空调排风热回收在我国应用节能潜力分析

介绍空调排风热回收系统的工作原理,对不同地区的室外温度、焓值的逐时变化参数进行分析.在气象数据基础上动态分析我国不同典型气候区域城市热回收的适应性及热回收方式的选择,并对热回收节能潜力进行分析,进而得出热回收系统在我国不同气候区域的适应范围,研究表明排风热回收装置在我国节能效果明显.     

多级蒸发冷却在化工厂变频器室通风降温的应用

介绍传统变频器室的降温方式以及多级蒸发冷却技术的特点,并以贵州福泉某变频器室为例,进行多级蒸发冷却通风降温设计,通过与传统机械全面通风降温及单元式空调柜机降温方案进行比选,可以得出多级蒸发冷却通风降温系统在节能方面和运行投资方面均具有很大的优势,为该系统在贵州地区的应用提供技术参考.     

谈谈普通家庭夏天降温节电的有效措施

1 我国近几年,每年出现连续多天的酷热高温天气,影响着千家万户的日常生活,如何克服夏天酷热,切实降低家庭内环境温度,这是大家关注的话题.上述内容属通风降温、空气调节专业范畴,涉及房屋结构、地区热环境,空调工程与单元技术等条件因素,还有人的生活习惯、年龄、健康等.现实急需降温,目前只能因地制宜,把现有可实施通风降温的器材物资积极的组合使用,力求既降温又节电,减少经济开支.     

人体散湿对严寒地区办公建筑全热回收的影响

我国北方严寒地区冬季室外寒冷且干燥,潜热量较少,但办公建筑室内人流量较大,人体散湿不能被忽视。通过模拟分析以及实测对比,探究人体散湿对办公建筑室内湿量的影响。结果显示,人数越多,室内相对湿度越大。例如在人均面积3m~2的情况下,人员停留时间4h可使室内相对湿度上升约24%。因此,在考虑选择热回收器种类时,全热回收器仍可作为选择且有良好的应用潜力。     

通风斜屋顶隔热性能及气候适应性分析

对在热压作用下的通风斜屋顶传热过程进行分析,并建立相应的通风屋顶模型,运用CFD数值模拟技术研究其在不同的气候因素（太阳辐射及室外空气温度）下的隔热性能表现,结果表明：太阳辐射强度的增加有利于增强通风屋顶的隔热性能,而室外空气温度的增加则作用相反,且其对屋顶隔热性能的影响要大于太阳辐射强度;对于通风层间距较大的通风屋顶,其隔热性能还应考虑通风层内非边界层空气厚度的热阻影响。分析了通风屋顶在不同地区的隔热性能表现,分析其气候适应性,结果表明,通风屋顶在室外气温低且太阳辐射强度大的地区会拥有更好的隔热性能表现。     

太阳能反季节蓄热采暖蓄冷降温技术研究(2)

三对25个典型气候省会城市及直辖市的计算分析所选25个省会城市及直辖市哈尔滨、长春、沈阳、呼和浩特、西宁、乌鲁木齐、拉萨、兰州、银川、太原、石家庄、北京、天津、西安、郑州、济南、合肥、上海、南京、杭州、南昌、武汉、长沙、重庆及成都代表了我国严寒、寒冷、夏热冬冷建筑气候区的主要经济区域。     

瓦斯发电机房通风降温问题研究

叙述了针对瓦斯发电机房隔声与通风降温之间产生的矛盾,对通风量计算的依据、过程以及各种通风降温方式的比较结果。     

严寒地区内廊式教学楼室内自然通风的优化

严寒地区建筑虽以保温为主,但也应适量引进自然风以改善室内空气品质、提高舒适度和降低能耗。针对我国严寒地区内廊式教学楼面临的室内通风不畅、空气质量差、空调能耗高等问题,本文以呼和浩特市为例,通过Weather tool软件对该地区风环境进行了分析,得出建筑通风良好的朝向,再利用Airpak软件优化教学楼的走廊、教室、侧窗及高窗,并根据各要素与室内适宜的风速区面积占比进行了灵敏度分析,为严寒地区内廊式教学楼的通风优化提供了参考和实践指导。     

太阳能供热采暖技术讲座（1）太阳能采暖的意义、特点及分类

一太阳能采暖的意义 利用太阳能加热的系统,既可以为用户提供生活热水,又可供建筑物采暖.我国气候大体可划分为严寒、寒冷、夏热冬冷、夏热冬暧、温和五大热工地区.其中,东北、华北和西北(简称"三北"地区)全年累计日平均温度等于或低于5℃的天数,一般都在90天以上,最多(满洲里)达211天.历年来习惯将这些地区称之为采暖地区,其总面积约占全国国土面积的70%.     

建筑节能浅议

0前言一个国家的经济越发达，建筑能耗也就越高。建筑的能源消耗量已成为衡量一个国家经济技术水平的一个重要标志。根据一些资料分析，我国建筑能耗，（包括建材生产用能和现场施工用能及日常采暖用能等）约占国民经济总能耗的30％～40％。我国北方寒冷及严寒地区，供热能耗约     

Performance evaluation of passive cooling in office buildings based on uncertainty and sensitivity analysis

Natural night ventilation is an interesting passive cooling method in moderate climates. Driven by wind and stack generated pressures, it cools down the exposed building structure at night, in which the heat of the previous day is accumulated. The performance of natural night ventilation highly depends on the external weather conditions and especially on the outdoor temperature. An increase of this outdoor temperature is noticed over the last century and the IPCC predicts an additional rise to the end of this century. A methodology is needed to evaluate the reliable operation of the indoor climate of buildings in case of warmer and uncertain summer conditions. The uncertainty on the climate and on other design data can be very important in the decision process of a building project.The aim of this research is to develop a methodology to predict the performance of natural night ventilation using building energy simulation taking into account the uncertainties in the input. The performance evaluation of natural night ventilation is based on uncertainty and sensitivity analysis.The results of the uncertainty analysis showed that thermal comfort in a single office cooled with single-sided night ventilation had the largest uncertainty. The uncertainties on thermal comfort in case of passive stack and cross ventilation were substantially smaller. However, since wind, as the main driving force for cross ventilation, is highly variable, the cross ventilation strategy required larger louvre areas than the stack ventilation strategy to achieve a similar performance. The differences in uncertainty between the orientations were small.Sensitivity analysis was used to determine the most dominant set of input parameters causing the uncertainty on thermal comfort. The internal heat gains, solar heat gain coefficient of the sunblinds, internal convective heat transfer coefficient, thermophysical properties related to thermal mass, set-point temperatures controlling the natural night ventilation, the discharge coefficient C_d of the night ventilation opening and the wind pressure coefficients C_p were identified to have the largest impact on the uncertainty of thermal comfort.The impact of the warming climate on the uncertainty of thermal comfort was determined. The uncertainty on thermal comfort appeared to increase significantly when a weather data set with recurrence time of 10 years (warm weather) was applied in the transient simulations in stead of a standard weather data set. Natural night ventilation, designed for normal weather conditions, was clearly not able to ensure a high probability of good thermal comfort in warm weather. To ensure a high probability of good thermal comfort and to reduce the performance uncertainty in a warming climate, natural night ventilation has to be combined with additional measures. Different measures were analysed, based on the results of the sensitivity analysis. All the measures were shown to significantly decrease the uncertainty of thermal comfort in warm weather. The study showed the importance to carry out simulations with a warm weather data set together with the analysis under typical conditions. This approach allows to gain a better understanding of the performance of a natural night ventilation design, and to optimize the design to a robust solution.     

Cooling-energy reduction in air-conditioned offices by using night ventilation

Night ventilation has been applied successfully to many passively-cooled or low-energy office buildings. This paper investigates the applicability of night ventilation in air-conditioned office buildings. A thermal and ventilation simulation model, together with suitable weather data were used to examine the potential for energy savings and/or improved internal comfort conditions by applying night ventilation cooling. It was found that natural ventilation strategies could save cooling energy in typical air-conditioned offices. However, the use of mechanical ventilation could lead to increased energy-consumption. If typical offices are modified to incorporate features assisting the application of night ventilation, then cooling energy could be saved when mechanical ventilation is used and further reduced in the case of natural ventilation. Such features would include exposed thermal mass or offices designed to ‘best practice’ guidelines, such as airtight construction and minimisation of internal and solar heat gains.     

单一地板辐射供冷空调方式适用区域的划分

叙述了不加置换通风等其他空气处理方式单一地板辐射供冷空调系统的局限性和可行性以及结合中国各主要城市逐时气象参数,对普通住宅建筑,划分了单一地板辐射供冷空调方式的适用区域。     

Night ventilation control strategies in office buildings

In moderate climates night ventilation is an effective and energy-efficient approach to improve the indoor thermal environment for office buildings during the summer months, especially for heavyweight construction. However, is night ventilation a suitable strategy for office buildings with lightweight construction located in cold climates? In order to answer this question, the whole energy-consumption analysis software EnergyPlus was used to simulate the indoor thermal environment and energy consumption in typical office buildings with night mechanical ventilation in three cities in northern China. The summer outdoor climate data was analyzed, and three typical design days were chosen. The most important factors influencing night ventilation performance such as ventilation rates, ventilation duration, building mass and climatic conditions were evaluated. When night ventilation operation time is closer to active cooling time, the efficiency of night ventilation is higher. With night ventilation rate of 10 ach, the mean radiant temperature of the indoor surface decreased by up to 3.9 °C. The longer the duration of operation, the more efficient the night ventilation strategy becomes. The control strategies for three locations are given in the paper. Based on the optimized strategies, the operation consumption and fees are calculated. The results show that more energy is saved in office buildings cooled by a night ventilation system in northern China than ones that do not employ this strategy.     

Performance of a heat pipe assisted night sky radiative cooler

A passive radiative cooling system was designed, constructed and tested under clear skies. This refrigerator operates by losing heat to the night sky through infrared (i.r.) radiation emission. It consists of a radiator, an array of heat pipe elements and a cold chamber. The heat pipe elements are so arranged that they act as thermal diodes, transferring heat from the cold chamber to the radiator. Performance tests show that the system has a cooling capacity of 628 kJ/m² per night with a sky coefficient of performance of 0.26. The lowest temperature attained in the cold chamber was 12.8°C for an ambient temperature of 20°C. The overall results indicate that the system has a great potential for providing a cold storage facility in developing countries and in remote areas.     

Night cooling and ventilation design for office-type buildings

The suitability of night ventilation for cooling is first discussed by presenting a plot of summer weather conditions on the bioclimatic chart and by reporting on the results of energy and ventilation simulations of a typical UK office module. The development of a simplified design tool suitable for the early stages of design process is then described. For this model, user input is limited to a few key variables and the technique allows the designer to explore rapidly the effects of a range of design variables including variable external temperatures, internal gains and ventilation rates during the day and night.     

Thermal mass and night ventilation as passive cooling design strategy

We calculated the influence of thermal mass and night ventilation on the maximum indoor temperature in summer. The results for different locations in the hot humid climate of Israel are presented and analyzed. The maximum indoor temperature depends linearly on the temperature difference between day and night at the site. The fit can be applied as a tool to predict from the temperature swing of the location the maximum indoor temperature decrease due to the thermal mass and night ventilation. Consequently, the fit can be implemented as a simple design tool to present the reduction in indoor temperature due to the amount of the thermal mass and the rate of night ventilation, without using an hourly simulation model. Moreover, this design tool is able to provide for the designer in the early design stages the conditions when night ventilation and thermal mass are effective as passive cooling design strategy.     

Bedroom ventilation: Attitudes and policies

A behavioural study by Brundrett in 1977 indicated that in the U.K. a substantial number of persons slept with their bedroom windows open. Such a habit, if it prevailed during cold weather, could lead to considerable energy losses. However Brundrett's sample was small and the data, which were gathered in the summer, might reflect behaviour which varied with the seasons and so were biased. The present investigation questioned a larger sample during the winter. The questionnaire also invited respondents to cite the ill-effects from which they might suffer if their bedroom window were closed all night. The results generally confirmed Brundrett's indications regarding the prevalence of window opening. The reasons for it appear to be related to beliefs regarding ventilation and health. These could have their origins in the writings of Florence Nightingale.     

Energy performance of a hybrid space-cooling system in an office building using SSPCM thermal storage and night ventilation

Thermal performance of a hybrid space-cooling system with night ventilation and thermal storage using shape-stabilized phase change material (SSPCM) is investigated numerically. A south-facing room of an office building in Beijing is analyzed, which includes SSPCM plates as the inner linings of walls and the ceiling. Natural cool energy is charged to SSPCM plates by night ventilation with air change per hour (ACH) of 40 h⁻¹ and is discharged to room environment during daytime. Additional cool-supply is provided by an active system during office hours (8:00-18:00) necessary to keep the maximum indoor air temperature below 28 °C. Unsteady simulation is carried out using a verified enthalpy model, with a time period covering the whole summer season. The results indicate that the thermal-storage effect of SSPCM plates combined with night ventilation could improve the indoor thermal-comfort level and save 76% of daytime cooling energy consumption (compared with the case without SSPCM and night ventilation) in summer in Beijing. The electrical COPs of night ventilation (the reduced cooling energy divided by fan power) are 7.5 and 6.5 for cases with and without SSPCM, respectively.     

Cooling strategies,summer comfort and energy performance of a rehabilitated passive standard office building

One of the first rehabilitated passive energy standard office buildings in Europe was extensively monitored over two years to analyse the cooling performance of a ground heat exchanger and mechanical night ventilation together with the summer comfort in the building. To increase the storage mass in the light weight top floor, phase change materials (PCM) were used in the ceiling and wall construction. The earth heat exchanger installed at a low depth of 1.2 m has an excellent electrical cooling coefficient of performance of 18, but with an average cooling power of about 1.5 kW does not contribute significantly to cooling load removal. Mechanical night ventilation with 2 air changes also delivered cold at a good coefficient of performance of 6 with 14 kW maximum power. However, the night air exchange was too low to completely discharge the ceilings, so that the PCM material was not effective in a warm period of several days. In the ground floor offices the heat removal through the floor to ground of 2–3 W m⁻² K⁻¹ was in the same order of magnitude than the charging heat flux of the ceilings. The number of hours above 26 °C was about 10% of all office hours. The energy performance of the building is excellent with a total primary energy consumption for heating and electricity of 107–115 kW h m⁻² a⁻¹, without computing equipment only 40–45 kW h m⁻² a⁻¹.