水冷式表冷器传热研究(6):机器露点表达式的建立

建立了水冷式表冷器冷盘管表面平均热状态在干工况和湿工况下的数学表达式，通过理论和实验分析了各影响因素及影响程度。指出结构特性一定的表冷器，干工况下冷盘管表面平均热状态温度和进风干球温度、冷水初湿成线性关系；湿工况下在空调常用范围内，冷盘管表面平均热状态焓值和进风焓值，冷水初温成线性关系，且两种工况下冷盘管表面平均热状态温度（或焓值）都随迎面风速增大而增大，随水流速增大而减小。     

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.     

Culturable and Total Fungi in Dust Accumulated in Air Ducts in Single-Family Houses

Abstract Fungal spore content in dust accumulated in air ducts was investigated in 24 mechanically ventilated single-family houses of which 15 had also a central air heating system. Dust was collected from the ducts simultaneously with cleaning of the ventilation systems. Besides spore concentrations and flora of culturable fungi, total fungal spore concentrations were determined in dust samples by the aqueous two-phase technique and spore counting with epifluorescence microscopy. Culturable spore concentrations in the dust varied from 10⁴ to 10⁷ CFU/g and total spore concentrations from 107 to 108 spores/g. Total spore concentrations in the duct dust were significantly higher in the air heated houses than in the other mechanically ventilated houses. The difference resulted mainly from a higher proportion of recirculation air and a higher age of the air heated houses. Cladosporium, Penicillium, Aspergillus and yeasts consisted of >90% of fungal flora in the dust. Although total spore concentrations were at the same level both in the exhaust and in the supply ducts in both types of house, culturable fungal spore concentrations were slightly higher in the exhaust ducts than in the supply ducts. The proportion of culturable spores was <5% of total spores in dust accumulated in the ducts.     

室内游泳馆防结露控制模式分析

为解决结露问题，从自控角度，按开馆和闭馆两种状态，对室内游泳馆空气温湿度进行了分析，通过降低室内空气湿度，使室内游泳馆的空气露点温度低于围护结构的内表面温度；同时提出实现自然通风的外部条件。     

An experimental study of a novel dew point evaporative cooling system

A novel dew point evaporative cooling system for sensible cooling of the ventilation air for air conditioning application was constructed and experiments were carried out to investigate the outlet air conditions and the system effectiveness at different inlet air conditions (temperature, humidity and velocity) covering dry, temperate and humid climates. The results showed that wet bulb effectiveness ranged between 92 and 114% and the dew point effectiveness between 58 and 84%. A continuous operation of the system during a typical day of summer season in a hot and humid climate showed that wet bulb and dew point effectiveness were almost constant at about 102 and 76%, respectively. The experiment results were compared with some recent studies in literature.     

The moisture content distribution of a room with radiant ceiling cooling and wall-attached jet system

Radiant ceiling cooling is a comfortable and energy saving air conditioning system, but condensation on the panels limits its application. The moisture distribution of a radiant cooling room is one of the key factors affecting the condensation of radiant panels. This paper uses a simulation model validated by experimental data to investigate the influence of wall-attached jets on the moisture content distribution of a room with radiant cooling. The influence of diffuser types and air velocities on the moisture content distribution is analyzed in the pre-dehumidification stage. This paper also studies the moisture content distribution and dew point temperature variation of the attached air layer with the cooling system operating with and without pre-dehumidification. The results show that a linear diffuser has a better attach effect, and the moisture content distribution is more uniform. The time it takes to reduce the moisture content to the design value of different diffusers is similar, approximately 25 min. With increasing air velocity and decreasing linear diffuser length, the non-uniformity coefficient (NUC) of the moisture content distribution increases and the pre-dehumidification time becomes longer. When the radiant cooling system operates without pre-dehumidification, the attached layer moisture content is high at the beginning, which may cause condensation in the first 7 min. Pre-dehumidification can decrease the moisture content and dew point temperature and effectively prevent condensation.     

Feasibility study of a novel dew point air conditioning system for China building application

The paper investigated the feasibility of a novel dew point evaporative cooling for air conditioning of buildings in China regions. The issues involved include analyses of China weather conditions, investigation of availability of water for dew point cooling, and assessment of cooling capacity of the system within various regions of China. It is concluded that the dew point system is suitable for most regions of China, particularly northern and west regions of China where the climate is hot and dry during the summer season. It is less suitable for Guangzhou and Shanghai where climates are hot and humid. However, an air pre-treatment process involving a silica-gel dehumidification will enable the technology to be used for these humid areas. Lower humidity results in a higher difference between the dry bulb and dew point of the air, which benefits the system in terms of enhancing its cooling performance. Tap water has adequate temperature to feed the system for cooling and its consumption rate is in the range 2.6–3 litres per kWh cooling output. The cooling output of the system ranges from 1.1 to 4.3 W per m³/h air flow rate in China, depending on the region where the system applies. For a unit with 2 kW of cooling output, the required air volume flow rate varies with its application location and is in the range 570–1800 m³/h. For a 50 m² building with 60 W/m² cooling load, if the system operates at working hours, i.e., 09:00 to 17:00 h, its daily water consumption would be in the range of 60–70 litres. Compared with mild or humid climates, the dry and hot climates need less air volume flow rate and less water.     

用排水板治理地下室结露施工技术

湿热空气遇到低于露点温度的冷表面,就会产生结露现象,严重破坏了墙体的美观性、安全性和实用性。本文以某住宅项目地下室工程结露现象为例,介绍了采用DELTA-PT排水板进行治理的施工工艺。     

Determination of fungal spore release from wet building materials

The release and transport of fungal spores from water-damaged building materials is a key factor for understanding the exposure to particles of fungal origin as a possible cause of adverse health effects associated to growth of fungi indoors. In this study, the release of spores from nine species of typical indoor fungi has been measured under controlled conditions. The fungi were cultivated for a period of 4-6 weeks on sterilized wet wallpapered gypsum boards at a relative humidity (RH) of approximately 97%. A specially designed small chamber (P-FLEC) was placed on the gypsum board. The release of fungal spores was induced by well-defined jets of air impacting from rotating nozzles. The spores and other particles released from the surface were transported by the air flowing from the chamber through a top outlet to a particle counter and sizer. For two of the fungi (Penicillium chrysogenum and Trichoderma harzianum), the number of spores produced on the gypsum board and subsequently released was quantified. Also the relationship between air velocities from 0.3 to 3 m/s over the surface and spore release has been measured. The method was found to give very reproducible results for each fungal isolate, whereas the spore release is very different for different fungi under identical conditions. Also, the relationship between air velocity and spore release depends on the fungus. For some fungi a significant number of particles smaller than the spore size were released. The method applied in the study may also be useful for field studies and for generation of spores for exposure studies.     

计算机模拟在大空间建筑幕墙结露分析中应用

应用IES软件建立大空间三维几何模型,分层模拟冬季及夏季的室内热环境,选用相关参数作为CFD分析的边界条件.根据该边界条件,利用STAR-CD软件对大空间内各点的空气温度进行CFD模拟分析,通过幕墙最不利点表面温度同露点温度的比较,进行结露分析.     

LPG等压强制气化过程的再液化和水分冷凝

通过等压强制气化过程中各阶段液化石油气露点和水蒸气分压的计算，得出露点和水蒸气分压与环境温度、液化石油气成分之间的关系。分析了再液化或水分冷凝的可能性，提出了防范措施。     

Investigation of moisture condensation on papermaking plant envelopes in high humidity environment by orthogonal analysis and CFD simulation

The objective of this study is to investigate the problem of moisture condensation on papermaking plant envelopes in high humidity environment. In this study, orthogonal experiment method is combined with CFD simulation to explore how moisture condensation varies with governing factors, such as the thermal parameters of building envelopes, temperature and humidity distributions or ventilation and air distribution. The criteria used by our work to determine whether the condensation will occur on envelopes are to calculate the temperature differences between the inner surface and the air dew point near the envelopes. Specifically, the temperature differences have a linear relationship with the governing parameters, and a first-order linear regression equation is derived, which is validated by data from investigation and measurement. This research provides theoretical support and measurement data for solutions of the envelope condensation problems and anti-condensation design of HVAC systems in papermaking plants.     

香港地区应用干式风机盘管系统节能和室内空气品质分析

冷板辐射加置换通风空词系统在保证室内环境的前提下比常规全空气空调系统节能,但在天气湿热的香港地区应用会出现冷板凝露现象,且采用置换通风方式,风量有限从而影响热舒适性.本文将干式风机盘管系统与独立除湿通风系统组合应用于香港地区办公楼,干式风机盘管系统处理室内显热负荷,独立除湿通风系统承担室内湿负荷和室外全热负荷.采用EnergyPlus软件模拟分析了该空调系统在香港地区某办公楼中的使用性能,结果表明该系统能很好地控制室内温、湿度,特别是湿度,与常规全空气空调系统相比,全年节能达10.3%.     

宿州地区气候潮湿强度指标特征研究

本文采用典型气象年法,以近30年(1989~2018年)逐时气象参数为计算依据,分析研究了宿州地区空气潮湿程度年分布特征与变化规律。以典型气象年自然通风工况下建筑围护结构内表面结露为判定特征指标,定义了结露温度基数。当室外逐日干球温度与露点温度的差值低于结露温度基数时,其差值倒数的累加值为潮湿强度值。研究表明宿州地区全年潮湿程度呈现季节性变化,夏季气候潮湿强度出现极大值达到15.31 d/℃,全年占比35%,潮湿程度出现最大38天。冬季出现极小值7.84 d/℃,全年占比18%,潮湿程度出现最小18天。各月中7月潮湿强度值最大,2月最小。全年潮湿强度值达到43.35 d/℃,潮湿程度出现98天。自然气象年中与前20年比较近10年潮湿强度均值下降16%,表明宿州地区气候有偏干燥的趋势。     

通风管道材料性能分析及选择

就中央空调系统中常用的镀锌薄钢板风管、无机玻璃钢风管、复合玻纤板风管三种通风管道，从消声、保温、防火，防潮、漏风量、强度、重量、摩擦阻力、使用寿命、施工安装、经济、市场等各方面进行了对比分析，指出了三种风管的各项优缺点，对三种风管的优劣，给出了客观的评价，解决了通风管道材料选择的难题。     

烧结机尾大烟罩除尘系统防结露问题

分析了烧结机尾除尘系统中，除尘器滤料腐蚀的原因，确定了露点温度，论述了除尘系统防止结露的技术措施，即控制烟气的温度高于露点温度，选择了既经济又适合现场条件的方法：保温法＋混入热风直接加热法。     

Effectiveness of duct cleaning methods on newly installed duct surfaces

Two kinds of air duct cleaning methods, mechanical brushing with different brushes and compressed air cleaning, were compared in the laboratory and in newly built buildings. The ducts were contaminated either with test dust or with dust originated from a construction site. The amount of dust on the duct surface was measured with the vacuum test method and estimated visually before and after the cleaning. In addition, the cleaning times of the different techniques were compared and the amount of residual oil in the ducts was measured in the laboratory test. The brushing methods were more efficient in metal ducts, and compressed air cleaning was more efficient in plastic ducts. After the duct cleaning the mean amount of residual dust on the surface of the ducts was 相似文献   

Numerical study of a novel dew point evaporative cooling system

Dew point evaporative cooling system is an alternative to vapor compression air conditioning system for sensible cooling of ventilation air. This paper presents the theoretical performance of a novel dew point evaporative cooling system operating under various inlet air conditions (covering dry, moderate and humid climate) and influence of major operating parameters (namely, velocity, system dimension and the ratio of working air to intake air). A model of the dew point evaporative cooling system has been developed to simulate the heat and mass transfer processes. The outlet air conditions and system effectiveness predicted by the model using numerical method for known inlet parameters have been validated with experimental findings and with recent literature. The model was used to optimize the system parameters and to investigate the system effectiveness operating under various inlet air conditions.     

气溶胶颗粒在风管系统中沉降的实验研究

气溶胶颗粒是室内外空气中存在的一类重要污染物。为了研究气溶胶颗粒在风管系统中分布和沉降的规律,本文以滑石粉为代表,通过在接近实际工程的矩形镀锌钢板风管系统中释放气溶胶颗粒对其在风管系统中的沉降进行了初步实验研究。实验在不同风速下共进行了两次,并主要在风管系统中的水平直段和局部构件处测量了滑石粉的沉降量。根据滑石粉的沉降量计算出滑石粉的沉降速度,并且对比和分析了不同风速下,风管系统中不同位置的滑石粉的沉降速度。实验表明,气溶胶颗粒在水平直段的底面上的沉降速度最大,侧面上的其次,顶面上的最小;并且气溶胶颗粒的沉降速度随着风速的减小而减小。根据实验数据,分析了影响气溶胶颗粒沉降速的主要因素,包括:风速、沉降面的朝向、局部构件的形状、管道漏风。     

大连某芯片工厂墙体结露与冷凝分析

对大连某芯片工厂部分墙体结露与冷凝情况进行了分析.根据Michell饱和水气压计算公式等水蒸气的物理特性,给出了露点温度计算公式,再计算出墙体内表面温度.将二者进行比较,从而验证墙体是否结露;同时计算出墙体内部各材料层温度,求出墙体内部各材料层的饱和水蒸气分压力及各材料层实际水蒸气分压力,将两者比较,从而验证墙体内部是否出现冷凝.通过计算与分析得出:C节点处墙体将会出现冷凝现象.建议采取如下措施:C节点处采用空心砌块墙体,且新风入口的一侧加20 mm挤塑板保温层.