Heat Transfer Analysis of an Oil Pipeline Crossing a River

Mini-project : Oil Pipeline

In this problem you will analyze the heat transfer associated with an oil pipeline as it passes through a river. You may find it necessary to iterate your solution to find final values. When iterating, please make sure the temperatures used to evaluate fluid properties are converged to at least 3 significant figures.

For all other intermediate calculations, however, you should be using full precision in your answers. For all questions listed below please provide your final answers, that is after any necessary iteration of surface and/or fluid temperatures.

Oil flowing through a 12XS schedule pipe crosses through a river that is 10 m wide. This pipe has a 11.75 inch inner diameter, a 12.75 inch outer diameter, and is made of steel. Assuming the steel has a conductivity of 40 W/m-K,

1. what is the thermal resistance of heat transfer radially through the pipe? Please report your answer in K/W.

The oil flows at an average velocity of 1.5 m/s through the pipe and is heated to reduce viscosity and related pumping losses. Assume the oil is 30 °C as the pipe enters the river. Oil properties may be approximated from Table A-13 in the textbook (also provided below).

2. What is the temperature at which you evaluated the oil properties for use in the heat transfer correlations?
   
   
3. What is the flow Reynolds Number, and is the flow turbulent?
   
   
4. What is the Nusselt Number and convective heat transfer coefficient for the oil? Please include which Nusselt Number correlation you used and why it is appropriate/why you chose it.
   
   
5. What is the convective thermal resistance in the oil? Please report your answer in K/W.

During late Winter/early Spring as the Spring melt is just starting, this section of river can be quite icy and the average temperature is very close to (i.e. can be approximated as) 0 °C. The river water itself is flowing at 2 m/s over the pipeline.

Assume the pipe goes through the river far enough from the bottom and top surfaces such that any effects of the riverbed or water surface may be neglected.

6. What is the temperature at which you evaluated the water properties for use in the heat transfer correlations?
   
   
7. What is the Reynolds Number of the water over the pipe, and is the flow turbulent?
   
   
8. What is the Nusselt Number and convective heat transfer coefficient for the water? Please include which Nusselt Number correlation you used and why it is appropriate/why you chose it.
   
   
9. What is the convective thermal resistance in the water? Please report your answer in K/W. For the overall system

10. What is the approximate total heat transfer from the oil to the water? Please report your answer in
    
    
11. What are the temperatures of the inner and outer surfaces of the pipe?

   12. What is the temperature change of the oil as it crosses through the icy river?

Table 1: Properties of oil. extract of table A-13 in Heat and Mass Transfer: Fundamentals and Applications by cengel and Ghajar