Chillers and Refrigeration

Question 1

What are chillers used for?

Answer 1

Cool water in a Chilled Water system for use by HVAC equipment to cool rooms for equipment and personnel

Question 2

What are the stages of the Refrigeration Cycle?

Answer 2

Compression, Condensation, Expansion, and Evaporation

Question 3

What are the corresponding components of a Chiller?

Answer 3

Compressor, Condenser, Expansion Valve (Flash Economizer), and Cooler

Question 4

What is Compressor Surge?

Answer 4

Reversal of refrigerant flow from the Condenser to the Cooler

Question 5

How is Compressor Surge prevented?

Answer 5

Hot Gas Bypass Valve and line routed from the Compressor discharge to the Cooler, which raises Cooler pressure

Question 6

What is Refrigerant Stacking?

Answer 6

Collection of refrigerant in the Condenser rather than it moving back to the Cooler

Question 7

What causes Refrigerant Stacking?

Answer 7

Low d/p between the Condenser and Cooler

Question 8

How is Refrigerant Stacking prevented?

Answer 8

The Essential Chillers have a Refrigerant Head Pressure Control Valve to throttle the Condenser Cooling Water flow, which controls Condenser pressure

Question 9

What is the purpose of the Compressor’s Inlet Guide Vanes?

Answer 9

Control the capacity of the Chiller to control the cooling of the Chilled Water

Question 10

What parameter is used to control the Inlet Guide Vanes?

Answer 10

Chilled Water leaving the Cooler, going to the HVAC loads

Question 11

What’s the power supply voltage to a Chiller’s Compressor?

Answer 11

4.16 kV

Question 12

How many stages is the Compressor?

Answer 12

2

Question 13

What enters the second stage of the Compressor?

Answer 13

Flash Gas from the Flash Gas Chamber of the Flash Economizer

Question 14

What cools the Compressor?

Answer 14

Liquid refrigerant from a sump at the bottom of the Condenser

Question 15

What maintains the flow of the refrigerant?

Answer 15

The d/p between the Condenser and cooler

Question 16

What lubricates the Compressor bearings?

Answer 16

Oil from a Reservoir in the base of the Compressor is pumped through a Cooler and Filter to the bearings.

Question 17

What controls the oil temperature when the Chiller is shutdown?

Answer 17

Heaters immersed in the oil sump.

Question 18

Why is the oil maintained heated?

Answer 18

Minimize the absorption of refrigerant by the oil

Question 19

What function does the Chiller’s Condenser perform?

Answer 19

Transfer heat from the refrigerant to the Cooling Water system

Question 20

What is the function of the Thermal Economizer?

Answer 20

Subcool the liquid refrigerant to increase efficiency

Question 21

Where does the liquid refrigerant from the Thermal Economizer go?

Answer 21

Into the Flash Gas Chamber of the Flash Economizer, via the High Side Float Valve

Question 22

What is the purpose of the Flash Economizer?

Answer 22

Provides an intermediate pressure barrier between the Condenser and the Cooler and regulates the flow of refrigerant

Question 23

What is the function of the High Side Float?

Answer 23

It serves as a level controller for refrigerant in the Condenser, maintaining refrigerant in the Thermal Economizer

Question 24

What causes the liquid refrigerant to flash to a vapor in the Flash Gas Chamber?

Answer 24

The expanded volume of the Chamber drops the pressure

Question 25

What is the purpose of the Chiller’s Cooler?

Answer 25

Transfer heat from the Chilled Water to the refrigerant

Question 26

What is the purpose of the Chiller’s Pump Down Unit?

Answer 26

Transfer refrigerant to and from the refrigerant storage tanks, as necessary for maintenance.