Hotel Service Unit 11 Refrigeration

What is the purpose of compressing the refrigerant in a refrigeration cycle?

B) To increase its pressure and temperature, preparing it for condensation

What is the state of the refrigerant when it exits the condenser?

A) High-pressure liquid

Why is a high dielectric strength important for refrigeration oil in certain systems?

B) It prevents the oil from conducting electricity, reducing electrical breakdowns in systems with electrical components

What remedial action should be taken if a refrigeration plant is found to be undercharged with refrigerant?

B) Add the required amount of refrigerant to restore the proper charge

Which of the following is a common method for detecting a refrigeration gas leak?

B) Use of electronic leak detectors that sense refrigerant gases

What safety device is essential to prevent a person from becoming trapped inside a storage room?

C) Emergency release latch that can be operated from the inside

What is the safe method for bringing the refrigerant charge back to its normal working level?

B) Recharging the system through the low-pressure side in vapor form to avoid compressor damage

How does the thermal bulb influence the operation of a thermostatic expansion valve?

B) By sensing the evaporator outlet temperature and sending a pressure signal to the diaphragm

What happens to the refrigerant’s pressure and temperature in the expansion valve?

C) Pressure and temperature both decrease as the refrigerant expands

What is another common indication that a refrigeration system has lost refrigerant?

A) Low suction pressure

Which additional device can enhance safety in a storage room?

A) Alarm button inside the room

What is the appropriate remedial action if air is detected in a refrigeration system?

B) Purge the system to remove air from the refrigerant lines

What is the name of the international agreement that mandates the phase-out of ozone-depleting compounds?

B) Montreal Protocol

What is an effective remedial action to remove moisture from a refrigeration system?

B) Use a vacuum pump to evacuate moisture and install a dehydrator or filter-drier

What is the refrigerant’s state as it enters the evaporator?

C) Low-pressure liquid

What effect does the thermostatic expansion valve have if the evaporator temperature drops below the setpoint?

A) It closes slightly to reduce refrigerant flow

Which device is used to detect refrigerant leaks that are too small to be visible?

C) Electronic leak detector

Where should refrigerant gas bottles be stored on a vessel?

B) In a dedicated, well-ventilated storage area away from direct sunlight and heat sources

What is considered the weakest part of a refrigerant storage bottle?

B) The valve and connections

What problem can water or moisture cause if present in a refrigeration system?

B) Formation of ice blockages in the expansion valve or capillary tubes

Why is chemical stability an important property for refrigeration oil?

B) To ensure the oil does not react with refrigerants or system materials, maintaining performance over time

What happens to the valve opening if the evaporator temperature rises?

C) The valve opening increases to allow more refrigerant to enter

What is one of the main effects of an undercharge of refrigerant in a refrigeration plant?

B) Reduced cooling capacity and possible compressor overheating

What is a common effect of having air in a refrigeration system?

C) Increased system pressure and higher condenser temperature

Which of the following is an indication of a loss in refrigerant charge?

B) Reduced cooling capacity and higher evaporator temperature

Why is it essential for the thermostatic expansion valve to maintain proper refrigerant flow into the evaporator?

B) To prevent the evaporator from freezing or overheating, maintaining efficient cooling

How should excessive refrigerant be removed from the system to comply with MARPOL regulations?

B) By discharging it into a recovery cylinder for safe disposal

At which point in the system does the refrigerant reach its highest pressure and temperature?

A) Compressor

Which of the following is a key property of refrigeration oil?

B) Low pour point to remain fluid at low temperatures

What role does the diaphragm play in a thermostatically controlled expansion valve?

A) It regulates refrigerant flow based on temperature and pressure changes

How does an oil separator operate to remove oil from refrigerant?

B) By forcing the refrigerant and oil through a series of baffles that separate the heavier oil particles

What is a potential danger in a storage room used for vegetables and fruit?

B) Accumulation of carbon dioxide and ethylene gases due to produce respiration, which can displace oxygen and create a suffocation hazard

Which principle involves the removal of heat from a refrigerant to condense it into a liquid?

D) Removal of heat through condensation

What is the primary purpose of an oil separator in a refrigeration system?

B) To separate oil from the refrigerant and return it to the compressor

Which of the following is a main component of a basic refrigeration system?

A) Evaporator

Which property of refrigeration oil is crucial for reducing wear in system components?

B) Adequate lubricating ability

For recharging, liquid refrigerant can be added through the liquid line, while vapor charging is done via the low-pressure side to avoid damaging the compressor. Both methods ensure controlled refrigerant flow into the system. What is another method for recharging a refrigeration system?

D) Vapor charging via the suction side of the compressor

What happens to the separated oil after it is collected in the oil separator?

B) It is returned to the compressor through an oil return line

What role does the condenser play in a refrigeration system?

B) It removes heat from the refrigerant, condensing it back into a liquid

Which of the following is one of the three basic principles of refrigeration?

B) Absorption of heat during evaporation

Which component regulates the flow of refrigerant into the evaporator?

C) Expansion Valve

What property helps refrigeration oil separate easily from the refrigerant in the oil separator?

B) Low miscibility with refrigerant

Which method is used to recharge a refrigeration system, and where should the connection be made?

B) Liquid charging into the liquid line and vapor charging into the low-pressure side

What is the primary function of the compressor in a refrigeration system?

B) To increase the refrigerant pressure and temperature, moving it to the condenser

What is another reliable method to detect a refrigeration gas leak?

A) Spraying soap solution on joints and watching for bubbles

Which of the following is a commonly used method to detect the location of a refrigerant leak?

B) Applying a soap solution to fittings and observing for bubbles

Which of the following is a main component of a thermostatically controlled expansion valve?

B) Thermal bulb

What is the state of the refrigerant as it enters the compressor?

B) Low-pressure vapor

How can it be determined if refrigerant is leaking from a gas bottle?

B) Using a soap solution around the valve and looking for bubbles

Which component of the thermostatic expansion valve helps control the force applied to the diaphragm?

B) Spring

Where is the oil separator typically located in a refrigeration system?

A) After the compressor, before the condenser

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