Chapter 26
The most common temperature ranges for refrigeration systems are
High, medium,low
A secondary fluid or refrigerant
A low temp antifreeze solution
The _____ of a gas is the highest temperature that the gas can have and still be condensible by the application of pressure
Critical point
On a system with multiple evaporators kept at different temps, what component is used on the higher temp evaporator to prevent pressures from dropping below design
Evap pressure regulator
A system that operates at the lowest possible head pressure by taking advantage of cool ambient temperatures that are used as the condensing medium, is said to operate with
Floating head pressure
Refrigerated air driers typically use a ______ to place a false load on the refrigeration circuit when there is no heat
Hot gas bypass valve
When the compressors are located in the equipment room,the piping is routed
In floor chases or in plastic pipes under the floor
The two common methods for rejecting heat from refrigerated cases are
Inside the store(package unit) outside the store(split system)
The type of cooler that is made up of interlocking panels that are assembled on the job site
Knock down cooler
In low temp walk in systems, the condensate drain like
Must be heated to prevent freezing
CO2, ammonia, butane ,isobutane are all examples of what
Natural refrigerants
The two broad categories of display cases are
Open and closed type
A mullion heater is used to
Prevent the formation of moisture on refrigerated fixtures
Parallel compressor systems that apply two or more compressors to a common suction header, a common discharge header,and a common receiver are called
Rack systems
How are conditions maintained in open display cases where there are high shelves
Sinking cold air creates a curtain effect
A co2 refrigeration cycle that takes place over the refrigerants triple point and below the refrigerants critical point is called
Subcritical cycle
When one large compressor is used, what desirable feature should it have?
Suction muffler
The term used to describe the point at which CO2 exist, all three phases(solid,liquid,gas) simultaneously in equilibrium is
Triple point
exactly matching the refrigeration load with the capacity of refrigeration compressors is referred to as
load matching
compressors on parallel compressor racks, which can be large or small and are usually dedicated to the coldest cases are called
satellite or booster compressors
