Question

External problem 1 - Chapter 8: Engine heat transfer correlation The following table reports experimental results obtained for an engine overall Nusselt number for different engine speeds. N (rpm) 1000 Nu/1000 186 5000 4000 3000 2000 752 653 548 319438 The engine tested is a single cylinder engine with a 0.12 m bore and 0.12 m stroke. Assume k0.06W Im.K and 20x10 Ns/m2. The volumetric efficiency is e, 0.85 b) Write In( Nu) in function of InN), Conclude the heat transfer correlation expressing Nu in function ofN. a) Plot In(Nu) in function of In(N). What do you conclude? c) Obtain an expression for the Nusselt number in function of Reynolds number. Assume P 1.17 kg Im3 d) Calculate the overall heat transfer coefficient at a Reynolds number of 5000. e) Calculate the heat flux from the engine to the coolant at a Reynolds number of 5000. The average combustion gas temperature is 1050 K and the coolant temperature is 350 K

Answer 1

In this solution some basic concepts and formulas of Heat Transfer are used. For more information, refer to any standard textbook or drop a comment below. Please give a Thumbs Up, if solution is helpful.

Solution :

a.) The plot can be created using the following matlab code,

N = 1000:1000:6000;
Nu = 1000 * [186 319 438 548 653 752];

plot(log(N),log(Nu))
xlabel('ln(N)')
ylabel('ln(Nu)')

13.6 13.4 13.2 13 z 128 12.6 12.4 12.2 28 6 7.2 7.6 7.8 In(N) 8.2 8.8 7.4 8.4 8.6 8

Thus the Ln(N) and ln(Nu) are related with a straight line equation.

eno w and for Our cale, Nu em Ce n (A Thu hol reqwired velot'on becom e P) CamScanner

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