A hot process stream with properties similar to those of water with a flow rate of 100 L/min must be cooled from 100 to 80 ◦C by use of cooling water available at 5 ◦C. The cooling water must be...

A hot process stream with properties similar to those of water with a flow rate of 100 L/min must be cooled from 100 to 80 ◦C by use of cooling water available at 5 ◦C. The cooling water must be returned at a temperature no greater than 30 ◦C. The heat exchanger will be constructed of schedule 40S stainless steel pipes, 3 in. for the inner pipe (through which the process stream will flow) and 5 in. for the outer pipe (through which the cooling water will flow) and is completely insulated from the surroundings. Data for the thermal properties of water as well as for the pipe are given in the following tables below (from Welty et al., 2001).

Thermal properties of water:

a. Given the process conditions and information in the preceding table, which heat transfer correlation would be most applicable to this process?

b. Compute the minimum flow rate of cooling water required to carry out this operation. Using this flow rate, determine the maximum length of heat exchanger required.

c. Compute and plot the cooling water flow rate as well as the length of exchanger required as a function of the outlet cooling water temperature in the range of 10– 30 ◦C. Your calculations should be plotted in a similar manner to that shown in Figure E3.6.

d. How would you choose a flow rate and exchanger length for the final design, and what factors would be important?