Testy

F-Gas English Low GWP

Všetky otázky
HFC | Flammable | CO₂ | NH₃
Ľahké otázky | Stredne ťažké otázky | Ťažké otázky

1

Ľahká

What is the base unit of mass according to the International System of Units (Système International d’Unités)?


Pound
t
kg
N

2

Stredne ťažká

What process takes place in the condenser of a refrigeration system?


The refrigerant releases the heat absorbed in the compressor via the condenser
The medium flowing through the evaporator (glycol, water) condenses, whilst the refrigerant evaporates.
In the condenser, the refrigerant releases the heat absorbed in the evaporator into the surroundings.
Hot refrigerant vapour is pumped from the compressor to the condenser, where it is cooled and then condensed. In this heat exchanger, the resulting liquid refrigerant is also slightly subcooled.

3

Stredne ťažká

What determines the condensation temperature of an air-cooled unit?


On the compressor and discharge temperatures
On the evaporation (boiling) temperature.
On the superheat temperature.
On the ambient temperature.

4

Stredne ťažká

Is energy required when heat is transferred from the condenser to the surroundings?


Yes, but only when using HFC refrigerants.
The heat flow balances the energy input.
Yes, in every case.
No, because according to the second law of thermodynamics, thermal energy always flows from a body at a higher temperature to a body at a lower temperature.

5

Stredne ťažká

What should you pay attention to during the operation of the condenser?


Care should be taken to ensure that the air temperature at the condenser inlet is lower than the air temperature at the condenser outlet.
You should ensure the general maintenance of the condenser and keep the heat exchange surfaces clean.
Ensure that the air temperature at the condenser outlet is higher than the condensation temperature.
Pay attention to the fan’s operation and the ambient temperature.

6

Stredne ťažká

What criteria should be considered when selecting a suitable condenser?


The required capacity of the condenser and the technical specifications declared by the manufacturer must be taken into account.
Condensers should be selected based on your own experience, and the condenser’s geometric parameters should be taken into account.
These include size and the number of fans. The geometric parameters of the condenser must be taken into account.
First and foremost, you should consider the operating noise level of the fans, the diameter of the connection pipes and the colour scheme.

7

Stredne ťažká

How do contaminants (dust, particulates, deposits) affect the performance and efficiency of heat exchange surfaces in condensers?


Contaminants restrict heat transfer (reducing the heat transfer coefficient) and cause a reduction in condensing pressure.
Contaminants restrict heat transfer (reducing the heat transfer coefficient) and cause an increase in condensing temperature and pressure, which in turn leads to a reduction in the condenser’s efficiency.
Contaminants increase the heat transfer area and reduce the condensing pressure.
Contaminants do not significantly affect the efficiency and effectiveness of the heat exchange surfaces in condensers.

8

Stredne ťažká

If an air-cooled condenser becomes contaminated, will the condensation efficiency?


It will decrease.
It remains unchanged.
It will increase.
It will increase as a result of the fan speed being raised further.

9

Stredne ťažká

What can cause frost to form on the evaporator?


Frost build-up on the evaporator increases airflow resistance and, consequently, causes the fan motor to work harder.
An increase in refrigerant flow resistance and a reduction in the refrigerant flow rate through the evaporator.
A reduction in the temperature of the cooled substance.
a drop in cooling capacity.

10

Stredne ťažká

What happens when the evaporation temperature drops?


The compressor’s cooling capacity decreases.
The condenser fan speed increases.
The compressor’s cooling capacity increases.
The discharge temperature decreases.

11

Stredne ťažká

When is defrosting using the refrigerant possible?


Defrosting using the refrigerant is not possible at all.
In the case of air-cooled chillers, only when the air temperature is above 0°C.
Only when using speed-controlled fans.
Never. We use electricity for defrosting (for example, using a special electric heater).

12

Stredne ťažká

When can frost form on the evaporator surface?


Only in the case of air coolers, when the air temperature drops below 0°C.
In the case of finned evaporators.
Frost forms only when the refrigeration system is operating continuously.
Frost always forms on air coolers.

13

Stredne ťažká

In the case of extensive pipework systems, secondary evaporation of the refrigerant can be prevented by...


using larger-diameter pipes.
using smaller-diameter pipes.
additional cooling.
by insulating the pipes between the compressor and the condenser.

14

Stredne ťažká

How does hot gas defrosting of the evaporator work?


We swap the outlet and inlet sides of the evaporator.
This involves reversing the direction of rotation of the compressor.
Heated vapour (hot gas) from the compressor is directed into the evaporator piping.
We switch on the gas heater directed at the evaporator.

15

Stredne ťažká

What is the function of the evaporator in a refrigeration system?


It cools the refrigerant.
Thanks to the evaporator, the cooled medium transfers heat to the boiling refrigerant.
It ensures that the refrigerant is superheated over the largest possible heat exchange surface area.
It evaporates the water flowing through the evaporator.

16

Stredne ťažká

What conditions must be met for the evaporator to be defrosted using electric heaters?


The electric heaters must be positioned beneath the evaporator’s heat exchange surface.
The electric heaters must be positioned in direct contact with the refrigerant so that the refrigerant flowing through the evaporator is at a sufficiently high temperature.
Thanks to the forced air flow created by the fans, the heat from the heaters is transferred to the heat exchanger.
The electric heaters must be in contact with the evaporator’s heat exchange surface (the heater must touch the fins).

17

Stredne ťažká

Refrigerant distributor:


ensures even distribution of the refrigerant to the individual sections of the condenser.
ensures an even distribution of the refrigerant to the individual sections of the evaporator.
acts as a buffer for the refrigerant in the event that the pressure upstream of the expansion valve is exceeded.
ensures the even distribution of the refrigerant discharged by compressors connected in parallel.

18

Stredne ťažká

What are the possible methods of defrosting air coolers?


Electric defrosting only.
Electric defrosting, liquid defrosting or defrosting using hot refrigerant vapour.
Hot gas defrosting.
Natural defrosting; there are no other effective methods.

19

Stredne ťažká

The boiling point increases (and consequently the rate of evaporation increases) if the pressure above the liquid...


Falls.
Rises.
Remains constant.
It behaves differently depending on the ambient temperature.

20

Stredne ťažká

MOP in thermostatic expansion valves stands for:


minimum flow opening.
self-cleaning of the valve in the event of moisture in the refrigerant freezing.
maximum operating pressure.
maximum pressure switch protection.

21

Stredne ťažká

The function of a thermostatic expansion valve (TEV) in a refrigeration system is:


to maintain a constant suction pressure to the compressor.
to control the amount of refrigerant supplied to the evaporator depending on the superheat of the vapour leaving that heat exchanger.
to consistently adjust the evaporation pressure in the condenser depending on the temperature of the refrigerant vapour leaving the condenser.
regulating the superheat of the refrigerant leaving the evaporator so that it is at the minimum value.

22

Stredne ťažká

When using a capillary tube, what type of motor can be used in the compressor?


An electronically commutated motor approved for use with the compressor should be used.
A motor with high starting torque must be used.
A motor with low starting torque can be used.
A low-speed motor should be used.

23

Stredne ťažká

What does the thermostatic expansion valve regulate?


Evaporation pressure after.
Cooling.
The mass flow of the refrigerant injected into the evaporator.
Discharge temperature.

24

Stredne ťažká

The refrigerant absorbs heat when...


sublimates
freezes.
it condenses.
it evaporates.

25

Stredne ťažká

In the case of a thermostatic expansion valve, the manufacturer specifies...


  ...the degree to which the valve is filled with refrigerant liquid.
…the degree of refrigerant expansion.
...the superheat value during valve operation.
...the static superheat of the valve.

26

Stredne ťažká

How do we charge a new or repaired system with refrigerant when it is fitted with an expansion valve


Charging with refrigerant takes place during operation via the outlet connection of the refrigerant capillary tube.
in any way.
to the suction side of the compressor.
behind the condenser to the liquid refrigerant receiver.

27

Stredne ťažká

What does a thermostatic/electronic expansion valve regulate?


The number of revolutions of the compressor per unit of time.
Condenser subcooling by adjusting the condensing pressure.
The amount of refrigerant by controlling the evaporator superheat.
The evaporation pressure, closing when it falls below the setpoint temperature.

28

Stredne ťažká

What does the MOP function in expansion valves mean?


This means that these expansion valves are set to limit subcooling.
This means that these expansion valves are set to prevent overheating.
It means that these expansion valves are set to limit the maximum operating pressure.
This means that these expansion valves are set to a specific suction pressure.

29

Stredne ťažká

The lower the temperature of the liquid refrigerant upstream of the expansion valve,


  ...the lower the theoretical coefficient of cooling efficiency qo will be, whilst the cooling capacity Qo remains unchanged.
...the lower the theoretical coefficient of refrigeration efficiency qo will be, and the lower the refrigeration capacity Qo will be.
... the higher the theoretical coefficient of cooling capacity qo will be, and the greater the cooling capacity Qo will be.
...the lower the theoretical coefficient of cooling efficiency qo will be, and the lower the system’s energy efficiency will be.

30

Stredne ťažká

The MOP point in the expansion valve, due to the maximum evaporation temperature of the refrigeration system, ...


...must be approximately 7 K lower.
The value of the MOP point is irrelevant.
...must be approximately 7 K higher.
...must be approximately 5 K lower.

31

Stredne ťažká

What is the function of the suction pressure regulator?


It maintains the suction pressure at a constant level.
To maintain the suction pressure at the highest possible level.
It limits the suction pressure and protects the compressor from excessively high suction pressure.
It prevents a drop in suction pressure and, if necessary, shuts down the refrigeration system.

32

Stredne ťažká

What is the function of the valve regulating water flow through the condenser?


To maintain the water temperature at the highest level.
To maintain the condensing pressure at the lowest possible level.
To maintain the condensing pressure at a constant level.
To maintain the condensing pressure at the highest possible level.

33

Stredne ťažká

The use of a refrigerant distributor requires a thermostatic expansion valve …


… with external pressure equalisation.
… with a MOP function.
… with internal pressure equalisation.
… with an adsorption-type sensor filling.

34

Stredne ťažká

What properties should good insulation materials have?


It must have a good antistatic coating
It must have a high thermal conductivity.
It must be able to absorb large amounts of moisture.
It must have a low thermal conductivity.

35

Stredne ťažká

When do we encounter the superheated state?


This is a state that arises as a result of the temperature difference between the suction side and the discharge side of a compressor.
It is the temperature difference between the evaporation temperature and the ambient temperature.
It is a condition in which the compressor motor temperature rises excessively.
This is the temperature difference between the actual vapour temperature and the vapour temperature at saturation.

36

Stredne ťažká

How can you check whether the liquid refrigerant is reaching the expansion valve without vapour bubbles?


We check this using a sight glass.
We check using a liquid pressure gauge.
We are unable to check this.
We check using a pressure gauge fitted on the discharge side of the compressor.

37

Stredne ťažká

The liquid lines are located...


between the evaporator and the compressor.
between the evaporator and the regenerative heat exchanger.
between the compressor and the condenser.
between the condenser and the liquid receiver.

38

Stredne ťažká

What is the function of the liquid receiver in a refrigeration system?


The tank is used to collect the liquid refrigerant and excess oil in the system.
When an installation technician does not know the exact amount of refrigerant required, the tank serves as a safety reserve for the entire refrigeration system.
The tank is used to store and ensure an adequate supply of refrigerant in the event of fluctuations in the thermal load of the refrigeration system.
The reservoir is used to further cool the liquefied refrigerant leaving the condenser.

39

Stredne ťažká

What is the purpose of the liquid refrigerant reservoir?


The tank is used to collect the liquid refrigerant and excess oil in the system.
The tank is used to further cool the liquefied refrigerant leaving the condenser.
The tank is required during maintenance work, when there is a temporary need to store the refrigerant that has been circulating in the refrigeration system up to that point.
When an installation technician does not know the exact amount of refrigerant required, the tank serves as a safety reserve for the entire refrigeration system.

40

Stredne ťažká

Where should the liquid receiver be installed?


It should be fitted between the compressor and the condenser.
It should be fitted just before the compressor.
It should be installed downstream of the condenser, upstream of the expansion valve.
It should be fitted after the evaporator.

41

Stredne ťažká

What is the function of the suction pressure regulator fitted to the suction pipe when the compressor starts up?


It closes when the suction pressure upstream of the compressor drops.
It regulates the evaporation pressure.
It regulates the condensing pressure.
It opens when the suction pressure upstream of the compressor drops.

42

Stredne ťažká

The use of microchannel heat exchangers, compared with conventional heat exchangers made of copper tubes and fins, results in:


A reduction in the system’s energy efficiency.
A reduction in the amount of refrigerant and an increase in energy efficiency.
There is no effect whatsoever on either the amount of refrigerant or energy efficiency.
An increase in the amount of refrigerant in the system and an increase in condensing pressure.

43

Stredne ťažká

Which refrigerants belong to the HFC group?


R134a, R32, R22, R507A, R290.
R11, R12, R502.
R134a, R404A, R507A, R410A.
R22, R401A.

44

Stredne ťažká

Which refrigerants belong to the HFO group?


R1234yf, R1234ze.
R134a, R404A.
R134a, R290.
R22, R12.

45

Stredne ťažká

What are the characteristics of R410A refrigerant compared to R407C refrigerant?


The saturation pressure of R410A refrigerant is higher than that of R407C.
The saturation pressure of R407C is 150% higher than that of R410A.
The saturation pressure of both refrigerants is roughly the same.
The saturation pressure of R407C refrigerant is much higher than that of R410A.

46

Stredne ťažká

What does the TEWI parameter define?


This is a parameter that quantifies the impact of refrigerants on the ozone layer.
It is the total (global) greenhouse gas equivalent – this indicator takes into account the refrigerant’s direct capacity to contribute to the greenhouse effect and its indirect impact on it through the energy consumption (during the production of which CO₂ is generated) by the refrigeration unit in operation.
This is a parameter defining the ozone layer’s ability to recover (regenerate).
It is the global warming potential, expressed in terms of carbon dioxide (CO₂), over a 100-year time horizon.

47

Stredne ťažká

What are the characteristics of R452A refrigerant compared to R404A?


Both refrigerants are homogeneous refrigerants with no temperature glide.
It is a flammable and toxic homogeneous refrigerant from the HFC group.
The temperature glide of R452A is half that of R404A.
It is a non-flammable refrigerant, a mixture from the HFC/HFO group with thermodynamic properties similar to those of R404A and a GWP approximately 45% lower than that of R404A.

48

Stredne ťažká

What is the distinguishing feature of R1234yf compared to R134a?


greater toxicity.
a higher boiling point at standard pressure.
greater flammability.
A higher critical temperature.

49

Stredne ťažká

Compared to R134a, the refrigerant CO₂ is characterised by?


It has identical thermodynamic properties and can be used as a drop-in replacement for R134a.
It has a lower critical temperature, higher operating pressures and greater volumetric efficiency, allowing for the use of a smaller quantity of refrigerant compared to R134a.
It has a temperature slip of 7K greater than R134a.
Unlike R134a, it is an azeotropic mixture.

50

Stredne ťažká

The following are not classified as fluorinated greenhouse gases:


Carbon dioxide (CO₂).
Sulphur hexafluoride (SF6).
Hydrofluorocarbons (HFCs).
Perfluorocarbons (PFCs).

51

Stredne ťažká

What is the greenhouse effect?


It alters the composition of the atmospheric air.
It causes an increase in temperature close to the Earth’s surface (up to 10 metres above the surface).
It lowers the average surface temperature of the Earth.
It causes the thermal radiation emitted by the Earth to be trapped in the upper atmosphere.

52

Ľahká

What does the GWP indicator mean?


It is a unit expressing the ability to enhance the ozone layer.
It is the global warming potential. The impact on global warming caused by 1 kg of a given gas or chemical substance, expressed as a GWP value, where GWP=1 represents the global warming caused by 1 kg of CO₂ over a period of 100 years (the global warming potential of a unit mass of a given gas over a 100-year period, relative to the warming caused by a unit mass of CO₂).
It is an expansion of the abbreviation ‘Global Warming Potential’ and indicates the rate of increase in air temperature
This is an indicator expressing the potential to deplete the ozone layer.

53

Stredne ťažká

How do refrigeration systems contribute to the greenhouse effect, i.e. the rise in atmospheric temperature at the Earth’s surface?


As a result of oil being emitted into the atmosphere by the condenser and filter
Indirectly (through energy consumption) and directly (through the emission of refrigerants into the atmosphere)
Through the leakage of refrigerant into the environment.
Refrigeration equipment emits CO₂ both directly and indirectly.

54

Stredne ťažká

What is the greenhouse effect, also known as the greenhouse phenomenon?


The absorption of radiation reaching the Earth’s surface.
The filtering out of solar radiation.
This is the formation of a layer that traps only the heat generated by the combustion of fuel in aeroplanes.
It is the phenomenon of heat being trapped in the Earth’s atmosphere (making it difficult for heat to radiate out of the Earth’s atmosphere).

55

Stredne ťažká

Which EU regulation is currently the primary piece of legislation governing the use of fluorinated greenhouse gases (F-gases) in the European Union?


Regulation (EU) 2015/1188
Regulation (EU) No 517/2014
Regulation (EU) 2024/573
Directive 2009/125/EC

56

Stredne ťažká

What is the main objective of Regulation (EU) 2024/573?


Standardising metal recycling standards
To reduce taxes on refrigeration equipment
Prevention of F-gas emissions and the achievement of the EU’s climate targets
To facilitate the import of electrical appliances

57

Stredne ťažká

What are the obligations of manufacturers of refrigeration appliances in the context of ecodesign, and which regulation governs them?


The manufacturer must ensure minimum energy efficiency, reparability and recyclability of equipment, as regulated by Regulation (EU) 2019/2019
Manufacturers must comply solely with ISO 9001 standards, without any link to EU regulations
Manufacturers are only required to use energy labels, and this is regulated by Regulation (EU) 2024/573
Manufacturers are only required to declare the quantity of F-gas used, in accordance with Regulation (EU) No 517/2014

58

Stredne ťažká

What is the main objective of the Ecodesign Directive?


To increase sales of electrical appliances in the EU
To facilitate the import of products from outside the EU
To standardise the appearance of products in the EU
Reducing the negative environmental impact of products by improving energy efficiency, durability and recyclability

59

Stredne ťažká

What is the function of a ball valve in a refrigeration system?


Enables the refrigerant flow to be completely shut off
It prevents excessive pressure build-up in the system
It measures the moisture content of the refrigerant
It regulates the temperature of the refrigerant

60

Ľahká

What is the main function of a relief valve?


Relieves pressure in the system in the event of excessive pressure
It controls the oil level in the compressor
Prevents the evaporator from freezing
It monitors the moisture content of the refrigerant

61

Stredne ťažká

How do certain substances or gases contribute to the greenhouse effect?


Some substances damage the ozone layer
Certain substances trap the thermal radiation that the Earth should radiate into the atmosphere. In this way, the Earth gradually warms up and the greenhouse effect occurs.
Certain substances limit the impact of the Sun’s ultraviolet radiation on the Earth’s surface.
When released into the atmosphere, certain substances cause the air to heat up as a result of reactions with the oxygen and nitrogen contained in the air.

62

Stredne ťažká

What is the purpose of the sight glass in a refrigeration system?


To shut off the flow in the event of an emergency
To measure the condenser temperature
For visual assessment of the presence of refrigerant and oil, and for monitoring moisture levels
To regulate compressor pressure

63

Stredne ťažká

What is the function of the temperature regulator in a refrigeration system?


Controls the operation of the compressor and valves to maintain the set temperature
It restricts oil flow
It drains excess refrigerant into the receiver
To maintain a constant pressure in the compressor

64

Ťažká

What is the role of the liquid separator in systems using flammable or toxic refrigerants?


They are used solely to measure the moisture content of the refrigerant
It prevents liquid from entering the compressor
Heats the refrigerant before it enters the evaporator
It separates the liquid from the oil

65

Ťažká

What is the function of an oil separator in systems using flammable or toxic refrigerants?


It prevents liquid from entering the compressor
They are used solely to measure the moisture content of the refrigerant
Separates oil from the refrigerant and facilitates the return of oil to the compressor
Heats the refrigerant before it enters the evaporator

66

Stredne ťažká

What is the purpose of oil level regulators in a refrigeration system?


They control the pressure in the condenser
They control the evaporator temperature
Maintains the correct oil level in the compressor
They drain off excess refrigerant

67

Stredne ťažká

What is the function of the refrigerant receiver in the system?


It controls the evaporator temperature
It maintains a constant pressure in the system
Stores excess refrigerant and facilitates the detection of leaks
Regulates the oil flow

68

Stredne ťažká

What is the role of the manifold thermometer in the refrigeration system?


It monitors the moisture content of the refrigerant
Relieves pressure in the system in the event of excessive pressure
Controls the oil level
Measures the refrigerant temperature at the compressor inlet and outlet, which helps to identify leaks

69

Stredne ťažká

What is the role of the defrost control valves?


Protect the evaporator from excessive icing and reduce the risk of leaks
They are used to monitor the moisture content of the refrigerant
They drain off excess oil
They control the pressure in the compressor

70

Ľahká

What is the base unit of pressure according to the International System of Units (SI)?


bar
Pa
Psi
Atm.

71

Stredne ťažká

Where can I find lists detailing fluorinated greenhouse gases (F-gases)?


In the Act on Ozone-Depleting Substances and Certain Fluorinated Greenhouse Gases.
In the Vienna Convention for the Protection of the Ozone Layer.
In Regulation (EU) No 2024/573 of the European Parliament and of the Council
In the Regulation of the Minister for the Economy on the introduction of a list of fluorinated greenhouse gases.

72

Stredne ťažká

Where can I find the lists specifying controlled substances?


In the Vienna Convention for the Protection of the Ozone Layer.
In the current Act on Ozone-Depleting Substances and Certain Fluorinated Greenhouse Gases.
In the Regulation of the Minister for the Environment on the list of controlled substances.
In Regulation (EU) No 2024/590 of the European Parliament and of the Council.

73

Stredne ťažká

Where and by when should annual reports on ODS and F-gases be submitted?


Reports for the previous year must be submitted by 31 January electronically by completing the special forms available in the central register of operators ‘CRO’.
Reports for the previous year must be submitted by 31 March of the relevant year electronically to the Ministry of the Environment.
Reports on ODS and F-gases for the previous year must be submitted by 28 February of the following year, via the IT system available in the reports database at the Office for the Protection of the Ozone Layer and Climate (BOWOiK) on the ICHP website.
Reports must be submitted by the end of the relevant calendar year, using a special form at the regional branch of the Office of Technical Inspection (UDT)

74

Stredne ťažká

Which measure has the greatest impact on improving the compressor’s energy efficiency during installation?


Installation without filters
Correctly create a vacuum and remove moisture from the system
Installation without a leak test
Increasing the amount of refrigerant

75

Stredne ťažká

How does regular monitoring of the oil level affect the compressor’s operation?


It reduces cooling capacity
It has no effect
Causes a rise in pressure
Ensures proper lubrication and improves energy efficiency

76

Stredne ťažká

How do system leaks affect the compressor’s energy efficiency?


Have no effect
They lower the operating temperature
They improve efficiency
These cause a drop in performance and an increase in energy consumption

77

Stredne ťažká

Regulation (EC) No 2024/590 relates to:


Health and safety at work during the recovery of refrigerants.
Ozone-depleting substances.
Alternative refrigerants serving as substitutes for fluorinated greenhouse gases.
The conditions for obtaining F-gas certificates by companies carrying out the recovery and reclamation of waste refrigerants.

78

Stredne ťažká

What is the significance of regulating suction and discharge pressure?


Helps maintain optimal operating conditions for the compressor
It has no effect on efficiency
Increases oil consumption
Causes leaks

79

Stredne ťažká

What maintenance measure reduces the compressor’s energy consumption?


Increasing the refrigerant charge
Disabling safety devices
Lack of servicing
Regular replacement of filters and dryers

80

Stredne ťažká

How does the presence of air in the refrigeration system affect performance?


It improves efficiency
Leads to increased pressure and reduced efficiency
It has no effect
Reduces energy consumption

81

Stredne ťažká

What role do control systems (e.g. regulators) play in compressor efficiency?


Enables optimisation of operation and a reduction in energy consumption
Causes leaks
It increases the amount of refrigerant
It doesn’t matter

82

Stredne ťažká

How does refrigerant superheat at the compressor suction affect performance?


Excessive overheating reduces efficiency and increases energy consumption
It always improves performance
It has no effect
It only causes a drop in temperature

83

Stredne ťažká

How does the correct layout of the system affect efficiency?


It increases the pressure
Shortens flow paths and reduces energy losses
It doesn’t matter
It causes the temperature to rise

84

Stredne ťažká

How important is pipe insulation?


Causes a rise in pressure
It increases energy consumption
It has no effect
Reduces heat loss and improves energy efficiency

85

Stredne ťažká

Which measure most improves the condenser’s energy efficiency?


Contamination of the heat exchange surface
Increasing the amount of refrigerant
Regular cleaning of heat exchange surfaces
Restricted airflow

86

Stredne ťažká

How does a dirty condenser affect the operation of the refrigeration system?


It has no effect
Causes an increase in pressure and energy consumption by the compressor
It improves efficiency
It lowers the condensing pressure

87

Stredne ťažká

Why is adequate airflow through an air-cooled condenser important?


Insufficient airflow reduces efficiency
It doesn’t matter
Ensures effective heat dissipation and improves energy efficiency
Causes a drop in pressure

88

Stredne ťažká

Which refrigerants cause damage to the ozone layer?


All refrigerants that contain fluorine and hydrogen in their molecules.
All refrigerants that contain chlorine or bromine in their molecules.
All refrigerants that are hydrocarbon derivatives.
All refrigerants that contain carbon in their molecular structure.

89

Stredne ťažká

How does the presence of limescale in a water-cooled condenser affect performance?


Impairs heat exchange and increases energy consumption
It has no effect
It improves heat transfer
It lowers the condensation temperature

90

Stredne ťažká

How does correct condensation pressure control affect efficiency?


Causes leaks
It increases energy consumption
Maintains optimum operating conditions and reduces energy consumption
It has no effect

91

Stredne ťažká

How do condenser leaks affect energy efficiency?


They improve efficiency
They lower the temperature
Have no effect
Causes refrigerant loss and a drop in efficiency

92

Stredne ťažká

How important is the correct positioning of an air-cooled condenser?


It should be close to heat sources
It should be installed in a well-ventilated area with unobstructed airflow
It doesn’t matter
It should be housed in a small room

93

Stredne ťažká

How does hot air recirculation affect the condenser?


It has no effect
Impairs cooling and increases energy consumption
It reduces the pressure
It improves efficiency

94

Stredne ťažká

How does the insulation of central heating and domestic hot water pipework affect the operation of the heat pump’s condenser?


Reduces energy losses and improves the efficiency of the entire system
It impairs cooling
It increases the pressure
It doesn’t matter

95

Stredne ťažká

Which measure most improves the energy efficiency of the evaporator?


Increasing the amount of refrigerant
Restricted airflow
Regular defrosting of the evaporator
Increasing the condensation temperature

96

Stredne ťažká

How does evaporator icing affect the system’s operation?


It has no effect
It improves cooling performance
It lowers the condensation temperature
Impairs heat exchange and increases energy consumption

97

Stredne ťažká

How does dirt on the evaporator surface affect its performance?


It improves efficiency
It reduces the pressure
It has no effect
Impairs heat exchange and increases energy consumption

98

Stredne ťažká

What maintenance task is crucial for the evaporator?


Lack of maintenance
Increasing the refrigerant charge
Regular cleaning and defrosting
Reduced airflow

99

Stredne ťažká

What does an F-gas personal certificate (Category A2) authorise?


to make permanent joints by brazing in systems containing fluorinated greenhouse gases.
To recover refrigerant from equipment containing less than 3 kg of fluorinated greenhouse gases, or less than 6 kg in the case of hermetically sealed systems.
for the purchase of lubricants and refrigeration oils, and for the testing of safety valves.
to repair, maintain or service refrigeration equipment and systems containing controlled substances.

100

Stredne ťažká

How does superheating of the refrigerant at the evaporator outlet affect efficiency?


It only causes a drop in temperature
Excessive superheat reduces energy efficiency
It always improves performance
It has no effect

101

Stredne ťažká

How do leaks in the evaporator affect efficiency?


Increase capacity
Have no effect
Improves performance
These cause refrigerant loss and a drop in efficiency

102

Stredne ťažká

How important is correct expansion valve adjustment?


It doesn’t matter
Ensures optimal evaporator charge and improves efficiency
It increases energy consumption
Causes leaks

103

Stredne ťažká

How does inadequate insulation of the heat transfer circuit pipes affect evaporator performance?


It lowers the condensation temperature
It has no effect
Causes cooling losses and increased energy consumption
It improves efficiency

104

Stredne ťažká

How does correct TEV valve adjustment affect the system’s energy efficiency?


It has no effect
Ensures optimum superheat and improves system efficiency
It increases energy consumption
Causes leaks

105

Stredne ťažká

What happens if the superheat set by the TEV is too high?


It has no effect
Cooling efficiency will improve
The refrigerant charge will increase
Efficiency will drop because the evaporator is not being fully utilised

106

Stredne ťažká

How does a low superheat setting on the TEV affect performance?


It may lead to improved efficiency, but it increases the risk of the compressor becoming flooded with liquid
It increases operational safety
It has no effect
It reduces refrigerant flow

107

Stredne ťažká

How do contaminants in the system affect the operation of the TEV?


Have no effect
They can cause it to become blocked and reduce efficiency
They lower the temperature
They improve its performance

108

Stredne ťažká

What role does the filter-drier play in terms of system efficiency?


Removes moisture and contaminants, improving the system’s efficiency
It lowers the temperature
It increases the amount of refrigerant
It doesn’t matter

109

Stredne ťažká

How does proper insulation of components (e.g. pipes near the TEV) affect the system?


It increases energy consumption
It causes leaks
Prevents unwanted heat gains and improves efficiency
It doesn’t matter

110

Stredne ťažká

What does Regulation (EU) No 2024/573 of the European Parliament and of the Council cover?


The Regulation sets out requirements relating to brazing of refrigeration systems.
The Regulation concerns leak testing of stationary refrigeration, air-conditioning and heat pump equipment containing fluorinated greenhouse gases. The Regulation sets out the requirements relating to leak testing of such equipment.
The Regulation concerns gases that contribute to the greenhouse effect.
The Regulation sets out health and safety requirements for soldering work.

111

Stredne ťažká

How important is it to check the operation of the condensing pressure control valve in the system?


Ensures operation within the optimum pressure range and reduces energy losses
It has no effect
It increases energy consumption
It causes a significant rise in temperature

112

Stredne ťažká

How does the correct selection of a TEV affect energy efficiency?


It doesn’t matter
Ensures the system is matched to its capacity and operates optimally
It increases the amount of refrigerant
It lowers the temperature

113

Stredne ťažká

What is the main design difference in hydrocarbon-based refrigeration systems?


The need for explosion-proof measures due to the flammability of the refrigerant
No need for safety measures
Higher operating pressures
Lower energy efficiency

114

Stredne ťažká

What differences are there in the compressors used in hydrocarbon systems?


They must be designed to operate with flammable refrigerants (e.g. hermetic compressors)
No differences
They must operate at higher pressures
They do not require lubrication

115

Stredne ťažká

How can one check whether the system has been overcharged with refrigerant?


This cannot be checked with sufficient reliability, as the sight glass is not designed for this purpose.
The refrigeration system is overcharged with refrigerant whilst in operation, and even under a very small heat load, frost forms on the suction side of the compressor
Under normal conditions, there is a marked increase in condensing pressure because an excessive amount of refrigerant accumulates in the condenser, reducing the heat exchange surface area within it.
The compressor will operate under a lower load and the suction pressure will decrease

116

Stredne ťažká

Before charging the refrigeration unit with refrigerant, it is essential to…


carry out a start-up test.
check the compressor’s suction and discharge connections.
carry out a leak test.
complete the unit’s data sheet.

117

Stredne ťažká

What information must appear on the unit’s label?


It does not matter what should be included on the device label.
Markings regarding the weight and capacity of the pipework, together with the colour code and chemical composition of the paints used to coat the frame and casing.
The manufacturer’s logo and the weight of the unit.
Among other things: information stating that the unit contains a fluorinated greenhouse gas, together with the industrial designation of the gas or its chemical name, the mass of the gas and its CO₂ equivalent

118

Stredne ťažká

What is the base unit of temperature according to the International System of Units (Système International d’Unités)?


K
°R
°F
°C

119

Stredne ťažká

Which of the following are the most important pieces of information that should be included in the unit’s data sheet:


The owner, installer and service technician of the unit.
Information regarding refrigerant recovery and unit dismantling.
Operator details, unit details, type and quantity of refrigerant, information regarding servicing and repairs.
The make and model of the unit, so that the manufacturer can be contacted to obtain the technical information necessary for servicing.

120

Stredne ťažká

Who is responsible for drawing up the equipment or installation record?


The person responsible for risk assessment.
The equipment maintenance technician.
There is no such obligation.
The operator of the unit or system.

121

Stredne ťažká

Oil traps on the suction pipework are required:


always before any rise in the pipeline.
at the inlet to each component of the refrigeration system.
before the compressor.
before the safety valve.

122

Stredne ťažká

When is there a refrigerant leak, even though the compressor is still running?


When the condensing pressure and suction pressure rise, but there is no superheat.
When the suction pressure is low, superheat is high, subcooling is negligible and the temperature difference between the condenser and the expansion valve is small.
When the sight glass is full of liquid refrigerant and we observe a rise in the oil level in the compressor sump.
When we observe a rise in the refrigerant level in the liquid receiver and the subcooling increases.

123

Stredne ťažká

Which components of a refrigeration system can be classified as potential leak points (leaks) subject to regular leak tests?


Fittings, valves including their stems, seals – including those in replaceable filters and dryers, components exposed to vibration, and connections to measuring, control and safety devices.
Parts of the system located on the high-pressure side (from the compressor up to and including the expansion valve).
Hermetic compressors, liquid refrigerant tanks and liquid separators.
All parts of the refrigeration unit that are connected to the suction side of the refrigeration system.

124

Stredne ťažká

What is the test pressure during the pressure leak test of the unit?


The test pressure for leak testing is equivalent to the maximum operating pressure measured during the operation of the refrigeration unit.
According to the PN-EN 378 standard, at least 0.25 times the maximum permissible pressure for the system (PS).
The test pressure is determined by the person carrying out the leak test based on their experience.
The test pressure (maximum) is 30 bar.

125

Stredne ťažká

In which part of the refrigeration unit must the recommended leak test be carried out?


The check must be carried out on all parts of the refrigeration system that are connected to the discharge side of the refrigeration circuit.
The test must be carried out on the compressor shut-off valves, solenoid valves and filters.
The test must be carried out at all points on the refrigeration unit where there is a potential risk of refrigerant leakage.
The check should only be carried out at the connection points for measuring instruments (pressure switches, pressure gauges, temperature sensors).

126

Stredne ťažká

When can a given unit be considered perfectly leak-tight?


A device can be considered perfectly leak-tight if gas bubbles appear when it is submerged in water.
The device in question is perfectly leak-tight when we have carried out a check using a permanently installed electronic detector.
A given unit can be considered perfectly leak-tight if, during a leak test, the pressure remains constant, taking into account pressure changes caused by temperature variations. Any drop in pressure indicates a leak and requires the location of the leak to be identified.
A given device can be considered perfectly leak-tight when the pressure drop during the test does not exceed 0.1 bar.

127

Stredne ťažká

What does EU Regulation 1516/2007 cover?


The Regulation sets out health and safety requirements for soldering work.
The Regulation concerns leak testing of stationary refrigeration, air-conditioning and heat pump equipment containing fluorinated greenhouse gases. The Regulation sets out the requirements for leak testing of such equipment.
The Regulation addresses the disposal of gases that contribute to the greenhouse effect.
The Regulation sets out requirements relating to brazing of refrigeration systems.

128

Ťažká

Which parts of refrigeration systems must be inspected on a mandatory and regular basis in accordance with EU Regulation 1516/2007?


Fittings, 2. valves, 3. seals, 4. parts/components exposed to vibration, 5. connections at safety devices.
Connections on the condenser, as there is high pressure and the refrigerant is in liquid form
Compressor connections, 2. connections on the liquid refrigerant tank
Only compressor connections, as these are subject to vibration.

129

Ľahká

What is superheat?


It is the amount of heat required to cause the vapour formed from a liquid to become superheated.
It is the amount of heat required to turn a liquid into vapour.
It is the amount of heat required to heat a liquid.
It is the amount of heat required to increase the pressure.

130

Ťažká

In accordance with EU Regulation 1516/2007, there are several methods of leak testing. What are these methods called?


We distinguish between methods for quality control of supplied materials and leak testing methods that do not involve quality control of supplied materials.
We distinguish between direct and indirect methods of leak detection.
We distinguish between physical and chemical methods.
We distinguish between quality control methods for supplied materials and electronic testing methods.

131

Ťažká

In accordance with EU Regulation 1516/2007, to whom can we entrust the responsibilities for leak testing of refrigeration systems?


The test may only be carried out by a competent person with the relevant skills, who holds a certificate attesting to the necessary knowledge in this field. They must also hold a certificate for companies regarding the operation and maintenance of refrigeration equipment charged with F-gases.
The check may only be carried out by a person who has previously carried out such a check.
The check may be carried out by a specialist in leak testing.
The inspection may be carried out by a person employed and appointed by the owner of the installation.

132

Ťažká

In accordance with EU Regulation 1516/2007, what conditions must be met in order to carry out a leak test on refrigeration systems using ultraviolet (UV) light?


The manufacturer of the refrigeration equipment must confirm that the aforementioned UV method can be used. A UV leak test may be carried out by a qualified person who holds the relevant qualifications (certificate).
A prerequisite for carrying out a leak test using UV is that such a test is technically feasible.
A prerequisite for carrying out a leak test using UV is having the appropriate technical resources, the relevant materials supplied, and suitable safety goggles.
A prerequisite for carrying out the inspection is holding the relevant authorisation for pressure testing issued by the UDT.

133

Ťažká

In accordance with EU Regulation 1516/2007, which leak testing methods are classified as direct leak testing methods?


Leak test following the creation of a vacuum and leak detection using a foaming solution.
Leak testing by measuring pressure changes and the method of submerging the device/system in water.
Detection of leaks using a handheld leak detector and/or a fixed leak detection system; 2. Detection of leaks using a special dye with UV-fluorescent properties; 3. Detection of leaks using a foaming solution.
Leak test using nitrogen with a tracer gas, an electronic detector and pressure measurement.

134

Ťažká

In accordance with EU Regulation 1516/2007, which methods are classified as indirect leak testing methods?


Leak detection using a UV tracer.
This method is based on the analysis of the following parameters: pressure, temperature, operating pressure, liquid level, oil leakage, etc.
It utilises pressure and temperature measurements, as well as an ultrasonic method.
This method is based on electronic leak detection.

135

Stredne ťažká

How should the pressure be increased during a pressure leak test?


We increase the pressure gradually whilst checking for leaks, until the test pressure is reached, at a rate of no more than 2 bar/min
We increase the pressure at a rate of 10 bar/s.
We increase the pressure as quickly as possible.
We increase the pressure in any way.

136

Stredne ťažká

What electronic equipment should be used to carry out leak testing?


Only with devices fitted with an ‘Ion Pump’ sensor.
Only with devices fitted with an infrared detector.
Only using devices with verified measurement sensitivity.
Only with devices fitted with hot cathodes.

137

Stredne ťažká

What documentation should be checked before starting a leak test?


Check the stock ledger (accounts).
Check the time sheets of the staff responsible for the machinery/equipment.
The maintenance log and the machine/device operating instructions must be checked.
Check the operating instructions for the machine/equipment.

138

Stredne ťažká

What information must be recorded when drawing up the leak test report?


The date of the inspection, the number of faults (leaks), the location of the faults (leaks), the proposed method of rectifying the fault/defect (leak), attached documents and a signature.
The method used to carry out the leak test, the number of faults, the method of repairing the faults, the time taken to work on the installation, and the cost of the repair.
The number of locations where leaks have occurred and the date of the inspection.
The date of the inspection, a record of the occurrence of the leak, and a signature.

139

Stredne ťažká

What pressure values should be used for the pressure leak test?


The pressure value for the leak test is 10–12 bar.
The pressure for the leak test is 2–3 bar.
Use a pressure not exceeding the maximum permissible pressure for the system (PS).
At the discretion of the person authorised to carry out the pressure test.

140

Stredne ťažká

What is temperature slip?


It involves a decrease in temperature.
A specific temperature corresponds to a given vapour pressure.
A specific temperature cannot be assigned to a given vapour pressure. There is a temperature difference between the start and end of evaporation.
It involves an increase in temperature.

141

Ťažká

What does a vacuum leak test involve?


If the pressure in the refrigeration system were to rise, we switch on the vacuum pump as required.
With the vacuum pump running continuously, we are able to maintain the required vacuum level in the system.
With the vacuum pump switched on, check whether the pressure in the system rises as a result of a leak.
After switching off the vacuum pump, we check whether the pressure in the system rises

142

Ťažká

How often should leak tests be carried out on equipment containing 1.5 kg of R404A refrigerant (5.9 tonnes of CO₂ equivalent)?


At least once every 12 months.
Only when servicing the unit.
On initial commissioning.
Once every six months.

143

Ťažká

How often should leak tests be carried out on equipment containing 7 kg of R404A refrigerant (27.45 tonnes of CO₂ equivalent)?


At least once every 12 months.
Once every six months.
On initial commissioning.
Only when servicing the unit.

144

Stredne ťažká

In which appliances and systems is the installation of a permanent leak detection system required?


In equipment and installations containing at least 30 kg of fluorinated greenhouse gases.
In equipment and systems containing at least 50 tonnes of CO₂ equivalent.
In equipment and systems containing at least 500 tonnes of CO₂ equivalent.
In equipment and systems containing at least 5 tonnes of CO₂ equivalent.

145

Ťažká

In accordance with Regulation (EU) 2024/573 of the European Parliament and of the Council, a fixed leak detection system is required when:


The refrigerant charge of the refrigeration equipment is at least 100 kg of ODS.
The charge of an F-gas refrigerant in a refrigeration unit is at least 500 tonnes of CO₂ equivalent.
The refrigeration equipment is operated in an enclosed space.
The installation of a fixed leak detection system is optional, but it helps to reduce the number of leak checks required on the equipment each year.

146

Ťažká

Under Regulation (EC) No 1516/2007 and the F-gas Act, which leak detection methods may not be carried out by a person holding a Category E certificate?


Visual leak inspection.
Leak detection using a foaming solution.
Measuring leaks using a handheld leak detector.
Leak testing using a fluorescent dye.

147

Ťažká

According to the current regulation, what sensitivity must a handheld leak detector have?


3 g/year.
8 g/year.
10 g/year.
5 g/year.

148

Stredne ťažká

Which category of F-gas certificate (A1, A2, B, C, D, E) authorises the performance of leak tests on refrigeration equipment:


Only categories A1 and A2.
Category E only.
All except category D.
Categories D and E.

149

Ťažká

Within what timeframe must a leak test be carried out on a stationary refrigeration system after a leak has been repaired, in accordance with EU Regulation 2024/573 on F-gases?


At any time.
Immediately after the repair.
At the next periodic inspection.
Between 24 hours and 1 month after the repair.

150

Ťažká

At what intervals should leak tests be carried out on refrigeration equipment containing more than 500 tonnes of CO₂ equivalent of fluorinated greenhouse gases that does not have a leak detection system installed?


Once a month.
Once every 6 months.
Once every 12 months.
Once every 3 months.

151

Stredne ťažká

Why is it advisable to subcool the liquid refrigerant?


This is advisable because it allows a smaller condenser to be used (smaller heat exchange surface area).
This is advisable because it allows a smaller evaporator to be used (lower refrigerant temperature at the evaporator inlet).
This is advisable because it allows a smaller expansion valve to be used (less superheat at the valve).
This is advisable because it ensures that the liquid refrigerant, free of vapour bubbles, enters the expansion valve.

152

Stredne ťažká

What should be done following repairs to a leak in the refrigeration unit of a refrigerated trailer?


You must enter the details into the equipment log (including the quantities of refrigerant recovered and used) and inform the Operator that an additional leak test must be carried out by a certified person within one month of the repair.
A visual inspection should be carried out only on bolted and soldered joints.
An invoice for the service work carried out must be issued as soon as possible.
The unit must be charged with an alternative refrigerant, started up, and the refrigerant parameters checked at the service valve located on the liquid receiver.

153

Stredne ťažká

Recovery of fluorinated greenhouse gases means:


The reprocessing of fluorinated greenhouse gases to achieve their specified standard properties.
The collection and storage of fluorinated greenhouse gases originating, for example, from machinery, equipment and containers.
The final decommissioning and withdrawal from service or use of a product or piece of equipment containing fluorinated greenhouse gases.
The reuse of fluorinated greenhouse gases following a basic purification process.

154

Stredne ťažká

Who is authorised to recover refrigerant from stationary refrigeration equipment:


A service technician holding an F-gas certificate in the relevant category.
The administrator of the operator’s account.
The owner of the installation.
The operator.

155

Stredne ťažká

Recovered refrigerants must be stored:


In any pressure vessel that has been officially certified.
In any used refrigerant cylinder.
In a specially adapted and labelled cylinder fitted with a two-way valve.
In a cylinder that previously contained the same type of refrigerant.

156

Stredne ťažká

When should the recovery of fluorinated greenhouse gases be carried out:


Always during servicing and maintenance of equipment.
Before the final disposal of equipment and, where applicable, during its servicing and maintenance.
Before each leak test of the equipment.
Only prior to the final disposal of equipment.

157

Stredne ťažká

What should be done if the refrigerant recovered from the system is contaminated, e.g. with acid, air or moisture?


You should attempt to purify the mixture yourself using a dehydrating filter.
Purify the mixture by passing it through a particulate filter and reuse it.
Such a mixture must be handed over to a specialist authorised company for regeneration or disposal.
Add a special contaminant neutraliser to the mixture.

158

Stredne ťažká

What should be done if different types of refrigerants become mixed in a storage cylinder (container)?


You should attempt to separate the mixture into its individual components.
The mixture should be purified by passing it through a filter-drain and reused.
Send this mixture to a specialist authorised company to have it neutralised.
Add a special refrigerant to the mixture.

159

Stredne ťažká

How does refrigerant recovery using the Push-Pull method work?


This involves using a suction device (compressor) to ensure that the refrigerant, in liquid form, is transferred into the cylinder.
This involves the refrigerant being alternately drawn from the suction side and then from the discharge side of the refrigeration unit (compressor).
It involves using a recovery unit to draw (pull) the refrigerant vapour from the cylinder and then force it (push) into the low-pressure side of the system.
This involves injecting nitrogen from the cylinder into the unit and expelling the liquid refrigerant from the unit.

160

Stredne ťažká

What are the methods for managing waste refrigerant?


Disposal, storage.
Recovery, disposal.
Regeneration, recovery.
Recycling, regeneration, disposal.

161

Stredne ťažká

The most advantageous method of managing waste refrigerant is:


Disposal.
Recycling.
Regeneration.
Storage.

162

Stredne ťažká

The lower the evaporation temperature, ...


...the lower the refrigerant density, and the greater the cooling capacity of the compressor.
…the greater the density of the refrigerant and the lower the mass flow rate of the refrigerant.
...the lower the density of the refrigerant and the lower the mass of the flowing refrigerant.
...the greater the density of the refrigerant and the mass flow rate of the flowing refrigerant.

163

Stredne ťažká

How should pressure vessels (e.g. refrigerant cylinders) be marked?


They should bear only markings relating to weight and capacity.
It is irrelevant how pressure vessels should be marked.
They should bear the manufacturer’s logo and the date of manufacture.
They should bear, amongst other things, information such as: the number of the standard applied to their design, construction and testing; the identification marks of the country of approval and the inspection body; the date of the acceptance test; and the manufacturer’s and operational marks.

164

Stredne ťažká

The recovery of refrigerants does not require the use of:


Hoses with shut-off valves.
A refrigerant recovery station.
Scales with a measurement range suitable for the size of the cylinder being filled.
An electronic leak detector.

165

Stredne ťažká

What functions does the compressor perform in a refrigeration system?


The compressor creates a vacuum on the suction side of the system
The compressor condenses the refrigerant.
The compressor compresses ambient air and increases the pressure of the refrigerant.
The compressor draws in refrigerant vapour from the evaporator, compresses it, and then forces it into the condenser, raising the pressure to the required condensing pressure.

166

Ľahká

What is the compressor’s compression ratio?


It is the ratio of the suction pressure to the discharge pressure of the compressor (po/pk).
It is the ratio of the discharge pressure to the effective capacity of the compressor (p/Vk).
It is the amount of refrigerant that will be compressed in a single compressor cycle relative to the heat capacity.
It is the ratio of the discharge pressure to the suction pressure of the compressor (pk/po).

167

Stredne ťažká

What is compressor flooding?


Flooding of the compressor due to rainfall.
A large amount of liquid refrigerant in the evaporator.
Suction of liquid refrigerant into the compressor’s suction line.
Flooding the compression chamber with liquid refrigerant or oil.

168

Stredne ťažká

To what extent do we regulate the compressor motor’s rotational speed when using a frequency converter?


Approximately from 30 to 75 Hz, which corresponds to around 60% to 150% of the cooling capacity.
Regulating the compressor motor speed is not the same as regulating the cooling capacity.
Up to a maximum of 10 per cent.
From approximately 30% to 90% of capacity.

169

Ľahká

What is the theoretical displacement of a compressor?


This is the volume of refrigerant that flows through a reciprocating compressor during a single piston cycle.
The displacement of a compressor is determined by the dimensions of the cylinder – its volume (cm³)
It is the volume of refrigerant delivered by a reciprocating compressor per unit of time, usually referred to by the manufacturer as the displacement. It depends on the compressor’s geometric dimensions and rotational speed.
The displacement capacity of a compressor is expressed by the coefficient of performance (COP)

170

Stredne ťažká

Why is it essential to observe the correct phase sequence for scroll compressors and screw compressors?


Because changing the phase sequence would reverse the direction of rotation of the compressor rotors, which could result in damage to the compressors.
Because this type of compressor has difficulty starting up if the phase sequence is changed.
Because these types of compressors are sensitive to voltage drops.
Because the motor speed would decrease, and consequently the compressor’s capacity.

171

Stredne ťažká

The cycle of a two-stage vapour-compression refrigeration system should have, in each stage of the system:


a compression ratio greater than 8.
a compression ratio of less than 18.
a compression ratio of less than 8.
a compression ratio of less than 6

172

Stredne ťažká

Why is it necessary to seal the shafts in gland-sealed refrigeration compressors?


Because it prevents oil leakage.
Because we need to prevent air from entering the compressor and we need to prevent refrigerant from leaking from the compressor.
Because it ensures the bearing remains lubricated.
Because it protects the compressor’s crankshaft bearing.

173

Stredne ťažká

When is the refrigerant sufficiently cooled?


When no vapour bubbles are observed forming in the liquid sight glass.
When the evaporator is covered in frost.
When the liquid distributors are warm.
When the outlet from the condenser is cold.

174

Stredne ťažká

Why should the compressor crankcase be heated?


Heating improves the dissolution of the refrigerant in the oil, which is beneficial for its viscosity.
Heating ensures that the lubricating oil is de-watered.
Heating keeps the lubricating oil in a liquid state.
Heating prevents the refrigerant from dissolving in the oil.

175

Ľahká

What is the dead volume of a compressor?


This is the space between the side surface of the piston and the cylinder.
It is the space between the valve plate and the top of the piston.
It is the space between the valve plate and the bottom dead centre of the piston.
This is the space between the bottom of the piston and the crankshaft cover.

176

Stredne ťažká

What are compressor sets?


These consist of a larger number (several) of compressors connected in parallel and mounted on a common frame.
These are units consisting of two-stage compressors.
These are multiple (several) air-cooled condensers.
These are sets comprising several compressors connected in any configuration.

177

Stredne ťažká

What are the advantages of compressor units?


The ability to adjust the cooling capacity as required.
Easy modification of the system.
These are inexpensive and easy-to-install units.
Space-saving and lower energy consumption.

178

Stredne ťažká

What do we mean by the ‘application range’ of a compressor?


By this term, we mean the following parameters: compressor capacity, type of refrigerant, and the compressor’s geometric dimensions.
By this term, we mean the following parameters: the evaporation and condensation temperatures (to and tk), or the pressure values that determine the compressor’s application.
By this term, we mean that the compressor’s operating range is determined by the evaporation temperature ‘to’ during operation.
By this term, we mean that the compressor’s application range is determined by the evaporation temperature ‘to’ at a given ambient temperature.

179

Stredne ťažká

What are the basic functions of oil in a compressor?


The oil lubricates both the bearings and the sliding surfaces of the compressor components, and cools the compressor by transferring the heat generated during compression to the compressor’s outer casing.
The oil seals the gap between the piston and the cylinder.
The oil seals any leaks that develop in the system.
The oil absorbs moisture from the refrigerant that enters the compressor.

180

Stredne ťažká

What are the most effective ways of regulating the compressor’s cooling capacity?


By means of pressure control valves.
Using an expansion valve.
By changing the compressor’s displacement, by varying the rotational speed, or by deactivating individual cylinders.
By partially covering the evaporator to reduce the heat exchange surface area.

181

Stredne ťažká

What does compressor bypass control involve?


Refrigerant in the form of cooled, high-pressure vapour is introduced into the suction line.
High-pressure liquid refrigerant is injected on the suction side of the compressor.
The bypass control is not used to regulate the compressor.
Hot, high-pressure refrigerant vapour is drawn in on the suction side of the compressor.

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What is the fundamental difference between hermetic and semi-hermetic compressors?


The housing of a hermetic compressor and the compressor itself form a single unit.
The casing of semi-hermetic compressors can be dismantled, whereas the casing of hermetic compressors cannot be dismantled.
Both types of compressors are disassemblable, and the difference lies in their varying capacities.
Semi-hermetic compressors are characterised by the quiet operation of the entire unit.

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Stredne ťažká

How does a scroll compressor work?


A scroll compressor is also known as a turbo compressor.
It is a device fitted with two spirals. It is a type of positive displacement (volumetric) compressor in which compression takes place through the interaction of the two spirals.
It is a type of piston-type device.
It uses two screws to compress the refrigerant.

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Stredne ťažká

What physical process takes place in the evaporator?


The medium flowing through the evaporator (glycol, water) evaporates, whilst the refrigerant condenses.
The liquid refrigerant evaporates and a small amount of it becomes superheated.
It cools the refrigerant flowing through it.
It causes the refrigerant flowing through it to condense.

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Stredne ťažká

What is the purpose of regulating the compressor’s capacity?


It ensures that the cooling capacity is adjusted based on condensing temperatures.
It ensures adequate lubrication of the compressor.
It allows the cooling capacity to be adjusted to meet requirements.
Capacity control protects the compressor from low thermal loads.

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Why is inverter speed control suitable for refrigeration compressors?


Inverter speed control reduces energy consumption only under natural conditions.
By reducing the speed of the refrigeration compressor motor, inverter speed control improves the return oil flow to the compressor.
Inverter speed control enables continuous, smooth regulation of cooling capacity.
Inverter speed control can be used with any type of compressor to ensure adequate lubrication.

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Stredne ťažká

Does the suction gas temperature affect the cooling capacity of the compressor?


It does, but only for reciprocating compressors.
Temperature has no effect on the compressor’s cooling capacity.
It has a significant effect on performance.
It does, but only if the gas is deeply cooled.

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Stredne ťažká

In the case of compressor units fitted with an oil level control system, is it necessary to install the compressors at the same height?


No.
Yes.
Only scroll compressors.
Only screw compressors.

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Stredne ťažká

What functions does a compressor powered by the vehicle’s engine perform in a transport refrigeration system?


This compressor draws in refrigerant vapour from the evaporator, compresses it and then forces it into the condenser whilst the vehicle’s engine is running.
This compressor creates a vacuum on the suction side of the system whilst the vehicle’s engine is switched off.
This compressor condenses the refrigerant whilst the vehicle is in motion.
The compressor compresses ambient air and increases the pressure of the refrigerant.

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Stredne ťažká

Which natural fluids absorb heat from the refrigerant in the condenser?


Ammonia
Water and an antifreeze mixture.
Air and CO2.
Water or air.

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What is the function of the condenser in refrigeration systems?


The heat absorbed in the evaporator is then released into the environment via the condenser
Heat released in the regenerative heat exchanger is absorbed by the condenser.
The heat absorbed in the evaporator and transferred during the compression process is then released into the environment via the condenser.
Heat from the compressor is then released into the environment via the condenser.

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Stredne ťažká

If the condensation temperature is higher than the critical point temperature of the refrigerant, condensation:


will occur provided a specially designed condenser is used.
will not occur.
will always occur regardless of the temperature.
temperature has no effect on condensation.

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How does the subcooling of the refrigerant take place within a refrigeration system?


Subcooling of the liquid refrigerant in the final section of the condenser.
Subcooling using an additional heat exchanger and liquid nitrogen.
Subcooling using high-pressure hot vapour.
Subcooling of the refrigerant using oil (dissolving the refrigerant in oil).

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What is the purpose of controlling the condenser fan speed?


Condenser fan speed control reduces energy efficiency.
Condenser fan speed control ensures that the condensing pressure is maintained at the correct level.
Condenser fan speed control safeguards against the maximum permissible condensing pressure.
Dispersion of the refrigerant in the event of a system leak.