Cylindric body element with metabolism and blood perfusion

System

System and boundary conditions

Quantity Value Units Description
T init 0 °C
w bl 0.005 ml / cm 3 *s Basal values for blood perfusion
q m 600 W / m 3 Basal values for metabolic rate
k 0.42 W / m*K Conductivity
ρ 1085 kg / m 3 Density
c 3768 J / kg*K Heat capacitance
T bla 37 °C Fixed aterial blood temperature
R 5.48 cm Radius
BE 1 Number of body elements

Problem description

Comparison of predicted muscle tissue temperature in a leg-cylinder with exact analytically derived values following the instantaneous introduction of a high blood flow and metabolic heat. The prediction time step was 10 minutes. Results from D. FIALA's simulation had been presented originally in Fig. 3.8, [1].

Results

Tissue temperature, radius 5.48 cm

Dead man in a cold environment (10°C)

System and boundary conditions

Quantity Value Units Description
T init 37 °C Initial temperatur of the abdomen
w bl 0 ml / cm 3 *s Basal values for blood perfusion
ε w 0.93 Surrounding wall emissivity
T a = T w 10 °C Ambient temperature
v a 0.1 m / s Environment air velocity
rh 30 % Environment air relative humidity
BE 1 Number of body elements

Problem description

Comparison of simulated rectal temperature with results presented in literature [2], [3]. Switching metabolism and blood perfusion off inside the dead man, heat transport takes place only via conduction in the human abdomen.

Results

Rectal temperature vs. time
Temperature distribution vs. radius

Naked Manikin

System

System and boundary conditions

Quantity Value Units Description
act 0.8 met Activity
ε w 0.93 Surrounding wall emissivity
T a = T w 30 °C Ambient temperature
v a 0.05 m / s Environment air velocity
rh 40 % Environment air relative humidity
BE 10 Number of body elements

Results

Quantity Value Value Units Description
Wght 73.50 73.53 kg Body weight
Body Fat 14.00 14.44 % Fat/body-mass ratio
A sk 1.90 1.86 m 2 Skin surface area
CardOut 4.90 4.89 ltr / min Cardiac output
M bas,0 87.10 87.13 W Basal metabolism
T sk,m 34.40 34.42 °C Mean skin temperature
T msc,m 36.20 36.02 °C Mean muscle temperature
T hy 37.00 36.89 °C Head core (hypothalamus) temperature
T re 36.88 36.79 °C Abdomen core (rectal) temperature
h c,m 2.70 2.66 W / m 2 *K Mean convective heat transfer coefficient
h r,m 5.00 4.50 W / m 2 *K Mean radiative heat transfer coeeficient
Q sk 78.50 78.20 W Skin heat loss
Q sk,c 21.50 21.83 W Heat loss by convection
Q sk,r 38.90 36.94 W Heat loss by (long wave) radiation
Q sk,e 18.10 19.43 W Heat loss by skin evaporation
Q rsp 8.50 8.93 W Heat loss by respiration
Q sum 87.00 87.13 W Sum of heat losses

Changing environment 28-18-28°C

System

System and boundary conditions

Quantity Value Units Description
act 1.15 met Activity
ε w 0.93 Surrounding wall emissivity
v a 0.1 m / s Environment air velocity
rh 40 % Environment air relative humidity
BE 10 Number of body elements
n 3 Number of test persons

Problem description

Exposure to sudden changes in ambient temperature of Ta = 28-18-28 °C investigated by HARDY et al. [4].
Simulation includes 60 min preconditioning at Ta = 22 °C and act = 2.5 met. The preconditioning phase is not plotted in the diagrams below.

Results

Mean skin temperature
Metabolism
Rectal temperature
Comparison of comfort indices

Changing environment 28-48-28°C

System

System and boundary conditions

Quantity Value Units Description
act 1.0 met Activity
ε w 0.93 Surrounding wall emissivity
v a 0.1 m / s Environment air velocity
BE 10 Number of body elements
n 3 Number of test persons

Problem description

Exposure to sudden changes in ambient temperature of Ta = 28-48-28 °C investigated by STOLWIJK et al. [5].
Simulation includes 60 min preconditioning at Ta = 29 °C and act = 2.0 met. The preconditioning phase is not plotted in the diagrams below.

Results

Mean skin temperature
Evaporation heat loss
Rectal temperature
Comparison of comfort indices

Cool environment at 10°C

System

System and boundary conditions

Quantity Value Units Description
act 0.8 met Activity
ε w 0.93 Surrounding wall emissivity
v a 0.1 m / s Environment air velocity
rh 67 % Environment air relative humidity
Icl 0.1 clo Global value for Icl for the PMV calculation
BE 10 Number of body elements
n 4 Number of test persons

Problem description

Exposure to an environment of Ta = 10 °C investigated by BUDD et al. [6].

Results

Mean skin temperature
Metabolism
Shoulder temperature
Arm temperature
Abdomen temperature
Deviation from initial value

Naked manikin - 1 hour exposure - wide range of environmental conditions

System

System and boundary conditions

Quantity Value Units Description
act 1 met Activity
ε w 0.93 Surrounding wall emissivity
v a 0.1 m / s Environment air velocity
rh 30 % Environment air relative humidity
Icl 0.1 clo Global value for Icl for the PMV calculation
BE 10 Number of body elements
n ≥3 Number of test persons

Problem description

Skin temperature, body core temperature and regulatory responses as measured and as predicted by the model over a wide range of environmental conditions [7], [4]. Each data point represents a separate 1-hr exposure to the particular ambient temperature.

Results

Mean skin temperature, after 1hr exposure at different ambient temperatures
Extra metabolism, after 1hr exposure at different ambient temperatures
Rectal temperature, after 1hr exposure at different ambient temperatures
Evaporation, after 1hr exposure at different ambient temperatures

Bibliography

[1] FIALA D. Dynamic simulation of human heat transfer and thermal comfort. PhD thesis. De Montfort University, Leicester. 1998
[2]  HENSSGE, C., MADEA, B., Methoden zur Bestimmung der Todeszeit an Leichen, Schmidt-Römhild, Lübeck, pp 133-201, 1988.
[3]  ECKL, M. ,Temperaturgestützte Todeszeitschätzung bei nur partiell bekannten Umgebungsbedingungen, PhD thesis, LMU Munich, 2004.
[4]  HARDY J.D., and J.A.J. STOLWIJK. Partitional calorimetric studies of man during exposures to thermal transients. J. Appl. Physiol., vol. 21, pp. 1799-1806, 1966.
[5]  STOLWIJK J.A.J., and J.D. HARDY. Partitioned calorimetric studies of responses of man to thermal transients. J. Appl. Physiol., vol. 21, pp. 967-977, 1966.
[6]  BUDD, G.M., and N. WARHAFT. Body temperature, shivering, blood pressure and heart rate during a standard cold stress in Australia and Antarctica. J. Physiol. (London), vol. 186, pp. 216-232, 1966.
[7]  GAGGE A.P., J.A.J. STOLWIJK, and J.D. HARDY. Comfort and the thermal sensation and associated physiological responses at various ambient temperatures. Environmental Research 1, pp. 1-20, 1967.