Question

1- In a system with outdoor air for ventilation:
(a) the load on coil is equal to the load on building
(b) the load on building is greater than the load on coil
(c) the load on building is less than the load on coil
(d) the Coil ADP is less than room ADP.

2- Evaporative cooling systems are:
(a) attractive for hot and humid climates
(b) attractive for hot and dry climates
(c) ideal for comfort applications
(d) ideal for several industrial applications

3- Selection of a suitable air conditioning system depends on:
(a) Type of the building
(b) Initial and running costs
(c) Reliability and serviceability
(d) All of the above

3- Match the following:
(a) A large precision laboratory a. Variable air volume system
(b) Perimeter zone of a building b. Constant air volume system
(c) Simultaneous cooling and heating c. Multiple zone, single duct system
(d) A large building complex d. Dual duct system

4- A dedicated outside air unit is used to pre-cool 2,500 CFM(1.18m3 /s) of outside air at
31 °C DB and 85% relative humidity to 15.5 °C DB, 14 °C WB. What is the quantity of
water removed by the coil in GPM?
(a) 0.29 ?PM
(b) 0.33 ?PM
(c) 2.9 ?PM
(d) 2.4 ?PM

5- Which of the following statements are TRUE?
(a) Compared to central systems, the initial cost of a unitary system is less
(b) Unitary systems can be installed quickly and their operation is relatively simple
(c) Unitary systems consume less power compared to central systems of same capacity
(d) Unitary systems are ideal for retrofitting applications

6-Unitary refrigerant based systems are:
(a) used for very small capacities only
(b) are available only for cooling applications
(c) couldnot factory assembled with a performance guaranteed by the manufacturer
(d) also called as package units.

7- State which of the following statements are TRUE?
(a) By improving the internal air movement, the energy consumption of the air
conditioning system can be reduced substantially
(b) By increasing air movement, the thermostat of the air conditioning system can be set at a lower temperature
(c) By increasing air movement, the thermostat of the air conditioning system can be
set at a higher temperature
(d) Solar chimneys are ideal under all conditions

8- valves that can be used for shutoff duty:
(a) butterfly,
(b) gate,
(c) ball
(d) All of the above.

9- A single zone, single duct, constant volume system:
(a) used for both cooling and heating simultaneously
(b) The cooling capacity is controlled by controlling the supply air temperature
(c) not suitable when the space conditions have to be controlled precisely
(d) can be used for large single rooms only

10- Dual duct systems are:
(a) provide either cooling or heating
(b) constant air volume systems
(c) energy efficient
(d) occupy more space compared to single duct systems

11-In all- water system of centeral air conditioning system
(a) Cooling medium is chilled water or brine water and not direct refrigerant
(b) The cooling medium may be supplied from a source away from the conditioned
space
(c) The cooling medium may be circulated through the coils of an air terminal
(d) All the above are true

12-In Dual-conduit system of All-Air system of air conditioning
(a) There are two separate air streams
(b) One of the two conduit is permanent by supplying cold and variable air volume for
fluctuating internal and solar load
(c) One of the two conduit supplies constant air volume but variable temperature air
for varying building transmission losses
(d) All of the above statements are true

13-Factors for selection of air conditioning system are
(a) Purpose, location, orientation, and shape of the space or building
(b) Temperature, humidity, wind, exposure to sun and shade of environments of the
space or building
(c) Occupancy, lighting, and other heat exchanges and heat storage capability
(d) All of the above.

14- Which of the following statements are TRUE?
a) All water systems are suitable in buildings requiring individual room control
b) In an air-water system, all the latent load on the building is handled by the primary
air only
c) Dual duct systems are constant air volume systems
d) In all air systems, it is sometimes possible to switch of the cooling coil and use only
outdoor air for air conditioning
e) Variable air volume systems occupy less space compared to constant volume systems

15- For air conditioning the operation theater in a hospital, the percentage of outside air
in the air supplied is:
(a) Zero.
(b) 20
(c) 50
(d) 100.

16- The minimum temperature to which water can be cooled in a cooling tower is:
(a) Dew point temperature of air
(b) Wet bulb temperature of air
(c) Dry bulb temperature of air
(d) Ambient air temperature.

17- The central air conditioning system has ___________ overall efficiency as compared
to individual systems.
(a) Same
(b) Lower
(c) Higher
(d) None of these

18- The choice of chiller determines how the facility is prepared. Examples of parameters
that determine the chiller are:
(a) Electrical requirements
(b) Ease of installation (air-cooled chillers are easier to set up)
(c) Location or available space
(d) Comfort or process cooling
(e) All of the above

19- Ventilated outdoor air can be used:
(a) for cooling of the buildings throughout the year in all locations
(b) for cooling of the buildings during many days of the year in most of the locations
(c) greater potential for cooling of buildings in hot and humid areas
(d) greater potential for cooling of buildings in hot and dry areas

20- State which of the following statements are TRUE?
a) For effective utilization of outdoor air, both natural and mechanical ventilation
should be used in a building
b) Design of windows and other openings in the buildings plays a major role in
natural ventilation
c) For maximum airflow rate, the openings should be as close to the neutral pressure
level as possible
d) All of the above.

21- In comfort-cooling applications, cooling loads are often satisfied by air handlers
equipped with coils to transfer heat from the conditioned space air to circulating
chilled-water. Heat transferred from the loads can be controlled in a number of
ways:
a) Three-way valve
b) Two-way valve
c) Variable-speed pump
d) All of the above.

22- An air handler supplies 5,000 CFM (2.36m3 /s) at a temperature of 13°C. The air handler
was designed for 1,000 CFM of outside air at 31°C DB and 26°C WB. The remaining
return air from the space is at 25 °C DB and 55% relative humidity. What are the
entering conditions of the air into the coil, in DB and WB?
(a) 26 C ?BT, 20 C ?BT
(b) 26 C ?BT, 15 C ?BT
(c) 29.5 C ?BT, 23.5 C ?BT
(d) 29.5 C ?BT, 24 C ?BT

23- In variable air volume systems:
(a) In single duct, variable air volume systems, the supply air flow rate remains
constant, but the temperature of the supply air is varied depending upon the load
(b) Variable air volume systems generally consume less power compared to constant
volume systems
(c) Variable air volume systems occupy less space compared to constant volume
systems
(d) Variable air volume systems always ensure adequate ventilation and good room
air distribution

24- For air-water system, Which of the following statements are TRUE?
(a) An air-water system uses both air and water in the thermal distribution system
(b) In an air-water system, all the latent load on the building is handled by the
primary air only
(c) In an air-water system, the cooling coil kept in the conditioned space operates
under dry conditions
(d) Compared to all water systems, an air-water system is difficult to maintain

25- For fan coil unit ,Which of the following statements are TRUE?
(a) A fan coil unit is used with all water systems only
(b) A fan coil unit can be used either with an all water system or with an air-water
system
(c) It is possible to control the cooling capacity by controlling either liquid flow rate
or air flow rate in a fan coil unit
(d) A fan coil unit used in an all water system requires a provision for draining the
condensed water

26- For a convector, Which of the following statements are TRUE?
(a) In a convector, heat transfer takes place by forced convection
(b) Convectors are commonly used for heating applications
(c) In a radiator, heat transfer takes place by both radiation and convection
(d) A unit ventilator is a fan coil unit with a provision for fresh air entry

27- For Small unitary systems, Which of the following statements are TRUE?
(a) Small unitary systems have air cooled condensers, while larger systems can be
either air cooled or water cooled
(b) A split type room air conditioner should be used when the room does not have an
exterior wall
(c) A split type air conditioner is more reliable compared to a window air conditioner
(d) It is possible to provide fresh air in a window air conditioner, whereas this is not
possible in a split air conditioner

Answer 1

Answer 1. Option B and D are correct

Explanation

Because of humility and latent heat of air outside and inside the cooling area or building the In a 100% re-circulation system, the load on coil is equal to the load on building and In a system with outdoor air for ventilation, the load on building is greater than the
load on coil. Furthermore, In a system with outdoor air for ventilation, the Coil ADP is less than room ADP.

Answer 2. Option B and D are correct

Explanation

Evaporative cooling

This system is based on the principle that when moist but unsaturated air comes in contact with a wetted surface whose temperature is higher than the dew point temperature of air, some water from the wetted
surface evaporates into air. The latent heat of evaporation is taken fromwater, air or both of them. In this process, the air loses sensible heat but gains latent heat due to transfer of water vapour. Thus the air gets cooled and humidified. The cooled and humidified air can be used for providing thermal comfort.

This is why it is suitable for

B. Hot and dry climates

B. Several Industry application

Answer 3. D. All of the above

Explanation

While setting up a HVAC(Heating ventilation and air conditioning) system everything comes under consideration.

Answer 3.   a-b, b-a, c-d, d-c

EXPLANATION

With the type of place and the amount of load the Air-conditioning system changes beause there are.many and each are designed for a particular space and load.

Answer 5.  a), b) and d)

Central systems

Central air conditioning (or central A/C) is a system in which air is cooled at a central location and distributed to and from rooms by one or more fans and ductwork. The work of the air conditioner compressor is what makes the whole process of air conditioning possible.

Unitary system

A unitary or package air conditioning system uses equipment where most or all of the basic components have been assembled in the factory e.g., room air conditioner .

Answer 6. C and D

A unitary or package air conditioning system uses equipment where most or all of the basic components have been assembled in the factory e.g., room air conditioner .

Answer 7. A and C

Explanation

By improving the internal air movement, the energy consumption of the air conditioning system can be reduced substantially and By increasing air movement, the thermostat of the air conditioning system can be
set at a higher temperature.

Answer 8.D All of the above

Explanation

Ball valves

A ball valve is a form of quarter-turn valve which uses a hollow, perforated and pivoting ball to control flow through it.

Butterfly valve

A butterfly valve is a valve that isolates or regulates the flow of a fluid. The closing mechanism is a disk that rotates.

Gate valve

A gate valve, also known as a sluice valve, is a valve that opens by lifting a barrier out of the path of the fluid.

Answer 9. B

A single zone, single duct, constant volume system can be used either for cooling
or for heating, but not for both cooling and heating simultaneously.

The cooling capacity of a single zone, single duct, constant volume system is controlled by controlling the supply air temperature.

Answer 10. D

Dual duct system

dual-duct system. An air-conditioning system in which two supply ducts run to each space being conditioned, one for cold air, the other for warm air; at each individually controlled space, air from the two ducts is blended in a sheet-metal box (called a mixing box) and then supplied to the conditioned space.

Answer 11. All of the above

Properties

(a) Cooling medium is chilled water or brine water and not direct refrigerant
(b) The cooling medium may be supplied from a source away from the conditioned
space
(c) The cooling medium may be circulated through the coils of an air terminal

Answer 12. All of the above

in a dual duct system the supply air fan splits the flow into two streams. One stream flow through the cooling coil and gets cooled and dehumidified to about 13o
C, while the other stream flows the heating coil and is heated to about 35–45oC. The cold and hot streams flow through separate ducts. Before each conditioned space or zone, the cold and hot air streams are mixed in required proportions using a mixing box arrangement, which is controlled by the zone thermostat. The total volume of air supplied to each zone remains constant, however, the supply air temperature varies depending upon load.

Answer 13 All.of the above

Answer 14 a b and d

Answer 15 d 100

For air conditioning the operation theater in a hospital, the percentage of outside air in the air supplied is 100.

Answer 16 b. Wet bulb tempreture of air

The minimum temperature to which water can be cooled in a cooling tower is Wet bulb temperature of air

Answer 17 c. Higher

The central air conditioning system has Higher overall efficiency as compared to individual systems.