Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA

Heat exchangers transfer heat from one fluid to another fluid. Multiple classes of heat exchangers exist to fill different needs. Some of the most common types are shell and tube exchangers and plate exchangers¹. Shell and tube heat exchangers use a system of tubes through which fluid flows¹. One set of tubes contains the liquid to be cooled or heated, while the second set contains the liquid that will either absorb heat or transmit it¹. Plate heat exchangers use a similar concept, in which plates are closely joined together with a small gap between each for liquid to flow¹. The fluid flowing between the plates alternates between hot and cold so that heat will move into or out of the necessary streams¹. These exchangers have large surface areas, so they are usually more efficient¹.

The goal for this experiment is to test the heat transfer efficiency of a finned-tube heat exchanger (Figure 1) and compare it to the theoretical efficiency of a heat exchanger without fins. The experimental data will be measured for three different flow rates of monoethylene glycol (MEG). Two different water flow rates for each MEG flow rate will be used. Using the Wilson plot method the heat transfer coefficients will be determined from the experimental data. Additionally, the Reynold's number and the amount of heat transferred will be compared for flow with and without the fins to evaluate heat transfer efficiency.

Figure 1: Finned-tube Heat Exchanger. 1) MEG outlet temperature 2) water inlet temperature 3) MEG inlet temperature 4) water outlet temperature 5) water meter 6) MEG accumulation sight glass/cylinder.

1. Start and Flow Rate Determination

1. Open the charge valve located below the steam generator.
2. Start the unit, and allow 15 min for steam to begin forming.
3. Calculate the flow rate of water
   1. Start a stopwatch and monitor the gauge displaying the volume of water.
   2. Stop the watch after 30 s and record the total volume of water displayed on the gauge.
   3. Divide the volume of water by the time to determine the volumetric flow rate.
4. Record the

The finned tube heat exchanger did not reach turbulent flow (Figure 2). The fins provide additional surfaces on which boundary layers form, as known through laminar and turbulent flow theory. If the fluid is not at a sufficient velocity, the fluid will not reach turbulence. The boundary layers between the fins overlap in the laminar region, so the fluid will remain laminar.