A A Hairdryer Shown In Figure Q4 A Comes With A Constant Duct Diameter And Has A Few Layers Of Electric Resistors Pl 1 (32.47 KiB) Viewed 41 times
A A Hairdryer Shown In Figure Q4 A Comes With A Constant Duct Diameter And Has A Few Layers Of Electric Resistors Pl 2 (42.32 KiB) Viewed 41 times
A A Hairdryer Shown In Figure Q4 A Comes With A Constant Duct Diameter And Has A Few Layers Of Electric Resistors Pl 3 (34.72 KiB) Viewed 41 times
(a) A hairdryer shown in Figure Q4(a), comes with a constant duct diameter and has a few layers of electric resistors placed in it. A small fan pulls the air in and forces it through the resistors where it is heated. If the density of air is 1.20 kg/m3 at the inlet (point 1) and 1.05 kg/m3 at the exit (point 2), determine the percent increase in the velocity of air as it flows through the dryer. ( 5 marks) (b) Air flows steadily through an air compressor at a rate of 0.4 kg/s, as shown in Figure Q4(b). The air enters the compressor at 6 m/s with a pressure of 1 bar and a specific volume of 0.85 m3/kg It leaves at 4.5 m/s with a pressure of 6.9 bar and a specific volume of 0.16 m3/kg. The internal energy of the air leaving the compressor is 88 kJ/kg greater than that of the air entering it. Cooling water absorbs heat from the air at the rate of 59 kW in a jacket surrounding the compressor cylinder. Determine: (i) the power required to drive the compressor; (10 marks) (ii) the inlet cross-section area of the pipe; and (3 marks) (iii) the outlet cross-section area of the pipe. (2 marks)
NHมाए Q4(21)
Figure Q4(b)
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