A shell-and-tube heat exchanger with the characteristics given below is to be used to heat 27,000 kg/h of water before it is sent to a reaction system. Saturated steam at 2.36 atm absolute pressure is available as the heating medium and will be condensed without sub-cooling on the outside of the tubes. From previous experience, the steam-side condensing coefficient may be assumed constant and equal to 11,300 W/(m² K). If the water enters at 16°C, at what temperature will it leave the exchanger? Use reasonable estimates for fouling coefficients.

Exchanger specifications

- Tubes – 2.5 cm OD, 2.3 cm ID, horizontal copper tubes in six vertical rows

- Tube length = 2.4 m

- Total number of tubes = 52

- Number of tube-side passes = 2

GIVEN

• Shell-and-tube heat exchanger - water in copper tubes, saturated steam is shell
• Water flow rate (m_w) = 27,000 kg/h = 7.5 kg/s
• Steam pressure = 2.36 atm = 239 kPa
• Steam-side coefficient (h_o) = 11,300 W/(m² K)
• Water entrance temperature: T_w,in = 16°C
• Tube diameters
• D_o = 2.5 cm = 0.025 m
• D_i = 2.3 cm = 0.023 m
• Tube length (L) = 2.4 m
• Number of tubes (N) = 52
• Number of tube passes = 2

ASSUMPTIONS

• Length given is total tube length for both passes

Transcribed Image Text:

Steam Water mw - 7.5 kg/s Twan = 16°C