Refrigeration System Equipment Quiz

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

To divide the high pressure side and low pressure side

To compress the refrigerant and raise its pressure (correct)

To cool down the refrigerant

To remove heat from the hot vapor refrigerant

Where does the evaporator operate in a refrigeration system?

Low pressure side (correct)

Expansion device side

High pressure side

Compressor side

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

To remove heat from the hot vapor refrigerant

To cool down the refrigerant

To absorb heat and change liquid refrigerant into vapor (correct)

To raise the refrigerant's pressure

Where is the condenser located in a refrigeration system?

High pressure side Signup and view all the answers

What is the purpose of the expansion device in a refrigeration system?

To divide the high and low pressure sides Signup and view all the answers

Why must the temperature of the boiling refrigerant in the evaporator be lower than that of the surrounding medium?

To prevent heat flow to the refrigerant Signup and view all the answers

Which type of compressor is best suited for refrigerants with moderate or low condensing pressures like R-21 and R-114?

Reciprocating compressor Signup and view all the answers

What type of compressor is recommended for refrigerants that require a large displacement and operate at low condensing pressure?

Centrifugal compressor Signup and view all the answers

What defines the ratio of the clearance volume to the swept volume in reciprocating compressors?

Clearance factor Signup and view all the answers

Which component in a reciprocating compressor expands from discharge pressure to suction pressure, filling part of the cylinder space before suction begins?

Clearance space Signup and view all the answers

What is the primary motion involved in compressing the vapour refrigerant in reciprocating compressors?

Back-and-forth motion Signup and view all the answers

Which type of compressor is commonly used in domestic refrigerators?

Rotary compressor Signup and view all the answers

What type of refrigerants are reciprocating and screw compressors best suited for?

$R-12$ and $R-22$ Signup and view all the answers

What is the volume that remains in the cylinder during the operation cycle of a reciprocating compressor?

$Vc$ Signup and view all the answers

Which factor is normally around 5% and represents the effect of clearance on reducing the volume of sucked vapour in reciprocating compressors?

$0.005L + 0.5$ Signup and view all the answers

In a reciprocating compressor, when does the discharge valve open?

At position 2 when cylinder pressure equals discharge pressure Signup and view all the answers

What happens to the volumetric efficiency of a reciprocating compressor as suction pressure decreases?

Decreases Signup and view all the answers

What effect does wire-drawing at the valves have on the overall volumetric efficiency of a compressor?

Decreases efficiency Signup and view all the answers

Which method is NOT mentioned as a way to improve the volumetric efficiency of a reciprocating compressor?

Increasing pressure drops at the valves Signup and view all the answers

What role does the diffuser play in a single-stage centrifugal compressor?

Convert kinetic energy into pressure energy Signup and view all the answers

Which material is commonly used for making the impeller of a centrifugal compressor?

Alloy (chrome-nickel) steels Signup and view all the answers

What is the effect of a large clearance volume on the volumetric efficiency of a reciprocating compressor?

Decreases efficiency Signup and view all the answers

How does the pressure drop across suction and discharge valves affect their operation in a compressor?

Open when there is a pressure drop Signup and view all the answers

What happens to the refrigerating capacity of a reciprocating compressor with decreasing evaporator pressure?

Becomes zero Signup and view all the answers

What is the main reason for the effect of clearance volume on the work of compression in a reciprocating compressor?

Expansion and contraction of clearance gas like a spring Signup and view all the answers

What is the purpose of an inlet casing in a single-stage centrifugal compressor?

Accelerate the fluid to the impeller inlet Signup and view all the answers

What is the purpose of a condenser in a refrigeration system?

To desuperheat the gas Signup and view all the answers

How does a rotary screw compressor function?

By injecting oil to seal leakage paths Signup and view all the answers

What is the primary advantage of a screw compressor over reciprocating compressors?

Avoids surging issues Signup and view all the answers

What function does the slide valve serve in a screw compressor?

Controls capacity Signup and view all the answers

How do air-cooled condensers differ from water-cooled condensers?

Use air as the cooling medium instead of water Signup and view all the answers

Why are high pressure refrigerants like R-22 and ammonia used in screw compressors?

To increase the compressor's capacity Signup and view all the answers

How many basic continuous phases are involved in the working cycle of a screw compressor?

3 Signup and view all the answers

What type of rotors does a rotary screw compressor have?

Four-lobe male and five-gully female Signup and view all the answers

What eliminates leakage in a screw compressor?

Injecting oil to seal the leakage paths Signup and view all the answers

Why is oil injected into a screw compressor?

To cool, lubricate, and seal leakage paths Signup and view all the answers

What is the main limitation of a natural convection condenser?

Cannot reject heat rapidly Signup and view all the answers

Which material is generally used for the condenser tubes in small refrigeration units?

Steel Signup and view all the answers

What purpose do the wires welded to the condenser tubes serve?

Increase mechanical strength Signup and view all the answers

Why are fins in forced-air circulation condensers closely spaced?

To prevent dirt and lint accumulation Signup and view all the answers

In a water cooled condenser, what issue can arise due to impurities present in water?

Formation of scale on the tube surface Signup and view all the answers

What is the purpose of the shell in a shell-and-coil condenser?

To contain the refrigerant Signup and view all the answers

Why are intermediate tube supports provided in a shell-and-tube condenser?

To enhance mechanical stability Signup and view all the answers

How does the liquid flow from the accumulator to the evaporator coil?

By gravity Signup and view all the answers

What prevents the carry-over of liquid particles from the accumulator to the suction line?

Liquid eliminators at the accumulator top Signup and view all the answers

In a 'liquid-overfeed system', how is the refrigerant circulated from the accumulator to the evaporator coil?

By liquid pump Signup and view all the answers

What is the purpose of a liquid- suction heat exchanger on the suction line?

To superheat the suction vapour Signup and view all the answers

In what way does 'dry expansion' differ from 'flooded' in refrigeration systems?

In the manner of feeding refrigerant into the evaporator Signup and view all the answers

What describes 'natural convection' in cooling/circulating a fluid around the evaporator?

Colder layer rises up, warmer layer falls down Signup and view all the answers

What phenomenon in centrifugal compressors occurs when the load decreases to below 35 per cent of the rated capacity?

Surging Signup and view all the answers

What is one of the methods mentioned to control the capacity of centrifugal compressors?

Variable inlet whirl vanes Signup and view all the answers

What is the purpose of a speed-reduction gear in centrifugal compressors?

Control the compressor speed Signup and view all the answers

In a rolling piston type rotary compressor, what role does the spring play?

Maintains contact between roller and blade Signup and view all the answers

Why are rotary compressors preferred for low-temperature applications in chemical and industrial processing?

High volumetric efficiencies Signup and view all the answers

What contributes to achieving high tip speeds in centrifugal compressors?

Large diameter impeller Signup and view all the answers

What causes surging in centrifugal compressors?

Load decreasing to below 35 per cent of rated capacity Signup and view all the answers

How does capacity control vary in rotary compressors as compared to centrifugal compressors?

By maintaining contact between the roller and blade Signup and view all the answers

Which component in rotary compressors ensures the seal between high-pressure and low-pressure sides?

Oil film surrounding rotor and vanes Signup and view all the answers

In a water-cooled condenser, how is the overall resistance calculated?

By adding all the resistances in series Signup and view all the answers

What is the purpose of the expansion valve in a dry expansion evaporator?

To control the rate of flow of refrigerant to the evaporator Signup and view all the answers

Why is a flooded evaporator more efficient in terms of heat transfer?

Because it maintains a constant liquid level inside Signup and view all the answers

How is the refrigerant supplied to a dry expansion evaporator?

By an expansion valve Signup and view all the answers

What distinguishes a dry expansion evaporator from a flooded evaporator?

The liquid level maintained inside Signup and view all the answers

Which component contributes to maintaining a constant liquid level in a flooded evaporator?

'Accumulators' Signup and view all the answers

What happens to the refrigerant in a direct expansion evaporator as it passes through?

It turns into a mix of liquid and vapor Signup and view all the answers

What does the cooling process involve in an evaporator?

Vaporizing the refrigerant to remove heat Signup and view all the answers

Which factor determines the heat-transfer efficiency of a flooded evaporator?

'Liquid level' maintained inside Signup and view all the answers

Why is an expansion device crucial in a refrigeration system?

To regulate the flow of refrigerant into the evaporator Signup and view all the answers

What type of tubes are used in ammonia condensers to prevent the effects of ammonia on copper?

Steel tubes Signup and view all the answers

What is the purpose of the small grooves in the holes of the tube sheets?

To prevent tubes from getting loose at the ends Signup and view all the answers

Why are removable water boxes provided at the ends of the condenser?

To facilitate brushing of the water tubes Signup and view all the answers

What is the purpose of extra rows of water tubes provided at the lower end of some condensers?

Sub-cooling the liquid below the condensing temperature Signup and view all the answers

Why is it important not to overcharge the refrigeration system with refrigerant?

To prevent excessive head pressure and condensing temperature Signup and view all the answers

What safety feature is fixed on the shell of the condenser to protect against excessive pressures?

Fusible plug Signup and view all the answers