地板辐射供冷系统地面温度的确定

在分析地板辐射供冷系统地面温度传热规律的基础上,建立了地板辐射供冷系统的二维稳态传热数学模型;进而利用有限单元法数值计算了地板供冷系统的地面温度,根据地面温度随供回水平均温度和室内温度的变化规律,给出了地板供冷系统适宜的供回水平均温度,最后提出了地板辐射供冷系统防止地板结露的措施,这对于地板辐射供冷系统优化系统设计,推广应用提供参考依据。     

浅析太原市地板辐射供冷的应用

通过对太原市夏季室内空气温度和相对湿度的调查,结合地板辐射供冷系统的节能、舒适等特点,对太原市采用地板辐射供冷的可行性进行了分析,得出了地板辐射供冷用于太原市居住建筑夏季降温理论上可行的结论。     

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。     

地板辐射供冷系统的控制方法的探讨

地板辐射供冷系统属于辐射空调的一种形式,该系统因其节能、舒适的特点,成为了近些年暖通空调领域研究的热点。由于该系统传热过程复杂,数学模型难以建立,影响室温波动的因素多,大滞后、慢时变,非线性,使得应用于地板辐射供冷的控制系统与传统空调存在很大差异。本文通过分析地板辐射供冷的特点,回顾以前提出的各种控制策略,分别探讨了传统PID控制、神经网络控制及模糊控制在地板辐射供冷系统中的应用。     

新风与地板辐射联合供冷系统的设计研究

以贵州地区某医院病房为研究对象,分析了新风与地板辐射联合供冷系统的原理及设计路线。贵州地区医院病房采用联合供冷系统可行,新风送风温度较低,送风口应采取防结露措施。     

地板供冷/置换通风复合空调系统的可行性探讨

随着地板辐射供暖的迅速推广，地板辐射供冷的可行性备受关注，本文探讨了地板辐射系统和置换通风系统相结合用于夏季供冷的可行性。     

无保温楼板辐射供冷系统热过程的研究

楼板辐射供冷是一种舒适度很高的新型空调技术：楼板内若不设保温层，天棚和地板均成为冷辐射表面向房间供冷：系统的供冷能力和楼板上下表面温度是空调供冷系统运行和调节的关键参数，研究它们与影响因素之间的关系是十分重要的。本文建立了无保温楼板辐射供冷系统的物理模型和数学模型，并对控制方程进行数值模拟，给出了系统供冷能力和楼板上下表面温度和诸多影响因素之间的关系。研究结果显示：冷水温度越低，天棚和地板的表面温度越低，系统提高的冷量越大；天棚表面温度略大于地板表面温度；随着冷水温度的升高，天棚和地板之间的温度差异将减小，房间的舒适性好；地板辐射换热量远大于对流换热量，天棚辐射换热量略大于对流换热量；天棚提供给房间的冷量大于地板提供的冷量。且冷水温度越低，相差越大；管子埋深越大，天棚和地板表面温度越大，系统供冷量越小，但差别不显著；埋管间距越大，天棚和地板表面温度越大，系统供冷量越小；埋管管径越大，天棚和地板温度越小，系统供冷量越大，但差异不显著。研究结果可为实际工程的设计、运行参数的选择和系统的可行性分析提供依据和指导。     

地板辐射供冷-置换通风的实验研究

为了研究地板辐射供冷的热工性能,测试了北京地区不同室外气温下地板辐射供冷系统的运行工况,得到了该系统的制冷量,地板表面温度,室内温度场分布等参数,并且把单独地板辐射供冷系统的运行参数与地板辐射供冷-置换通风复合式系统进行了对比,提出了将地板辐射供冷与置换通风配合用于夏季空调室内供冷除湿的新型空调方式,置换通风系统在近地面处形成干燥空气层,可有效防止夏季热湿天气在地板表面出现结露现象,并且使这种新型空调系统条件下地面与室内的换热得到强化.通过理论分析和实验研究指出这是一种舒适、节能的空调方式.     

地板供冷研究的新进展

对国内地板辐射供冷的研究和应用状况进行了简要总结,对地板辐射供冷的供冷量、防结露措施、新风与卫生条件、热舒适性等方面进行了介绍,研究结果表明,在一定条件下,地板供冷的使用效果良好。     

三种方式辐射供冷室内热环境对比分析

辐射供冷是一种舒适、节能的新型空调形式。为了比较相同面积顶板、地板和墙壁三种不同辐射供冷方式与置换通风相结合系统的室内热环境情况,建立供冷系统室内数值模型并运用DTRM辐射模型进行不同供冷情况的数值模拟。对室内垂直温差、吹风感、PMV-PPD指标及能量利用效率进行分析比较,发现在统一设置参数下顶板辐射供冷系统热舒适指标最为理想,地板辐射供冷系统最差;但是地板辐射供冷系统能量效率最高。计算为合理优化各不同系统提供了一定的理论依据。     

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.     

地板辐射与置换通风组合空调系统的模拟

探讨了地板辐射供暖、供冷系统与置换通风系统的组合空调系统的流程,对组合空调系统进行了数值模拟。地板辐射供暖、供冷系统与置换通风系统相结合获得了良好的室内温度场和速度场,提高了空气品质,改善了室内的热舒适性。     

Development of a radiant heating and cooling model for building energy simulation software

Efficient radiant heating and cooling systems are promising technologies in slashing energy bills and improving occupant thermal comfort in buildings with low-energy demands such as houses and residential buildings. However, the thermal performance of radiant systems in buildings has not been fully understood and accounted for in currently available building energy simulation software. The challenging tasks to improve the applicability of radiant systems are the development of an accurate prediction model and its integration in the energy simulation software. This paper addresses the development of a semi-analytical model for radiant heating and cooling systems for integration in energy simulation software that use the one-dimensional numerical modeling to calculate the heat transfer within the building construction assemblies. The model combines the one-dimensional numerical model of the energy simulation software with a two-dimensional analytical model. The advantage of this model over the one-dimensional one is that it accurately predict the contact surface temperature of the circuit-tubing and the adjacent medium, required to compute the boiler/chiller power, and the minimum and maximum ceiling/floor temperatures, required for moisture condensation (ceiling cooling systems), thermal comfort (heating floor systems) and controls. The model predictions for slab-on-grade heating systems compared very well with the results from a full two-dimensional numerical model.     

Application of the control methods for radiant floor cooling system in residential buildings

In applying radiant floor cooling, its control system must prevent the floor surface condensation in hot and humid weather conditions. With no additional dehumidification system, only the radiant floor cooling system prevents floor condensation. In this case, the effects of the control of the cooling system on the indoor conditions can be changed because of the thermal inertia of the systems. Also different types of control system can be composed according to the control methods, which can affect the construction cost in the design stage. Therefore, the control methods for the radiant cooling system with respect to floor surface condensation must be studied. Furthermore, because Korean people's lifestyle involves sitting on the floor, it is necessary to evaluate if a floor cooling system will influence the thermal comfort of the occupants. This study intends to clarify the control methods of the radiant floor cooling system and to analyze the control performance and applicability of each control method with regard to the floor surface condensation and comfort by computer simulations and experiments on the control methods of the radiant floor cooling system. The results of computer simulations and experiments show that water temperature control is better than water flow control with respect to temperature fluctuations in controlling room air temperature. To prevent floor surface condensation, the supply water temperature could be manipulated according to the dew point temperature in the most humid room, and in individual rooms, the water flow rate (on/off control) can be controlled. Also, the results of radiant cooling experiments show that the floor surface temperature remained above 21 °C, the temperature difference among surfaces remained below 6 °C, and the vertical air temperature difference remained below 1.9 °C, conforming well to comfort standards.     

地板辐射供冷的技术与经济性分析

对地板辐射供冷系统的合理性、节能性、舒适性、结构进行了探讨。结合工程实例,对地板辐射供冷系统的技术与经济性进行了分析,可满足夏季室内温度的要求,技术与经济性优于常规冷水机组空调系统。     

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.     

天棚辐射供冷系统换热过程的研究

天棚辐射供冷是一种舒适度很高的新型空凋技术。系统的供冷能力和天棚表面温度是系统设计和运行的关键，研究它们与影响因素之间的关系是十分重要的：通过建立天棚辐射供冷系统的物理模型和数学模型，对控制方程进行数值模拟，给出了影响系统供冷能力的诸多因素之间的关系。研究结果显示：冷水温度越低，天棚表面温度越低，系统提供的冷量越大。天棚表面与室内环境之间的辐射换热量大于对流换热量，舒适度好。管子埋深越大，天棚表面温度越大，换热能力越小，但差别不显著：埋管间距越大，天棚表面温度越大，换热能力越小，所以埋管间距不宜取得过大。埋管管径的变化对天棚表面温度及换热量的影响不大。研究结果可为实际工程的设计、运行参数的选择和系统的可行性分析提供依据和指导。