胸部送风工位空调的局部送风参数范围研究

工位空调由于可提高吸入空气品质和热舒适度的同时节能而备受关注。本文提出胸部送风的工位空调方式,并通过人体热舒适实验的方法研究了在背景温度为28℃,即略高于混合通风一般设定温度时,采用不同局部送风口面积、送风温度及风速的工位送风改变人体热感觉及提高人体热舒适度的可能性。实验采用主观投票方法调查人体的热感觉和热舒适。研究结果表明,人体的热感觉在所研究的胸部工位送风工况下比背景环境下更加偏中性或偏凉;相对于背景环境,胸部工位送风可以使人体的热舒适度显著升高,且热不满意度可降低至小于15%。进一步分析了可提高人体热舒适度的局部送风温度、风速和风口尺寸3个因素的合理范围,可为设计开发提供参考。     

基于等效温度的工位空调环境下热舒适区研究北大核心

针对工位送风空调形式营造的非均匀热环境,利用等效温度指标对人体的局部和整体热感觉进行了评价。在准办公室环境对受试者进行了人体热反应实验,得到了不同刺激工况下人体各部位的热感觉和等效温度值,对比分析后发现:刺激部位等效温度值与非刺激部位等效温度值出现明显的分离现象;刺激温度和风速是影响刺激部位等效温度值的重要因素。由热感觉投票值与等效温度值的散点图发现,二者有很好的线性关系,通过拟合得到了适用于工位送风非均匀环境的等效温度舒适区范围。     

基于等效温度的工位空调环境下热舒适区研究

针对工位送风空调形式营造的非均匀热环境,利用等效温度指标对人体的局部和整体热感觉进行了评价。在准办公室环境对受试者进行了人体热反应实验,得到了不同刺激工况下人体各部位的热感觉和等效温度值,对比分析后发现:刺激部位等效温度值与非刺激部位等效温度值出现明显的分离现象;刺激温度和风速是影响刺激部位等效温度值的重要因素。由热感觉投票值与等效温度值的散点图发现,二者有很好的线性关系,通过拟合得到了适用于工位送风非均匀环境的等效温度舒适区范围。     

稳态环境下个体送风人体热舒适数值模拟

为了提高空调能效和人体的热舒适性,工位空调(TAC,Task Ambient Conditioning),即个体送风,渐渐成为研究的热点。本文探讨了在常规空调提供的稳态环境下,个体送风对人体热舒适的影响。在不同的背景温度、送风温度以及送风速度等边界条件下,对人体周围的热环境进行了数值模拟,比较分析了人体的热舒适性指标PMV。与传统空调模式的对比,个体送风在保证人体热舒适性的前提下,可以适当提高送风温度和背景环境温度,从而达到节能的效果。     

稳态条件下人体对个体送风的热反应研究

试验研究了不同背景温度、送风温差和送风速度下的人体热反应，给出了稳态条件下整体热感觉的预测公式，研究结果表明个体送风可以改善局部热环境，在一定条件下可以满足使用者整体热感觉的要求。     

工位辐射供暖末端对人体局部及整体热感觉的影响

将辐射供暖末端与工位相结合,组成一种新型个性化舒适系统。为了探索工位辐射末端的供暖效果,通过实验收集了24名受试者在不同环境温度下的局部与整体热感觉,并与传统空调环境进行对比。实验结果表明:当环境温度偏离舒适温度区间时,工位辐射末端能有效地提升受试者的热感觉;使用工位辐射末端后,受试者上肢和下肢热感觉改善明显,躯干热感觉变化不大;在16℃的环境下,受试者整体热感觉也能达到热中性。工位辐射末端在保证人体热舒适的同时,拓展了舒适温度区间。     

基于BP神经网络的过渡环境热舒适评判模型

突变环境下的人体热反应是由许多主客观因素所决定的,利用神经网络具有通过学习最佳逼近非线性映射的能力,将其应用于突变环境下人体热反应的研究,具有一定的可行性。本文通过局部非均匀环境与背景均匀环境之间的过渡实验,利用Matlab工具,分别建立了向热环境过渡和向冷环境过渡的整体热感觉以及头部执感觉的BP(Back Propagation)神经网络热舒适评判模型。经验证,该模型对不同工况过渡后的逐时热感觉预测较为准确,从而为非均匀环境与均匀环境之间过渡的热舒适模型的建立提供了一种可借鉴的方法。     

基于工位空调冷风感的送风参数影响研究

实验分析了送风温度、送风风速等参数对工位送风空调室内热环境的影响,得到了送风温度、送风速度对冷风感的影响规律:在一定范围内,送风速度越高、送风温差越大,冷风感不满意度越高.     

热湿工况下工位辐射空调的热舒适实验研究

为研究热湿工况下使用工位辐射空调的人体热舒适情况,在人工环境实验室内,通过改变环境背景温度来影响人体的热感觉,并采用热感觉投票(TSV)作为评价标准,重点研究了人体头部、躯干、上肢、下肢以及整体热感觉情况。实验结果表明,尽管背景环境参数超出舒适范围,但使用工位辐射空调能维持受试者的舒适状态,即背景温度稳定在28℃时,平均整体热感觉投票值低于+0.2;背景温度为30℃时,受试者热感觉仍能满足ASHRAE规范中规定的80%可接受范围要求。     

空间站座舱工位送风的性能分析

分析了工位送风在空间站的适用性,确定了评价指标.建立了物理模型和数学模型,分析了不同工位送风量和送风速度对舱内乘员工位区空气质量的影响,得到了CO2浓度、空气龄、空气新鲜度比、局部换气效率和工位区风速分布,同时与无工位送风进行了对比.结果表明,工位送风在较小风量时就可以满足空气质量要求,符合航天器轻量化原则;在相同总风量下加大工位送风量后,工位区的性能指标均有所改善;在工位送风量一定情况下,送风速度提高有助于改善舱内的沉闷感.     

Effects of temperature steps on human skin physiology and thermal sensation response

Air-conditioning is frequently used as a means of adjusting indoor thermal environment in hot-and-humid areas. However, when entering an air-conditioned building from outdoors people may experience thermal discomfort and risk health consequence if the instantaneous change of air temperature exceeds the thermoregulatory capacity. A study was conducted to investigate the alteration in thermal perception and in thermoregulation that simultaneously occurred in response to temperature step in a thermal transient. In this study, two temperature down-steps from 32/28 to 24 °C and an up-step from 20 to 24 °C were created in a climatic chamber consisting of two microclimate-controlled rooms, and subjects were evaluated for change in thermal sensation as well as in skin physiological properties, including skin capillary blood flow (SCBF), skin moisture, transepidermal water loss (TEWL), and skin temperature over the course of acclimation. As the results show, a cold sensation overshot occurred in thermal sensation vote (TSV), skin temperature, and SCBF in 1 min after the temperature dropped from 32 to 24 °C. TSV correlated the best with skin temperature (r = 0.60) and moderately with skin moisture and TEWL (r = 0.42–0.54) when the temperature down-step reached 8 °C. TEWL acclimated in a two-stage pattern, demonstrating a difference between the sensational change and thermoregulation. The gender-specific influence occurred in thermoregulation but not in subjective sensation. The findings of the study suggest that thermoregulatory burden might be adequately controlled when the temperature step in thermal transition zone is limited to 4 °C or lower.     

Numerical Method for a Full Assessment of Indoor Thermal Comfort

Heat, mass and momentum transfer takes place simultaneously in ventilated rooms. For accurate predictions of the indoor environment, all the environmental parameters that influence these transport phenomena should be taken into consideration. This paper introduces a method for a full assessment of indoor thermal comfort using computational fluid dynamics in conjunction with comfort models. A computer program has been developed which can be used for predicting thermal comfort indices such as thermal sensation and draught risk. The sensitivity of predicted comfort indices to environmental parameters is analysed for a mechanically ventilated office. It was found that when the mean radiant temperature was considered uniform in the office, the error in the predicted percentage of dissatisfied (PPD) could be as high as 7.5%. The prediction became worse when the mean radiant temperature was taken to be the same as air temperature point by point in the space. Moreover, disregarding the variation of vapour pressure in the space resulted in an error in PPD of abour 4% near the source of moisture generation. The importance of evaluating both thermal sensation and draught risk is also examined. It is concluded that in spaces with little air movement only the thermal sensation is needed for evaluation of indoor thermal comfort whereas in spaces with air movement induced by mechanical vantilation or air-conditioning systems both thermal sensation and draught risk should be evaluated.     

Thermal sensation of Hong Kong people with increased air speed,temperature and humidity in air-conditioned environment

In the warm and humid climate zone, air-conditioning (AC) is usually provided at working places to enhance human thermal comfort and work productivity. From the building sustainability point of view, to achieve acceptable thermal sensation with the minimum use of energy can be desirable. A new AC design tactic is then to increase the air movement so that the summer temperature setting can be raised. A laboratory-based thermal comfort survey was conducted in Hong Kong with around 300 educated Chinese subjects. Their thermal sensation votes were gathered for a range of controlled thermal environment. The result analysis shows that, like in many other Asian cities, the thermal sensation of the Hong Kong people is sensitive to air temperature and speed, but not much to humidity. With bodily air speed at 0.1–0.2 m/s, clothing level 0.55 clo and metabolic rate 1 met, the neutral temperature was found around 25.4 °C for sedentary working environment. Then recommendations are given to the appropriate controlled AC environment in Hong Kong with higher airflow speeds.     

厦门高校教室冬季热环境测试及热舒适预测

为考察冬季非空调环境下人体热感觉,对厦门某高校教室的热舒适度进行了现场测试.在测量室内外热舒适参数的同时,通过问卷调查得到了人体热反应样本.分析样本得出厦门高校教室冬季非空调工况下人体热中性温度和热期望温度分别为19.3和19.4℃.综合考虑温度、相对湿度、平均辐射温度、风速及服装热阻对坐姿轻度活动状态人体的热舒适影响,使用MATLAB软件进行非线性回归,得到非空调工况下热舒适预测方程.该预测方程与实测得到的人体热舒适投票两者结果有较高相关度,同时较大程度上反映了冬季非空调环境下人体热感觉的变异.     

Evaluating the performance of thermal sensation prediction with a biophysical model

Neutral thermal sensation is expected for a human body in heat balance in near‐steady‐state thermal environments. The physiological thermoneutral zone (TNZ) is defined as the range of operative temperatures where the body can maintain such heat balance by actively adjusting body tissue insulation, but without regulatory increases in metabolic rate or sweating. These basic principles led to the hypothesis that thermal sensation relates to the operative temperature distance from the thermoneutral centroid (dTNZ_op). This hypothesis was confirmed by data from respiratory climate chamber experiments. This paper explores the potential of such biophysical model for the prediction of thermal sensation under increased contextual variance. Data (798 votes, 47 participants) from a controlled office environment were used to analyze the predictive performance of the dTNZ_op model. The results showed a similar relationship between dTNZ_op and thermal sensation between the dataset used here and the previously used dataset. The predictive performance had the same magnitude as that of the PMV model; however, potential benefits of using a biophysical model are discussed. In conclusion, these findings confirm the potential of the biophysical model with regard to the understanding and prediction of human thermal sensation. Further work remains to make benefit of its full potential.     

氧化还原作用对铀成矿的意义——以相山西部流纹英安岩铀矿为例

铀是敏感的变价元素,在氧化状态下U6+能随岩浆热液迁移;而在还原状态下U4+形成沥青铀矿、钛铀石等发生沉淀。本文通过对相山西部流纹英安岩原岩和含铀矿石的鉴定和化学分析,大致说明流纹英安岩中的铀矿石主要是赋存在岩石微裂隙中的沥青铀矿。同时推断深部岩浆上没有喷涌过程中,U4+在深部弱还原环境下被氧化成UO22+而随热液迁移;热液进一步上涌逐渐转为弱氧化环境。UO22+又在弱氧化环境下被还原成U4+而富集沉淀形成铀矿体,U4+和UO22+的相互转化不仅仅和热液氧化还原状态相关,还和热液的成分及温度、压力、pH值等物理条件相关。     

过渡季节不同气候区公共建筑热环境研究(Ⅱ)

选择长沙、广州、沈阳和西安4个不同气候区公共建筑作为研究对象,于2008年过渡季节通过采用现场建筑内热湿参数实测和室内人员问卷调查相结合的方式对公共建筑热环境现状进行了研究。实测结果得到过渡季节我国不同气候区公共建筑室内空气温度、空气相对湿度、空气流速、操作温度和服装热阻的分布特征,而问卷调查分析则表明,过渡季节各地区公共建筑内绝大部分人员热感觉投票值TSV都在-1~+1之间,热感觉比较合适,但各地区公共建筑内都还有约30%的人感觉稍不舒适,热感觉与热舒适存在差异。进一步的线性回归分析得到了不同地区建筑内的热中性温度和热舒适温度范围。过渡季节各地区公共建筑室内实测热中性温度都要小于理论热中性温度,人们更偏向低于理论值的室内温度,而实际热舒适温度范围则要比理论热舒适温度范围更加宽泛,说明过渡季节各地区的人们对环境的适应性更强了。     

Numerical investigation of local thermal discomfort in offices with displacement ventilation

Local thermal discomfort in offices with displacement ventilation is investigated using computational fluid dynamics. The standard κ-ϵ turbulence model is used for the prediction of indoor air flow patterns, temperature and moisture distributions, taking account of heat transfer by conduction, convection and radiation. The thermal comfort level and draught risk are predicted by incorporating Fanger's comfort equations in the airflow model. It has been found that for sedentary occupants with summer clothing common complaints of discomfort in offices ventilated with displacement systems result more often from an unsatisfactory thermal sensation level than from draught alone. It is shown that thermal discomfort in the displacement-ventilated offices can be avoided by optimizing the supply air velocity and temperature. It is also shown that optimal supply air conditions of a displacement system depend on the distance between the occupant and air diffuser.     

A relation between calculated human body exergy consumption rate and subjectively assessed thermal sensation

Application of the exergy concept to research on the built environment is a relatively new approach. It helps to optimize climate conditioning systems so that they meet the requirements of sustainable building design. As the building should provide a healthy and comfortable environment for its occupants, it is reasonable to consider both the exergy flows in building and those within the human body.Until now, no data have been available on the relation between human-body exergy consumption rates and subjectively assessed thermal sensation. The objective of the present work was to relate thermal sensation data, from earlier thermal comfort studies, to calculated human-body exergy consumption rates.The results show that the minimum human body exergy consumption rate is associated with thermal sensation votes close to thermal neutrality, tending to the slightly cool side of thermal sensation.Generally, the relationship between air temperature and the exergy consumption rate, as a first approximation, shows an increasing trend. Taking account of both convective and radiative heat exchange between the human body and the surrounding environment by using the calculated operative temperature, exergy consumption rates increase as the operative temperature increases above 24 °C or decreases below 22 °C. With the data available so far, a second-order polynomial relationship between thermal sensation and the exergy consumption rate was established.