Question

Question 3 (40 marks) (a) Air enters a horizontal nozzle with a velocity of 1 m/s, a pressure of 2 bar and a temperature of 350 K. At exit from nozzle, the air temperature is 450 K. The combined rate of specific heat transfers, and specific work transfers, w to the air as it passes through the nozzle is 150 kJ/kg. Assume that the air flow is steady and air can be treated as perfect gas with = 1005 J/(kg.K). Calculate the velocity of air at the nozzle exit using Steady Flow Energy Equation (SFEE). (10 marks) (b) An orifice plate meter situated in a horizontal pipe of 120 mm in diameter has an orifice of diameter 50 mm and C=0.6. The pressure difference across the orifice is equivalent to 80 mm of mercury. Density of mercury is 13600 kg/m”. Calculate the actual mass flow rate, assuming that the fluid is oil with a specific density of 0.8. (15 marks) Page 12 (c) Determine the pressure difference, Po-PA of the manometer system as shown in Figure 23c. The specific gravity of oil and mercury is 0.8 and 13.6. respectively. (15 marks) oil 15 cm water 60 cm mercury 25 cm B Figure 0.3c

Answer 1

Given - Question 3 Imis Gived combined a) Hooizantal nozzle Inlet conclictions vel velocity v Pressure Pizzbar Temperactive T,=35010: exart of the nozzle the nozzle. Temperature. To zu506 rate of Heat transfer a & specific art transfer wis qtw 150 kJ/kg Assume perfect gas go = 1:005 kJ/Age let out velocity is re Accord reling steadly flow enegry equation 2 + CP Tl zoof z? wa is z) 9 to q tuz + Cp Tz 2000 2000 over (2+0) + Gp(71-71) +_y? 2000 2 22 Va 2000 150 + 1005 (350-uso) + 2 2000 Z 314.cue mis pas exit velocity of a air at Nozzle exit

b). tameter of orifice pripe = 12 120mm Pipe discharge pipe diameter D - tromm orifice diameter: l = 50mi coefficient of d:0.6 Pressure difference spro ha comm of the op Lenggh 13600K 9.81 x 80x103 sp: 10673.28 pa 0.01067328 mpa specific dencity of oil 0.8 as density of oil: p= 800 kg/m3 to.cT Accoveling to barnoulli ecos Ara Arva ve P2 AV r = AMI V₂ = 12o xn a > Pai & fg zg Az + 22 Jg zg 502 23 V₂ ² 5-6701 2) AP pg 2) => V₂ ²²-v2 29. 80 x103 = 5-67% xu - w? 2x9.81 Boxcö}x2x9.81 2 12>) V, 2 0.22086mls 5-672-1 31-252277 mis 3) volume flowrate da Edx AZUL Q: 0.6** Csoxió?)x1-252273 z? 0.001475 mil regsee mass flow rate flow rate om Qxp = 0.0014754800 Me 1.18ozun kg of in orifice u 2) ma 7) Mass flowrate See

C) U-tube mane manometer Dit Reference line 1 15CM density of Alg 60cm mo water Pw 1000 kg Pour 5cm Hg = Poig = 13600 kg oil wafat ~ 800 kg nd 25CM m} P = P2 2) 27 PB-PA= 1000x0.6 + 800X0.15 - 2) at reference line PA + Pwxgx0.6+ Pax 9x0.15 = Pg the proces (1000 13600X1) 9.81 2) PG- PA= -126352-8 pa 2) pressure difference PA-PB = 126- 3528 kpä