Chapter 15 (AIR CONDITIONING) Flashcards
How do you call the water vapor content of air?
B. Humidity
When air contains all of the water vapor it can hold, it is said to be
C. Saturated
What is the instrument used to register relative humidity?
A. Hygrometer
Humidity is a measure of which of the following?
A. Water Vapor Content
Air conditioning is the process of:
C. Maintaining the air at a required temperature and humidity
In an air-conditioning system, before the air is circulated to the required area, it is:
D. All of the above
The temperature at which water vapor in the atmosphere begins to condense is known as the:
B. Dew Point
Saturationg temperature is the same as:
A. Dew Point
When the bypass factor is B, the coil efficiency for sensible cooling of air is equal to:
B. 1-B
The psychrometric chart in air conditioning determines the
D. Moist Air Conditions
Which of the following is considered as comfort condition in air conditioning?
D. 20°C DBT, 60% RH
The drift loss in cooling towers is about:
C. 10-20%
Cooling towers are used for cooling water:
D. To be used for cooling the compressor
By which of the following processes heat mainly dissipates in cooling towers?
D. Evaporation
Which one is commonly used in liquid absorbent?
C. Ethylene Glycol
In sensible heating cooling following parameter remains unchanged
D. Humidity Ratio
Heating and dehumidification can be obtained simultaneously if air is passed through:
D. Any one of B and C
Dirt and foreign materials normally build-up on the side of the condenser tubes. To ensure adequate condenser capacity, a certain factor is used in calculating the overall heat transfer through the walls of the tubes including the heat transfer rate of the layers dirt and foreign materials. What is this factor?
C. Fouling Factor
The engineer was tested to design the air conditioning system for a ball room dance hall. Comsidering that this involve a lot of activity from its users, the engineer would design that will require:
A. Maximum Attainable Effective Temperature
What is the value of the Mach No. throat of the converging-diverging nozzle?
C. One
What do bodies at a temperature above absolute zero?
B. It emits Thermal Radiation
When air is saturated, the wet bulb depression is:
A. Zero
In a window air conditioning unit, which of the following is usually done by the owner
A. Semiannual cleaning or replacement of filters
Fan motors in air conditioning units usually have:
A. 2 or 3 speeds
Which of the following capacitors that can usually be found in an air conditioning unit?
D. All of these
Which of the following troubles commonly occurs inside an air conditioning unit?
D. All of these
The motor condition of an air conditioning unit can be checked with:
A. The continuity of light or with an ohmmeter
An air conditioning system wherein the entire systems are mounted in the cabinet:
A. Console Air Conditioners
The use of water to carry heat occupied spaces
A. Hydronic Heating System
The method of cooling which primarily used where ambient air temperatures are high and relative humidity is used:
A. Swamp Cooling
The other name for swamp cooling is
C. Wet Roof Cooling
Evaporative Condenser is used to cool
A. Condenser Vapor
A method of cooling which uses water as refrigerant. Pressure on the water surface is reduced to lower its boiling temperature.
A. Steam Jet Cooling
How should the window type air conditioning unit be placed?
B. Slant toward the outside of the home
The amount of CO can be determined by the color of Palladium Chloride. An amount of 30ppm to 70ppm will cause:
A. Slight Darkening
The term used to express the amount moisture in a given sample of air. It is compared with the amount of moisture in a given sample of air.
B. Relative Humidity
A dehumidifier is usually a smalk hermitic refrigerating system. It has both a condenser and an evaporator. Many older systems use R-12 or R-500. The newer units use:
A. R-134a
Palladium Chloride may be used to measure the presence of:
B. CO
The normal cut-out setting of a window unit thermostat is between:
A. 13°C to 16°C
Thermostat are used with most window units. They have differentials which vary between:
A. 2°C to 4°C
In an air conditioning unit, the thermostat fails. The unit did not start. How do you test the operation of the thermostat?
A. Cover the air outlet and air inlet with a cloth. The air will recirculate into the unit and the temperature will quickly drop to the cut out temperature.
Which of the following dehumidifier is often used to reheat the air after moisture is removed?
C. Condenser
Which of the following refrigerant is added sometimes to other refrigerant to improve oil circulation?
C. R-170 (Ethane)
A refrigeration that deals with producing temperature of -157°C or lower
D. Cryogenics
Measurement of a device’s ability to remove atmospheric air from test air.
A. Atmospheric Dust Spot Efficiency
A liquid mixture having constant maximum and minimum boiling points. Refrigerants comprising this mixture do not combine chemically, yet the mixture provides constant characteristics.
A. Azeotropic Mixture
Refrigerant in Group A1 (R-11). Chemical combination of carbon, chlorine, and fluorine.
A. Carrene
Which of the following refrigerants is popular in the industrial refrigerating system; also popularly absorption system of refrigerant.
A. R-717 (Ammonia)
Which of the following is a function of air conditioning?
D. All of these
Oxygen is approximately what percent by weight in the atmosphere?
A. 23%
Substances that have the ability to absorb moisture from the air are called:
A. Desiccants
When the dry bulb and the wet bulb temperatures are identical, the air is said to be:
A. Saturated
In What form that water exists in air?
C. Vapor
When air is heated, what happened to its relative humidity
B. Decreases
The Horizontal Scale (Abscissa) in the Psychrometric Chart represents:
A. Dry bulb temperature
Most people are comfortable with the relative humidity of:
A. 30% to 70%
The temperature below which water vapor in the air will start to condense:
C. Dew Point Temperature
Which of the following is not used as method to measure air velocities?
D. Open Type Barometer
It is a form of oxygen photochemically produced in nature.
A. Ozone
What is the chemical formula of Ozone?
A. O3
In the upper atmosphere, ozone is made by ultraviolet light reacting with:
A. Oxygen
The ozone concentration of 0.10 parts per million (ppm) is generally considered the maximum permissible for how many hours exposure?
A. 8hrs
How many moisture be removed from air?
C. A and B
In cooling cycle, the dry bulb temperature (db) of the air is lowered. When this happens the relative humidity
A. Increases
What is the effect of superheating the refrigerant?
A. It increses the Coefficient of Performance
In sensible heating the absolute humidity remains constant but the relative humidity:
B. Decreases
The relative humidity becomes 100% and where the water vapor starts to condense.
A. Dew Point
Why should you avoid bending or twisting of fan blades in an air conditioning unit?
B. It will wear out the motor bearings and cause noise
A type of refrigerant that will not damage the ozone layer.
A. Hydrofluorocarbons (HCF’s)
Which of the folllowing is the type of refrigerant that damages Ozone layer
D. All of these
Large-bulb alcohol thermometer used to measure air speed or atmospheric conditions by means of cooling.
A. Kata Thermometer
Which of the following components of the window air conditioning system must be cleaned annually?
D. All of these
Air delivered to the room from the supply duct, moving at a velocity of 150 ft/min or more is called:
A. Primary Air
The phenomenon that warm air rise and cold air settle is called:
A. Stratification
From what principle that air ducts operate?
A. Principle of Pressure Difference
Carries needed to deliver air to the conditioned space. It is made of sheet of metals like aluminum, galvanized sheet steel and some structural materials that will not burn.
A. Duct
Which of the following is the common classification of ducts?
D. All of these
It is used to deliver concentrated airstreams into a room. Many have one-way or two-way adjustable air stream deflectors.
A. Register
It is used to control the air-throw distance, height, and spread, as well as the amount of air.
A. Grille
It is used to deliver widespread, fan-shaped flows of air into the room.
C. Diffuser
Which of the following fans in air conditioning systems which can be classified as centrifugal flow?
B. Propeller Fan
A thermostat that functions as increase or decrease instead of starting and stopping system is called:
A. Modulate
The most common controller in the heating and cooling system.
A. Thermostat
A number used to compare energy usage for different areas. It is calculated by dividing the energy consumption by the fottage of the conditioned area.
C. Energy Utilization Index
The ratio of the rated cooling capacity divided by the amount of electrical power used:
A. Energy Efficiency Ratio (EER)
Heat exchanger in which water flows by gravity over the outside of the tubes or plates.
A. Baudelot Cooler
A popular air conditioning system that includes a single outdoor condenser, three independent evaporators, and individual evaporator temperature control. The condensing unit is located outside on a slab. They are frequently used in legal and medical offices, motels and homes without ducts.
A. Multizone Ductless Split System
Which of the following is to be checked as regular monthly maintenance schedule of a console air conditioning units?
D. Duct Dampers, Registers and Diffusers
An air conditioning system which is a combination of heating and cooling system. It is designed to serve an individual room or zone.
B. Packaged Terminal Air Conditioner
Which of the following is to be checked as part of the weekly maintenance schedule of a console air conditioners?
D. Cooling Tower
A mechanism that removes moisture.
B. Dehumidifiers
When coil surface temperature is below the dew point of the air.
A. Moisture will condense out of the air
Nitrogen occupied almost how much of the Earth’s Atmosphere
B. Three-fourths
Water in vapor form remains a vapor as long as its temperature is what relations to the dew point temperature
C. Below
An instrument used in measuring air velocity by velocity-pressure method.
A. Pitot Tube
What is the specific humidity of dry air?
C. 0
When hot soup was served in a cup during dinner, an engineer was so eager to drink it. Since it was hot, he added ice cubes of ice to cool the soup stirred it. He noticed that dew starts to form on the outermost surface of the cup. He wanted to check the temperature of the outermost surface of the cup. What is this temperature equal to?
D. Equal to air’s dew point temperature
The temperature at which the water vapor in the gas begins to condense in a constant pressure process.
A. Dew point
All of the following processes can be found on a psychrometric chart except:
C. Natural Convection
All of the following processes can be found on a psychrometric chart except:
C. Black Body Radiation
Which is not commonly used to cool and dehumidify equipment?
A. Calcium Chloride
All of the following temperatures have meaning in psychrometrics except:
C. Adiabatic Wall Temperature
The relative humidity is given by the:
B. Ratio of the partial pressure of water vapor to the saturation pressure
The determination of properties and behavior of atmospheric air usually the purview of:
B. Psychrometrics
PAST ME BOARD QUESTION
Which of the following statements is correct? The relative humidity of an air water vapor mixture
D. is the ratio of the partial pressure of water vapor to the saturation pressure at the mixture temperature
PAST ME BOARD QUESTION
In sensible cooling process, moisture content,
A. Does not change
PAST ME BOARD QUESTION
The design of an air supply duct of an air conditioning system__________.
D. affects the distribution
PAST ME BOARD QUESTION
What amount of air is required in a low bypass factor?
B. Lesser
PAST ME BOARD QUESTION
What is the lowest temperature to which water could possibly be cooled in a cooling tower?
B. The temperature of adiabatic compression
PAST ME BOARD QUESTION
Combined process of cooling and humidifying is also known as:
C. Evaporative Cooling Process
PAST ME BOARD QUESTION
In a cooling tower, the water is cooled mainly by:
C. Convection
PAST ME BOARD QUESTION
Which of the following types of air dryers works by absorbing moisture on a solid dessicant or drying material sush as activated alumina, silicon gel or molecular sieve?
B. Deliquescent dryer
PAST ME BOARD QUESTION
The relationship of water vapor in the air at the dew point temperature to the amount that would be in the air if the air were saturated at the dry bulb temperature is:
C. Relative Humidity
PAST ME BOARD QUESTION
When the air is saturated the wet bulb depression is:
A. Zero
PAST ME BOARD QUESTION
A temperature measurement in an ordinary thermometer which has constant specific humidity.
B. Dew point temperature
PAST ME BOARD QUESTION
During sensible heating, the humidity remains constant but the relative humidity.
B. Decreases
PAST ME BOARD QUESTION
The relative humidity becomes 100% and where the water vapor starts to condense.
C. Dew Point
PAST ME BOARD QUESTION
What is the specific humidity of dry air?
D. 0
PAST ME BOARD QUESTION
An engineer inspected an air-conditioning unit. He found out that the unit does not produce any cooling effect, however, the air-conditioning unit is running. He checked the temperature of the condenser and evaporator and had the unit run. He found out that there was no change in the temperature. What should he do?
B. Charge with new refrigerant
PAST ME BOARD QUESTION
What is the temperature range of air in air conditioning application where the dry air can be considered ideal gas?
D. -10°C to 50°C
PAST ME BOARD QUESTION
What is the value of air stratification in air conditioning design fit for human comfort?
C. Less than air temperature
