This is an individual assignment, and is worth 30 marks in total. You will need to answer all questions,

and you need to bear in mind that in some instances you may need to use knowledge you have previously

gained in other courses to solve these questions. Please submit your assigment online. Typed solutions

are recommended, but clearly presented hand-written solutions will also be accepted. This assignment

is due on 8th October at 11pm. If you submit your assignment late, you will be deducted 4 marks (i.e.

20%) per day that you are late.

Question 1

Sheets of steel are typically made by rolling heated steel at high temperatures, resulting in a

flat plate as shown in figure 1. The resulting hot flat plates are cooled by passing air at a fixed

temperature of 295 K over the plate. The plate is 4 m long, and 1.2 m wide, and has a uniform

temperature of 600 K. The velocity of the flow of air is 9.5 m/s.

Air

4 m

Figure 1: Flow of air over a flat plate.

Assuming the sheets are oriented such that the air flow along the length of the plate (i.e., along

the a direction, as denoted by the blue arrow), calculate:

a) The local heat transfer coefficient at a distance 1 m from the leading edge of the plate

(i.e. at x = 1 m) [4 marks]

b) The average heat transfer coefficient over the entire plate [3 marks]

c) The rate of heat transfer from the plate to the air. [1 mark]

If the plate is re-oriented such that the flow of air now flows along the width of the plate (i.e.

along the y direction, as denoted by the red arrow), calculate the rate of heat transfer from the

plate to the air. [4 marks]

In all cases above, you may neglect any heat transfer from the bottom of the plate.