列车经过某单线无竖井隧道时的活塞风速计算

采用非恒定流活塞风计算理论,按列车行驶在隧道中的不同位置分四种情况计算活塞风风速,并通过MATLAB软件进行数值求解,得到列车经过某区间隧道时的活塞风速度,为地铁环控系统设计中计算活塞风引起的空调能耗以及降低地铁能耗提供一定的参考。     

太阳能溶液除湿空调系统的室内热舒适性模拟

结合高温高湿地区的气候特点,设计一种新型的太阳能溶液除湿空调系统,并通过CFD模拟软件Airpak对采用太阳能溶液除湿空调系统的室内舒适性进行模拟分析。模拟主要是在稳态的情况下采用对比分析的方法对同一房间分别采用太阳能溶液除湿辐射空调系统和传统一次回风空调系统进行模拟,对比分析使用这2种空调系统的室内热舒适环境,主要包括室内温度、湿度和风速。结果表明:模拟房间1人体活动区域内温度基本保持在约26℃,相对湿度在55%～60%之间,风速在0.05～0.15 m/s之间,温度和相对湿度分布较为均匀,无吹风感,热舒适性较强;而模拟房间2人体活动区域内温度基本保持在约24℃,相对湿度在40%～80%之间,风速在0.3～0.5 m/s之间,温度和相对湿度分布的均匀性较差,有吹风感,热舒适性较差。设计的太阳能溶液除湿空调系统的室内温度、湿度及速度均分布均匀、波动小且都在相应的舒适区内,室内速度场及室内热湿环境比传统空调系统优越,克服了传统溶液除湿空调系统在热湿地区的应用限制,且可充分利用热湿地区丰富的太阳能等可再生能源,并为高温高湿地区空调系统的节能改造提供一种有益参考。     

建筑围护结构相变蓄热与自然通风技术耦合模拟分析——以合肥地区为例

随着人们对建筑室内热舒适性要求的提高,建筑能耗,尤其是供暖、通风和空调系统的能耗也在不断增加,因此建筑节能潜力巨大的通风蓄热储能系统受到越来越广泛的关注。以位于夏热冬冷地区的合肥为研究地域,对3种非相变围护结构材料和相变围护结构材料的蓄热与自然通风耦合过程进行非稳态模拟研究,通过分析室内风速场分布和温度场分布,获得合肥地区建筑围护结构的自然通风与不同材料蓄热耦合规律,为改善建筑室内热环境、降低建筑能耗以及被动式建筑设计与开发提供理论依据。     

YW25G型空调硬卧列车车厢内热舒适性研究

从满足旅客的热舒适性出发,研究空调列车室内空气的流动及温度分布情况至关重要。以YW25G型空调硬卧列车车厢为研究对象,物理模型中考虑了旅客以及车厢内各障碍物（包括边桌、行李架、床铺、折座等）等的影响,采用k-ε湍流模型对车厢内三维湍流流动和传热进行了数值模拟,研究车厢内流场及温度场的分布变化规律,从而获得热舒适性指标PMV值的分布情况。研究结果表明：整个车厢内的流场及温度场关于隔间存在良好的对称性;硬卧车厢内各区域的热舒适性优劣排序依次是：过道区域、下铺区域、中铺区域、上铺区域;合理的铺位纵向间隔有利于旅客的散热。研究结果对如何改善列车车厢内热舒适性提供了重要参考。     

空调列车运行能耗调查与分析

本文以K135次（长沙-上海)空调列车为例，介绍了我国空调列车的运行能耗状态，其中包括耗油量、发电量和用电量，并对用电量的构成进行了调查和分析。研究结果表明：能耗随季节变化而变化，冬、夏两季的能耗最大，且夏季大于冬季，过渡季节的能耗较小；在用电量的构成中，空调设备耗电量最大，约点总耗电量的70%，通过对空调列车能耗的分析，找到了影响空调列车运行能耗的关键因素，并提出了节能的合理化建议。     

太阳能驱动转轮空调在近零能耗建筑中的应用

为实现近零能耗建筑能耗指标，提出一种热管型转轮除湿空调系统应用于湿热地区近零能耗建筑，并可通过三种太阳能系统驱动。在TRNSYS中进行建模，用搭建的实验平台进行实验验证。动态模拟太阳能驱动转轮空调系统全年运行情况。模拟结果表明：室外新风经太阳能驱动转轮空调系统处理后，可使室内温湿度满足人体热舒适性要求，其中采用光伏光热系统的热管型转轮除湿空调系统的耗电量最低，性能系数（COP）最高可达2.1，与传统空调系统相比，COP提高两倍，年平均能耗降低64.7%。     

办公建筑空调水系统形式分析

两管制空调水系统与四管制空调水系统均为办公建筑常见的水系统配置,具体选择则是室内热舒适性、系统初投资和运行能耗权衡的结果。本文对南京市一幢采用变风量空调系统的办公建筑进行了相关分析,以供参考。     

基于载客量的地铁车厢冬季热舒适研究

以郑州地铁为例,对车厢热环境与乘客数量进行现场实测,对空载、半载、满载这3种工况车内温度进行对比分析,得到地铁车厢的空调设定应考虑载客量的情况分早晚高峰时段和日间平峰时段进行设定。模拟高峰满载和平峰半载车厢不同送风温度、送风速度的热环境状况,最后根据PMV指标对其进行热舒适评价,提出地铁车厢冬季平峰期与高峰期的空调设计参数,以期在满足乘客舒适性的同时降低空调能耗,为车厢的温度设定、地铁热舒适的改善提供参考。     

室温传感器偏差故障对武汉地区暖通空调系统的影响研究

暖通空调系统的高效节能运行高度依赖于传感器测量的准确性。在传感器全寿命运行周期中,不可避免发生各种故障,影响其准确性。为探究传感器故障对不同暖通空调系统的影响,文章以室温传感器偏差故障为例,针对武汉地区某办公建筑,同时开展地源热泵和"冷水机组+锅炉"两种暖通空调系统形式的能耗建模,对比分析-5℃~+5℃偏差故障对两种系统运行能耗、工作性能及室内热舒适性的影响差异。结果表明:室温传感器故障的偏差幅值方向对两种系统运行能耗、工作性能及室内热舒适性的影响规律不同。其中,地源热泵系统能耗受室温传感器偏差故障影响相对更小。     

超市空调的室内设计参数与总能耗

目前有关超市的室内设计温、湿度对环境舒适性影响的研究匮乏，对超市空调和制冷的相互作用往往忽视或误解。在综合分析了超市室内温度、相对湿度对超市环境舒适性、超市空调能耗、陈列柜能耗的影响后，找出了超市夏季空调最佳温、湿度设定点。     

不同送风方式对热舒适度的影响

为了研究不同送风方式对空调房间内舒适度的影响,用实验方法测得下送风、侧送风和上送风3种方式下空调房间不同位置的热舒适度。实验结果表明,空调房间侧送风方式下的舒适性最好,此结论可为空调房间的设计提供参考。     

Efficiency assessment of indoor environmental policy for air-conditioned offices in Hong Kong

To reduce carbon dioxide (CO₂) emissions through thermal energy conservation, air-conditioned offices in the subtropics are recommended to operate within specified ranges of indoor temperature, relative humidity and air velocity. As thermal discomfort leads to productivity loss, some indoor environmental policies for air-conditioned offices in Hong Kong are investigated in this study with relation to thermal energy consumption, CO₂ emissions from electricity use, and productivity loss due to thermal discomfort. Occupant thermal response is specifically considered as an adaptive factor in evaluating the energy consumption and productivity loss. The energy efficiency of an office is determined by the productivity which corresponds to the CO₂ generated. The results found that a policy with little impact on occupant thermal comfort and worker productivity would improve the office efficiency while the one with excessive energy consumption reduction would result in a substantial productivity loss. This study is a useful reference source for evaluating an indoor thermal environmental policy regarding the energy consumption, CO₂ emissions reduction, thermal comfort and productivity loss in air-conditioned offices in subtropical areas.     

Thermal comfort standards for air conditioned buildings in hot and humid Thailand considering additional factors of acclimatization and education level

This paper presents the result of a large thermal comfort survey conducted using 1520 Thai volunteers from different climatic regions of Thailand. The survey was conducted using different types of air-conditioned buildings from the private and public sectors.Apart from common thermal comfort factors such as air dry bulb temperature, relative humidity and air velocity, two non-quantifiable factors were considered. These are the acclimatization to the use of air conditioner at home and the education level, i.e., post graduate, graduate and scholar. A general database for thermal comfort studies in Thailand was created, and different thermal comfort standards were developed for the three climatic regions of Thailand. Twenty six degree Celsius and 50–60% relative humidity could be used as a comfortable environment condition for the whole country. The data was then used to generalize an earlier concept we developed for setting thermal comfort standard using data from non air-conditioned buildings.     

Earth-to-air heat exchangers for Italian climates

The European Energy Efficiency Building Directive 2002/91/CE, as well as other acts and funding programs, strongly promotes the adoption of passive strategies for buildings, in order to achieve indoor thermal comfort conditions above all in summer, so reducing or avoiding the use of air conditioning systems.In this paper, the energy performances achievable using an earth-to-air heat exchanger for an air-conditioned building have been evaluated for both winter and summer. By means of dynamic building energy performance simulation codes, the energy requirements of the systems have been analysed for different Italian climates, as a function of the main boundary conditions (such as the typology of soil, tube material, tube length and depth, velocity of the air crossing the tube, ventilation airflow rates, control modes). The earth-to-air heat exchanger has shown the highest efficiency for cold climates both in winter and summer.The possible coupling of this technology with other passive strategies has been also examined. Then, a technical-economic analysis has been carried out: this technology is economically acceptable (simple payback of 5–9 years) only in the cases of easy and cheap moving earth works; moreover, metallic tubes are not suitable.Finally, considering in summer a not fully air-conditioned building, only provided with diurnal ventilation coupled to an earth-to-air heat exchanger plus night-time ventilation, the possible indoor thermal comfort conditions have been evaluated.     

Thermal comfort in Japanese schools

Comfort standards (ASHRAE 55, ISO 7730) specify exact physical criteria for producing acceptable thermal environments, which include temperature, air movement, and humidity limits that are often difficult to comply with, particularly in the subtropical climate of Japan. Changing expectations of comfort are important in evaluating comfort since schools in Japan are not typically air-conditioned. With the rapid growth of school buildings in the US and all over the world, provisions for comfort are critical to student performance and occupant well-being. Are these temperate-climate, air-conditioning based standards applicable in these locations? This paper builds upon previous thermal comfort work that has focused primarily on office environments. For this project we adapt traditional methods of data collection and inquiry for use in the school environment. During the late summer 2000, we conducted surveys in naturally ventilated and air-conditioned schools, polling responses from 74 students, while simultaneously measuring indoor climate variables. Air-conditioned classrooms had conditions within the comfort zone, causing occupants to report ‘slightly cool’ thermal sensations. The naturally ventilated classrooms were 3 °C warmer than the air-conditioned classrooms and occupants voted that conditions were also within the central three categories (surrounding neutral) of the ASHRAE thermal sensation scale—therefore equated with comfort. These ‘neutral’ sensations, however, do not correlate to people’s preferred thermal state. Comfort responses are discussed in terms of comparisons to ASHRAE Standard 55-92 Thermal Conditions for Human Occupancy.     

Thermal comfort enhancement by using a ceiling fan

A parametric analysis on the effect of using a ceiling fan in an air-conditioned room is performed by two-dimensional (2D) numerical simulation of steady state airflow and heat transfer. Thermal comfort analysis is done for a person standing in a room with an inlet and an outlet for air conditioning and a ceiling fan. Representative three-dimensional (3D) simulation is also performed for the comparison of results obtained by using 2D and 3D models. Distributions of velocity, temperature, and relative humidity are presented. Different cases in which the ceilings fan may be not in use or in use with different air speed normal to the plane of fan blades due to different rotational speeds are considered. Predicted mean vote is computed and used to assess the thermal comfort characteristics. It is found that as the normal air speed from the fan increases, thermal comfort significantly shifts toward the cooler scale to allow higher supply air temperature or higher heat load in the room while maintaining the same comfort level.     

Temperature distributions in air-conditioned rooms

This paper contributes to a better understanding of the parameters which influence the thermal comfort achievable in an air-conditioned room. First, simplified relationships were established to enable a study to be made of the temperature distribution using reduced scale models. A prototype and a 0·3 scale model were constructed. An experimental technique for measuring the air temperature at various points in the two rooms was then established. Experiments to test the validity of the similarity criteria were next carried out.A study was then made, for various supply conditions, of the temperature distribution in a room heated by blown hot air. In this way it was shown that the Archimedes number could be considered a characteristic number for the room air supply. The limit values required for good thermal comfort in a given room were established in this way.The differing results obtained should facilitate temperature distribution forecasting in air-conditioned rooms.     

An energy benchmarking model for ventilation systems of air-conditioned offices in subtropical climates

Since the energy crisis in 1973, engineers have endeavoured to implement energy conservation in buildings. Unfortunately, the effort resulted in energy savings without the fundamental delivery of indoor satisfaction in many cases. In this study, a benchmarking model for the energy consumption of ventilation systems in air-conditioned offices was proposed. This model was developed from the fundamental psychrometric analysis under probable office design conditions in Hong Kong. The results showed that the annual energy-consumption of a ventilation system per unit floor area would be correlated closely with the carbon dioxide (CO₂) concentration in the space, but its correlation with the air temperature set-point would be less significant. In some offices, significant energy-savings potential was demonstrated to provide satisfactory indoor air quality (IAQ) without any comfort penalty to the occupants. This model would be useful for the energy performance evaluation and benchmarking of ventilation systems in air-conditioned offices.