Heating Sources and Refrigeration

Question 1

Natural gas is

Answer 1

Most common

Question 2

Electricity is

Answer 2

Most expensive

Question 3

Fuel oil/diesel may be used

Answer 3

in rural locations and is more common outside US

Question 4

Liquefied Petroleum (LP)

Answer 4

may be used in rural locations

Question 5

Steam

Answer 5

used in some urban areas (and on Cornell campus by Statler Hotel)

Question 6

Centralized for heating

Answer 6

for heating, use a boiler to produce hot water and sometimes steam

Question 7

Heat exchange or heat transfer

Answer 7

when two objects (typically liquid) come near each other and exchange heat

Question 8

Centralized for chilled water

Answer 8

supplies cold water for water-based centralized HVAC systems

Question 9

Secondary water

Answer 9

water used for heating and cooling
-chilled water supply and return
-condenser water supply and return

Question 10

Refrigeration or vapour compression cycle

Answer 10

a circulating refrigerant removes heat from one location and transfers this heat to another location where it is rejected

Question 11

Heat removal occurs in

Answer 11

the evaporator

Question 12

Heat is rejected in

Answer 12

the condenser

Question 13

The compressor provides

Answer 13

the energy necessary to accomplish this heat transfer

Question 14

The expansion valve controls

Answer 14

the flow of refrigerant through the system

Question 15

Chillers (and all refrigeration equipment) rely on the

Answer 15

refrigeration cycle

Question 16

Refrigeration components

Answer 16

1. expansion valve (controls flow of refrigerant)
2. evaporator (liquid to vapour – super cools)
3. compressor (vapour to compressed to hot, high pressure gas)
4. condenser (vapour to liquid, hot gas cooled –condenses into liquid state)

Question 17

Expansion valve/metering device

Answer 17

controls the flow of the refrigerant into the evaporator

Question 18

Evaporator

Answer 18

refrigerant expands (to fill the space), boils, and evaporates
-refrigerant becomes very cold (below 0ºF) and is now able to absorb heat from space (air or water) you want to cool
-the refrigerant gets warmer and returns to the compressor

Question 19

Compressor

Answer 19

refrigerant gas is compressed into a hot, high-pressure gas (around 125ºF)

Question 20

Condenser

Answer 20

compressed gas travels to the condenser where it is cooled by either water or an air fan
-as it cools, it condenses into a liquid state
-refrigerant is now warm, high-pressure liquid (around 110ºF) leaving condenser

Question 21

Lower pressure is

Answer 21

easier to boil

Question 22

Higher pressure is

Answer 22

harder to boil

Question 23

CFC. Chlorofluorocarbons. (“Freon”)

Answer 23

-often hear of R-11, R-12
-very detrimental to the ozone (at 100%)
-Montreal accords. Can no longer be produced. Phased out
of usage in new equipment. (But it is still being used)

Question 24

HCFCs. Hydrochlorofluorocarbons

Answer 24

-often hear of R-22
-somewhat detrimental to the ozone (at around 5%)
-slated for phaseout by 2020

Question 25

HFCs. Hydrofluorocarbons

Answer 25

no ozone impact

Question 26

Other "refrigerants"

Answer 26

Ammonia, sulfur dioxide, carbon dioxide, methane “Recharge” or Refill refrigerants

Question 27

Cooling tower

Answer 27

equipment that transfers waste heat into the atmosphere -supply cooled water to the condenser in the Chiller

Question 28

Cooling tower fill

Answer 28

Forces the hot condenser water (return) to mix with air, promoting evaporation, which cools the condenser water

Question 29

Cooling towers are large consumers of water because of the

Answer 29

evaporation and "blowdown" loss