1-122 A4-m-long section of an air heating system of a house passes through an unheated space in the attic. The inner diam- eter of the circular duct of the heating system is 20 cm. Hot air enters the duct at 100 kPa and 65°C at an average velocity of 3 m/s. The temperature of the air in the duct drops to 60°C as a result of heat loss to the cool space in the attic. Determine the rate of heat loss from the air in the duct to the attic under steady conditions. Also, determine the cost of this heat loss per hour if the house is heated by a natural gas furnace having an effi- ciency of 82 percent, and the cost of the natural gas in that area is $0.58/therm (1 therm = 105,500 kJ). Answers: 0.488 kJ/s, $0.012/h 4 m Hot air 60°C 65°C 3 m/s FIGURE P1-122

1-122 A4-m-long section of an air heating system of a house passes through an unheated space in the attic. The inner diam- eter of the circular duct of the heating system is 20 cm. Hot air enters the duct at 100 kPa and 65°C at an average velocity of 3 m/s. The temperature of the air in the duct drops to 60°C as a result of heat loss to the cool space in the attic. Determine the rate of heat loss from the air in the duct to the attic under steady conditions. Also, determine the cost of this heat loss per hour if the house is heated by a natural gas furnace having an effi- ciency of 82 percent, and the cost of the natural gas in that area is $0.58/therm (1 therm = 105,500 kJ). Answers: 0.488 kJ/s, $0.012/h 4 m Hot air 60°C 65°C 3 m/s FIGURE P1-122

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

See similar textbooks

Similar questions

(d) The rate of heat generated, Btu/min
Which one of the following processes of heat transfer requires the presence of a fluid? a. conduction b. radiationc. convectiond. none of the above choices are valid
i need the answer quickly
* What is the specific heat of metal if its mass is 27 g and it requires 420 J of heat energy to increase its ?temperature from 25°C to 50°C 0.19 cal/g.KO 62.2 J/kg. °C O 41.90 J/kg. KO 25.4 kg. °C O None of them. O
Tell
AB POWER ENGINEERING Introduction about the cooling system of internal combustion engines use in agriculture, and how cooling system works
A metal spoon and a wooden spoon are left overnight in a room. Why do we feel colder when we touch the metal spoon than when we touch the wooden one? a. Since metals usually have a lower heat capacity than non-metals, the metal spoon loose more heat to the room and consequently has a lower temperature b. Metals release heat faster than non-metals because of their higher thermal conductivity c. This is merely psychological since we are conditioned to think of metals as “cold” d. Metals absorb heat faster than non-metals because of their higher thermal conductivity
I need the answer as soon as possible
The given diagram shows three processes, i.e., isochoric, isobaric and isothermal. The correct sequence of the processes, in the same order is given by Select one: O a. bad O b. dba O c.dab O d. abd
Which of the following will have a higher rate of heat transfer. With conduction heat transfer. A. pulverized shale stone B. the stone and the pulverized shale will have the same heat transfer as they have the same conductivity constant. C. a solid block of shale stone D. the pulverized shale will have a higher heat transfer as it has a higher duction coefficient
In an isothermal process, the internal energy of gas molecules Select one: O a. Decreases O b. Remain constant c. Increases O d. May increase/decrease depending on the properties of gas
Help me answer letter A.