5.16 A thermal energy storage unit consists of a large rectan- gular channel, which is well insulated on its outer surface and encloses alternating layers of the storage material and the flow passage. Storage material Hot gas Th BAGE Each layer of the storage material is an aluminum slab of width W = 0.05 m, which is at an initial temperature of 25°C. Consider conditions for which the storage unit is charged by passing a hot gas through the passages, with the gas temperature and the convection coefficient assumed to have constant values of T = 600°C and h = 100 W/m² K throughout the channel. How long will it take to achieve 75% of the maximum possible energy storage? What is the temperature of the alu- minum at this time?

5.16 A thermal energy storage unit consists of a large rectan- gular channel, which is well insulated on its outer surface and encloses alternating layers of the storage material and the flow passage. Storage material Hot gas Th BAGE Each layer of the storage material is an aluminum slab of width W = 0.05 m, which is at an initial temperature of 25°C. Consider conditions for which the storage unit is charged by passing a hot gas through the passages, with the gas temperature and the convection coefficient assumed to have constant values of T = 600°C and h = 100 W/m² K throughout the channel. How long will it take to achieve 75% of the maximum possible energy storage? What is the temperature of the alu- minum at this time?

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Example 5.16. An aluminium alloy fin (k= 200 W/m.K), 3.5 mm thick and 2.5 cm long protrudes from a wall. The base is at 420°C and ambient air temperature is 30°C. The heat transfer coefficient may be taken as 11 Wlm2.K. Find the heat loss and fin efficiency, if the heat loss from fin tip is negligible.
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Example 16.3 Determine the thickness of a glass window 120 × 120 cm² that separates a room at temperature of 25°C from outside temperature of 44°C and allows not more than 7 × 10° cal of heat to enter the room each day. Assume thermal conductivity of glass as 0.0024 cal/cm.s.K.
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Due higher viscosity, the heat-transfer coefficient of moving liquid hydrocarbons is generally higher than that of moving water Select one: O True O False The proper strategy to enhance heat transfer of a heat exchanger is trying to increase the heat transfer coefficient of the side with the lower heat resistant. Select one: O True O False For the universal 3-D heat transfer equation (see topic 7 in URCourses notes), we have to simplify by eliminating terms that are zero or near zero first, and then we can only use numerical methods (such as finite difference) to solve those problems. Select one: O True O False
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14.3 The external brick wall of a building has a surface area A of 830 m² and thickness 8 of 300 mm. The wall has a thermal insulation on its outer sur- face. The thermal conductivity of concrete k is 1.6 W/m K and of insulation k; is 0.04 W/m K. The indoor and outdoor air temperatures are t₁ = 21°C and to = 3°C, respectively. The heat-transfer coefficients are h; = 14 W/m²K (on the inner surface) and h = 20 W/m²K (on the outer surface). Determine (1) the rate of heat loss through the wall without insulation and (2) the thick- ness of the insulation required to reduce the rate of heat loss by 60%.
Please help. I am not sure how to approach this problem. This problem involves heat transfer and internal flow within a retangular channel. Thank you.
a. An air stream passing through a 2-inch (1/6 ft) diameter, thin-walled tube is to be heated by high- pressure steam condensing on the outer surface of the tube at 320 °F. The overall heat transfer coefficient, h between steam and air can be assumed to be 25 Btu/(ft2.hr °F) with the air entering at 100 ft/sec, 10 psia, 40 °F. The air is to be heated to 150 °F. Determine the tube length required. Assuming Rayleigh Line flow, calculate the static pressure change due to heat addition. Also, for the same inlet conditions, calculate the pressure drop due to friction, assuming Fanno flow in the duct with f = 0.018. b. c. d. To obtain an approximation to the overall pressure drop in this heat exchanger, add the two results. Discuss the accuracy of this calculation.
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