記憶度
15問
35問
0問
0問
0問
アカウント登録して、解答結果を保存しよう
問題一覧
1
What is the cause of pressure drop in the boiler, condenser and the pipings between different components? Because of this drop, steam leaving the boiler is at lower pressure.
Fluid friction
2
There are three basic boiler types, namely:
Cast-iron, fire-tube and water tube boilers
3
A valve that releases steam from the boiler by opening at a pre-determined pressure in order to keep the steam pressure from rising more than the pressure from which the valve is set is called a
Safety valve
4
The ratio of the average load to that of the rated capacity of a plant is called:
Capacity factor
5
What will happen when the pressure at any point inside ¢ centrifugal pump goes below the vapor pressure corresponding to the temperature of the liquid?
Cavitation
6
For Brayton cycle, the result of regeneration is:
Increase in thermal efficiency
7
The force when applied to a mass of one kilogram will give mass an acceleration of one meter per second for every second called:
Newton
8
The kinetic energy of a moving fluid is used to isentropically compressed the fluid to state of zero velocity. The temperature of a moving fluid at the state zero velocity is called:
Stagnation temperature
9
Arefrigeration control that guards the compressor from overloads brought about by abruptly increases loads resulting from defrosting, warm products and others, is called:
Suction hold-back valve
10
When there is no work between the thermodynamic system and its surrounding, the quantity of net heat transfer is equal to:
Temperature of a closed system
11
Which of the following plant is suitable for peak load?
Diesel engine plant
12
An instrument for determination of the composition of the gas mixture by measuring variations in the thermal conductivity.
Kathramometer
13
Fans that are used to draw combustion products through the furnace bed, stack, and pollution control system by injecting air into the stack after combustion.
Induced draft
14
Chimneys that rely on natural draft are sometimes referred to as
gravity chimney
15
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 temperatures of the condenser and evaporator and had the unit run. He found out that there was no change in temperature. What should he do?
Charge with new refrigerant
16
Which of the following statements is correct? The relative humidity of an air water vapor mixture
is the ratio of the partial pressure of water vapor to the saturation pressure at the mixture temperature
17
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 the temperature equal to?
equal to air's dew point temperature
18
An instrument used in measuring air velocity by velocity pressure method
Pitot tube
19
A mechanism that removes moisture.
Dehumidifiers
20
What is the effect of superrheating the refrigerant?
It increases the Coefficient of Performance
21
The ozone concentration of 0.10 parts per million (ppm) is generally considered the maximum permissible for how many hours exposure?
8 hrs
22
Substances that have the ability to absorb moisture from the air are called:
Dessicants
23
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?
Fouling factor
24
Which one is commonly used liquid absorbent?
ethylene glycol
25
The psychrometric chart in air conditioning determines the
moist air conditions
26
The temperature at which water vapor in the atmosphere begins to condense is known as the:
dew point
27
Whatis the instrument used to register relative humidity?
Hygrometer
28
It prevents the refrigerant from the condenser to go back to the compressor.
Check valve
29
The dividing point between the high pressure and low pressure sides of the refrigeration cycle occurs at the:
expansion valve
30
What do you call a plate or vane used to direct or control movement of fluid or air within the confined area?
baffle
31
What is the cycle where a refrigeration system generally operates?
close cycle
32
The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy diagram represents:
evaporation of the refrigerant liquid
33
Which of the following uses a secondary refrigerant?
ice plant
34
Dry ice is
solidified form of carbon dioxide
35
Bell-Coleman Cycle is also known as ________
reversed Joule cycle
36
If one of the ship’s service boxes suddenly stops cooling, the most likely cause would be the malfunction of the:
solenoid valve
37
What will happen if the expansion valve is opened too wide?
liquid will flow back to the compressor
38
How is a thermostatic valve tested?
immersing its bulb in ice water
39
Which of the following will cause an automatically controlled F-12 compressor to start?
opening the solenoid valve
40
The suction pressure control valve is actuated by which of the following?
pressure diaphragm
41
What do you usually do to correct slugging and flooding back?
check the expansion valve
42
The solenoid valve is actuated by which of the following?
a magnet
43
With one machine serving several compartments, with one compartment reaches the desired temperature in that compartment is maintained by:
the solenoid valve
44
Which of the following is not essential to a comiression refrigeration system?
A receiver
45
What is the effect if the refrigerant is removed from the system too fast?
it may "freeze-up" the condenser
46
The process that takes place in the evaporator is called:
Absorption of the latent heat of vaporization
47
Moisture in a system will cause a:
Faulty expansion valve
48
Which of the following is not essential to a centrifugal type of compressor system?
Distiller
49
Which of the following is the reason when the crankcase is cooler than the suction line?
Too much refrigerant
50
What is the use of back pressure regulating valve?
Too much refrigerant
51
What is the use of back pressure regulating valve?
Maintains a fixed pressure in the evaporator coils
52
If refrigeration controls were constructed with little or no differential, the:
Compressor would short cycle
53
Which of the following devices will prevent the relief valve from opening in the event of excessive pressure?
High-pressure cutout switch
54
Which of the following would cause the suction switch to remain open?
Bellows broken or jammed
55
The temperature of the refrigerant is highest just before it enters the:
Condenser
56
Which of the following types of valve are not used for suction or discharge?
Gate
57
What is the first step that must be done when securing a system?
Close receiver (King) valve
58
Which of the following characteristics that is not desirable in a refrigerant?
Low latent heat of vaporization
59
The cooling component of a refrigeration cycle is called ______
An evaporator
60
When ordering an expansion valve which of the following information is necessary?
Size, tonnage, temperature and pressure
61
Refrigerant leakage from the compressor crankcase is prevented by
Using shaft seals
62
The heat used to change a liquid to a gas or vapor is called latent heat of
Vaporization
63
What do you call a material in a dryer?
C.Dessicant
64
An automatically controlled Freon -12 compressor will start when the
Solenoid valve opens
65
Which of the following type valves are not found on a Freon -12 system?
Duplex
66
If the compressor discharge becomes frosted, the irobable cause would be
Refrigerant flooding back
67
there were a 15°F to 20°F temperature differential between the temperature corresponding to the pressure at the compressor discharge and the temperature at the condenser outlet, it would probably indicate the need for
Purging the system
68
The temperature bulb of a solenoid valve is attached to the ______
Wall of the icebox
69
What usually happens if the specific gravity of the brine is too low?
The brine will freeze
70
What is the use of the suction pressure regulating valve?
Maintains the back pressure in the evaporator coils
71
If there is too much lube oil in the system, what must be done?
Remove same at once
72
Whal is the cause of Iiquid “slugging"?
Liquid in the compressor clearance space
73
The solenoid valve controls which of the following
Flow of refrigerant to the expansion valve
74
Where is solenoid coil installed?
Vertically above the valve
75
Which of the following would not be cause for a refrigerating system to short cycle on HP cutout?
Discharge valve leaking
76
A good refrigerant should have a
High latent heat
77
Which of the following is the most common method of heat flow in refrigeration?
Convection
78
What is the combination of a wet and dry bulb thermometer is called a
A or B
79
Oil is added to a Freon compressor by
Puping in with a hand pump
80
When adding oil to a Freon system, one must be sure that
All air is removed from the pump and fitting
81
The solenoid valve is controlled by
The temperature in the icebox
82
A thermostat is a
Temperature-operated switch
83
The solenoid valve controls the
Amount of refrigerant going to the expansion valve
84
When charging Freon system, all the valves should be in their normal position except the:
King (liquid) valve
85
The function of the expansion valve is to:
Regulate the amount of liquid refrigerant to the expansion coils
86
When heavy electrical currents are involved, the thermostat will be operated by a:
Relay
87
Which of the following would not cause high suction pressure?
Insufficient refrigeration
88
If the head pressure is too high:
The high-pressure cutout switch should operate before the relief valve opens
89
Low suction pressure is caused by
Solenoid valve not functioning properly
90
Which of the following would cause a high head pressure?
Insufficient cooling water
91
The suction pressure in a Freon system should be
The pressure which corresponds with a temperature about 20 F below the temperature of the icebox
92
If any of the electrically controlled devices in a Freon system malfunction, which of the following valve will also automatically shut off?
Solenoid valve
93
A leaky discharge valve can usually be detected by
Any of the above
94
If the compressor short-cycles on the highpressure cutout, which of the following would you check?
Check for too much refrigerant in the system
95
The most likely cause of high superheat would be
Expansion valve closed too much
96
What do you call the liquid reaching the compressor through the suction?
Flooding back
97
Which of the following is the probable cause of hot suction line?
Insufficient refrigerant
98
What do you call the device that is used as a lowpressure control and high-pressure cutout on a compressor?
Pressure controller
99
If the solenoid valve closed by accident, the compressor would be stopped by which of the following?
Low-pressure cutout switch
100
The purpose of the low-pressure cutout switch is to:
Cut compressor in and out at a preset pressure