Steam in a heating system flows through tubes whose outer diameter is 5 cm and whose walls are maintained at a temperature of 19
8.06°C. Circular copper alloy fins (k =285 W/m · °C) of outer diameter 6 cm and constant thickness 1 mm are attached to the tube. The space between the fins is 3 mm, and thus there are 250 fins per meter length of the tube. Heat is transferred to the surrounding water at T= 43.06°C, with a heat transfer coefficient of 5300 W/m2 · °C. Determine the increase in heat transfer from the tube per meter of its length as a result of adding fins and fin effectiveness
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Answer:
Work = 651,1011 kJ
Explanation:
Let´s take the car as a system in order to apply the first law of thermodynamics as follows:
Where
And considering that there is no mass transfer and that the only energy flows that interact with the system are the heat losses and the work needed to move the car we have:
Regarding the energy system we have the following:
By doing the calculations we have:
Consider that in the previous calculation, the kinetic and potential energy terms were divided by 1.000 to change the units from J to kJ.
Finally, the work needed to move the car under the required conditions is calculated as follows:
Consider that in the previous calculation, the heat loss was changed previously from BTU to kJ.
Answer :
The force needed to move the cylinder is 25.6 N
<h2>Further explanation </h2>Given that,
Length of the cylinder, l = 0.5 m
Outer diameter of the cylinder, d = 8 cm = 0.08 m
Outer radius of the cylinder,
Inside diameter of the pipe, d = 8.5 cm = 0.085 m
Inside radius of the pipe,
Specific gravity of the oil,
Density of oil,
Kinematic viscosity of the oil,
Velocity of the cylinder, u = 1 m/s
We need to find the force needed to move the cylinder. Let the force is F.
Specific gravity is defined as the ratio of the density of the substance to the density of water.
Kinematic viscosity is the acquired resistance of a fluid when there is no external force is acting except gravity. It is denoted by v.
Absolute viscosity is given by :
Where, = density of oil
And (density of oil = specific gravity × density of water )
So,
..............(1)
The separation between the cylinder and pipe is given by :
are diameter of pipe and cylinder respectively.
The mathematical expression for the Newton's law of viscosity can be written as:
..........(2)
Where
= Shear stress,
............(3)
= viscosity
= rate of shear deformation
On rearranging equation (1), (2) and (3) we get :
...............(4)
A is the area of the cylinder,
Equation (4) becomes :
..............(5)
Now, equation (5) becomes :
F = 25.6 N
<h2>Learn more </h2>Kinematic viscosity : brainly.com/question/12947932
<h2>Keyword : </h2>Specific gravity, Kinematic viscosity, Area of cylinder, fluid mass density.