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The fuel assembly shown in the left figure consists of periodic arrays of annular bare fuel rods, which are cooled by passing water through the center of the rods as well as over the outer surface. We want to analyze the thermal performance of the fuel rods by dividing the assembly into a number of unit cells (control volumes) and evaluating the

The fuel assembly shown in the left figure consists of periodic arrays of annular bare fuel rods, which are cooled by passing water through the center of the rods as well as over the outer surface. We want to analyze the thermal performance of the fuel rods by dividing the assembly into a number of unit cells (control volumes) and evaluating the

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
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.
Chapter5: Analysis Of Convection Heat Transfer
Section: Chapter Questions
Problem 5.4P: 5.4 Evaluate the Stanton number for flow over a tube from the following data: , , , , .
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The fuel assembly shown in the left figure consists of periodic arrays of annular bare fuel rods, which are cooled by passing water through the center of the rods as well as over the outer surface. We want to analyze the thermal performance of the fuel rods by dividing the assembly into a number of unit cells (control volumes) and evaluating the performance of a cell, as shown in the right figure.

Fuel Inner coolant channel Outer coolant channel a) Find the ratio of the average coolant velocities in the inner and outer channels at the axial level z. At this level, the pressure drop per unit length is the same in both channels and the bulk coolant temperature is 293 C. Assume that the flow is tur- bulent and fully developed in both channels. b) Find the maximum temperature in the rod, and the radius at which the maxi- mum temperature occurs, for a particular axial location where the inner and outer surface temperatures of the rod are 371 C. At that level the volumetric heat gen- eration rate may be assumed to be uniform and equal to 0.1 MW/m³. Assume constant fuel conductivity for the fuel. c) Find the mean temperature of the coolant at the core exit (i.e., the mixture of the coolant passing through the inner channel and that passing through the outer channel). The fuel rod is 4.3 m long and the axial power profile along the channel is give by: TZ 4"(z)=ġ", cos 4.3 where z is in m and 4 =0.52 MW/m³. Other pertinent data: Inlet water temperature = 293 C, water pressure at the outlet = 14 MPa, water flow rate per unit cell = 18.37 kg/s, unit cell side (L) = 6.35 cm, fuel inner radius (r¡) = 1.27 cm, and fuel outer radius (r2) = 2.54 cm.
Transcribed Image Text:Fuel Inner coolant channel Outer coolant channel a) Find the ratio of the average coolant velocities in the inner and outer channels at the axial level z. At this level, the pressure drop per unit length is the same in both channels and the bulk coolant temperature is 293 C. Assume that the flow is tur- bulent and fully developed in both channels. b) Find the maximum temperature in the rod, and the radius at which the maxi- mum temperature occurs, for a particular axial location where the inner and outer surface temperatures of the rod are 371 C. At that level the volumetric heat gen- eration rate may be assumed to be uniform and equal to 0.1 MW/m³. Assume constant fuel conductivity for the fuel. c) Find the mean temperature of the coolant at the core exit (i.e., the mixture of the coolant passing through the inner channel and that passing through the outer channel). The fuel rod is 4.3 m long and the axial power profile along the channel is give by: TZ 4"(z)=ġ", cos 4.3 where z is in m and 4 =0.52 MW/m³. Other pertinent data: Inlet water temperature = 293 C, water pressure at the outlet = 14 MPa, water flow rate per unit cell = 18.37 kg/s, unit cell side (L) = 6.35 cm, fuel inner radius (r¡) = 1.27 cm, and fuel outer radius (r2) = 2.54 cm.
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