3. CALCULATION OF CONCENTRIC TUBES HEAT EXCHANGERS

3.1. Calculation hypothesis

Here the hypothesis used in mathematical models of concentric tubes heat exchangers or double tube:

1- It works with stationary regime.

2- The temperature is based on the length.

3- Kinetic ∆E is approximately 0 ( with the same diameter pipe, will have the same rate all the time).

4- ∆E potential is approximately 0 ( It doesn't matter if the pipe is horizontal or vertical).

5- Heat (q) of radiation is approximately 0 ( Non-radiating materials and non-radiating fluids).

6- The physical properties of fluids are constant with temperature.

7- The convection coefficient (h) is not a function of temperature.

8- The global coefficient of heat pass (U) are not a function of temperature.

9- Working with adiabatic conditions (no heat exchange with the environment).