N5 Power Machines Air compressor exercise

QUESTION 5 A two-stage single-acting reciprocating compressor takes in 54 000 cm’ of air per cycle at a pressure of 100 kPa and a temperature of 26 °C whilst rotating at 300 r/min. 2a The air is compressed to 400 kPa in the low-pressure cylinder, while the volumetric efficiency of the low-pressure cylinder is 89%. The stroke length of the low-pressure cylinder is 1,2 times the diameter of the piston. The index for compression for both cylinders is 1,3 and the intercooler extracts 26 kJ of heat per second. Take R for air as 0,288 kJ/kg.K, C, for air as 1,008 kJ/kg.K, and calculate the following quantities: Sot Mass of air delivered by the compressor in kg/min 5.2 Absolute temperature of the air after compression in the low-pressure cylinder 6.3 Absolute temperature of the air at the inlet to the high-pressure cylinder 5.4 For the low-pressure cylinder: ea 5.4.1 Swept volume in m?/stroke 5.4.2 Diameter of the piston in mm, and the stroke length in mm 9:9 Volume of air taken in by the high-pressure cylinder in m*/stroke Da TOTAL: Downloaded from hlayiso.com (3) (3) (5) : 3 [20] 100 o ENN YAMA

(8190046) 6 T1400(E)(N29)T QUESTION 4 A three-stage, single-acting, reciprocating compressor rotates at 516 r/min while delivering 583 cm? of air per cycle to the aftercooler. The index for compression and expansion is both 1,32 and the pressure ratio for all stages is 3,6:1. The initial pressure and temperature for the low-pressure cylinder is 100 kPa and 26 °C respectively. Intercooling is perfect for maximum efficiency and the clearance volume for the low- pressure cylinder is 4% of its swept volume. Take Cp for air as 1,005 kJ/kg.K and R for Calculate: 41 The absolute delivery tempe: O42 =~ Thema 43 The pi 4.4 The h 4.5 The hea 4.6 For the lo’ ecimal places ct to FOUR decimal places 4.6.4 The cylinder voltime. i rect to FIVE decimal places Downloaded from hlayiso.com (2) (3) (2) (2) (3) (1) (2) [20]