Suez University
Faculty of Engineering
Department: Mechanical Power Engineering
1st term Exam 2025 -2026
Maximum Mark: 10 Marks
Level: 3rd
Semester: 1st Semester
Exam: Practical
Time: 1 hours
Date:
Exam consists of 2 pages
Answer the Following questions and assume any missing data
Question (1)
1. For the Following Heat Exchangers Mention the name and describe each one.
2. Can the temperature of the hot fluid drop below the inlet temperature of the cold
fluid at any location in a heat exchanger? Explain.
(5 Marks)
Question (2)
A double-pipe (shell-and-tube) heat exchanger is constructed of a stainless steel (k = 15.1 W/m ·
°C) inner tube of inner diameter Di 1.5 cm and outer diameter Do 1.9 cm and an outer shell of
inner diameter 3.2 cm. The convection heat transfer coefficient is given to be hi = 800 W/m2 · °C
on the inner surface of the tube and ho = 1200 W/m2 · °C on the outer surface. For a fouling
factor of Rfi =0.0004 m2 · °C/W on the tube side and Rfo = 0.0001 m2 · °C/W on the shell side,
determine (a) the thermal resistance of the heat exchanger per unit length and (b) the overall
heat transfer coefficients, Ui and Uo based on the inner and outer surface areas of the tube,
respectively.
(5 Marks)
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