A Sonirvey of Wnnnd Speeds Inn Imioor Workplaces
( The applicability of the inhalable convention for sampling aerosols relies on its being a valid model for typical sampling environments. The current convention is based on measurements carried out in external wind speeds between 1 and 4 ms~'. However these measurements show a degree of wind speed dependence, and it is uncertain at present how valid the convention is for describing human aspiration efficiency outside these wind speed limits. Following concerns that wind speeds in many indoor workplaces may be significantly below this range, measurements have been made in 55 work areas covering a wide range of workplaces. Measurements have concentrated on 'background' wind speeds where Hie influence of specific air movement sources is minimised. The pooled wind speed measurements show a highly skewed distribution with an arithmetic mean of approximately 0.3 m*s '. Approximately 85% of all individual measurements were below this mean value. No obvious correlation was found between wind speed distribution parameters and industry type, room size or ventilation type. A limited number of comparisons were made between static anemometers and devices mounted on workers. It was found that modal wind speeds experience by workers were typically 0.05 m-s~' higher than those measured using a static anemometer. These measurements agreed well with previously published data for similar work- places as well as housesJCrown copyright © 1998 Published by Elsevier Science Ltd on behalf of
Airflow characteristics in the occupied zone of ventilated spaces
A.K. Melikow, Ph.D. P.O. Fanger ASHRAE Fellow Draft is one of the most common causes of complaint in ventilated or air-conditioned spaces. Therefore, knowing the turbulent airflow in these spaces and the impact of this flow on the sensation of draft is very important. The characteristics of turbulent flow (turbulence intensity, length scales of turbulence, turbulence kinetic energy, etc.) were investigated in 20 typically ventilated spaces. Relationships between these characteristics and the mean velocity were found. The mean velocities and turbulence intensities of all ventilated spaces varied widely the mean velocity from less than 0.05 mis to 0.40 m/s and the turbulence intensity from 10% to 70%. The turbulence energy spectra are similar to those in a fully developed turbulent flow. The spectra reveal the major contribution to total turbulent energy made by the larger eddies in the low-wave number range. Some of the experimental results were compared with existing numerical predictions. INTRODUCTION Draft, defined as unwanted local cooling of the human body caused by air movement, is perhaps one of the most common causes of complaint in ventilated or air-conditioned spaces. Draft may cause people to stop ventilation systems and to plug up air diffusers. The occupants may also try to counteract the draft by elevating the air temperature, and during the winter this will normally increase energy consumption. Earlier draft criteria were based on climate chamber studies where subjects were exposed to laminar or low turbulent airflow (Houghton 1938; Mcintyre 1979). However, the airflow in ventilated spaces is not normally laminar. Typically the air velocity fluctuates and Fanger and Pedersen (1977) have shown that periodically fluctuating airflow is more uncomfortable than nonfluctuating (laminar) airflow. Exposing subjects to well-defined periodic velocity fluctuations in a climate chamber, they found that the discomfort had a maximum at velocity frequencies around 0.3 0.5 Hz. Later, Fanger and Christensen (1986) exposed 100 subjects to turbulent airflow and presented the results in a draft chart predicting the percentage of dissatisfied occupants as a function of mean velocity and temperature. In a field gtudy, Thorshauge (1982) identified the velocity fluctuations that occurred in practice through measurements in several ventilated spaces. He found a linear relationship between the mean velocity and the standard deviation of the velocity fluctuations. But still there is lack of information about the actual airflow in ventilated rooms. The purpose of this study is to identify, by means of modern measuring techniques, the characteristics of turbulent airflow occurring in the occupied zone of a wide range of ventilated Hisashi Hanzawa worked on this study as visiting Research Associate at the Laboratory of Heating and Air Conditioning, Technical University of Denmark. His affiliation is Takenaka Komuten Co. Ltd., Environmental and Mechanical Engineering Unit, Technical Research Laboratory, 5-14, 2-Chome, Minamisuna, Koto-ku, Tokyo. Arsen K. Melikow is Research Associate and P.O. Fanger is Professor at the Laboratory of Heating and Air Conditioning, Technical University of Denmark, Building 402, DK-2800 Lyngby, Denmark. 524 spaces in practice. Such information is essential for assessing previous studies, for planning fut ure studies on the impact of turbulent airflow on man's sensation of draft, and for modelling airflow in ventilated spaces . Several studies have applied twoor three-dimensional models for numerical calculation of airflow, using experimental data measured in reduced models (Nielsen 1974; Gosman et al. 1980; Unno et al. 1983; Sakamoto and Matsuo 1980). The predicted mean velocity distribution was in good agr eement with measured data in reduced models, but there are discrepancies between the predicted turbulent characteristics of airflow and the experimental results of these characteristics (Sakamoto and Ma tsuo 1980). Moog (1981) discusses the complexity of the room airflow in connection with its prediction. To modify the numerical models, the present measurements of characteristics of room a irflow on the scale 1:1 will be useful. CHARACTERISTICS OF TURBULENT AIRFLOW IN SPACES The turbulent airflow in spaces may be characterized by the following magnitudes. The instantaneous velocity V = V + V' which was assumed to be the sum of the mean velocity, V, and the velocity fluctuations, V', in the main direction of the flow. The mean velocity, V, is the average of the instantaneous velocity, V, over an interval of time, t1
Second-Generation Process Research Towards Eletriptan: A Fischer Indole Approach
The development of a second-generation process for the synthesis of eletriptan via a Fischer indole cyclisation is described. The finalised process offers several potential advantages over the current route of manufacture including cost, throughput, and safety.