Sensitivity analysis of the effect of airflow velocity on the thermal comfort in underground mines

Abstract Displeasure in respect to air volumes and associated airflow velocities are well-documented complaints in underground mines. The complaints often differ in the form that there is too little airflow velocity or too much. In hot and humid climates such as those prevailing in many underground mines, convection heat transfer is the major mode of heat rejection from the human body, through the process of sweat evaporation. Consequently, the motion of the mine air plays a pivotal role in aiding this process. In this paper, a method was developed and adopted in the form of a “comfort model” to predict the optimum airflow velocity required to maintain heat comfort for the underground workforce at different activity levels (e.g. metabolic rates). Simulation analysis predicted comfort limits in the form of required sweat rate and maximum skin wetness. Tolerable worker heat exposure times were also predicted in order to minimize thermal strain due to dehydration. The results indicate that an airflow velocity in the range of 1–2 m/s is the ideal velocity in order to provide a stress/strain free climate and also guarantee thermal comfort for the workers. Therefore, an optimal airflow velocity of 1.5 m/s for the miners' thermal comfort is suggested.

[1]  F. Engelbrecht,et al.  Practical choice of thermal comfort scale and range in naturally ventilated buildings in South Africa : technical paper , 2005 .

[2]  P. Höppe,et al.  The physiological equivalent temperature – a universal index for the biometeorological assessment of the thermal environment , 1999, International journal of biometeorology.

[3]  Graham P Bates,et al.  Limiting metabolic rate (thermal work limit) as an index of thermal stress. , 2002, Applied occupational and environmental hygiene.

[4]  R. Dear,et al.  Air movement acceptability limits and thermal comfort in Brazil's hot humid climate zone , 2010 .

[5]  P. O. Fanger,et al.  Thermal comfort: analysis and applications in environmental engineering, , 1972 .

[6]  Patrick J Coleman,et al.  Measuring mining safety with injury statistics: lost workdays as indicators of risk. , 2007, Journal of safety research.

[7]  Barbara Griefahn,et al.  Working in Moderate Cold: A Possible Risk to Health , 1997 .

[8]  Shi Xiaowei,et al.  Progress of heat-hazard treatment in deep mines , 2011 .

[9]  M. A. Humphreys,et al.  The optimum diameter for a globe thermometer for use indoors. , 1977, The Annals of occupational hygiene.

[10]  G. Zhou.  Human perception of air movement: Impact of frequency and airflow direction on sensation of draught , 1999 .

[11]  Ken Parsons,et al.  Human Thermal Environments: The Effects of Hot, Moderate, and Cold Environments on Human Health, Comfort and Performance , 1999 .

[12]  J. Toftum.  Human response to combined indoor environment exposures , 2002 .

[13]  Joseph H. Saleh,et al.  Safety in the mining industry and the unfinished legacy of mining accidents: Safety levers and defense-in-depth for addressing mining hazards , 2011 .

[14]  A Michael Donoghue,et al.  Heat illness in the U.S. mining industry. , 2004, American journal of industrial medicine.

[15]  Howard L. Hartman,et al.  Mine ventilation and air conditioning , 1961 .

[16]  B. W. Jones,et al.  Ceiling fans as extenders of the summer comfort envelope , 1983 .

[17]  L. G. Berglund,et al.  Subjective human response to low-level air currents and asymmetric radiation , 1987 .

[18]  J. Malchaire,et al.  Prediction of mean skin temperature in warm environments , 2004, European Journal of Applied Physiology and Occupational Physiology.

[19]  G Havenith,et al.  Criteria for estimating acceptable exposure times in hot working environments: a review , 2000, International archives of occupational and environmental health.

[20]  P. Fanger,et al.  Perception of draught in ventilated spaces. , 1986, Ergonomics.

[21]  Edward Arens,et al.  Air movement and thermal comfort , 1993 .

[22]  Arun S. Mujumdar,et al.  Dust dispersion and management in underground mining faces , 2014 .