| 51. |
- Wang, Faming, et al.
(författare)
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Development and Validation of an Empirical Equation to Predict Sweating Skin Surface Temperature for Thermal Manikins
- 2010
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Ingår i: Textile Bioengineering and Informatics Symposium Proceedings. - 1942-3438. ; 1-3, s. 1213-1218
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Konferensbidrag (refereegranskat)abstract
- Thermal manikins are useful tools to study the clothing comfort and environmental ergonomics. The simulation of sweating can be achieved by putting a highly wicking stretchable knit fabric “skin” on top of the manikin. However, the addition of such a fabric skin makes it is difficult to accurately measure the skin surface temperature. Moreover, it takes considerable amount of time to measure the fabric skin surface temperature for each test. At present the attachment of temperature sensors to the wet fabric skin is still a challenge. The distance of the sensors to the fabric skin could significantly influence the temperature and relative humidity values of the wet skin surface. Hence, we conducted an intensive skin study on a dry thermal manikin to investigate the relationships among the nude manikin surface temperature, heat losses and the fabric skin surface temperature. An empirical equation was developed and validated on the thermal manikin "Tore" at Lund University. The empirical equation at ambient temperature 34 oC is Tsk =34.00- 0.0103HL. This equation can be used to enhance the prediction accuracy on the sweating skin surface temperature and the calculation of clothing evaporative resistance.
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| 52. |
- Wang, Faming, et al.
(författare)
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Development and validation of an empirical equation to predict wet fabric skin surface temperature of thermal manikins
- 2010
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Ingår i: Journal of Fiber Bioengineering and Informatics. - : Textile Bioengineering and Informatics Society. - 1940-8676 .- 2617-8699. ; 3:1, s. 9-15
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Tidskriftsartikel (refereegranskat)abstract
- Thermal manikins are useful tools to study clothing comfort and environmental ergonomics. The simulation of sweating can be achieved by putting a highly wicking stretchable knit fabric “skin” on top of the manikin. However, the addition of such a fabric skin makes it difficult to accurately measure the skin surface temperature. Moreover, it takes considerable amount of time to measure the fabric skin surface temperature at each test. At present the attachment of temperature sensors to the wet fabric skin is still a challenge. The distance of the sensors to the fabric skin could significantly influence the temperature and relative humidity values of the wet skin surface. Hence, we conducted an intensive skin study on a dry thermal manikin to investigate the relationships among the nude manikin surface temperature, heat losses and the fabric skin surface temperature. An empirical equation was developed and validated on the thermal manikin „Tore‟ at Lund University. The empirical equation at an ambient temperature 34.0 ºC is Tsk =34.00-0.0103HL. This equation can be used to enhance the prediction accuracy of wet fabric skin surface temperature and the calculation of clothing evaporative resistance.
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| 53. |
- Wang, Faming, et al.
(författare)
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Development and validity of a universal empirical equation to predict skin surface temperature on thermal manikins
- 2010
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Ingår i: Journal of Thermal Biology. - : Elsevier BV. - 0306-4565. ; 35:4, s. 197-203
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Clothing evaporative resistance is an important input in thermal comfort models. Thermal manikin tests give the most accurate and reliable evaporative resistance values for clothing. The calculation methods of clothing evaporative resistance require the sweating skin surface temperature (i.e., options 1 and 2). However, prevailing calculation methods of clothing evaporative resistance (i.e., options 3 and 4) are based on the controlled nude manikin surface temperature due to the sensory measurement difficulty. In order to overcome the difficulty of attaching temperature sensors to the wet skin surface and to enhance the calculation accuracy on evaporative resistance, we conducted an intensive skin study on a thermal manikin ‘Tore’. The relationship among the nude manikin surface temperature, the total heat loss and the wet skin surface temperature in three ambient conditions was investigated. A universal empirical equation to predict the wet skin surface temperature of a sweating thermal manikin was developed and validated on the manikin dressed in six different clothing ensembles. The skin surface temperature prediction equation in an ambient temperature range between 25.0 and 34.0 °C is Tsk=34.0–0.0132HL. It is demonstrated that the universal empirical equation is a good alternative to predicting the wet skin surface temperature and facilitates calculating the evaporative resistance of permeable clothing ensembles. Further studies on the validation of the empirical equation on different thermal manikins are needed however.
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| 54. |
- Wang, Faming, et al.
(författare)
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Development of Empirical Equations to Predict Sweating Skin Surface Temperature for Thermal Manikins in Warm Environments.
- 2010
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Ingår i: ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Clothing evaporative resistance is one of the most important parameters for clothing comfort. The clothing evaporation resistance can be measured on a sweating guarded hotplate, a sweating thermal manikin or a human subject. The sweating thermal manikin gives the most accurate value on evaporative resistance of the whole garment ensemble compared to the other two methods. The determination of clothing evaporative resistance on a thermal manikin requires sweating simulation. This can be achieved by either a pre-wetted fabric skin on top of the manikin (TORE), or a waterproof but permeable Gore-tex skin filled with water inside. The addition of a fabric skin can introduce a temperature difference between the manikin surface and the sweating skin surface. However, calculations on clothing evaporative resistance have often been based on the thermal manikin surface temperature. A previous study showed that the temperature differences can cause an error up to 35.9 % on the clothing evaporative resistance. In order to reduce such an error, an empirical equation to predict the skin surface temperature might be helpful. In this study, a cotton knit fabric skin and a Gore-tex skin were used to simulate two types of sweating. The cotton fabric skin was rinsed with tap water and centrifuged in a washing machine for 4 seconds to ensure no water drip. A Gore-tex skin was put on top of the pre-wetted cotton skin on a dry heated thermal manikin ‘Tore’ in order to simulate senseless sweating, similar to thermal manikins ‘Coppelius’ and ‘Walter’. Another simulation involved the pre-wetted fabric skin covered on top of the Gore-tex skin in order to simulate sensible sweating. This type of sweating simulation can be widely found on many thermal manikins worldwide, e.g. ‘Newton’. Six temperature sensors (Sensirion Inc, Switzerland) were attached on six sites of the skin outer surface by white thread rings to record the skin surface temperature. Twelve skin tests for each skin combination were performed at three different ambient temperatures: 34, 25 and 20 oC. Two empirical equations to predict the skin surface temperature were developed based on the mean manikin surface temperature, mean fabric skin surface temperature and the total heat loss. The prediction equations for the senseless sweating and sensible sweating on the thermal manikin ‘Tore’ were Tsk=34.0-0.0146HL and Tsk=34.0-0.0190HL, respectively. Further study should validate these two empirical equations, however.
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| 55. |
- Wang, Faming, et al.
(författare)
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Does PHS Model Predict Acceptable Skin and Core Temperatures While Wearing Protective Clothing.
- 2010
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Ingår i: ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Mathematical modeling is very important when experimental settings with human subjects are restricted to thermal limits necessary to protect the individual. The predicted heat strain (PHS) model has been published AS ISO 7933 for about six years. It describes a method for predicting the sweat rate and internal core temperature that the human body will develop in response to the working conditions. The PHS model was developed based on thousands of laboratory and field experiments collected from eight European laboratories. However, most of the laboratory and field tests were performed on human subjects with light clothing ensembles (0.38±0.34 clo < Icl < 0.77±0.18 clo). The prediction of physiological responses while human wearing highly insulating protective clothing might be weak. In order to check the prediction accuracy of current PHS model while using protective clothing, we conducted totally series of human subject tests at a simulated hot environment. The results of 18 tests involving the high visibility (HV), military (MIL) and firefighting (FIRE) clothing are reported here. Six human subjects were asked to walk on a treadmill at 4.5 km/h at 40 oC for 70 min. Two humidity levels were chosen: 2 kPa (RH = 27 %) and 3 kPa (RH = 41 %) depending on the garment. The rectal temperature, skin temperature, heart rate and metabolic rate were measured. The clothing and the subjects were weighed before and after the exposure in order to calculate the sweat and evaporation rate. The observed and predicted rectal temperatures and mean skin temperatures were compared. The PHS model failed to predict the final rectal temperature in FIRE and the predicted estimate was 1.83 oC higher than the observed value after 63-min exposure. The predicted curve showed a much deeper linear increase during the whole exercise. None of the predicted mean skin temperatures during the three testing scenarios were accurately predicted. The PHS model was consistently providing conservative mean skin temperature evaluations. The predicted curve in HV and MIL showed a much shallower increase during the early portion of the exposure and plateaued at temperatures lower than ever achieved by the subjects. The observed sweat rates were 556±110 g/h in HV, 717±200 g/h in MIL, and 834±274 g/h in FIRE. There was no significant difference between the predicted total sweat values and the experimental data (P=0.073). In summary, the PHS model produce prediction of core temperature which has an unacceptable error when human wore thick protective clothing. The weak prediction on the mean skin temperature in HV and MIL was in agreement with the empirical prediction equation in the source codes has the poorest and lowest correlation when a clothed human subject exercised at the humidity level above 2 kPa. It is therefore recommended that the PHS model should be amended to development and validated by manipulation of individual algorithms or physical (or physiological) parameters.
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| 56. |
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| 57. |
- Wang, Faming, et al.
(författare)
-
Effect of Different Fabric Skin Combinations on Predicted Sweating Skin Temperature of a Thermal Manikin
- 2010
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Ingår i: Proceedings Of The Second International Conference On Advanced Textile Materials & Manufacturing Technology. - 9787308079587 ; , s. 184-186
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Konferensbidrag (refereegranskat)abstract
- In this study, a knit cotton fabric skin and a Gore-tex skin were used to simulate two sweating methods. The Gore-tex skin was put on top of the pre-wetted knit cotton skin on a dry heated thermal manikin 'Tore' to simulate senseless sweating, similar to thermal manikins 'Coppelius' and 'Walter'. Another simulation involved the pre-wetted fabric skin covered on top of the Gore-tex skin in order to simulate sensible sweating. This type of sweating simulation can be widely found on many thermal manikins worldwide, e.g. 'Newton'. Two empirical equations to predict the wet skin surface temperature were developed based on the mean manikin surface temperature, mean fabric skin surface temperature and the total heat loss. The prediction equations for the senseless sweating and sensible sweating on the thermal manikin 'Tore' were T-sk=34.05-0.0193HL and T-sk=34.63-0.0178HL, respectively. It was found that the Gore-tex skin limits moisture evaporation and the predicted fabric skin temperature was greater than that in the G+C skin combination. Further study should validate those two empirical equations, however.
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| 58. |
- Wang, Faming, et al.
(författare)
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Effect of temperature difference between manikin and wet fabric skin surfaces on clothing evaporative resistance: how much error is there?
- 2012
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Ingår i: International Journal of Biometeorology. - : Springer Science and Business Media LLC. - 1432-1254 .- 0020-7128. ; 56, s. 177-182
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Tidskriftsartikel (refereegranskat)abstract
- Clothing evaporative resistance is one of the inherent factors that impede heat exchange by sweating evaporation. It is widely used as a basic input in physiological heat strain models. Previous studies showed a large variability in clothing evaporative resistance both at intra-laboratory and inter-laboratory testing. The errors in evaporative resistance may cause severe problems in the determination of heat stress level of the wearers. In this paper, the effect of temperature difference between the manikin nude surface and wet textile skin surface on clothing evaporative resistance was investigated by both theoretical analysis and thermal manikin measurements. It was found that the temperature difference between the skin surface and the manikin nude surface could lead to an error of up to 35.9% in evaporative resistance of the boundary air layer. Similarly, this temperature difference could also introduce an error of up to 23.7% in the real clothing total evaporative resistance (R ( et_real ) < 0.1287 kPa m(2)/W). Finally, it is evident that one major error in the calculation of evaporative resistance comes from the use of the manikin surface temperature instead of the wet textile fabric skin temperature.
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| 59. |
- Wang, Faming, et al.
(författare)
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Effects of Air Velocity and Clothing Combination on Heating Efficiency of an Electrically Heated Vest (EHV): A Pilot Study
- 2010
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Ingår i: Journal of Occupational and Environmental Hygiene. - : Informa UK Limited. - 1545-9632 .- 1545-9624. ; 7:9, s. 501-505
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Tidskriftsartikel (refereegranskat)abstract
- Cold endangers the heat balance of the human body. Protective clothing is the natural and most common equipment against cold stress. However, clothing for cold protection may be bulky and heavy, affecting human performance and increasing the work load. In such cases, a heated garment with built-in heating elements may be helpful. This pilot study presents a method based on a thermal manikin to investigate the effects of air velocity and clothing combination on the heating efficiency of an electrically heated vest (EHV). An infrared thermal camera was used to detect surface temperature distributions of the EHV on the front and back. Results show that the heating efficiency of the EHV decreases with increasing air velocity. Changes in EHV sequence in the three-layer clothing combination also significantly affect the heating efficiency: it increases with the increasing number of layers on top of the EHV. The highest mean temperature on the inner surface of the EHV was 40.2°C, which indicates that it is safe for the wearers. For the EHV to heat the human body effectively, we suggest that it be worn as a middle layer. Finally, the EHV is especially suitable for occupational groups whose metabolic rate is below 1.9 Mets.
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| 60. |
- Wang, Faming, et al.
(författare)
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Effects of various protective clothing and thermal environments on heat strain of unacclimated men: The PHS (predicted heat strain) model revisited
- 2013
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Ingår i: Industrial Health. - 1880-8026. ; 51:3, s. 266-274
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Tidskriftsartikel (refereegranskat)abstract
- Five protective garments were assessed on eight unacclimated male subjects at two WBGT temperatures: 19.0 and 24.5 °C. The thermophysiological responses and subjective sensations were reported. The PHS model (ISO7933) was used for predicting thermophysiological responses for each testing scenario. It was found that there were significant differences between clothing FIRE and other clothing on thermal sensation (p<0.05). Significant differences were found on skin humidity sensation between FIRE and L, HV or MIL (p<0.001). The RPE value in FIRE is significant different with L and HV (p<0.05). At 19.0 °C WBGT, the post-exercise mean skin temperatures increased by 0.59 and 1.29 °C in MIL and CLM. In contrast, mean skin temperatures in L, HV, MIL, CLM and FIRE at WBGT=24.5 oC increased by 1.7, 2.1, 2.1, 2.8 and 3.3 °C, respectively. The PHS model presented good performance on predicted mean skin temperatures in MIL and CLM at both two thermal environments. However, the skin temperature prediction with light clothing in high humidity (RH> 80%) was weak. For thick protective clothing, the prediction on rectal temperature was greatly conservative. It is thus concluded that the PHS model is inapplicable for high insulating clothing and measurements performed in high humidity environments.
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