The thermal conductivities of human tissues vary greatly. Fat and skin have cond

Question

The thermal conductivities of human tissues vary greatly. Fat and skin have conductivities of about 0.20 W/m · K and 0.020 W/m · K respectively, while other tissues inside the body have conductivities of about 0.50 W/m · K. Assume that between the core region of the body and the skin surface lies a skin layer of 1.0 mm, fat layer of 0.50 cm, and 3.2 cm of other tissues.

(a) Find the R-factor for each of these layers, and the equivalent R-factor for all layers taken together, retaining two digits.
Rskin ____ m2·K/W
Rfat _____ m2·K/W
Rtissue ____ m2·K/W
R ______m2·K/W

(b) Find the rate of energy loss when the core temperature is 37°C and the exterior temperature is 0°C. Assume that both a protective layer of clothing and an insulating layer of unmoving air are absent, and a body area of 2.0 m2.
____ W

Explanation / Answer

the equation to find R is L/K

so you have
Rskin = Lskin/Kskin = .001m/.02W/mK = .05
Rfat = .005m/.2W/mK = .025
Rtissure = .032m/.5W/mK = .064

then R = Rtotal = Rskin + Rfat + Rtissue = .139


b) A(Thot - Tcold)/Rtotal
2m^2(37Kelvin)/.139 = 532.37W

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.