Question

In: Mechanical Engineering

Assume the water for a boiler is preheated using flue gases from the boiler stack. The...

Assume the water for a boiler is preheated using flue gases from the boiler stack. The flue gases are available at a rate of 0.25 kg/s at 150°C, with a specific heat of 1000 J/kg · K. The water entering the exchanger at 15°C at the rate of 0.05 kg/s is to be heated to 90°C. The heat exchanger is to be of the type with one shell pass and four tube passes. The water flows inside the tubes, which are made of copper (2.5 cm ID, 3.0 cm OD). The heat transfer coefficient on the gas side is 115 W/m2 · K, while the heat transfer coefficient on the water side is 1150 W/m2 · K. A scale on the water side and gas side offer an additional total thermal resistance of 0.000176 m2 · K/W. a. Determine the overall heat transfer coefficient based on the outer tube diameter. b. Determine the appropriate mean temperature difference for the heat exchanger. c. Estimate the required total tube length. d. Calculate the percent over surface design and the cleanliness factor.

Solutions

Expert Solution

Where thermal conductivity for copper =385 W/m2 K

  

  ............................... Ans

2) Logarithmic mean temperature difference

   

........................ Ans

Heat gained by water

  

4)   

Where   

...................   Ans

  

................Ans

samet mamat answered 2 years ago
Next > < Previous

Related Solutions

Flue gases from an incinerator are released to atmosphere using a stack that is 0.62 m...
Flue gases from an incinerator are released to atmosphere using a stack that is 0.62 m in diameter and 10.0 m high. The outer surface of the stack is at 45°C and the surrounding air is at 10°C. Determine the rate of heat transfer from the stack, assuming a. there is no wind and, b. the stack is exposed to 21 km/h winds.
(a) Dry saturated steam at a temperature of 180ºC is to be produced in a fire tube boiler from the cooling of 50 000 kg h–1 of flue gases from a pressurised combustion process.
  (a) Dry saturated steam at a temperature of 180ºC is to be produced in a fire tube boiler from the cooling of 50 000 kg h–1 of flue gases from a pressurised combustion process. The gases enter the tubes of the boiler at 1600ºC and leave at 200ºC. The feed water is externally preheated to 180ºC before entering the boiler. The mean specific heat capacity of the flue gases is 1.15 kJ kg–1 K–1. The latent heat of vaporisation...
Evaluate the proportion of the heat of fuel carried away by the flue gases for the...
Evaluate the proportion of the heat of fuel carried away by the flue gases for the following data: Coal with Calorific Value of 30 MJ/kg has composition by mass as follow: C= 78%, H=5%, 02,=8%, S=2%, N2=2% and the remaining is ash. The coal is burnt in the furnace with 50% excess air. The flue gases leaving the chimney at 327°C and the atmospheric temperature is at 15 °C. Assume perfect combustion. Specific heat for dry product (Cp) is 1045J/kg....
Evaluate the proportion of the heat of fuel carried away by the flue gases for the...
Evaluate the proportion of the heat of fuel carried away by the flue gases for the following data: Coal with Calorific Value of 30 MJ/kg has composition by mass as follow: C= 78%, H=5%, 0,=8%, S=2%, N2=2% and the remaining is ash. The coal is burnt in the furnace with 50% excess air. The flue gases leaving the chimney at 327°C and the atmospheric temperature is at 15 °C. Assume perfect combustion. Specific heat for dry product (Cp) is 1045J/kg....
why would one choose a fire tube boiler instead of a water tube boiler
why would one choose a fire tube boiler instead of a water tube boiler
Exhaust gases from a manufacturing plant are being discharged through a 10-m-tall exhaust stack with outer...
Exhaust gases from a manufacturing plant are being discharged through a 10-m-tall exhaust stack with outer diameter of 1.2 m. The exhaust gases are discharged at a rate of 1.2 kg/s, while temperature drop between inlet and exit of the exhaust stack is 30°C, and the constant pressure specific heat of the exhaust gasses is 1600 J/kg·K. On a particular day, wind at 27°C is blowing across the exhaust stack with a velocity of 10 m/s, while the outer surface...
Reverse the contents of a stack using only stack operations [ push() and pop()  ]. Using the...
Reverse the contents of a stack using only stack operations [ push() and pop()  ]. Using the java and give the explanation
In the boiler of a power plant are tubes through which water flows as it is...
In the boiler of a power plant are tubes through which water flows as it is brought from 0.8 MPa, 150°C to 240°C at essentially constant pressure. The total mass flow rate of the water is 100 kg/s. Combustion gases passing over the tubes cool from 1067 to 277 °C at essentially constant pressure. The combustion gases can be modeled as air as an ideal gas. There is no significant heat transfer from the boiler to its surroundings. Assuming steady...
Problem 10: Water is drawn from a well using a leaky bucket. Assume the following: •...
Problem 10: Water is drawn from a well using a leaky bucket. Assume the following: • The well is 23 ft deep and requires 23 ft of rope to pull the bucket to the top. • The rope weighs a total of 12 lbs. • The bucket weighs 3 lbs when empty. • The bucket holds 16 lbs of water. It is full at the bottom of the well and loses half of its water by the time it reaches...
Assume you have a stack and a queue implemented using an array of size 4. show...
Assume you have a stack and a queue implemented using an array of size 4. show the content of the array for the stack (then the queue) for the following operations: (for the queue replace push by add and pop by remove; keep in mind that the queue uses a circular array): push(-3), push(-5), push(-9), push(-10), pop(), pop(), push(-13), pop(), push( -15), push(-17). java code
ADVERTISEMENT
Subjects
ADVERTISEMENT
Latest Questions
ADVERTISEMENT