Comparative analysis of methods for determining the metabolic rate in order to provide a balance between man and the environment

The incorrect determination of metabolic rate can be linked to discrepancies between the model of the PMV (Predicted Mean Vote) and real thermal sensation collected in field studies. Aiming to improve the correlation of the PMV model and the real thermal sensation, this work established new values for the metabolic rate: one way being called “calculated” using Newton's Method and the other called "measured" using a metabolic analyzer. Welder's activities were evaluated, through the measurements of environmental and personal variables. New values of metabolic rate were determined for this activity. The values found for the calculated form and the measured one were, respectively, 178.63 and 145.46 W/m², different from the range provided by the table of ISO 8996 (2004) for this activity (75–125 W/m²). In order to verify which of the values of the metabolic rate was closer to the real thermal sensation of PMV, a linear regression was made between the PMV and the real thermal sensation in three ways: S × PMV_tabulated (R² = 0.1749), S × PMV_calculated (R ² = 0.7481) and S × PMV_measured (R² = 0.7854). It was found that the values measured by the instrument gave a higher coefficient of determination which was chosen for the correction of the table. The correction of the table provides a value of M_predicted, that is a value of metabolic rate that corrects the values provided by the tables of ISO 8996 (2004), by means of a correction coefficient. For the welder's activities in a metal-mechanics industry, tabulated values can be multiplied by the correction coefficient 1.4648 in order to minimize inaccuracies. The PMV_predicted, obtained through the M_predicted, when related to the actual thermal sensation, provides a coefficient of determination of 0.7511, thereby improving the model of the PMV.     

绿化屋顶室内热环境研究

屋顶绿化作为一种生态的屋顶隔热手段已得到了广泛的认同,以上海气候条件下轻型绿化屋顶为研究对象,采用实测与计算分析相结合的方法,用PMV指标比较室内空调状态下绿化屋顶与非绿化屋顶的室内热舒适性。结果表明,绿化屋顶室内PMV平均值比无绿化屋顶低0．2,波动幅度仅为无绿化屋顶的1／4,并经计算得到绿化屋顶的等效保温屋顶,进一步研究表明,在较高的室内温度情况下,绿化屋顶内表面温度将会低于等效保温屋顶。     

最小焓差在空调节能控制系统中的应用及仿真

在空气调节过程中不仅需要考虑房间内人员的舒适性需求,同时还需考虑如何节省能源。基于焓值理论将最小焓差算法与风阀开度调节过程相结合,使得进入空气处理单元前的空气更加接近舒适区域,然后基于质量及能量守恒理论推导出空气混合过程的数学模型,最后利用SIMULINK建立了空调系统仿真模型,并对所提控制策略从节能效果与舒适性能指标2个方面进行仿真验证。仿真结果表明最小焓差＋PID策略联合控制的空调系统不仅能够获得更佳的空气舒适状态而且系统耗能更少。     

HVAC系统多传感器数据融合研究

提出了一种简单的、易实现的PMV(Predicted Mean Vote)值的计算方法.针对HVAC(Heating Ventilation and Air Conditioning)系统检测装置和控制系统存在的时间滞后,使人体舒适性得不到很好的满足,并且有额外的能量消耗,进而研究了多传感器数据融合算法及基于D-S证据理论的最小风险决策算法以满足HVAC系统做出合理的决策.根据决策结果可以调节最优的空气量,改进空气处理系统的响应速率,最后利用Labview开发环境来实现数据融合算法.将Labview与多传感器数据融合应用于HVAC系统,增强了研究的系统的稳定性和快速性,保证了人体的舒适性,并且减少了能耗.     

基于TinyOS的无线热舒适度测量系统

单一的室内环境温度作为被控变量的控制系统,难以满足人们对室内环境舒适性以及节能的要求。开发了基于TinyOS操作系统的无线热舒适度测量系统,无线传感网络节点组成多跳网络,用以采集温湿度等室内环境参数,并实时计算热舒适度PMV（Predicted Mean Vote）指标值。分析了测量误差产生的主要原因,并利用超闭球CMAC（Hyperball CMAC,HCMAC）神经网络进行了误差补偿,实验结果表明,补偿后的PMV精度得到了明显的改善。该系统可为热环境舒适度实时控制提供便捷的无线数据采集和有效的PMV指标测量方法。     

Examination of thermal comfort in a hospital using PMV-PPD model

In this study, the performance of air conditioning system and the level of thermal comfort are determined in a state hospital located in Kermanshah city in the west of Iran in winter and summer using the Predicted Mean Vote (PMV) model which has been presented by ISO-7730 (2005). The Predicted Mean Vote (PMV) and the Predicted Percentage Dissatisfied (PPD) indices were computed using the data acquired from the experimental measurements performed in the building. The results showed that the values of PMV in some parts of the building, both for men and women, are not within the standard acceptable range defined by ISO. It was found that the most thermal problems in winter occur in morning work shift, and the worst thermal conditions in summer occur in noon work shift. The t-test results revealed that there is no noticeable difference between the thermal conditions of some rooms and those of the surroundings.     

西安市过渡季节办公建筑室内热环境研究

根据在过渡季节里对所选取的办公建筑进行现场测试所得的数据,并通过分析调查问卷内容得出:西安地区过渡季节气候相对比较舒适。这个季节室内主观热感觉中性温度与当PMV=0时的室内温度值较接近,分别为25.6℃、25.24℃。     

室内热舒适性指标PMV影响因素分析与研究

服装热阻、空气温度及气流速度是影响人体热舒适性的三个主要因素。本文针对上送上回气流分布方式，采用K-ε湍流模型及热舒适性指标PMV数学分析式，对室内三维湍流流动和传热及PMV指标进行了数值模拟，研究不同送风速度下的室内流场、温度场及PMV值分布变化规律，并分析比较了不同送风速度、送风温度及服装热阻对室内PMV值的影响。研究结果表明：送风速度是影响室内流场、温度场及PMV值分布模式的主要因素，送风温度的改变对PMV值有一定的影响，而室内人员的服装热阻对PMV值的影响较大。本文的研究对如何合理确定空调送风参数，达到满足热舒适性的目的奠定了理论基础，同时促进了以人居舒适为核心的空调技术发展。     

室内气流组织和空气品质的数值分析

根据Fanger热舒适方程,分析了影响人体热舒适的因素;根据通风效率、能量利用效率,分析了室内气流分布.将夏季、冬季的机械通风方式分成4种,利用计算流体动力学(CFD)对室内气流进行模拟,模拟室内气流的速度、温度、CO2浓度分布,并应用模拟结果分析不同气流组织形式下的空气品质、人体热舒适及空调能耗情况,指出不同的气流组织形式与空气环境、能耗有着密切的关系;且冷风工况与热风工况的气流分布不同,送冷风的置换通风方式与送热风的上送下回方式能获得良好的室内空气品质和有效的能源利用.     

Thermal acceptability assessment in buildings located in hot and humid regions in Brazil

The objective of this paper was to perform an analysis on thermal acceptability in naturally ventilated (NVB) and air-conditioned buildings (ACB) located in hot and humid climates in Brazil. Experiments were carried out in April and November 2005 with 1.301 questionnaires based on ISO 10551:1995(E). Indoor and outdoor climatic variables were monitored simultaneously. The results revealed that 53% of the occupants of NVB and 78% of ACB were thermally satisfied. However, some restrictions were observed with the applications of the following methodologies: ISO/FDIS 7730:2005(E); ANSI/ASHRAE Standard 55:2004; Adaptive Temperature Limits (ATG) and prEN15251: 2005(E). Differences were observed between thermal sensation (TSV) and predicted mean vote (PMV) and between the subject's percentages expressing thermal unacceptability of the environment and the PPD calculated according to ISO/FDIS 7730:2005(E).