地板辐射供冷

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.并比较了住宅用冷却地板单独供冷、风机盘管单独供冷及两者联合运行三种供冷方式.     

冷辐射地板系统的实验研究

为了研究冷辐射地板系统的热工性能，测试了地板辐射供冷系统的运行工况，得到了地板表面的最低温度、室内的实感温度、热流密度等参数，并初步探讨地板辐射供冷系统结露现象及防治措施，通过实验分析指出这是一种舒适、节能的供冷方式。     

西安地板辐射空调优化及室内热环境研究

在现有地板供暖设计状态下,采用有限元分析法对二维辐射地板导热微分方程进行数值模拟计算,研究不同供回水平均温度、填充层厚度、盘管间距对地面温度和热流密度的影响,分析高温冷水地板供冷系统的供冷能力和结露问题。获得保证地面不结露的地板设计参数以及表面释冷量限值;在该地板设计条件下,通过对具体房间热环境的模拟计算,得到在西安整个夏季室外温度时,该系统在供冷初期和末期可保证基本的热舒适要求,只有在供冷中期单一的地板辐射供冷不能满足人体的热舒适性,需加其他辅助空调。     

地板供冷应用的可行性分析

根据地板供冷的优缺点,分析地板辐射供冷系统在应用中可以采取与置换通风相结合,并通过模拟证实地板辐射供冷符合国际舒适标准,为后续研究奠定基础.     

SIMULATION AND EXPERIMENT RESEARCH ON THE HEAT RESISTANCE OF RADIANT FLOOR

建立辐射地板的传热模型,通过有限差分的方法,模拟大理石辐射地板、塑胶地面辐射地板的传热特性,计算两种辐射地板的等效热阻以及温度分布情况,辐射地板的等效热阻不受工作环境的影响.通过实验测试结果验证辐射地板热阻的数值模拟结果,误差约为10％.利用辐射板的热阻,计算分析在不同工作环境中辐射板的供冷量,辐射板的供冷量为20 ～ 50W/m2,太阳辐射会使辐射板的供冷量迅速上升.     

静压与喷口对风机盘管性能影响研究

通过实验,在高风量下,不同静压与喷口情况下,对使用交流电机和直流无刷电机的风机盘管的性能进行研究。研究结果表明,选择不同的喷口对风机盘管的风量、供冷量与供热量均变化不大。在不同静压下,随着出口静压的提高,风机盘管风量、供冷量与供热量变小。     

太阳直射辐射对地板供冷系统的影响分析

研究太阳直射辐射因素对地板供冷系统管内供水流速及地板表面温度的影响,给出建议的供水参数。通过谐波反应法分别计算出有无太阳直射辐射因素影响时的室内逐时冷负荷(即地板辐射供冷系统的供冷量);分析不同供回水温差下的管内供水流速以及不同供回水平均温度下的地板板面温度,并与已有研究进行对比。得到了是否考虑直射辐射影响这2种情况下的供冷量表,不同供回水温差下是否考虑直射辐射这2种情况的管内水流速表以及不同供回水平均温度及流速下的板面温度对比图。太阳直射辐射因素对地板辐射供冷系统影响较大,有太阳辐射影响的白天时间段内供回水平均温度建议选择14.5℃,可满足全天75%~80%的地板板面温度要求,无辐射影响的夜间时间段供回水平均温度建议选择16.5℃。     

被动房空调系统绿色设计——以某办公楼为例

以某四层办公楼为例,介绍了被动房的设计,详细描述了此工程带冷热盘管的热回收新风系统+地板辐射供暖供冷系统的设计过程,从设计的角度,本工程采用带冷热盘管的热回收新风系统+地板辐射供暖/供冷的系统,在很大程度上降低了单纯全空气系统大风量所带来的噪声、强吹风感,提高了办公环境的舒适性。冷热源采用空气源热泵,最大程度地利用可再生能源,减少一次性燃料的消耗,节约能源,保护环境,降低了对环境的污染。为人们提供健康、舒适的办公环境,与自然和谐共生。     

地板辐射供冷+置换通风复合式系统供冷性能的数值分析

利用CFD对考虑地板传热的三维建筑模型进行模拟,得出换气次数,供回水平均温度和建筑外墙的内表面温度对地板表面温度,辐射换热量和总换热量的影响,以此得出这些因素对地板辐射供冷+置换通风的复合式系统的供冷性能的影响。结果表明:换气次数每降低1h~(-1),地板表面温度升高约0.26℃,辐射换热量升高约1.07 W/m2;供回水平均温度每升高1℃,地板表面温度升高约0.65℃,辐射换热量降低约2.01 W/m~2,外墙的内表面温度每升高1℃,地板表面温度升高约0.25℃,辐射换热量升高约2.08 W/m~2;由于对流换热系数约为0.5～1.0 W/(m~2·K),地板表面的总换热量中对流换热量占比很小,这主要是置换送风时,地板附近空气的垂直温差较小导致的,所以在不考虑地板的供冷能力变化的条件下,其他形式的送风系统可能是更合适的选择。     

风机盘管机组变工况特性的实验研究

在风机盘管性能测试装置上对风机盘管的风侧和水侧分别进行了变工况性能实验,以确定各因素对供冷量的影响。实验结果表明:进水初温、迎面风速、水流速、进风状态的变化对风机盘管供冷量的影响很大。     

Performance evaluation of a radiant floor cooling system integrated with dehumidified ventilation

The radiant floor cooling system can be used as an alternative to all-air cooling systems, using the existing Ondol system (a radiant floor heating system) in Korea to save energy and maintain indoor thermal comfort. Unfortunately, a radiant floor cooling system may cause condensation on the floor surface under hot and humid conditions during the cooling season. In addition, the radiant floor system does not respond quickly to internal load changes due to the thermal storage effect of the concrete mass, which is usually present in radiant floor cooling systems.This study proposes a radiant floor cooling system integrated with dehumidified ventilation, which cools and dehumidifies the outdoor air entering through the cooling coil in the ventilator by lowering the dew-point temperature to prevent condensation on the floor surface. Furthermore, outdoor reset control was used to modulate the temperature of chilled water supplied to the radiant floor, and indoor temperature feedback control was then used to respond to the internal load changes.To evaluate the performance of the radiant floor cooling system integrated with dehumidified ventilation, both a physical experiment in a laboratory setting and TRNSYS simulation for an apartment in Korea have been conducted. As a result, it was found that the proposed system was not only able to solve the problem of condensation on a floor surface but also to control the indoor thermal environment within the acceptable range of comfort. Furthermore, the proposed system improved the responsiveness to internal load changes.     

Effect of modelling solar radiation on the cooling performance of radiant floors

When modelling buildings, solar radiation has a large impact on the thermal balance because it usually heats the rooms. In radiant systems that are used for heating and cooling buildings, solar radiation has a large influence both on indoor temperatures and on the efficiency of the radiant system.Many analyses have already been carried out in order to study how beam and diffuse radiation can be distributed in a room. One of the most difficult issues, when modelling room thermal balance, is how to simulate the solar radiation when it enters the room, which in turn depends on the reflectance characteristics of the surface finishing elements.In this study, four different radiation models have been applied in order to solve an overall detailed, dynamic thermal balance in a room with pipes embedded in the floor. Two of the models are detailed; the other two consider the radiation entering the room to be diffuse radiation. As for the behaviour of the impinging solar radiation on the covering materials in a room, measurements have been carried out to determine the reflectance coefficients, which will be used in simulations for characteristic materials used in buildings.Results of the simulations show that a simplified model, which considers solar radiation as uniformly distributed in a room, cannot be used for a detailed comfort analysis; however, when looking at the cooling output of a radiant floor system at the design stage, a simplified model can predict energy transfer to a certain level of accuracy. Moreover, results coming from combined measurements and simulations show that the reflectance characteristic of the covering materials does not affect the cooling capacity of the radiant floor systems, since the most important parameter for cooling performance is the thermal conductivity of the covering layer.     

Investigation of thermal performance of a passive solar building with floor radiant heating

This paper presents a theoretical study of an integrated radiant floor heating–direct gain passive solar system. Thermal mass is utilized both for storage of auxiliary heating energy and direct solar gains incident on the floor. An explicit finite difference model is developed to accurately model nonlinear effects and auxiliary heating control. The numerical simulation model is employed to study the performance of a passive solar outdoor test-room with different amounts of thermal mass under various control strategies with constant and sinusoidal room thermostat setpoints. A satisfactory thermal mass is determined based on energy savings, reduction of room temperature swings, and prevention of floor surface overheating. Control of auxiliary heating based on a room effective (operative) temperature is shown to result in improved thermal comfort and higher utilization of passive solar gains as compared to room air temperature control.     

Experimental investigation and theoretical analysis of the solar adsorption cooling system in a green building

A solar adsorption cooling system was constructed in the green building of Shanghai Institute of Building Science. The system consisted of evacuated tube solar collector arrays of area 150 m², two adsorption chillers with nominal cooling capacity of 8.5 kW for each and a hot water storage tank of 2.5 m³ in volume. A mathematical model of the system was established. According to experimental results under typical weather condition of Shanghai, the average cooling capacity of the system was 15.3 kW during continuous operation for 8 h. The theoretical analysis of the system was verified and found to agree well with the experimental results. The performance analysis showed that solar radiant intensity had a more distinct influence on the performance of solar adsorption cooling system as compared with ambient temperature. It was observed that the cooling capacity increased with the increase of solar collector area, whereas, solar collecting efficiency varied quite contrary. With the increase of water tank volume, cooling capacity decreased, while, the solar collecting efficiency increased. The system performances can be enhanced by increasing the height-to-diameter ratio of water tank. Additionally, it was observed that solar collecting efficiency decreased with the increase of the initial temperature of water in the tank; however, cooling capacity varied on the contrary. Also can be seen is that optimum nondimensional mass flow rate is 0.7 when the specific mass flow rate exceeds 0.012 kg/m² s.     

毛细管辐射供冷性能实验研究

以与温湿度独立空调系统相结合的毛细管辐射空调为研究对象,通过实验研究的方法研究了毛细管辐射空调采用高温水系统工况时,不同安装方式、水系统参数、空气设定参数等条件对毛细管空调供冷性能的影响。实验结果表明:裸露安装方式的毛细管辐射供冷能力约为表面与金属板结合的2倍;采用室内空气温度28℃条件比26℃条件下的供冷能力高20%～30%;通过调节流量降低泵耗的方式会使毛细管辐射空调供冷量能力降低。     

大庆地区太阳能地板辐射采暖研究与经济分析

设计了太阳能地板辐射采暖系统,给出了系统的工作原理。探讨了集热器单位面积有效利用能和集热器效率的计算方法。通过经济分析,得到大庆市某60 m2平顶民房安装太阳能地板辐射采暖的年计算费用为1 485元;安装散热器采暖年计算费用为1991元。经济分析结果表明,太阳能地板辐射采暖系统具有良好的经济效益。     

太阳能热泵低温地板辐射供暖系统的研究与展望

太阳能热泵低温地板辐射采暖系统是以太阳能热泵为热源,以地板辐射采暖系统为末端装置的新型供暖系统.本文综述了太阳能热泵在国内外的研究与应用,并阐述了太阳能热泵低温地板辐射供暖系统的工作原理及在国内的研究现状.分析了该系统的特点,结果表明该系统是一种舒适、经济和节能的理想供热系统.本文还探讨了该系统在当前的应用中尚待解决的问题.     

太阳能地板辐射采暖系统的实验与数值模拟分析

介绍了上海交通大学太阳能实验室的太阳能地板辐射采暖系统的实验情况，通过实验对该系统在连续循环运行模式下对室内热环境所产生的影响进行了研究，并与非采暖房间进行了比较。同时对整个采暖系统建立了数学模型，通过数值计算得到地板表面温度及室内空气温度动态变化，模拟结果与实验基本吻合。     

Solar hybrid cooling system for high-tech offices in subtropical climate – Radiant cooling by absorption refrigeration and desiccant dehumidification

A solar hybrid cooling design is proposed for high cooling load demand in hot and humid climate. For the typical building cooling load, the system can handle the zone cooling load (mainly sensible) by radiant cooling with the chilled water from absorption refrigeration, while the ventilation load (largely latent) by desiccant dehumidification. This hybrid system utilizes solar energy for driving the absorption chiller and regenerating the desiccant wheel. Since a high chilled water temperature generated from the absorption chiller is not effective to handle the required latent load, desiccant dehumidification is therefore involved. It is an integration of radiant cooling, absorption refrigeration and desiccant dehumidification, which are powered up by solar energy. In this study, the application potential of the solar hybrid cooling system was evaluated for the high-tech offices in the subtropical climate through dynamic simulation. The high-tech offices are featured with relatively high internal sensible heat gains due to the intensive office electric equipment. The key performance indicators included the solar fraction and the primary energy consumption. Comparative study was also carried out for the solar hybrid cooling system using two common types of chilled ceilings, the passive chilled beams and active chilled beams. It was found that the solar hybrid cooling system was technically feasible for the applications of relatively higher cooling load demand. The annual primary energy consumption of the solar hybrid cooling system was lower than that of the conventional vapour compression refrigeration system up to 36.5%. Between the two options of chilled ceilings, the passive chilled beams were more energy-efficient to work with the solar hybrid cooling system in the hot and humid climate. Harnessing solar energy for driving air-conditioning would help in reducing the carbon emission, hence alleviating the climate change.     

半透明晶体硅光伏热电制冷辐射窗的性能分析

针对一种新型半透明光伏-热电制冷辐射窗（STPV-TE-RCW）,通过实验和数值模拟方法对其热电性能进行研究,建立STPV-TE-RCW计算模型,验证其准确性,并针对STPV-TE-RCW中的热电模块不同排列形式、辐射板尺寸、散热形式等进行优化分析。在考虑结构自身发电量与耗电量关系的基础上,通过分析制冷系统COP和耗电量,认为5块热电片串联2个支路并联的热电模块排列形式,高度为1 m的辐射板尺寸和强制对流的散热形式效果更好,在这种情况下,STPV-TE-RCW的耗电量与发电量之比为0.83,制冷量能承担该结构产生的60%冷负荷,辐射铝板提供的制冷量为63.4 W/m²,热电模块的COP为1.41。