Water (cp = 4180 J/kg·°C) enters the 2.5 cm internal diameter tube of a double-pipe counter-flow heat exchanger at 17°C at a rat
e of 1.8 kg/s. Water is heated by steam condensing at 120°C (hfg = 2203 kJ/kg) in the shell. If the overall heat transfer coefficient of the heat exchanger is 700 W/m2 ·°C, determine the length of the tube required in order to heat the water to 80°C using (a) the LMTD method, and (b) the ????????–NTU method. Answers: 129.5 m; 129.6 m
1 answer:
Answer:
Length = 129.55m, 129.55m
Explanation:
Given:
cp of water = 4180 J/kg·°C
Diameter, D = 2.5 cm
Temperature of water in = 17°C
Temperature of water out = 80°C
mass rate of water =1.8 kg/s.
Steam condensing at 120°C
Temperature at saturation = 120°C
hfg of steam at 120°C = 2203 kJ/kg
overall heat transfer coefficient of the heat exchanger = 700 W/m2 ·°C
U = 700 W/m2 ·°C
Since Temperature of steam is at saturation,
temperature of steam going in = temperature of steam out = 120°C
Energy balance:
Heat gained by water = Heat loss by steam
Let specific capacity of steam = 2010kJ/Kg .°C
Find attached the full solution to the question.
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Answer:
The mechanical advantage is 3 to 1
Explanation:
A frictionless pulley with three support ropes carries equal tension on each of the ropes thus;
Tension in each pulley rope = T
Total tension in the 3 ropes = 3 × T = 3·T
Direction of the tension forces on each rope = Unidirectional
Total force provided by the 3 ropes = 3·T
Therefore, a force, T, applied at the end of the rope will result in a lifting force of 3·T
Hence, the mechanical advantage = 3·T to T which is presented as follows;
The mechanical advantage = 3 to 1.
Answer:
0
Explanation:
output =transfer function H(s) ×input U(s)
here H(s)=
U(s)= for unit step function
output =H(s)×U(s)
=×
=
taking inverse laplace of output
output=t×
at t=0 putting the value of t=0 in output
output =0