A spherical, 3 mm cryogenic probe at temperature -30°C is embedded into skin at 37°C. Frozen tissue develops and the interface between the frozen and normal tissue is 0°C. If the thermal conductivity of frozen tissue is 1.5 W/m-K and heat transfer at the phase front is characterized by a convection coefficient of 50 Wim2-K, what is the thickness of the frozen layer? 1=0.0015 m Probe 12 Ts.1=-30 °C -T32=0°C Normal tissue Ten = 37 °C h= 50 Wim2 -K Goond Frozen tissue, k= 1.5 WimK 9oonv

A spherical, 3 mm cryogenic probe at temperature -30°C is embedded into skin at 37°C. Frozen tissue develops and the interface between the frozen and normal tissue is 0°C. If the thermal conductivity of frozen tissue is 1.5 W/m-K and heat transfer at the phase front is characterized by a convection coefficient of 50 Wim2-K, what is the thickness of the frozen layer? 1=0.0015 m Probe 12 Ts.1=-30 °C -T32=0°C Normal tissue Ten = 37 °C h= 50 Wim2 -K Goond Frozen tissue, k= 1.5 WimK 9oonv

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.37P

See similar textbooks

Similar questions

A section of a composite wall with the dimensions shown below has uniform temperatures of 200C and 50C over the left and right surfaces, respectively. If the thermal conductivities of the wall materials are: kA=70W/mK,kB=60W/mK, kC=40W/mK, and kP=20W/mK, determine the rate of heat transfer through this section of the wall and the temperatures at the interfaces. Repeat Problem 1.34, including a contact resistance of 0.1 K/W at each of the interfaces.
1.63 Liquid oxygen (LOX) for the space shuttle is stored at 90 K prior to launch in a spherical container 4 m in diameter. To reduce the loss of oxygen, the sphere is insulated with superinsulation developed at the U.S. National Institute of Standards and Technology's Cryogenic Division; the superinsulation has an effective thermal conductivity of 0.00012 W/m K. If the outside temperature is on the average and the LOX has a heat of vaporization of 213 J/g, calculate the thickness of insulation required to keep the LOX evaporation rate below 200 g/h.
Both ends of a 0.6-cm copper U-shaped rod are rigidly affixed to a vertical wall as shown in the accompanying sketch. The temperature of the wall is maintained at 93C. The developed length of the rod is 0.6 m, and it is exposed to air at 38C. The combined radiation and convection heat transfer coefficient for this system is 34W/m2K. (a) Calculate the temperature of the midpoint of the rod. (b) What will the rate of heat transfer from the rod be?
A square silicon chip 7mm7mm in size and 0.5-mm thick is mounted on a plastic substrate as shown in the sketch below. The top surface of the chip is cooled by a synthetic liquid flowing over it. Electronic circuits on the bottom of the chip generate heat at a rate of 5 W that must be transferred through the chip. Estimate the steady-state temperature difference between the front and back surfaces of the chip. The thermal conductivity of silicon is 150 W/m K. Problem 1.6
It is designed in such a way that the internal temperature of a commercial heat treatment furnace can reach up to 165 oC. All surfaces of the furnace consist of firebrick (10 cm), insulation material and sheet metal (3mm) from the inside out. Given that the outdoor temperature is 22 oC, the outer sheet will be allowed to go up to 35 oC, which is a temperature that will not be disturbed by hand contact. In this case, determine the insulation material thickness to be used. Insulation material thermal conductivity coefficient is 0.066 insulation W / m oC, 60 W / m oC for sheet metal and 115 W / m oC for firebrick. Indoor heat transfer coefficient will be accepted as 25 W / m2 oC and 12 W / m2 oC for outdoor environment.
Presents the diagram of the problem, necessary formulas, clearance and numerical solution: Two heat reservoirs with respective temperatures of 325 and 275 K are brought into contact by an iron rod 200 cm long and 24 cm2 in cross section. Calculate the heat flux between the reservoirs when the system reaches its steady state. The thermal conductivity of iron at 25 ◦C is 79.5 W/m K.
A long wire of diameter D = 2 mm is submerged in an oil bath of temperature T∞ = 23°C. The wire has an electrical resistance per unit length of Re′=0.01 Ω/m. If a current of I = 180 A flows through the wire and the convection coefficient is h = 529 W/m2 · K, what is the steady-state temperature of the wire? From the time the current is applied, how long does it take for the wire to reach a temperature that is within 2°C of the steady-state value? The properties of the wire are ρ = 2,334 kg/m3, c = 537 J/kg · K, and k = 43 W/m · K.
You are designing a small heatsink to cool a high-powered IC on a control unit PCB. The IC puts out 40,000 W/m2 and has a size of 40mm x 20mm. A fan blows 40 degrees C air across the IC at a speed of 4 m/s. The IC is well insulated on its back face. If the convection coefficient is 62 W/m2K, what is the surface temperature of the IC?
The wall of a box furnace is made of a composite material. Layer A is directly in contact with the combustion gases inside the furnace and it has a thickness of 0.023 m, a thermal conductivity of 132 W/m-K, and a cross-sectional area of 0.42 m2. On the other hand, Layer C corresponds to the outermost layer that is in direct contact with the ambient air. It has a thickness of 0.036 m, a thermal conductivity of 2 W/m-K, and has the same cross-sectional area as Layer A. In between Layer A and Layer C are two parallel layers: LayerB and Layer D. Layer B has the same cross-sectional area as Layer D. The thickness of Layer B and Layer D is 0.066 m. Layer B has a thermal conductivity of 13 W/m-K; while, Layer D has a thermal conductivity of 23 W/m-K. The combustion gases inside the furnace has a temperature of 373 ; while, the ambient air has a temperature of 30 . Finally, the convection heat transfer coefficients at the inside and outside of the wall are 111 W/m2-K and 22 W/m2-K…
19) In fabrication process, steel components are formed hot and then quenched in water. Consider 2 m long, 0.2 m diameter steel cylinder (k = 40 W/m.°C, a = 10-5 m² /s), initially at 400 °C, that is suddenly quenched in water at 50 °C. If heat transfer coefficient is 200 W/m². K, calculate the following 20 min min after immersion: a) center temperature, b) surface temperature, c) The heat transferred to the water during the initial 20 min.
A 5cm copper plate has a thermal conductivity of 395 ?/m-k is used as a heat sink for a semiconductor. A 1mm layer of thermal paste lies in between the two and it has a thermal conductivity of 10 ? /m-k. Solve for the heat transferred at a 5cmx5cm area if the semiconductor is 80C, while the copper plate has a temperature of 30C since it is exposed to ambient air temperature.
It is designed in such a way that the internal temperature of a commercial heat treatment furnace can reach up to 165 oC. All surfaces of the furnace consist of firebrick (10 cm), insulation material and sheet metal (3mm) from the inside out. Given that the outdoor temperature is 22 oC, the outer sheet will be allowed to go up to 35 oC, which is a temperature that will not disturb in contact with hands. In this case, determine the insulation material thickness to be used. The thermal conductivity coefficient of the insulation material is insulation 0.066 W / m oC, 60 W / m oC for sheet metal and 115 W / m oC for firebrick. Indoor heat transfer coefficient will be accepted as 25 W / m2 oC and 12 W / m2 oC for outdoor environment.