fundamentals of food process engineering

1. Oda bultum university
Institute of technology
Course name: fundamental of food process engineering
Assignment one:
Part one: say true if the statement is correct, and false if the statement is
wrong. put your brief description/reason for your answer.
1. viscosity of non-Newtonian liquids is independent of the shear rate.
2. Heat is conducted in solids, liquids, and gases by the transfer of the energy of
motion from one more energetic molecule to an adjacent less energetic one.
3. Temperature gradient (𝒅𝑻/𝒅𝑿) during conductive heat transfer is positive.
4. The rate of heat transfer by conduction is calculated using Newton’s law of
cooling.
5. The presence of matter between the points that exchange energy by radiation
is not necessary.
Part two: answer the following questions accordingly. Briefly put your answer
with all possible requirements, including possible assumptions, body diagram,
given data’s.
1. Calculate the rate of heat transfer through a glass window with 3 m2
surface
area and 5 mm thickness if the temperature on the two sides of the glass is 14
⁰C and 15 ⁰C respectively and the thermal conductivity of the glass is 0.7 W/m
8⁰C (5 mark).
2. Air at 25 ⁰C blows over a heated steel plate with its surface maintained at 200
⁰C. The plate is 50 × 40 cm and 2.5 cm thick. The convective heat-transfer
coefficient at the top surface is 20 W/(m2
K). The thermal conductivity of

2. steel is 45 W/ (m K). Calculate the heat loss per hour from the top surface of
the plate (5 marks).