应用实验测试与计算流体力学(CFD)模拟的方法研究了置于环境实验室内的某办公环境.研究中分析比较了该办公环境内的空气速度、温度以及追踪气体污染物的浓度分布.研究结果表明,下送上回通风方式作供冷运行时空气温度及污染物浓度分层现象明显,空气处于半混合状态,置换效果较好;作供暖运行时,温度及污染物浓度趋于均匀,通风系统性能接近于混合送风系统,不具备良好的抑制交叉污染的能力.     

Validation and modification of modeling thermally activated building systems (TABS) using EnergyPlus

EnergyPlus (EP) integrates a low temperature radiant system module to evaluate thermal performance of radiant systems such as thermally activated building systems (TABS), but the assumptions in this module neglect thermal resistance of the pipe and thermal resistance between the pipe exterior surface and the pipe level, which may result in the inaccurate evaluation of TABS in terms of surface temperature and surface heat flow. In this paper, in order to validate this module used in EP, steady and transient heat transfer processes of TABS in buildings were studied by analytical solution, two-dimensional numerical simulation and EP simulation. The comparison shows that the assumptions indeed result in a largely overestimated cooling and heating capacity of TABS. In order to improve this radiant module, a simple solution of introducing a no mass material layer with the neglected thermal resistances to both sides of the pipe level was proposed. With this method, the results of mean surface temperature and mean heat flow show good agreement with that from analytical solution as well as numerical simulation. Furthermore, the results of the simulation coupling the modified module with room systems show very small deviation from the results found in the literature. In addition, the application of the modified module in a hollow core concrete deck structure with TABS was investigated.     

Building signatures: A holistic approach to the evaluation of heating and cooling concepts

A sustainable and environmentally responsible building concept aims at a high workplace comfort, a significantly reduced heating and cooling demand, a high-efficient plant system, and the use of renewable energy sources to condition the built environment. This paper presents a comprehensive analysis of the heating and cooling concepts of 11 low-energy buildings in terms of energy use, efficiency and occupant thermal comfort. All buildings investigated employ environmental energy sources and sinks – such as the ground, ground water, rainwater and the ambient air – in combination with thermo-active building systems. A limited primary energy use of about 100 kWh_prim/(m²_neta) as a target for the complete building service technology (HVAC and lighting) was postulated for all buildings presented. With respect to this premise, a comprehensive long-term monitoring in high time resolution was carried out for two to five years, with an accompanying commissioning of the building performance. Measurements include the useful heating and cooling energy use, auxiliary energy use for the hydraulic system, as well as end and primary energy use, occupant thermal comfort and local meteorological conditions. A new methodology is proposed for a holistic approach to the evaluation of heating and cooling concepts, which not only considers the occupants thermal comfort, but also the useful energy consumption and the efficiency of the generation, distribution and delivery of heating and cooling energy.     

辐射吊顶的实验研究

描述了在实验小室内对辐射吊顶夏季供冷和冬季供暖的热工性能进行的测试,根据实验数据,计算了对流和辐射的综合效果。表明了在我国应用辐射吊顶可以满足供暖的要求,而且具有适宜的室内温度分布和人体舒适感。     

地板辐射供冷系统分析

本文介绍了地板辐射供冷系统的室内外设计参数选取和负荷计算方法,通过采用CFD数值模拟的方法,分析了辐射供冷地板系统在不同的室内设计温湿度及冷水温度条件下的供冷量,冷损失量及表面温度等。应用该方法可以建立系统设计查找表格为地板辐射供冷系统设计提供基础数据。本文也给出了埋管辐射地板的系统布置方式及设计流程等。