Glossary
Glossary
- Sa ura ion
The s a e of sa ura ion is he coexis ence of a refrigeran in a liquid and gas s a e.
- Condensa ion empera ure and evapora ion empera ure
Condensa ion empera ure: in he condenser, he refrigeran is condensed by he high- empera ure gaseous refrigeran o
he empera ure of he liquid refrigeran , ha is, he sa ura ion empera ure under he condensing pressure.
Evapora ion empera ure: in he evapora or, he refrigeran evapora es from he liquid refrigeran o he empera ure of he
gaseous refrigeran , ha is, he sa ura ion empera ure under he evapora ion pressure.
- Degree of subcooling and superhea
Subcooling: condensing empera ure – condensing ou le empera ure.
Superhea : evapora ion ou le empera ure - evapora ion empera ure.
The lower subcooling can make he refrigera ion capaci y of he sys em be er. Adding subcooling circui and economizer in
he refrigera ion sys em is o increase he subcooling for refrigeran increasing.
The degree of expansion of he expansion valve (refrigeran charge) affec s he degree of superhea .
The grea er he degree of superhea , he smaller he opening of he expansion valve can be de ermined ( he refrigeran
charge is less).
- Sensible hea and la en hea
The amoun of hea required o raise he wa er empera ure from 0 degrees o 100 degrees is sensible hea , he wa er is
hea ed o 100 degrees, and he ho wa er becomes wa er vapor, bu he empera ure is s ill 100 degrees. The hea required
for his process is called la en hea .
- Gauge pressure and absolu e pressure
Gauge pressure: Gauge pressure refers o he pipeline pressure, refers o he pressure measured by pressure gauges,
vacuum gauges, U-shaped ubes, e c., also known as rela ive pressure. The “ able pressure” s ar s wi h a mospheric pressure
and he symbol is Pg.
Absolu e pressure: The pressure direc ly ac ing on he surface of a con ainer or objec is called "absolu e pressure", he
absolu e pressure value is absolu e vacuum as a s ar ing poin , he symbol is PABS (ABS is a subscrip ) and he absolu e
pressure is a mospheric pressure + gauge pressure.
A a mospheric pressure, he gauge pressure is 0 and he absolu e pressure is 1.013 bar.
- Dry bulb empera ure, we bulb empera ure and black ball empera ure
Dry bulb empera ure: he empera ure measured by ordinary hermome ers.
We bulb empera ure: a we clo h is wrapped around he hermome er, and he empera ure indica es a drop due o he
evapora ion of wa er. The empera ure a his ime is called he we -bulb empera ure.
The device, which has bo h he dry ball hermome er and he we bulb hermome er, is called he dry humidy me er, which
can be used o measure he rela ive humidi y in he a mosphere.
Black ball empera ure: also called ac ual empera ure, i indica es he ac ual sensory empera ure expressed by empera ure
when a person or an objec is combined wi h radian hea and convec ive hea in a radian hea environmen .
The black ball empera ure measured is generally higher han he ambien empera ure, which is he air empera ure.
- Rela ive humidi y and absolu e humidi y
Absolu e humidi y: he mass of wa er vapor in a uni volume of air is called he "absolu e humidi y" of air. I is a
represen a ion of he physical quan i y of a mospheric dryness and humidi y. I is usually expressed in grams of wa er vapor
con ained in 1 cubic me er of air.
Rela ive humidi y: he ac ual wa er vapor densi y in air and he percen age of sa ura ed wa er vapor densi y a he same
empera ure are called he “rela ive humidi y” of air.
The degree of dryness and humidi y of he air is rela ed o he degree of sa ura ion of wa er vapor con ained in he
air, bu i is no direc ly rela ed o he absolu e amoun of wa er vapor con ained in he air.
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