Effect of stove asymmetric radiation field on thermal comfort using a multisegmented bioheat model

The multinode multisegment bioheat model of Salloum et al. [Salloum M, Ghaddar N, Ghali K. A new transient bio-heat model of the human body. In: Proceedings of the ASME 2005 summer heat transfer conference, 17–22 July 2005, San Francisco, Paper no. HT2005-72303] is integrated with a space heat model to study human thermal response when subjected to radiant asymmetry in stove-heated domestic spaces in Lebanon. For any given person position, the overall comfort level is based on Frank et al. model correlations [Frank SM, Srinivasa NR, Bulcao CF, Goldstein DS. Relative contribution of core and cutaneous temperatures to thermal comfort and autonomic responses in humans. Journal of Applied physiology 1999;86(5):1588–93]. The assessment of local comfort level is based on the maximum deviation of the clothed segments skin temperature from the mean skin temperature and its relation to the radiant temperature asymmetry.

Experiments were run on human subjects at steady-state conditions to measure the variation of the skin temperature at different locations of the human body segments while standing in an asymmetric thermal radiation field generated by a stove-heating unit. The experiments were conducted to validate the applicability of the bioheat model in predicting skin temperature in asymmetric conditions. The measured skin temperature of various body segments and the radiative asymmetry agreed within ±5% of values predicted by the bioheat model [Salloum M, Ghaddar N, Ghali K. A new transient bio-heat model of the human body. In: Proceedings of the ASME 2005 summer heat transfer conference, 17–22 July 2005, San Francisco, Paper no. HT2005-72303].

The space heat model and the bioheat model are applied to a case study to predict both overall thermal comfort and local thermal discomfort in a typical radiant heat space at different standing positions of the person. Strong thermal discomfort exists within the vicinity of the stove high-temperature surface. The local discomfort is considered at values of maximum SD>1.1 °C derived from consideration of Fanger et al. [Fanger PO, Ipsen BM, Langkilde G, Olesen BW. Comfort limits for asymmetric thermal radiation. Energy and Buildings 1985;8(3):225–36] data of comfort limits and skin temperature measurements for asymmetric thermal radiation.     

深圳市高层住宅环境热舒适研究

本文通过对深圳市485位居民室内热舒适情况的问卷调查与实测数据的研究,结果显示,被调查热环境基本处于美国采暖、制冷和空调工程师协会(ASHRAE)制定的标准舒适区之外.预测值PMV(Vpm)高于实测得到的热感觉,约为vpm的2.45倍,而80%的人群可接受的热环境有效温度上限为29.5℃,远高于ASHRAE推荐的舒适温度上限值2 7℃.表明该地区的人群已经适应了当地的气候,对热有一定的承受能力,从而证实对环境的适应会改变人们的心理期望和热感觉, 现有的热舒适标准应该根据实际情况作相应的修正.     

关中村民人体热舒适性调查研究

关中农村有着悠久的文化历史,在生活方式和传统建筑中均有体现。而现今我们必须关注的是如何发展关中乡村住宅的可持续道路。在一年中最冷月和最热月,通过对数个村落的调研,发现住宅室内物理环境的恶劣现状。通过量化计算得出冬夏季室温都在人体舒适温度范围之外,特别是冬季,室温远离人体热中性温度。为了提高人体舒适度,提出关中乡村传统住宅的改善途径,以期引导农民建造舒适整洁、节能的新农居。     

A thermal theory for estimating the flammability limits of a mixture

Because it is difficult to treat the contributions of diluents explicitly using Le Chatelier's rule, a methodology based on thermal balance is proposed for estimating the flammability limits of a mixture. This method converts the flammability information of a mixture into a binary domain of heating/quenching potentials and, after some simple manipulations, converts them back into the flammability domain. The advantage of this conversion is the separation of the heating and quenching potential sums. The dual contribution (heating and quenching) of each species is stressed, while the simplicity of hand calculation is preserved. This method is equivalent to Le Chatelier's rule but has increased flexibility in dealing with various fuel/oxygen/diluents combinations. It will help safety engineers gain more confidence in the hazard analysis of flammable mixtures involving diluents.     

Geometric view factors for thermal radiation hazard assessment

Estimating the thermal radiation field surrounding a large fire involves characterization of the flame geometry and computation of radiant intensity at a given location. The latter requires computation of geometric view factors. In this article, closed form expressions that are common in the design of impoundment systems. These include tilted cylindrical and rectangular geometries. The computed geometric view factors compare very well with limited experimental data for circular geometries. The closed form expressions allow rapid computation of view factors that are necessary in estimating the fire hazards associated with large hydrocarbon pool fires.     

Comfort climate evaluation with thermal manikin methods and computer simulation models

With increasing demand for acceptable environment in the modern workplace is it necessary, already in the construction phase, to estimate what effect different environmental factors have on the occupants. Thermal sensation is affected by many factors in the work place environment, especially thermal factors and effects from air movement caused by different ventilation principles. A series of full scale measurements as well as numerical calculations have been carried out in order to investigate whether Computational Fluid Dynamics (CFD) calculations and measurements with a thermal manikin are able to predict the perceived thermal climate. When human thermal sensation is linked together in measurements and calculations, the thermal situation in the work place environment is visualized. The results show relatively good agreement with the measurements made in the real environment. However, numerical and experimental methods need to be further developed. Evaluation methods of this type, will enable engineers to make better predictions and early decisions in the design and construction process. This also opens possibilities to use results from a number of full scale tests providing means to improve the comfort, health and productivity in working life.     

Comfort in urban spaces: defining the boundaries of outdoor thermal comfort for the tropical urban environments

With rapid urbanisation, often without climate responsive guidelines, cities in the Tropics are progressively falling short of sustaining outdoor life. While at the building level such inadvertent climatic modifications have lead to a remarkable demand on the urban energy resources. The rationale for developing a thermally desirable outdoor ambience in such a context has implications that go beyond the requisites of urban design and well into the design of buildings. In order to re-establish and sustain life outdoors it is important that we try to make urban spaces comfortable as far as the ambient climate permits. In order to ascertain conditions of comfort for outdoor spaces we need to define comfort for outdoors. This paper presents findings on outdoor comfort based on field investigations conducted in Dhaka, a city in the wet-Tropics. Findings from a survey conducted on a large number of randomly selected people from urban spaces are presented. The findings include factors affecting comfort outdoors for Dhaka and a comfort regime based on environmental parameters for urban outdoors is presented. Interestingly, comfortable ambient climate leads to comfortable indoor environment particularly with regard to free running buildings. With regard to mechanically controlled indoor environments a comfortable outdoor produces lesser strain on energy environment relationship. By defining conditions of comfort for outdoor environments an important step towards achieving sustainability of our urban environments can be made.     

油罐火灾热辐射作用区确定方法

从计算火焰表面辐射力、计算热辐射强度、破坏区域确定具体步骤几方面时油罐区火焰热辐射的作用区域确定方法进行介绍.开发了确定热辐射作用区模型的RADAREA软件,应用软件进行案例计算.该软件可应用于实际火场中,帮助预测人员伤亡和火灾损失.     

Calculating thermal radiation hazards in large fires

The author has developed, and discusses here, a method for assessing the thermal radiation hazards to objects from fires. A comparison of the calculations to an actual fire experience seems to indicate that the method is reasonably accurate, though somewhat conservative.     

更智能的电梯传感器

今天，新兴的照相传感技术已可被运用在电梯技术中，从而提升了电梯的效率，安全和舒适。对于电梯效率最优化而言，轿厢面积被占用的百分比是一个关键数据。但是，现有的称重装置只能测出轿厢中的重量，却无法识别轿厢面积被占用的百分比。基于安全考虑，轿厢中的任何人或物都应被检测到。但是，现有的漫反射型传感器却无法实现，因为它无法检测到静止不动的物体。本文介绍的是基于新兴的CMOS照相技术研发的视觉传感器系统，对于该型传感器的分类使用，将解决上述问题，并使电梯更加舒适。对于该传感器的技术细节将在下文中，根据不同的应用事例做详细描述。     

室内取暖环境热舒适参数的至适值的探索

本论文应用预计冷热感指标(PMV)的热舒适方程式计算方法,在热舒适指标1≥PMV≥-1范围内,计算室内取暖环境的热舒适参数的阈值,探索其至适值。在冬季取暖环境相对湿度30%～60%,气流速度0.1～0.2m/s,静坐、坐姿轻作业的代谢量分别为58.15、69.78 W/m2的计算条件下,标准着衣量为0.155 m2.K/W满足PMV≥-1的空气取暖,静坐、坐姿轻作业的至适温度分别不小于21.0、18.4℃;在空气温度18℃的条件下,满足PMV≥-1的静坐、坐姿轻作业的,标准着衣量热辐射取暖的至适平均辐射温度分别不低于25.3、19.0℃,或空气取暖的至适着衣量各不少于0.217、0.163 m2.K/W。     

菅仙谷

项目周边是个有着20年历史的住宅小区，环境清幽，生长着许多天然的绿色植物。因此,设计的目标是要融入社区环境,并继续保留该项目和附近公园后面山坡优美的自然风光和绿色植物营造与季节变化相适应适宜野生动物生存的,丰富多彩的景观。为了在有限的空间里吸引和培育更多的自然物种,专家进行了生态调研。因而整合了附近的公园并改建为森林,使公共开放空间的池塘和溪流与操场的草坪相连，共同构成了生态环境的元素。     

Absorption of thermal energy in PMMA by in-depth radiation

An experimental technique is developed to quantify the absorption of thermal energy in black PMMA (Polycast) by in-depth radiation in semi-transparent media. In-depth heating occurs when non-reflected incident heat flux enters the solid without first being absorbed at the exposed surface. Transient conduction due to temperature gradients occurs within the solid in response to this in-depth absorption. An analytical model is developed for predicting time to ignition for such in-depth heating situations. Using the measured absorption coefficient, κ, the analytical prediction for time to ignition is found to be in excellent agreement with data from experiments of Saito and Delichatsios.     

Air movement acceptability limits and thermal comfort in Brazil's hot humid climate zone

In hot humid climates, natural ventilation is an essential passive strategy in order to maintain thermal comfort inside buildings and it can be also used as an energy-conserving design strategy to reduce building cooling loads by removing heat stored in the buildings thermal mass. In this context, many previous studies have focused on thermal comfort and air velocity ranges. However, whether this air movement is desirable or not remains an open area. This paper aims to identify air movement acceptability levels inside naturally ventilated buildings in Brazil. Minimal air velocity values corresponding to 80% and 90% (V80 and V90) air movement acceptability inside these buildings. Field experiments were performed during hot and cool seasons when 2075 questionnaires were filled for the subjects while simultaneous microclimatic observations were made with laboratory precision. Main results indicated that the minimal air velocity required were at least 0.4 m/s for 26 °C reaching 0.9 m/s for operative temperatures up to 30 °C. Subjects are not only preferring more air speed but also demanding air velocities closer or higher than 0.8 m/s ASHRAE limit. This dispels the notion of draft in hot humid climates and reinforce the broader theory of alliesthesia and the physiological role of pleasure due to air movement increment.     

Air entrainment and thermal radiation from heptane pool fires

An experimental study was made to explore the air entrainment into heptane pool fires and the smoke blocking effect on thermal radiation from fire. Heptane was burned in five different sized tanks 0.3 m, 0.6 m, 1 m, 2 m, and 6 m in diameter, and its burning rate, flame temperature, vertical hot gas velocity, and thermal radiation were measured. It was found that the total amount of air entrainment is about 5 times the stoichiometric air requirement. A smoke block effect appeared at tank diameter of 2 m or more.     

太空反射绝热涂料的研制

该涂料的创新点在于借鉴国外航天工业用高科技绝热瓷层的技术思路,利用国产原材料研制开发出了具有自主知识产权的薄层隔热保温新材料。     

Correlating thermal transmittance limits of walls and roofs to orientation and solar absorption

The presented research addresses the association of maximum thermal transmittance (U value) of walls and roofs with orientation and solar absorption. The study is performed on walls and a roof typically used in Kuwait when subjected to local hot climate conditions. A computer program employing the total equivalent temperature difference (TETD) method is developed to estimate the U values corresponding to solar absorption coefficients ranging from 0 to 1. At zero solar absorption coefficient, the maximum U values stipulated in the existing national energy code are used to induce the constant total daily heat flux for the developed correlations. Furthermore, the thermal inertia parameters affected by the established U values are also predicted. The results show that the orientation and absorption coefficient have a profound effect on the U value particularly for the roof and west and east wall orientations. Moreover, the decrease in the thermal transmittance significantly enhances the thermal inertia parameters of the aerated autoclaved concrete wall type.The developed correlations can be added to the Kuwait building energy code to extend the application scope of the U value limits based on surface orientation and external solar properties.     

Comfort level identification for irregular multi-storey building

In this article, the system identification approach is being used to identify the vertical frequencies of the top storey in a multi-storey building prefabricated from reinforced concrete in Stockholm. Before building construction, detailed investigation indicated that the building will not be affected by train vibrations from the nearby railway yard. After building completion, disturbing vibrations were observed in the building. Three measurement types, namely, ambient vibration test, forced vibration test on the rails, and forced vibration test, have been performed in order to specify the probable reasons for these vibrations.Five methods of structural identification approach, specifically ARX, ARMAX, BJ, OE, and state-space models, have been implemented for the identification process in this study using the tests' results. All the test types and model structures utilized have identified a concentration in the vertical frequencies within the range of (7.5–12.5) Hz for the 10th floor only, which is close to the frequencies of human body parts. Furthermore, the article concludes that the ARMAX model and the output error model have indicated an excellent performance to predict the mathematical models of vibration's propagation in the building, when compared with other models used from the three types of tests.In addition, the results of the aforementioned system identification methods, implemented for this study, have indicated that there are no other reasons for the disturbing vibrations still observed in the building. Furthermore, the results confirmed the correctness of the previous theoretical and experimental results obtained by different specialists, who stated that the values of floor acceleration are within the acceptable limits, and the probable reason for any disturbance is the resonance between the generated low frequencies and the human body parts' frequencies.     

享受野营乐趣

正是因为有了一批富有且喜欢探险的旅行者，他们想真切地拥抱自然且又想享受五星级度假村的舒适待遇，至此“奢华野营”这个词听起来就感 到不再“矛盾”了。这一群体大体上由两部分人组成，一部分是出生于婴儿潮的人，他们有足够的时间和金钱远行，从而体验自然的乐趣。