Final Part 1

Question 1

Refrigeration (definition)

Answer 1

System allows transfer of heat from the cooling chamber to a location where heat can easily be discarded

Question 2

Refrigeration Effect (definition)

Answer 2

The enthalpy difference of the refrigerant between the inlet and the outlet location of an evaporator

Question 3

Refrigeration Effect (equation)

Answer 3

H2 - H1

Question 4

Components of a refrigeration system

Answer 4

Evaporator
Compressor
Condenser
Expansion Valve

Question 5

Evaporator

Answer 5

Liquid refrigerant vaporizes to a gaseous state (latent heat)

Question 6

Compressor

Answer 6

Raises the pressure and temperature of the refrigerant

Question 7

Condenser

Answer 7

transfers heat from the refrigerant to another medium (air/water) by rejecting heat (gaseous refrigerant condenses to liquid)

Question 8

Expansion Valve

Answer 8

A metering device that controls the flow of liquid refrigerant to an evaporator

Question 9

Compressor (equation)

Answer 9

q = m(H3 - H2)

Question 10

Condenser (equation)

Answer 10

q = m(H3 - H1)

Question 11

Evaporator (equation)

Answer 11

q = m(H2 - H1)

Question 12

Coefficient of performance (COP)

Answer 12

= (H2 - H1)/ (H3 - H2)

Question 13

Practical Storage Life (PSL)

Answer 13

the period of frozen storage after freezing during which the product retains its characteristic properties and remains suitable for consumption

Question 14

High Quality Life (HQL)

Answer 14

the time elapsed from freezing of an initially high-quality product and the moment when a statistically significant difference from the initial can be established

Question 15

Just noticeable difference (JND)

Answer 15

The observed difference from the high-quality life and the initially high-quality product

Question 16

Direct Freezing

Answer 16

Product and refrigerant have direct contact

Question 17

Indirect contact

Answer 17

Product and refrigerant are separated by a barrier throughout the process

Question 18

Components of a microwave

Answer 18

Power Supply
Magnetron
Wave Guide
Stirrer
Oven Cavity

Question 19

Power Supply Function

Answer 19

Draw electrical power and convert to high voltage required by magnetron

Question 20

Magnetron Function

Answer 20

Converts power into microwave energy

Question 21

Wave guide function

Answer 21

transfers the generated energy to the oven cavity

Question 22

Stirrer Function

Answer 22

distributor that scatters the energy throughout the oven

Question 23

Oven Cavity function

Answer 23

encloses food to be heated with the metallic walls

Question 24

Which agency regulates microwaves

Answer 24

FDA

Question 25

Overall heat transfer coefficient

Answer 25

measure of the rate of heat transfer through a composite system

Question 26

Plate Heat Exchangers

Answer 26

* Indirect heating Application: Beverages and dairy

Question 27

Tubular Heat Exchanger

Answer 27

+ non-contact + Indirect

Question 28

Steam Infusion Heat Transfer

Answer 28

+ Direct heat exchanger Application: cooking, sterilization, pudding, etc.

Question 29

Evaporators (key components)

Answer 29

+ Heat exchanger enclosed in vacuum chamber (product boils at low temp) + Condenser

Question 30

Batch-Type Pan (Evaporator)

Answer 30

+ Spherical vessel +Steam Jacked + Connect (vacuum) Poor heat transfer

Question 31

Natural circulation evaporators

Answer 31

+Short vertical tubes product rises (heated) steam condenses on the outside of tube + Evaporation take place inside + Falls on base vessel through central annular section

Question 32

Rising-Film Evaporators

Answer 32

+ Tubes heated from the outside as liquid vaporizes (film formed moves upwards) + High convective heat transfer coefficients

Question 33

Falling-Film Evaporator

Answer 33

+ Thin film moves downwards + Viscous fluid Advan: allow more effects Best suited for heat sensitive (OJ)

Question 34

Combined Rising/Falling Film

Answer 34

+Connected in tandem + Concentrated by circulating * Through the rising-film section * Followed by the falling-film section

Question 35

Forced-circulation evaporators

Answer 35

+ Liquid is forced at high rate + /\T heating surface +Comparative - Low capital & operating cost

Question 36

Modes of Heat Transfer

Answer 36

Conduction Convection Radiation

Question 37

Specific Gravity (SG)

Answer 37

A measure of the density of a substance compared to the density of water

Question 38

Absolute Pressure

Answer 38

the pressure in a space relative to a perfect vacuum, or zero pressure

Question 39

Refractometer

Answer 39

Measures the amount of total soluble solids in a solution

Question 40

U-tube manometer

Answer 40

measure pressure differences in various processing and storage systems

Question 41

Dry bulb temperature

Answer 41

Temperature reading indicated by normal thermometer reading or sensor

Question 42

Wet bulb temperature

Answer 42

The thermometer or sensor covered with wetted wick

Question 43

Dew Point Temperature

Answer 43

Water vapor present in the air (considered steam at low pressure)

Question 44

Humidity ratio (W)

Answer 44

mass of water vapor per unit of dry air (referred as moisture content/specific humidity)

Question 45

Specific Volume

Answer 45

The volume of 1 kg dry air plus water vapor in air (m³/kg)

Question 46

Moisture Removal

Answer 46

Diffusion of liquid or vapor through the product structure

Question 47

Moisture removal process

Answer 47

Simultaneous heat and mass transfer

Question 48

Drying-Rate Curve: A-B

Answer 48

initial removal of water

Question 49

Drying-Rate Curve: B-C

Answer 49

Constant Rate Period + Significant reduction of moisture occurs +occur with the product at the wet-bulb temperature of the air

Question 50

Critical Moisture Content (B-C)

Answer 50

When an abrupt change in the rate of moisture removal occurs

Question 51

Drying-Rate Curve (C-D)

Answer 51

Falling Rate Period +Moisture removal begins to drop significantly with time

Question 52

Drying-Rate Curve (D-E)

Answer 52

More fall rate periods +This behavior is product dependent and other factors such: o Pre-treatment o Water activity o Drying conditions