ChE 123: Refrigeration and Liquefaction (1)

Question 1

these are reversed heat engine

Answer 1

heat pumps

Question 2

absorption refrigeration: Heat is added from an external source

Answer 2

regenerator

Question 3

absorption refrigeration: takes advantage of difference in volatility; separates the refrigerant vapor with the adsorbent solution (similar to distillation)

Answer 3

regenerator

Question 4

4 types of refrigeration and liquefaction

Answer 4

1. the carnot refrigerator
2. the vapor-compression cycle
3. the absorption refrigeration
4. heat pumps

Question 5

these can be used to heat up houses or commercial buildings during winter or
cooling them during summer (reversible process)

Answer 5

heat pumps

Question 6

three compositions of the carnot refrigerator

Answer 6

1. refrigeration
2. reversed heat-engine cycle/reverse carnot cycle
3. refrigerant

Question 7

what is the usual absorbent in absorption refrigeration?

Answer 7

water

Question 8

large temperature and pressure drop

Answer 8

throttling valve

Question 9

heat is rejected, temperature slightly reduced. Superheated vapor to saturated liquid

Answer 9

condenser

Question 10

these are reversible refrigeration system

Answer 10

heat pumps

Question 11

it is the working fluid

Answer 11

refrigerant

Question 12

absorption refrigeration: Vapor form of the refrigerant is absorbed into the diluted absorbent solution (this forms a strong solution) and heat is rejected

Answer 12

absorber

Question 13

absorption refrigeration: liquid refrigerant is vaporized by absorbing heat from the cold reservoir

Answer 13

evaporator

Question 14

absorption refrigeration: strong solution is pre-heated by the weak absorbent solution from the regenerator

Answer 14

heat exchanger

Question 15

absorption refrigeration: refrigerant vapor to liquid, heat is discarded to surrounding environment

Answer 15

condenser

Question 16

4 composition of the vapor-compression cycle

Answer 16

1. evaporator
2. compressor
3. condenser
4. throttling valve

Question 17

absorption refrigeration: strong solution is pumped to high pressure

Answer 17

pump

Question 18

isentropic compression or actual compression, P and T increases

Answer 18

compressor

Question 19

4 properties of refrigerant

Answer 19

1. low freezing point
2. low boiling point
3. high latent heat of vaporization
4. low condensing pressure

Question 20

absorption refrigeration: Liquid refrigerant expands to low pressure then returns to the evaporator

Answer 20

throttling valve

Question 21

it is defined as the maintenance of a temperature below that of the surroundings

Answer 21

refrigeration

Question 22

what is the usual refrigerant in absorption refrigeration?

Answer 22

ammonia

Question 23

what is the major difference between vapor-compression cycle and absorption refrigeration?

Answer 23

method of compression

Question 24

how many steps are there in the carnot refrigerator?

Answer 24

2 isothermal steps
2 adiabatic steps

Question 25

Heat is absorbed from the refrigerated area causing the liquid refrigerant to vaporize at constant T and P

Answer 25

evaporator

Question 26

this operates on the same shaft as the turbine

Answer 26

Centrifugal compressor