Chapter 115- Compression Refridgeration Systems Flashcards
Refrigeration may be broadly defined as
A controlled process of cooling or removing heat from a substance and then maintaining the temperature of that substance below that of the surrounding temperatures
Closed cycle refrigeration systems may be divided into two classes according to the method used to raise the pressure of the refrigerant after it leaves the compressor
The compression system
The adsorption system
Most modern refrigeration systems use the principle of absorbing heat by the rapid evaporation or boiling of a working medium. This process is called
Mechanical refrigeration
A simple closed cycle compression refrigeration system is composed of five principle parts which are called
Evaporator Compressor Condenser Liquid refrigerant control or regulating valve Liquid receiver
What is latent heat
Energy required to move a substance from solid to liquid, liquid to gas etc
What is sensible heat
Heat that changes the temperature of a substance
What cools the refrigerant in a refrigator
As the compressor increases the pressure the working fluid changes from a vapour to a liquid. When the liquid enters the low pressure area energy is required for it to transf back to a vapour. The working fluid takes energy from its surroundings in order to to move from a liquid to a vapour state thus cooling its surroundings
The heat added to the refrigerant is _________ to the heat removed from the refrigerant
Equal
In the low pressure side the temperature is
Low
In the high pressure side the refrigerant is
High tempurature
A direct system is
One in which the evaporator is in direct contact with the space being refrigerated
An indirect refrigeration system is one that
Is one that contains a separate working fluid, such as salt water, that is cooled and then transported to the area being cooled.
The first consideration when picking a working fluid for a refrigeration unit is
The temperature required for the medium to be cooled
A general rule regarding the working fluid of a refrigeration system
The evaporation temperature should be between 5 and 10 degrees Celsius lower than that of the cooled medium
A a general rule when dealing with the condensing temperature with the vapour state of your working fluid
It should be approximately 15-20 degrees Celsius when a water cooled condenser is used
