Exam 47: High-Pressure, Low-Pressure, and Absorption Chilled-Water Systems

A centrifugal compressor uses ____ for capacity control.

Since there are no "valves" in a scroll compressor, what must be done to prevent refrigerant from flowing backward when the compressor cycles off?

When a chiller using a low-pressure refrigerant is operating, the low pressure side of the system ____.

Two basic categories of chillers are the ____.

Electronic starters are much smaller than conventional starters.

In centrifugal compressors, capacity control is accomplished by the use of ___________________________________ at the impeller inlet.

Name two methods commonly used to unload a reciprocating compressor.

The evaporator of a chiller can be used to absorb heat from ____.

Speeds up to ____ rpm are used in centrifugal compressors.

Centrifugal compressors are designed with the lubrication isolated from the refrigerant vapor. Why?

A purge unit ____.

The refrigerant in an absorption chiller whose source of energy is steam or hot water is ____________________.

What is accomplished by having a compressor that is equipped with unloaders?

How is the capacity of a screw compressor controlled?

Lithium bromide is ideal for use in absorption systems because it is non-corrosive.

The ends of a chiller evaporator are closed off by standard or marine boxes. What is the difference?

To unload a reciprocating compressor, hot gas bypass across the cylinder is the best method.

Why are multiple smaller compressors sometimes preferred over one large compressor?

The compressors used in low pressure chillers are the ____ type.

Why are open-drive compressors often started up for a short time in the off season?