Pretest quiz Flashcards
Enthalpy describes:
a) moisture content in air
b) amount of refrigerant required in a system
c) amount of heat a substance contains
d) amount of heat a substance contains after boiling
c) the amount of heat a substance contains
When working with a pressure enthalpy diagram, what condition can be found to the right of the saturated vapour curve?
a) sub-cooked liquid
b) superheated vapour
c) saturated vapour
d) saturated liquid
superheated vapour
Define superheated refrigerant
temp of a vapour above its saturation temp
define sub-cooled refrigerant
temp of liquid when it’s cooled below it’s condensing temp
define saturated vapour refrigerant
when the temp is equal to its saturation temp
define saturated liquid refrigeration
when the temp is equal to its saturation temp
What does PH diagram mean
PE diagram
The vertical lines on a typical PE chart represent:
a) saturation curve
b) refrigerant in a liquid state
c) refrigerant in a vapour state
d) constant volume lines
e) constant quality lines
f) constant enthalpy lines
g) constant temp lines
constant enthalpy lines
The area between the saturated liquid curve and the saturated vapour curve PE chart represents
refrigerant in a liquid/vapour state
What is Thermal conductivity (K)
per inch thickness
What is Thermal conductance (C)
given thickness
What is Thermal resistance (R)
Material/Components resistance to heat transfer
One category of refrigeration is extra low temperature, what her names may be applied to this type of system?
Cryogenic, cascade and compound
Describe two applications of air conditioning systems?
comfort cooling and process cooling
Evaporator for refrigeration system will be constructed of a material with a ____ thermal resistivity and _____ thermal conductivity
low, high
Explain the difference between refrigerant vapour and refrigerant gas
vapour can be either saturated or superheated, gas is superheated
Identify the methods of heat transfer and explain each in detail
Conduction: Molecule to molecule through physical contact
Convection: heat travels through fluid
Radiation: TD required
What is Charles 1st law? and formula?
if volume of gas stays the same, then absolute pressure varies with absolute temp
P1xT2=P2xT1
What is Charles 2nd law and formula?
If pressure of gas stays the same then volume of gas varies directly with absolute temp.
V1xT2=V2xT1
What is Boyles law/formula?
If temp remains same then volume of gas varies inversely due to absolute pressure
P1xV1=P2xV2
