Shell and Tube Heat Exchanger Experiment

Introduction

The process of heat exchange between two fluids which are at different temperatures and flow rates occurs in many engineering applications. Several types of heat exchangers have been widely used in the industry. Shell-and-Tube heat exchangers are among the common types of heat exchangers.  A basic schematic for a single pass shell-and-tube heat exchanger is shown in Figure 1.  The stream to be cooled enters the tube side and is distributed amongst the tubes shown with red arrows.  

The stream that cools the liquid is shown in blue enters on the shell-side and flows perpendicular to the tube bundle for maximum heat transfer.  The shell-side flow passes around baffles placed around the tube bundle in order to increase both the residence time of the fluid around the tube bundle as well as to promote turbulence in order to maximize the efficiency of the heat exchanger. 

Heat exchangers are typically classified according to flow arrangement. In the parallel-flow heat exchanger, the hot and cold fluids enter at the same end, flow in the same direction, and leave at the same end. In the counter-flow arrangement, the hot and cold fluids enter the heat exchanger at different ends and flow in opposite directions. Each fluid arrangement leads to different heat rates and the calculations are different accordingly [1].

    

 

Figure 2 illustrates the Heat Exchanger experiment apparatus.  Based on long-term setup of the apparatus, the hot flow passes through the tube and the cold flow passes through the shell. Different configuration of valves can result in parallel and counter flows.  The hot and cold flow rates are measured by two flow meters, located along the incoming flows.

In order to measure the temperature of fluids and heat transfer surfaces, ten thermocouples have been installed in this apparatus. The measured temperature of each thermocouple is shown on the readout when the selector switch points to the thermocouple number. The thermocouples are located in different positions to measure the temperatures according to Table 1.

Table1. Thermocouples

Thermocouple	Measured Temperature	Thermocouple	Measured Temprature
1	Tube Inlet	5	Shell Inlet
2	Tube-side heat transfer surface at 16” *	6	Shell-side heat transfer surface at 16” *
3	Tube-side heat transfer surface at 19” *	7	Shell-side heat transfer surface at 19” *
4	Tube-side heat transfer surface at 21” *	8	Shell-side heat transfer surface at 21” *
10	Tube Outlet	9	Shell Outlet

* measured from the tube side.

Laboratory Procedure:

Parallel Flow Experimental Setup

1. Open the valves 1, 3, 4, 6, and 7 all the way.
2. Close valves 2 and 5.
3. Turn on the main power.
4. Turn on hot and cold water supply all the way.
5. Close valve 1 until it reads 2 GPM.
6. Close valve 3 until it reads 20% (2 GPM).
7. Wait at least 15 minutes so that the system reaches steady state.
8. Record temperatures of the system at steady state according to Table 2.
9. Turn off the hot and cold water supplies.
10. Proceed to the next configuration.

Counter Flow Experimental Setup

1. Open valves 1, 2, 3, 5, and 7 all the way.
2. Close valves 4 and 6.
3. Turn on the hot and cold water supplies all the way.
4. Close valve 1 until it reads 3 GPM.
5. Close valve 3 until it reads 30% (3 GPM).
6. Wait at least 15 minutes so that the system reaches steady state.
7. Record temperatures of the system at steady state according to Table 3.

Shut Down

1. Turn off the hot and cold water supplies.
2. Unplug the electrical cord.
3. Open all valves fully and wait until water stops draining from the apparatus.
4. Close all valves fully.

 For a complete write-up, click here.