Mechanical Engineering Answers

air enters a centrifugal compressor at 1 bar and leaves at 2.1 bar.During the passage of the air through the compressor, the compressor, the specific internal energy of the air increases by 56kj/kg and the specific volume decreases from 0.825 m^3/kh to 0.5m^3/kg.Assuming that the flow iss adiabatic and that the changes in kinetic energy are negligible, calculate the power required to drive the compressor when air flow rate is 135kg/min

8. Find the standard distance between sprocket having 4 in and 16 in diameters.

7. A chain with speed 800 fpm has driving sprocket turns at 900 rpm. If the pitch of chain is ¾ in, find the number of teeth of driving sprocket.

23. Find the sensible heat factor of an air-conditioning unit having a sensible heat load of 60 kw and latent heat

load of 20 kw.

A. 70% B. 80% C. 75% D. 85%

22. A coil has an inlet temperature of 50 oF and outlet of 85 oF. If the mean temperature of coil is 100 oF, find

the bypass factor of the coil. (SHOW THE SOLUTION)

A. 0.4 B. 2 C. 1.667 D. 0.3

21. Bypass factor of coil is 0.8 for one row. What is the bypass factor if there are 8 coils in a row? (SHOW THE SOLUTION NOT EXPLAINATION)

A. 0.029 B. 0.70 C. 0.80 D. 0.49

20. An air conditioned theater is to be maintained at 80 oF dry bulb temperature and 50% RH(h = 31.35 Btu/lb). The calculated total sensible heat load in the theater is 500,000 Btu/hr, and the latent heat load is 150,000 Btu/hr. The air mixture at 84 oF db and 72 oF wb temperature(h = 35.82 Btu/lb) is cooled to 63 oF dry bulb and 59 oF wet bulb temperature (h = 25.78 Btu/lb)by chilled water cooling coils and delivered as supply air to the theater. Calculate the tons of refrigeration required.

A. 83 B.130 C.127 D.122

19. An auditorium is supplied with 35 m3/s of air at 14oC db. The total heat load is 320 kw and has a sensible

heat factor of 0.82. Find the temperature inside the auditorium using air at standard pressure.

A.16oC B.18oC C. 20oC D. 24 oC

calculate tha height of chimny required to produce a draught equivalent to 1.7 cm of water if tha flue gas temperature is 270℃ and ambient temperature is 22℃ and minimum amount of air per kg of fuel is 17kg