Questions Mark Chapter

s
1. Explain briefly with necessary sketches the following: 05
a. Degree of saturation.
b. Relative Humidity.
2. Explain briefly with necessary sketches the following: 05
a. Due point Temperature.
b. Specific Humidity or Humidity ratio
3. The condition of a sample air is 25°C (77°F) dry bulb and 20°C (68°F) wet bulb. 05
Using the psychrometric chart find the following:
a. Rh of the air, b. Dew Point, c. Moisture Content d. Specific Volume and e.
Enthalpy.
4. If 150m3/min of air at 20°C DBT and 50% RH is adiabatically mixed with 10 1
100m3/min of air at 40°C DBT and 26°C WBT. Calculate:
a. Enthalpy of the mixture, b. Specific volume, c. humidity ratio and d. Final DBT
of the mixture.
5. If 170m3/min (6000cfm) of air at 25°C DBT and 20°C WBT is mixed with 10
17m3/min (600cfm) of air at 40.6°C DBT and 26.7°C WBT. Calculate:
a. Enthalpy of the mixture, b. Specific volume, c. humidity ratio and d. Final DBT
of the mixture.
6. Explain the following processes in conditioning of air with the help of diagram. 10
a. Latent heat process - humidification or dehumidification.
b. Sensible heat process – Heating or cooling.
7. Derive the Heat balance equation for a human being. 05
8. Explain briefly about metabolic rate of the human body. 05
9. Explain briefly about the selection of outside design conditions. 05
10. What are the factors affecting the thermal comfort. 05
11. With the help of process diagram explain summer air conditioning i.e cooling cycle. 10
(Basic RAC-PNA-Ch19-1) 2
12. With the help of process diagram explain winter air conditioning i.e heating cycle. 10
(Basic RAC-PNA-Ch19-1)
13. Explain the functioning of a reversing valve. How it enable the room air conditioner 05
to perform winter heating. (Basic RAC-PNA-Ch19-1)
14. With the neat sketch explain the packaged air conditioner system. 10
15. Explain briefly about Cooling and dehumidifying coil with necessary sketch. 10
16. Explain briefly the bypass factor with necessary sketch. 05
17. Explain briefly about air washer with sketch. 05
18. Explain briefly about forward centrifugal fans with necessary sketch. 05 3
19. Explain with necessary sketches fan performance curves. 10
20. Describe briefly ordinary air filters (or pre-filters) and Fine filters. 10
21. Describe briefly Absolute filters and Electronic filters. 10
22. Explain about the heat gain through glass with derivation. 05 4
23. How does the shading from reveals, overhangs and fin structures in the buildings 05
affect the heat transfer? Explain with necessary sketches.
24. Explain the importance of Equivalent Temperature difference (ETD) or Cooling 05
Load Temperature difference (CLTD). 19-22(Basic RAC- CAP-Ch 21)
25. Explain about sol-air temperature with necessary diagram. 05
26. For a window opening in a south-west wall of a building, the following data are 10
given:
latitude = 40º N
Outside air temperature = 40°C
Inside air temperature = 25°C
Size of glass window = 4m X 4m
Recess in the window = 0.4m
Absorptivity of glass = 0.06
Calculate the total heat gain of the space through the glass. The outside and inside
heat transfer coefficients from the glass surface may be taken as 23W/m 2K and
 8W/m2K respectively. The incident radiation normal to the sun’s rays at 40°N
latitude is given by the empirical relation
−0.182
I n=1082 e sinβ W/m2
(Sol is Below)
27. A controlled temperature test room is held at 25°C. The outside design temperature 10
is 40°C. The wall is constructed with 25mm pine boards (k=0.12Wm-1K-1) on the
inside and the outside with 100mm mineral wool block insulation (k=0.05Wm-1K-
1) in between. The pine boards are placed in position over the insulation by
18.75mm steel through-bolts placed at 300mm centres. Compute the overall heat-
transfer coefficient:
a. Not considering the presence of bolts.
b. Considering the presence of bolts
28. For a 2.5m wide and 3m high unshaded glass window in a south-west wall. 10
Calculate the heat gain of space assuming a single vertical glass. The following data
are given:
Direct radiation normal to sun’s rays, In = 720W/m2
Diffuse radiation, Id = 95W/m2
Sun’s altitude angle, β = 60º
Solar azimuth angle, = 15º west of south
Outside temperature = 40°C
Inside temperature = 21°C
Outside surface heat transfer co-efficient, fi = 17.5 W/m2K
Inside surface heat transfer co-efficient, fo = 11.5 W/m2K
29. What are the factors to be considered for cooling load estimate? 05 5
30. What are the factors to be considered for heating load estimate? 05
31. Explain briefly with necessary sketches the following: 10
a. High Latent Cooling load Application(Basic CAP-problem)
b. Grand Sensible Heat Factor (GSHF). (Basic RAC- SNP)
32. Explain briefly with necessary sketches the following: 10
a. Effective Room Sensible Heat Factor (ERSHF). (Basic RAC- SNP)
b. Grand Sensible Heat Factor (GSHF). (Basic RAC- SNP)
33. Explain briefly with necessary sketches the following: 10
a. Effective Room Sensible Heat Factor (ERSHF). (Basic RAC- SNP)
b. High Latent Cooling load Application(Basic CAP-problem)
34. A retail shop located in a city at 30°N latitude has the following loads: 10
Room sensible heat = 58.15kW
Room latent heat = 14.54 kW
The summer outside and inside design conditions are:
Outside = 40°C DB, 27°C WB
Inside = 25°C DB, 50 percent RH
70 cmm of ventilation air is used; assume a suitable bypass factor of the cooling coil.
Determine the following:
i Ventilation load.
ii Grand total heat.
iii Effective sensible heat factor.
iv Apparatus dew point.
v Dehumidified air quantity.
vi Condition of air entering and leaving apparatus.
35. A laboratory having a usually large latent heat gain is required to be air conditioned.
The design conditions and loads are as follows: 10
Summer design conditions = 40°C DBT, 27°C WBT
Inside design conditions = 25°C DB, 50 percent RH
Room sensible heat = 34.9kW
Room latent heat = 18.6 kW
The ventilation air is 85 cmm of used; assume a suitable bypass factor. Determine the
following:
i Ventilation load.
 ii Grand total heat.
iii Effective sensible heat factor.
iv Apparatus dew point.
v Dehumidified air quantity.
vi Condition of air entering and leaving apparatus.
Both Problems.(Basic RAC- CAP-problem)
36. Explain briefly with necessary sketches about Air Handling Unit. (Ch 21 Starting) 05
37. Derive the equation for mechanism of flow through duct outlet.(Basic RAC- CAP-Ch 10
21)
38. A grille has a core area of 0.3 m x 0.5 m. The free flow, area is 90percent. The 10
discharge coefficient may be taken as 0.8. The recommended value of coefficient K'
is 5.0. Find the core velocity, and cmm of air delivered, so that the air velocity is 0.25
m/s for a throw of 15 m.
39. Explain briefly with necessary sketch the pressure loss due to sudden enlargement in 05
duct.
6
40. Explain briefly with necessary sketch the pressure loss due to turn, bends and elbows 05
in duct.
41. An air distribution system has to be designed for the auditorium, with the help of neat 10
sketch explain any two types.(Basic RAC- SNP)
42. Explain with the help of neat sketch any two types of dynamic losses in ducts. 10
(R&AC Lecture 37)
43. Explain briefly with necessary sketches about wind induced natural ventilation. 05
(R&AC Lecture 40)
44. Explain briefly with necessary sketches about mechanical ventilation. 05
45. Explain briefly about the factors to be considered for the hood design. 05
46. Determine the various dimensions of hood, velocity & total hood air flow rate for an 10
circular high canopy hood having 4ft. diameter 1000ºF melting furnace, 100ºF metal
temperature is located at 10ft. above furnace.
47. Determine the various dimensions of hood, velocity & total hood air flow rate for an 10
rectangular high canopy hood having 2.5ft. X 4ft. rectangular melting furnace, 700ºF
7
metal temperature is located at 8ft. above furnace.
48. What are wet collectors? Explain with neat sketch of gaseous contaminant type of 10
wet collectors?
49. What are fabric collectors? Explain with neat sketch of tube type of fabric 10
collectors? 
50. What are the factors affecting air infiltration. Explain briefly. 05
51. What is the principle of dilution ventilation? 05 8
52. Explain the evaluation of heat strain. 05
53. Explain the limiting factors related to the use of dilution ventilation for health hazard 05
control for the steel plants?
54. Explain with necessary sketches about the capturing hood. 05
55. What are the factors to be considered as the safety measures for a person working in 05
heat area of casting?
56. Explain briefly about the components used for the ventilation of car parking area of 4 10
storied building.
57. Discuss briefly about the importance of steel plant blast furnace area ventilation by 10
explaining the components used.
58. Explain enclosing type of hood with necessary sketches. 05
59. State the different equations related with the different modes of heat exchange? 05
60. In general, what environmental factors does a ventilation system control depend 05
upon?
61. State the equation to compute the flow rate for dilution ventilation? 05
62. The initial concentration is zero in a room of volume 4500 m 3. A source of toluene is 10
operated for half an hour at a rate of 1.0 cfm. Find the flow rate so that the
concentration does not exceed 100 ppm. Use a mixing ratio of 4.
63. Air contains 0.22 mg/cum of Pb and 0.09 mg/cum of H 2SO4. Is the threshold limit 10
exceeded for the mixture?
64. What is q, the volume flow rate of vapor formed, if 500 grams of xylene are 10
evaporated uniformly over a 4-hr shift? What volume flow rate Q d is required for
dilution to 25 ppm, if Kmixing= 1.5? (Assume STP; d=1.0)
65. List the factors to be considered for the hood design. Explain any two. 10
Chapter 7 & 8 refer below and acgih.manual.1998

The limiting factors for D.V. For health are: