Question

(40 pts) Shell-and-Tube Heat Exchanger to make Jell-O Cups

A counter-current shell-and-tube heat exchanger is used to heat Jell-O solution (water + gelatin) using saturated steam

on the shell side. Jell-O solution must be heated to at least 80 oC, poured into individual plastic cups, and then cooled to

make the solid Jell-O cups. The Jell-O solution is heated with steam that enters the shell at 2.0 bar (Tsteam = 120oC) and

exits as a saturated liquid. At this temperature and pressure, the inlet volumetric flow rate of steam is 6.5 m3/min, the

density of steam is 1.13 kg/m3, and the enthalpy of vaporization of steam is 2201.6 kJ/kg. The Jell-O solution enters the

inner pipe at a mass flow rate of 1.0 kg/sec and a temperature of 20oC. The convective heat transfer coefficient for steam

on the shell side was measured to be 750 W/m2

-K. The properties of the Jell-O solution can be taken to be those of water.

Pipe: 2” schedule 40 stainless steel pipe.

- Di = 2.067 in (0.0525 m), tw = 0.154 in (0.0039m), Do = 2.375 in. (0.0603 m)

- k (stainless steel) = 17.3 W/m-K

a) Sketch and label the heat exchanger (designate side #1 as the Jell-O entrance).

b) With reference to a), sketch the expected temperature profile in the heat exchanger.

c) What is the energy available for heat transfer based on the condensing steam?

What is the temperature of the exiting Jell-O solution? Is the criteria met?

d) Calculate the overall heat transfer coefficient (U) for this double-pipe heat exchanger.

You may not neglect any heat transfer resistance term in the calculations, but as a first approximation you may assume

that Ao=Ai (thin wall approximation).

Where is the most significant resistance to heat transfer in this system?

e) Using the Heat Exchanger Design Equation, calculate the required heat transfer area and pipe length for the heat

exchanger? Is it a reasonable length? If not, what would you suggest for a new design?

need proper step by step and correct amswer. will give a thumps up.

Answer 1