Question

Unused engine oil at 27°C flows with a free stream velocity of 0.1 m/s over a 20 cm square plate. The plate temperature is maintained at 67°С. Consider the following: ii) iii) Determine the Reynolds number based on plate length Rel. Calculate the average Nusselt number based on plate length Nuu. Evaluate the heat transfer (W) from the plate.

Answer 1

In this problem properties of the unused engine oil are used at an average temperature of plate and with the help of these properties we solved the problem.

comment if any query.

engine plate oil initio =27c temperature = 67°C Queroge temperature = 27+67= 47°C =474273 = 320k. For unused engine oil, at 320k P=872 kg/m3 Specific heat, Cp = 1.99 kJ/kg.k viscosity, = 0.141 N-sim? Pr = 1990, v=0.lmis t = 0.141 Wim-K. Reynolds number Re - PVD I i لد D=plate length = 20cm=0. 2m Re=872X0.100.2 0.141 Re = 123.6879

(1) Average Nusselt numbese. Nu = IC NU(x) dx. 113 Re <sxios So, Flow is Jaminan No = 0.664 (Rey)" (p.) 13 0.664 (123-6879) (1990) No = 92.88] (4) heat transfer (W) from the plote. h = Noexk hero = 92.88×0.141 0.2 = 65.48 Wlmek heat transfer=hA (Tp-To) Tplate = 67c Tois = 27°C A = Area of plate= 0.2x0.2=0.04 m² heat transfer= 65.48X0.04x(67-27) heat transfor = 104.768 W from the plate