how to solve it? number 2.36 t be used if its thickness were to be limited to 5 mm. iation material that should d is Problem 2.35 2.36 The development of contact lenses has transformed the solutions that are available today for vision im- pairments. However, wearing them also poses several problems that includes the condition of dry eyes due to lack of cooling, oxygenation, and moisturizing or lubrication of the cornea, among others In the devel- opmental phase of a new protective liquid for contact lenses, the optometrist would like to know the rate of heat loss from the anterior chamber of the eye through the cornea and the contact lens. This system is mod- eled as a partial hollow sphere, as shown in the sche- matic diagram on the next page. The inner and outer radius of the cornea are, respectively, r 10 mm and -r: 12.5 mm. and the outer radius of theTittedCon- tact lens is ra 14.5 mm. The anterior chamber, which contains the aqueous humor that provides nutrients to the cornea (as the latter tissue has no blood vessels), ex- poses the inner surface of the cornea to a temperature of quickfacts-web.pdf 沈裕, 2019/3/7 Steady Heat Conduction Chapter 2 146 Less Pupil Cornea Antenor Retina Optic nerve Problem 2.36 of T, = 36.9°C with a convective heat transfer coef- ficient of h 10 W/m-K. The thermal conductivity of the transparent tissue of the cornea is 0.35 W/m K, and that of the contact lens material is 0.8 W/m-K. The outer surface of the contact lens is exposed to room air at Te 22°C and has a convection coeffi- cient of h, 5 W/m2 K. Draw a thermal circuit for the system showing all of the temperature potentials and thermal resistances. Then estimate the rate of heat loss from the anterior eye assuming that steady state exists and the eye aperture spherical angle is 100 an electroni are to be rec 0.25 cm thi be 100 fins coefficient, to be 35 W the percent finned wall 2.37 In cryogenic surgery, a small spherical probe is bought into contact with the diseased tissue which is frozen and thereby destroyed. One such probe can be mod- eled as a 3-mm diameter sphere whose surface is maintained at 240 K when the surrounding tiss 146 Chapter 2 Steady Heat Conduction Contact lens lris Lens nteri chamber Anterior chamber Iris Cornea Retina Optic nerve Problem 2.36 of T 36.9 C with a convective heat transfer coef- ficient of h,10 W/m K. The thermal conductivity of the transparent tissue of the cornea is 0.35 W/m-K and that of the contact lens material is 0.8 W/m K The outer surface of the contact lens is exposed to room air at T, 22°C and has a convection coeffi cient of h, 5 W/m2 K. Draw a thermal sicuit f an electronic device I m wide and I m tll Th li are to be rectangular in cross section, 2.5cm 0.25 em thick, as shown in the figure. Ther ae be 100 fins per meter. The convection heat coefficient, both for the wall and the fins, iso to be 35 Wiud be used if its thickness were to be limited to 5 mm. iation material that should d is Problem 2.35 2.36 The development of contact lenses has transformed the solutions that are available today for vision im- pairments. However, wearing them also poses several problems that includes the condition of dry eyes due to lack of cooling, oxygenation, and moisturizing or lubrication of the cornea, among others In the devel- opmental phase of a new protective liquid for contact lenses, the optometrist would like to know the rate of heat loss from the anterior chamber of the eye through the cornea and the contact lens. This system is mod- eled as a partial hollow sphere, as shown in the sche- matic diagram on the next page. The inner and outer radius of the cornea are, respectively, r 10 mm and -r: 12.5 mm. and the outer radius of theTittedCon- tact lens is ra 14.5 mm. The anterior chamber, which contains the aqueous humor that provides nutrients to the cornea (as the latter tissue has no blood vessels), ex- poses the inner surface of the cornea to a temperature of quickfacts-web.pdf 沈裕, 2019/3/7 Steady Heat Conduction Chapter 2 146 Less Pupil Cornea Antenor Retina Optic nerve Problem 2.36 of T, = 36.9°C with a convective heat transfer coef- ficient of h 10 W/m-K. The thermal conductivity of the transparent tissue of the cornea is 0.35 W/m K, and that of the contact lens material is 0.8 W/m-K. The outer surface of the contact lens is exposed to room air at Te 22°C and has a convection coeffi- cient of h, 5 W/m2 K. Draw a thermal circuit for the system showing all of the temperature potentials and thermal resistances. Then estimate the rate of heat loss from the anterior eye assuming that steady state exists and the eye aperture spherical angle is 100 an electroni are to be rec 0.25 cm thi be 100 fins coefficient, to be 35 W the percent finned wall 2.37 In cryogenic surgery, a small spherical probe is bought into contact with the diseased tissue which is frozen and thereby destroyed. One such probe can be mod- eled as a 3-mm diameter sphere whose surface is maintained at 240 K when the surrounding tiss 146 Chapter 2 Steady Heat Conduction Contact lens lris Lens nteri chamber Anterior chamber Iris Cornea Retina Optic nerve Problem 2.36 of T 36.9 C with a convective heat transfer coef- ficient of h,10 W/m K. The thermal conductivity of the transparent tissue of the cornea is 0.35 W/m-K and that of the contact lens material is 0.8 W/m K The outer surface of the contact lens is exposed to room air at T, 22°C and has a convection coeffi cient of h, 5 W/m2 K. Draw a thermal sicuit f an electronic device I m wide and I m tll Th li are to be rectangular in cross section, 2.5cm 0.25 em thick, as shown in the figure. Ther ae be 100 fins per meter. The convection heat coefficient, both for the wall and the fins, iso to be 35 Wiud