Answer:
the heat transfer from the pipe will decrease when the insulation is taken off for r₂<
where;
r₂ = outer radius
= critical radius
Explanation:
Note that the critical radius of insulation depends on the thermal conductivity of the insulation k and the external convection heat transfer coefficient h .
The rate of heat transfer from the cylinder increases with the addition of insulation for outer radius less than critical radius (r₂< ) 0, and reaches a maximum when r₂ = , and starts to decrease for r₂< . Thus, insulating the pipe may actually increase the rate of heat transfer from the pipe instead of decreasing it when r₂< .
The magnitude of shear stress (kPa) on an element a lying at a distance of 20 mm from neutral axis. (6 pts) are given, p = 2kn e = 210gpa distance from constant cease = 20mm = 0.2m.
<h3>What is the cantilever formula?</h3>
The cantilever beam equations (deflection) w = load. l = member length. e = young's modulus. i = the beam's moment of inertia.
- theta= 2000 2*210*10^ 9 * (0.006)^ four 12 [(0.1)^ 2 -(0.08)^ 2 ] =0.1587 rad
- ø at q i.e. x = 100 - 20 = 80mm = 0.08m from loose cease.
- theta = p/(2ei) * (l ^ 2 - x ^ 2) phase of facet a. i = (a ^ four)/12 for square.
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Answer:
Conduction is a heat transfer mechanism. It is the dominant heat transfer mechanism in solids and it involves the vibration of the molecules of the solid. As heat is transfered to one end of the solid, the molecules at that end start to vibrate and in this process, collides with the adjacent molecules setting it to vibrate too. Also free electrons around the solid atoms (especially in metals) contribute to this heat flow. The continuous vibration is transfered from molecule to molecule gradually along the solid until the average kinetic energy (a measure of temperature) of the molecules along the metal has increased.
Convection is the dominant heat transfer mechanism in fluids, it involves the complete movement of the fluid molecule from a hot spot in the fluid to a cooler spot in the fluid. For convectional movement to occur, the molecules must first come in contact with the heat and absorb the heat first by conduction. As the heat increases, the fluid molecules break from just vibrating about a fixed point to moving completely to a cooler spot due to buoyant forces (due to the difference in density of hot and cooler fluid molecules). This clearly point out the fact that convectional heat transfer is first conduction, and then complete later flow of the fluid molecules.
Answer: N has to be lesser than or equal to 1666.
Explanation:
Cost of parts N in FPGA = $15N
Cost of parts N in gate array = $3N + $20000
Cost of parts N in standard cell = $1N + $100000
So,
15N < 3N + 20000 lets say this is equation 1
(cost of FPGA lesser than that of gate array)
Also. 15N < 1N + 100000 lets say this is equation 2
(cost of FPGA lesser than that of standardcell)
Now
From equation 1
12N < 20000
N < 1666.67
From equation 2
14N < 100000
N < 7142.85
AT the same time, Both conditions must hold true
So N <= 1666 (Since N has to be an integer)
N has to be lesser than or equal to 1666.
Answer:
Qin = 448.23 kJ
Explanation:
given data
mass m1 = 0.6 kg
volume v1 = 0.1 m³
pressure P1 = P2 = 800 kPa
pressure Pi = 5 MPa
temperature Ti = 500°C
temperature T2 = 250°C
volume V2 = 2V1 = 2 (0.1) = 0.2 m³
solution
we get here some value from steam table
as we get first for initial state at pressure 800 kPA
v1 = ...........1
v1 =
v1 = 0.1667 m³/kg
and u1 = 2004.4 kJ/kg
and
for final state at pressure 800 kPa and temperature 250
u2 = 2715.9 kJ/kg
and
v2 = 0.29321 m³/kg
now we get for stream in supply line that is
hi = 3434.7 kJ/kg
for the preesure 5 MPa and temperature 500
and
now we get mass m2 = ............2
m2 =
m2 = 0.6821 kg
so
now we consider here tank as control system
so that steam cross control surface is
as mass balance
mi = m2-m1
mi = 0.6821 - 0.6
mi = 0.0821 kg
and
now we neglect microscopic for energies
so energy balance is
Qin - W (b) + mihi = m2u2 - m1u1 ............3
Qin - P(V2-V1) + mihi = m2u2 - m1u1
Qin - 800 (0.2-0.1) + 0.082 (3434.7) = 0.6821 × 2715.9 - 0.6 × 2004.4
Qin = 448.23 kJ