The BKM Company has decided to expand from the pharmaceuticals business into the brewing industry. They have been looking for a way to preheat city water at 25°C to 85°C for use in their new process; however until recently they have not known where to look. Upon hearing that a savvy group of Chemical Engineering students at The Ohio State University have recently performed a shell and tube heat exchanger experiment, they immediately asked that you come up with the heat exchanger they should purchase. 12,000 kg/hr of water is required for the process, and they have available a steam line of 150°C and 125kPa.
The BKM Company canât take any risks with the new investment and asks that the flow regime of your experiment be maintained (turbulent, laminar, etc.). They ask that you calculate the tube side ÎP/L ratio from your experiment and keep it constant when performing calculations for their heat exchanger. Additionally, assume that the pressure drop on the shell side is negligible and the pressure drop on the tube side has a maximum value of 200 Pa, and that the âTmin of the heat exchanger is 15â. The available specifications for the heat exchanger that the company can purchase are:
Tube Bundles 250 tubes 300 tubes 350 tubes
Tube Diameter 0.25 in 0.35 in 0.45 in 0.55 in
Length of HX 0.75 m 1.25 m 1.75 m
The company would like to know:
Which of the above combinations (tube bundle + diameter + length) to purchase.
The pressure drop through the tube side of the heat exchanger.
What flow rate of superheated steam (shell side fluid) they will need.
The overall heat transfer coefficient of the heat exchanger.
Note:
You should attempt to minimize the steam flow rate and surface area of the heat exchanger.
Also, the process to solve for which tube bundle and diameter to select is iterative.
Because the options are limited, do not expect an exact solution â just get the closest solution you can.
Use Ch. 8 in Incopera (See reference 3 on the E2 Lab Procedure)
You only have to pick one tube side flow rate from your experiment for the âP/L calculation.
