Lesson 6: Commercial Refrigeration, Part 2Lesson 6 Quizzes

subcritical cycle.

A CO2 refrigeration cycle that takes place above the refrigerant's triple point and below the refrigerant's critical point is called a A natural cycle. B supercritical cycle. C subcritical cycle. D transcritical cycle.

prevent the formation of moisture on refrigerated fixtures.

A mullion heater is used to A prevent the formation of moisture on refrigerated fixtures. B prevent ice formation on the TXV or capillary tubing. C keep the receiver warm in low-ambient conditions. D defrost the evaporator of medium-temperature fixtures.

a low-temperature antifreeze solution.

A secondary fluid or refrigerant is usually A a type of distilled water solution. B a low-pressure HFC refrigerant. C a methane-based refrigerant. D a low-temperature antifreeze solution.

floating head pressure.

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 a A subcritical cycle. B fixed head pressure. C floating head pressure. D transcritical cycle.

knock-down cooler.

A type of cooler that is made up of interlocking panels that are assembled at the jobsite, which can be disassembled to be relocated, is called a(n) A package cooler. B upright chest fixture. C reach-in fixture. D knock-down cooler.

natural refrigerants.

CO2 (R-744), ammonia (R-717), propane (HC-290), butane (HC-600), and isobutane (HC-600a) are all examples of A natural refrigerants. B HFCs. C secondary fluids. D HFOs.

satellite or booster compressors.

Compressors on parallel compressor racks, which can be large or small and are usually dedicated to the coldest cases, are called A remote compressors. B auxiliary compressors. C satellite or booster compressors. D off-site or off-location compressors.

load matching.

Exactly matching the refrigeration load with the capacity of refrigeration compressors is referred to as A capacity control. B load paralleling. C load shedding. D load matching.

Sinking cold air creates a curtain effect.

How are conditions maintained in open display cases when there are high shelves? A A continuous run cycle handles the constant heat load. B Warm air rises out of the cooler, leaving only cool air. C Sinking cold air creates a curtain effect. D Evaporating water from misting systems removes heat.

must be heated to prevent freezing.

In low-temperature walk-in systems, the condensate drain line A must terminate inside of the box. B must be piped above the evaporator for proper drainage. C must be heated to prevent freezing. D should be pitched toward the evaporator.

Evaporator pressure regulator

On a system with multiple evaporators that are kept at different temperatures, what component is used on the higher-temperature evaporators to prevent their pressures from dropping below the desired setting? A Crankcase pressure regulator B Hot-gas bypass valve C Pressure transducer D Evaporator pressure regulator

rack systems.

Parallel compressor systems that apply two or more compressors to a common suction header, a common discharge header, and a common receiver are called A loaded systems. B split systems. C booster systems. D rack systems.

hot-gas bypass valve

Refrigerated air driers typically use a(n) _______ to place a "false load" on the refrigeration circuit when there is no heat load. A hot-gas bypass valve B condenser flooding device C evaporator pressure regulator D condenser air recycler

critical point

The __________ of a gas is the highest temperature that the gas can have and still be condensable by the application of pressure. A critical point B dew point C triple point D flash point

high, medium, and low temperature.

The most common temperature ranges for refrigeration systems are A low and ambient temperature. B high and low temperature. C ambient and variable temperature. D high 47-60, medium 28-40, and low temperature 0 - 20.

triple point.

The term used to describe the point at which CO2 exists as all three phases (vapor, liquid, and solid) simultaneously in equilibrium is the A transcritical point. B triple point. C subcritical point. D critical point.

open- and closed-type.

The two broad categories of display cases are A open- and closed-type. B indoor and outdoor fixtures. C high- and low-pressure systems. D vertical and horizontal cases.

inside the store (package-system) or outside the store (split-system).

The two common methods for rejecting heat from refrigerated cases are A inside the store (package-system) or outside the store (split-system). B inside the store (ambient-dependent) or outside the store (geothermal). C inside the store (split-system) or outside the store (package-system). D inside the store (recirculated-type) or outside the store (ambient-dependent).

Cylinder unloaders or variable-speed drive

When one large compressor is used, what desirable feature should it have? A Suction muffler B Discharge muffler C Hot-gas bypass D Cylinder unloaders or variable-speed drive

in floor chases or in plastic pipes under the floor.

When the compressors are located in the equipment room, the piping is routed A in floor chases or in plastic pipes under the floor. B in suspended ceilings. C in back of the walls. D between the walls.