Chillers & Refridgerant Cycle

Question 1

What are chillers used for ?

Answer 1

Cool water in a chilled water system for us by HVAC equipment to cool rooms & equipment

Question 2

What are stages of the refrigeration cycle?

Answer 2

Compression,condensation,expansion,and evaporation

Question 3

What are corresponding components of 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

What causes compressor surge ?

Answer 5

High differential press. between cooler & condenser

Question 6

How is compressor surge prevented ?

Answer 6

Hot gas bypass valve and line routed from compressor discharge to cooler, which raises cooler press.

Question 7

What is refrigerant stacking ?

Answer 7

Collection of refrigerant in the condenser rather than it moving back to cooler

Question 8

What causes refrigerant stacking ?

Answer 8

Low d/p between condenser and cooler

Question 9

How is refrigerant stacking prevented ?

Answer 9

Essential chillers have refrigerant head pressure control valve that throttles condenser cooling water flow , which raises or lowers condenser Press.

Question 10

What is the purpose of the compressors inlet guide vanes ?

Answer 10

Control capacity of the chillers to control cooling of chilled water

Question 11

What parameter is used to control the inlet Guide Vanes?

Answer 11

Chilled water leaving the cooler, going to HVAC loads

Question 12

Whats the powers supply voltage to chillers compressor?

Answer 12

4.16kv

Question 13

How many stages is the compressor ?

Answer 13

2 stages

Question 14

What enters the second stage of the compressor ?

Answer 14

Flash gas from gas chamber in the Flash Economizer

Question 15

What cools the compressor ?

Answer 15

Liquid refrigerant from sump of the bottom of condenser

Question 16

What maintains the flow of the refrigerant ?

Answer 16

The D/P between the condenser and cooler

Question 17

What lubricates the compressor bearings?

Answer 17

Oil pumped through cooler and filter to bearings

Question 18

What controls the oil temp. When chiller is shutdown ?

Answer 18

Heaters in the oil sump

Question 19

Why is the oil maintained heated ?

Answer 19

Minimize absorption of refrigerant by oil

Question 20

What function does chillers condenser perform ?

Answer 20

Transfer heat from refrigerant to cooling water system

Question 21

What is the function of the thermal economizer?

Answer 21

Subcool liquid refrigerant to increase efficiency (bottom of condenser)

Question 22

Where does liquid refrigerant from thermal economizer go?

Answer 22

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

Question 23

What is purpose of Flash Economizer ?

Answer 23

Provides intermediate pressure barrier between condenser and cooler

Regulates flow of refrigerant

Question 24

What is the function of High Side Float ?

Answer 24

Serves as refrigerant level control for condenser, also maintaining level in thermal Economizer (bottom condenser)

Question 25

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

Answer 25

Expanded volume of chamber drops pressure

Question 26

What is the purpose of the chillers cooler?

Answer 26

Transfer heat from chilled water to refrigerant

Question 27

What is purpose of chillers pump down unit ?

Answer 27

Transfer to and from storage tanks, used for maintenance