顶棚辐射供冷房间人体与环境换热的实验研究

辐射供冷空调系统具有舒适、节能等优点,备受国内外工程设计和研究者的关注。在此通过实验研究了顶棚辐射供冷房间在冷吊顶辐射作用下,室内空气温度、房间壁面温度、人体表面温度的变化规律。在此基础上,分析了人体与环境的对流换热及辐射换热的变化规律。研究结果表明,在辐射供冷系统开启后约60min内,辐射板表面温度、室内空气温度有显著变化,人体服装外表面温度变化比较缓慢,人体和环境的对流及辐射换热量逐步增大,系统开启60min后,上述各项趋于稳定。     

大换气量房间冬季室内热环境实测与分析

通过对顶棚辐射、散热器与热风三种采暖方式在大换气量情况下室内热状况的实测，对其热舒适性与节能效应进行了分析和讨论，指出辐射采暖可以利用墙体的蓄热能力获得节能效果，房间空气温度垂直分布状况主要取决于通风路线而非采暖方式，因而房间设有通风系统时，顶棚辐射采暖房间的舒适性要优于另外两种采暖方式。     

不同换气次数下室内热环境的模拟

供暖方式不同时，房间换气次数的高低将对室内热环境产生明显的影响。本文用数值模拟的方法对三种典型供暖方式在不同换气次数下的室内热状况分别进行了模拟和分析。结果表明，在换气量较大时，三种供暖方式对应的室内气温和热舒适指标PMV分布将具有不同的特征。因此，对于大换气量房间，供暖方式的选择应综合考虑热环境特点。     

Experimental study of thermal condition in a room with hydronic cooling radiant surfaces

This paper presents a new approach for experimental analysis of chilled or heated ceiling systems and its environment (ventilation, windows and thermal loads distribution). The work is aimed at giving a better insight to crucial parameters as the contact thermal resistance, fin effectiveness of ceiling panels, mass flow rate, supply water temperature, thermal load distribution, fenestration and ventilation system effects on the radiant ceiling capacity and comfort conditions. The experimental methodology and its discussion are also presented. A test chamber is adapted in a way to reproduce as good as possible the characteristics of a hospital room with a cooling ceiling system. The convection and radiation heat transfer coefficients to room and losses through the ceiling void are also studied. Experimental data are used to fit the uncertain parameters mentioned and improve the capacity and performance of the ceiling system, but also to evaluate the design of this HVAC system and the applicable control strategies.     

空气源户式机组地板采暖系统应用研究

为了研究空气源热泵冷热水机组作为地板采暖的热源的运行特性,以一围护结构保温良好的房间为研究对象,分别测试了热泵机组采用低水温进行供暖运行时的能效、在高低温的运行环境下供暖房间内温度的变化。结果表明,在保温性能良好的建筑,采用热泵机组以35℃的低供水温配合高效地暖盘管进行地板供暖,既能保证室内的舒适性,又具有良好的节能效果。得出用于地板采暖的空气源热泵机组,其控制开停机的温差需要比传统的空气源热泵机组大,在低温环境下,机组性能衰减的特性对室内达到相同供暖效果所需的时间影响不大,为设备、工程设计提供参考。     

新型流态冰蒸发制冷循环及制冰量性能分析

介绍了蒸发过冷水制冰原理及系统流程,分析了相应的蒸发制冷循环,对单位质量(1k)干空气制冰量性能及影响因素进行了研究并建立了相关数学模型,计算结果显示,水的初始温度越高单位质量干空气制冰量越低,而单位质量干空气制冰量相同时水温越高对应的蒸发水量则越大,同时随着空气出口相对湿度增大,单位质量干空气制冰量也随之增加.另外,...     

Direct measurements of sample heating by a laser-induced air plasma in pre-ablation spark dual-pulse laser-induced breakdown spectroscopy (LIBS)

Direct measurements of temperature changes were made using small thermocouples (TC), placed near a laser-induced air plasma. Temperature changes up to ~500 °C were observed. From the measured temperature changes, estimates were made of the amount of heat absorbed per unit area. This allowed calculations to be made of the surface temperature, as a function of time, of a sample heated by the air plasma that is generated during orthogonal pre-ablation spark dual-pulse (DP) LIBS measurements. In separate experiments, single-pulse (SP) LIBS emission and sample ablation rate measurements were performed on nickel at sample temperatures ranging from room temperature to the maximum surface temperature that was calculated using the TC measurement results (500 °C). A small, but real sample temperature-dependent increase in both SP LIBS emission and the rate of sample ablation was found for nickel samples heated up to 500 °C. Comparison of DP LIBS emission enhancement values for bulk nickel samples at room temperature versus the enhanced SP LIBS emission and sample ablation rates observed as a function of increasing sample temperature suggests that sample heating by the laser-induced air plasma plays only a minor role in DP LIBS emission enhancement.     

Local nanoscale heating modulates single-asperity friction

We demonstrate measurement and control of single-asperity friction by using cantilever probes featuring an in situ solid-state heater. The heater temperature was varied between 25 and 650 °C (tip temperatures from 25 ± 2 to 120 ± 20 °C). Heating caused friction to increase by a factor of 4 in air at ～ 30% relative humidity, but in dry nitrogen friction decreased by ～ 40%. Higher velocity reduced friction in ambient with no effect in dry nitrogen. These trends are attributed to thermally assisted formation of capillary bridges between the tip and substrate in air, and thermally assisted sliding in dry nitrogen. Real-time friction measurements while modulating the tip temperature revealed an energy barrier for capillary condensation of 0.40 ± 0.04 eV but with slower kinetics compared to isothermal measurements that we attribute to the distinct thermal environment that occurs when heating in real time. Controlling the presence of this nanoscale capillary and the associated control of friction and adhesion offers new opportunities for tip-based nanomanufacturing.     

应用CFD技术对绿化建筑空调系统的节能分析

运用CFD软件对绿化建筑的室内热环境进行模拟分析,得出有绿化的空调房间与没有绿化的房间相比,可以提高2℃送风温度同样达到原来的舒适度要求。并在此基础上对空调系统的节能进行分析、探讨,发现绿化墙体后可以使建筑物的空调能耗降低16.7%,使室内冷负荷减小41.2%,从而实现节能降耗。     

Performance comparison between a single-stage and a cascade multi-functional heat pump for both air heating and hot water supply

Multi heat pumps have been widely used in buildings due to their higher energy efficiency. Recently, demands for multi-functional heat pumps, which can provide heating, cooling, and water heating in a building, have been increased. In this study, a cascade multi-functional heat pump, combining a multi heat pump using R410A for air heating with a water heating unit using R134a for hot water supply, was investigated experimentally. The performance of the cascade multi-functional heat pump was measured by varying the refrigerant charge amount, EEV opening, water flow rate, and water inlet temperature. Test results were compared with those of a single-stage multi-functional heat pump using R410A for air and water heating. The cascade multi-functional heat pump adopting the water heating unit showed more stable air and water heating operations and higher water outlet temperatures than the single-stage multi-functional heat pump.     

冷却吊顶空调系统运行能耗的模拟与算例

提出冷却吊顶空调系统运行能耗的计算机动态模拟评价方法。在建立系统数学模型的基础上。编制计算机模拟程序，对某建筑物采用冷却吊顶系统的实际运行过程进行逐时模拟，以此来判断冷却吊顶系统应用的可行性及合理性，分析表明，冷却吊顶水系统与新风水系统相独立这一新的系统形式具有良好的节能效果。     

Some aspects of the air distribution in ventilated rooms

A number of full scale and model scale experiments on room air distribution are reported. They are compared with calculated results from a numerical procedure which solves, in finite-difference form, the two-dimensional elliptic partial differential equations for the flow. The calculated velocity, temperature and concentration distributions are shown to be in close agreement with the experimental data. Some measurements on the influence from a ceiling mounted obstacle on the two-dimensional recirculating flow in the room are also reported. Some guidelines for calculating the dimensions of an air distribution system with two-dimensional recirculating flow are given.     

Thermal conductivity and heat capacity of solid nabr under pressure

Using the transient hot-wire method, measurements were made for solid NaBr of both the thermal conductivity and the heat capacity per unit volume. The measurements were performed in the temperature range 100 to 400 K and at pressures up to 2 GPa. An adiabatic compression technique allowed the determination of the thermal expansivity as a function of pressure at room temperature. The heat capacity did not vary with pressure. Analysis of the thermal conductivity data showed that it can be described adequately by the Leibfried-Schlömann formula. For temperatures up to 400 K only acoustic modes needed to be taken into account. A small contribution of optic modes to the heat transport might be apparent at the highest temperatures.     

辐射吊顶供冷房间结露特性研究

本文通过实验研究和数值模拟相结合的手段,研究了辐射供冷系统启动阶段辐射板表面温度变化及系统稳定阶段人体散湿的强度和人员散湿的位置对结露特性的影响,结果表明:在系统启动阶段单独运行辐射供冷系统6 min后就会发生结露现象,所以在系统启动阶段要及时采取有效的预除湿措施,在此过程中,辐射板表面温度的降低比人体散湿强度的变化对结露的时间的影响更显著;在系统稳定阶段,每增加一个成年男子轻度劳动时的散湿量,结露提前12 min左右发生,人体所在位置的辐射板比其他位置处辐射板先发生结露,在防止结露时,应重点监测人体上方区域的辐射板的表面温度。     

基于溶液除湿的辐射空调系统的初步研究

针对辐射板空调系统用于高热、高湿地区夏季供冷时辐射板表面结露的问题,提出基于热、湿负荷分开处理的液体除湿辐射空调系统；该系统采用LiCl溶液作为除湿剂,除湿干空气承担空调房间的湿负荷；对除湿后的干空气直接蒸发冷却,使空调回水降温,负担空调房间的热负荷；该系统具有辐射空调节能、舒适的优点,避免了表面结露的问题,同时不需要另外添加冷水机组,节约系统初投资,此外还考虑了能量回收和太阳能的利用。     

Thermal effects in model specimens under acoustic and convective actions

The temperatures of three model specimens placed in a nonheated air flow under convective and acoustic drying have been measured. It has been shown that in the dry specimens containing no water there occurs an appreciable heating of the internal region of the specimens by the acoustic field. The values of the moistureexchange coefficients of the specimens averaged over the drying period have been found. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 2, pp. 168–173, March–April, 2006.     

Thermal analysis of building roof assisted with water heater and insulation material

Traditional roof systems are constructed with concrete and weathering coarse layer and these roof systems absorb and reflect a certain amount of solar radiation. The absorbed solar energy is transferred into building indoor and causes significant discomfort to the occupants. Also, this solar energy gets dissipated without any useful energy conversion. Hence this paper is focused to use the available solar energy effectively through a novel solar water heating system and the transfer of heat in the building indoor is arrested by proper roof insulation material. The modified insulated roof with the solar water heater is designed and simulated numerically in commercial computational fluid dynamics code with validation. Through this study, the factors that affect the performance of solar water heating system and thermal insulation capacity are analysed and the best design of the modified roof system is identified. The modified roof system produces 25 L of hot water per day with a temperature raise of 60°C in the winter season. Also, the same roof system maintains the ceiling temperature at about 27°C for a complete day in a summer season.     

空调器送风参数对房间速度场和温度影响的计算模拟和试验研究

本文对天花板嵌入式空调器工作的房间,建立了空气流动的三维紊流数学模型,对不同送风参数下的流场和温度场做了计算.并对计算结果进行分析,总结出送风参数对空调房间的气流流动与温度分布的影响规律.又搭建试验台,对不同送风参数下空调房间的温度场和速度场进行试验研究.用小尺度实体模型试验的方法,首次把PIV新技术运用到空调房间流场的测量上.测试结果与计算结果吻合较好,验证了建立的数字模型的正确性,也验证了PIV技术可以运用到大空间的流场测量上.最后利用气流理论对嵌入式空调器不同送风参数下的房间温度场和流场进行了评价.     

大空间下送风分层空调的同步求解模型的研究

提出了一种大空间下送风分层空调环境下的同步求解模型,用于预测室内空气垂直温度分布和内壁面温度分布以及下送风环境下的空调冷负荷;进行了大空间建筑下送风环境下的夏季热环境实验,实测室内空气垂直温度分布和内壁面温度分布以及夏季冷负荷,并验证对比了实验值和模型计算值,结果表明温度数据吻合良好,冷负荷的相对误差小于10％.     

重庆地区高大空间冬季空调供暖实测分析

以重庆市的三栋不同功能、不同气流组织形式的高大空间建筑大厅为研究对象,分别对其进行冬季空调供暖实测分析,得到了分层空调与全室空调冬季工况温度场、速度场分布与运行能耗。针对两种送风方式的特点,对其实际运行情况进行了分析与比较,找出影响舒适性和运行能耗的主要因素,并针对设计和运行管理中出现的问题提出了建议。实测分析对高大空间建筑热环境设计和空调设计具有一定的指导意义。