Refrigeration, Cold Storage, and Air Conditioning

Question 1

It is defined as the process of achieving and maintaining a temperature below ambient, with the aim of cooling a product or space to the required temperature. It is also defined as artificial cooling.

Answer 1

REFRIGERATION

Question 2

is the machine that is used to extract heat from a body low temperature and then rejects this heat to a high temperature body.

Answer 2

Refrigerator

Question 3

is a machine used to heat a medium warmer than the surroundings

Answer 3

heat pump

Question 4

It is defined as the quantity of heat extracted from a cold body or space to be cooled in a given time

Answer 4

Refrigerating Effect (N):

Question 5

It is the quantity of heat required to raise or lower the temperature of one kg of water (or ice), through one kelvin or (10C) in one second.

Answer 5

Specific Heat of water and ice
Specific heat of water, Cpw = 4.19 kJ/kg K
Specific heat of ice, Cpice = 2.1 kJ/kg K.

Question 6

is defined as, “the quantity of heat abstracted (refrigerating effect) to freeze one ton of water into one ton of ice in a duration of 24 hours at 0oC”

Answer 6

One ton of refrigeration

Question 7

The latent heat of fusion of ice at 0°C

Answer 7

Latent heat of ice = 144 Btu/lb = 335 kJ/kg

Question 8

One ton of refrigeration is equal to?

Answer 8

= 12000 Btu/hr = 3.52 kJ/s

Question 9

It is defined as the ratio of heat extracted in a given time (refrigerating effect) to the work input.

Answer 9

Coefficient of Performance

Question 10

Any substance that absorbs heat through expansion and vaporization process and loses heat due to condensation in
a refrigeration process.

Answer 10

Refrigerant

Question 11

Synthetically produced (Derived from Methane, Ethane) and were developed as the Freon family of refrigerants.

Answer 11

Halocarbon Refrigerants

Commonly used in Domestic, Commercial and Industrial Purposes due to their wide range of boiling points at atmospheric pressure.

Question 12

A stable mixture of two or several refrigerants whose vapor and liquid phases retain identical compositions over a wide range of temperatures.

Answer 12

Azeotropes Refrigerants

Code starts with digit 5.
Thermodynamic properties remain fixed.

Question 13

is one whose composition in liquid phase differs to that in vapor phase and do not boil at constant temperatures

Answer 13

Zeotropes Refrigerants

Question 14

Designated by R followed by Number.

Answer 14

Inorganic Refrigerants

Carbon Dioxide, Water, Ammonia, Air, Sulphur dioxide
R717 - (NH3)Ammonia
717 = 700 + 17

Question 15

are highly flammable and require additional safety precaution during its use as refrigerants

Answer 15

Hydro-carbon Refrigerants

Question 16

this is the most widely used refrigerant. It is used primarily with reciprocating compressors for service in household refrigeration appliances, commercial and industrial air conditioning, and in a multitude of other types of refrigeration systems.

Answer 16

Refrigerant 12

Question 17

are the most-used refrigerants in centrifugal compressor system.

Answer 17

R11 and R113

Question 18

Ordinary ice is used for keeping the space at temperature below the surrounding temperature.

Answer 18

Ice refrigeration

Question 19

refrigeration system which applies the principle of boiling the water under 100°C by the process of reducing the pressure on the water surface below atmospheric pressure. The partial vacuum in the closed vessel evaporates the water, thus releasing the heat through evaporative cooling.

Answer 19

Steam Jet Refrigeration

Question 20

It is simply the process of reducing the pressure of the liquid refrigerant as it passes through the expansion device. By reducing the pressure, which makes the liquid refrigerant flash into a vapor, creating a cooling effect.

Answer 20

Throttling refrigeration

Question 21

refrigeration systems which use air as their refrigerant, which compresses and expands to create heating and cooling capacity.

Answer 21

Air refrigeration

Question 22

are commonly used for commercial and industrial refrigeration as well as air
conditioning. In these types of refrigeration systems, the refrigerant vapor is compressed by means of a centrifugal, screw, or reciprocating compressor.

Answer 22

Mechanical Compression Refrigeration

Question 23

systems which use water to cool the air brought in from outside the home. Water is pumped onto the pad through which air passes, and the air loses its heat from the water, then electrical power is supplied to the pumps and blower fans.

Answer 23

Evaporative Cooling

Question 24

a system that uses a heat source (which may be solar power or a fossil-fueled flame) to provide the energy needed to run the cooling process. It uses two types of coolant; the first coolant performs evaporative cooling and is then absorbed into the second coolant.

Answer 24

Absorption Refrigeration

Question 25

refrigeration system which normally works on the principle of the Peltier effect. This effect makes a variation in temperature by transferring heat between the two conductor junctions.

Answer 25

Thermoelectric Refrigeration

Question 26

The working agents employed in these types are vapors like ammonia, carbon dioxide, sulfur dioxide, Freons, etc.

Answer 26

Vapor Refrigeration

Question 27

This type of refrigeration uses a liquid refrigerant in a closed system that circulates the refrigerant through four stages in which it is compressed and expanded to alternate between vapor and liquid form without leaving the refrigerating area. This method is widely used for the air conditioning of buildings and automobiles.

Answer 27

Vapor Compression Refrigeration (VCR)

Question 28

refrigeration systems which are primarily used where high power is not readily available.

Answer 28

Vapor Absorption Refrigeration (VAR)

Question 29

provides a heat transfer surface through which heat can pass from the refrigerated space or product into the vaporizing refrigerant.

Answer 29

Evaporator

Question 30

conveys the low-pressure vapor from the evaporator to the suction inlet of the compressor.

Answer 30

Suction line

Question 31

removes the vapor from the evaporator and raises the temperature and pressure of the vapor to a point such that the vapor can be condensed with normally available condensing media.

Answer 31

Vapor compressor

Question 32

delivers the high pressure, high-temperature vapor from the discharge of the compressor to the condenser.

Answer 32

“Hot gas” or discharge line

Question 33

provides a heat transfer surface through which heat passes from the hot refrigerant vapor to the condensing medium.

Answer 33

Condenser

Question 34

provides storage for the condensed liquid so that a constant supply of liquid is available to the evaporator as needed.

Answer 34

Receiver tank

Question 35

carries the liquid refrigerant from the receiver tank to the refrigerant flow control.

Answer 35

Liquid Line

Question 36

meters the proper amount of refrigerant to the evaporator and reduces the pressure of the liquid entering the evaporator so that the liquid will vaporize in the evaporator at the desired low temperature.

Answer 36

Refrigerant flow control

Question 37

This is found mainly on large ammonia systems and on low-pressure centrifugalcompressor systems.

Answer 37

Purger- removes air from the system

Question 38

This is suited for ventilation of rooms and air ducts of low resistance. This is characterized by excessive noises at high speeds.

Answer 38

Propeller