The study of refrigeration is the study of removing heat. Heat can be changed
from one form to another: for example, electricity to heat. Heat can be moved from one
place to another. Heat travels from hot to cold. The larger the temperature difference,
the faster heat travels. Cold, then, is the absence of heat. All materials contain heat
down to -460 Fahrenheit, absolute zero. At absolute zero, there is nothing colder to
COMPONENTS OF A BASIC REFRIGERATION SYSTEM
Refer to figure 1-1. This figure illustrates the refrigeration system and the
location of the major components. The following paragraphs provide the functions of
the major components.
a. Evaporator. The evaporator boils or evaporates refrigerant. It changes the
state of the refrigerant from a liquid to vapor and absorbs heat.
b. Compressor. The compressor increases the vapor pressure and moves the
refrigerant. The types of compressors are hermetic, semihermetic, and open.
c. Condenser. The condenser condenses the refrigerant. It changes the state
of refrigerant from vapor to liquid and gives up heat to the atmosphere.
d. Flow Controls. The flow controls create a pressure difference and regulate
the quantity of refrigerant flow. Types of flow controls are as follows:
(1) Capillary tube. The inside diameter and length control the flow. This
tube is used on balanced manufactured units and only with hermetic compressors. It is
a simple and low cost method to control refrigerant flow. You must use an accumulator
strainer dryer with the capillary tube.
(2) High side float. This control is used in high volume centrifugal systems
and big chillers. It passes liquid but not vapor.
Low side float. This control is generally used with ammonia systems.
(4) Automatic expansion valve. The valve applies constant pressure on the
evaporator and is commonly used on water fountains.
(5) Thermostatic expansion valve. The sensing bulb refrigerant in the bulb