# Heat Transfer in a heat exchanger.

1. ### de312

8
So this concept is confusing me.

You have a 20GPM, 150Degree F, 40PSIG water coming in to a heat exchanger through a 1" diameter pipe.

Chilled water is available for cooling from a 6" diameter line at 40 Degrees F, With a pressure of 110PSIG and a flow of 270GPM.

The original solution needs to be cooled from 150 degrees to 80 degrees exiting in a 1.5" line.

1. The external vessel of the exchanger needs to be 316 stainless steel, any piping or tubing may be of any appropiate material as long as it is schedule 40.
2. What would be the overall heat transfer coefficient. What would be the hoop stress with a safety factor of 2.0.
3. Estimate chilled water flow requirements.
4. What would be the size of the shell, and how many tubes and their size would be required to properly cool the liquid.

This is confusing me ~.~

2. ### de312

8
So this concept is confusing me.

You have a 20GPM, 150Degree F, 40PSIG water coming in to a heat exchanger through a 1" diameter pipe.

Chilled water is available for cooling from a 6" diameter line at 40 Degrees F, With a pressure of 110PSIG and a flow of 270GPM.

The original solution needs to be cooled from 150 degrees to 80 degrees exiting in a 1.5" line.

1. The external vessel of the exchanger needs to be 316 stainless steel, any piping or tubing may be of any appropiate material as long as it is schedule 40.
2. What would be the overall heat transfer coefficient. What would be the hoop stress with a safety factor of 2.0.
3. Estimate chilled water flow requirements.
4. What would be the size of the shell, and how many tubes and their size would be required to properly cool the liquid.

This is confusing me ~.~

3. ### de312

8
So this concept is confusing me.

You have a 20GPM, 150Degree F, 40PSIG water coming in to a heat exchanger through a 1" diameter pipe.

Chilled water is available for cooling from a 6" diameter line at 40 Degrees F, With a pressure of 110PSIG and a flow of 270GPM.

The original solution needs to be cooled from 150 degrees to 80 degrees exiting in a 1.5" line.

1. The external vessel of the exchanger needs to be 316 stainless steel, any piping or tubing may be of any appropiate material as long as it is schedule 40.
2. What would be the overall heat transfer coefficient. What would be the hoop stress with a safety factor of 2.0.
3. Estimate chilled water flow requirements.
4. What would be the size of the shell, and how many tubes and their size would be required to properly cool the liquid.

This is confusing me ~.~

4. ### edgepflow

688
I would first ask which questions do you understand and which ones are confusing?

Much can be said about these topics - good to know where to start.

5. ### de312

8
I wanted to try and clarify this. If it is just a double tube simple heat exchanger like this shown here.

http://i56.tinypic.com/34znmti.png

*What is the calculation to calculate the heat transfer coefficient.
*How much surface area would be required between the two pipes for the solution to cool from 150 degrees to 80 degrees.

6. ### de312

8
I wanted to try and clarify this. If it is just a double tube simple heat exchanger like this shown here.

http://i56.tinypic.com/34znmti.png

*What is the calculation to calculate the heat transfer coefficient.
*How much surface area would be required between the two pipes for the solution to cool from 150 degrees to 80 degrees.

7. ### de312

8
I wanted to try and clarify this. If it is just a double tube simple heat exchanger like this shown here.

http://i56.tinypic.com/34znmti.png

*What is the calculation to calculate the heat transfer coefficient.
*How much surface area would be required between the two pipes for the solution to cool from 150 degrees to 80 degrees.

8. ### rock.freak667

6,228
For the value of U, I believe you need to use the fact that

$$\frac{1}{U} = \frac{1}{h_o} + \frac{1}{h_i}$$

where ho is the outer heat transfer coefficient and hi is the inner heat transfer coefficient.

so essentially

$$\frac{1}{U} = \frac{1}{h_{cold}} + \frac{1}{h_{hot}}$$

yes it is just like that in your diagram. You would need to look up how pressure and diameter relates to stress for the hoop stress.

For the chilled water requirements, you will just need a simple heat balance on the system.

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