Q1 a) What is the physical significance of Reynolds number? Write down 5 (five) factors that influcnce the convection heat transfer rates. b) Water is to be heated from 10°C to 80°C as it flows through a 2-cm-internal-diameter, 7-m- long tube. The tube is equipped with an electric resistance heater, which provides uniform heating throughout the surface of the tube. The outer surface of the heater is well insulated, so that in steady operation all the heat from the heater is transferred to the water in the tube. If the system is to provide hot water at a rate of 8 L/min, determine the convection heat transfer coefficient and temperature at the inner surface of the pipe at the exit. Q2 a) Consider heat transfer to oil flow inside a copper pipe. Is the pipe length affecting the heat transfer rate into the oil? Briefly explain. b) Used engine oil can be recycled by a patented reprocessing system. Suppose that such a system includes a process during which engine oil flows through a l-cm-internal diameter, 0.02-cm- wall copper tube at the rate of 0.05 kg/s. The oil enters at 35°C and is to be heated to 45°C by atmospheric-pressure steam condensing on the outside, as shown in figure given below. i) Determine the condensing steam temperature at I atm, T. ["C). ii) ii) iv) Calculate the convection heat transfer coefficient for the oil inside the pipe, [W/m'.KJ. Calculate the rate of heat transfer rate into the oil, [kW], and, determine the length of the tube required. Condensing steam at lam Oil in 35°C 0.05 kg/s Oil out 45°C I em 0.02 cm Copper tube L= ? Q3 a) A rectangular duct with width of 0.3 m and height of 0.2 m is used to deliver cold fresh air to a medium size master bedroom. Heat from roof causes the internal surface temperature of the duct to be 40°C. The fresh cold air enters the duct at 17C and exits at 23°C. Given the volumetric flow rate of the fresh cold air which enters the duct is 0.15 m'/s, assuming the flow inside the duct is fully developed: i) State two assumptions for analyzing this problem ii) Calculate the Reynolds number for the flow inside the duct ii) Calculate the heat transfer rate to the fresh cold air inside the duct, kW
Q1 a) What is the physical significance of Reynolds number? Write down 5 (five) factors that influcnce the convection heat transfer rates. b) Water is to be heated from 10°C to 80°C as it flows through a 2-cm-internal-diameter, 7-m- long tube. The tube is equipped with an electric resistance heater, which provides uniform heating throughout the surface of the tube. The outer surface of the heater is well insulated, so that in steady operation all the heat from the heater is transferred to the water in the tube. If the system is to provide hot water at a rate of 8 L/min, determine the convection heat transfer coefficient and temperature at the inner surface of the pipe at the exit. Q2 a) Consider heat transfer to oil flow inside a copper pipe. Is the pipe length affecting the heat transfer rate into the oil? Briefly explain. b) Used engine oil can be recycled by a patented reprocessing system. Suppose that such a system includes a process during which engine oil flows through a l-cm-internal diameter, 0.02-cm- wall copper tube at the rate of 0.05 kg/s. The oil enters at 35°C and is to be heated to 45°C by atmospheric-pressure steam condensing on the outside, as shown in figure given below. i) Determine the condensing steam temperature at I atm, T. ["C). ii) ii) iv) Calculate the convection heat transfer coefficient for the oil inside the pipe, [W/m'.KJ. Calculate the rate of heat transfer rate into the oil, [kW], and, determine the length of the tube required. Condensing steam at lam Oil in 35°C 0.05 kg/s Oil out 45°C I em 0.02 cm Copper tube L= ? Q3 a) A rectangular duct with width of 0.3 m and height of 0.2 m is used to deliver cold fresh air to a medium size master bedroom. Heat from roof causes the internal surface temperature of the duct to be 40°C. The fresh cold air enters the duct at 17C and exits at 23°C. Given the volumetric flow rate of the fresh cold air which enters the duct is 0.15 m'/s, assuming the flow inside the duct is fully developed: i) State two assumptions for analyzing this problem ii) Calculate the Reynolds number for the flow inside the duct ii) Calculate the heat transfer rate to the fresh cold air inside the duct, kW
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
Related questions
Question
![Q1
a) What is the physical significance of Reynolds number? Write down 5 (five) factors that
influence the convection heat transfer rates.
b) Water is to be heated from 10°C to 80°C as it flows through a 2-cm-internal-diameter, 7-m-
long tube. The tube is equipped with an electric resistance heater, which provides uniform
heating throughout the surface of the tube. The outer surface of the heater is well insulated, so
that in steady operation all the heat from the heater is transferred to the water in the tube. If the
system is to provide hot water at a rate of 8 L/min, determine the convection heat transfer
coefficient and temperature at the inner surface of the pipe at the exit.
Q2
a) Consider heat transfer to oil flow inside a copper pipe. Is the pipe length affecting the heat
transfer rate into the oil? Briefly explain.
b) Used engine oil can be recycled by a patented reprocessing system. Suppose that such a system
includes a process during which engine oil flows through a l-cm-internal diameter, 0.02-cm-
wall copper tube at the rate of 0.05 kg/s. The oil enters at 35°C and is to be heated to 45°C by
atmospheric-pressure steam condensing on the outside, as shown in figure given below.
i)
Determine the condensing steam temperature at 1 atm, T, ["C].
ii)
Calculate the convection heat transfer coefficient for the oil inside the pipe, [W/m'.K].
iii)
iv)
Calculate the rate of heat transfer rate into the oil, [kW], and,
determine the length of the tube required.
Condensing steam at lam
Oil in
Oil out
45°C
35°C
0.05 kg/s
I em
0.02 cm
Соррer wbe
L = ?
Q3
a) A rectangular duct with width of 0.3 m and height of 0.2 m is uscd to deliver cold fresh air to a
medium size master bedroom. Heat from roof causes the internal surface temperature of the
duct to be 40°C. The fresh cold air enters the duct at 17°C and exits at 23°C. Given the
volumetric flow rate of the fresh cold air which enters the duct is 0.15 m/s, assuming the flow
inside the duct is fully developed:
i) State two assumptions for analyzing this problem
ii) Calculate the Reynolds number for the flow inside the duct
iii) Calculate the heat transfer rate to the fresh cold air inside the duct, kW](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F0cb5da78-12c8-467b-adf0-b3ac60043831%2F9a8c5a7b-5ff5-47f2-ba14-73682b7dfeeb%2Fnjx9e5i_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Q1
a) What is the physical significance of Reynolds number? Write down 5 (five) factors that
influence the convection heat transfer rates.
b) Water is to be heated from 10°C to 80°C as it flows through a 2-cm-internal-diameter, 7-m-
long tube. The tube is equipped with an electric resistance heater, which provides uniform
heating throughout the surface of the tube. The outer surface of the heater is well insulated, so
that in steady operation all the heat from the heater is transferred to the water in the tube. If the
system is to provide hot water at a rate of 8 L/min, determine the convection heat transfer
coefficient and temperature at the inner surface of the pipe at the exit.
Q2
a) Consider heat transfer to oil flow inside a copper pipe. Is the pipe length affecting the heat
transfer rate into the oil? Briefly explain.
b) Used engine oil can be recycled by a patented reprocessing system. Suppose that such a system
includes a process during which engine oil flows through a l-cm-internal diameter, 0.02-cm-
wall copper tube at the rate of 0.05 kg/s. The oil enters at 35°C and is to be heated to 45°C by
atmospheric-pressure steam condensing on the outside, as shown in figure given below.
i)
Determine the condensing steam temperature at 1 atm, T, ["C].
ii)
Calculate the convection heat transfer coefficient for the oil inside the pipe, [W/m'.K].
iii)
iv)
Calculate the rate of heat transfer rate into the oil, [kW], and,
determine the length of the tube required.
Condensing steam at lam
Oil in
Oil out
45°C
35°C
0.05 kg/s
I em
0.02 cm
Соррer wbe
L = ?
Q3
a) A rectangular duct with width of 0.3 m and height of 0.2 m is uscd to deliver cold fresh air to a
medium size master bedroom. Heat from roof causes the internal surface temperature of the
duct to be 40°C. The fresh cold air enters the duct at 17°C and exits at 23°C. Given the
volumetric flow rate of the fresh cold air which enters the duct is 0.15 m/s, assuming the flow
inside the duct is fully developed:
i) State two assumptions for analyzing this problem
ii) Calculate the Reynolds number for the flow inside the duct
iii) Calculate the heat transfer rate to the fresh cold air inside the duct, kW
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