CIRO Energy Efficiency & System Optimization

Question 1

What is the relationship between condensing temperature and system energy consumption?

Accepted Answer

Higher condensing temperatures increase compressor work and energy consumption; lowering condensing temperature by 1°F saves approximately 1-2% energy

Answer

The compressor must work harder to reach higher discharge pressures (higher condensing temperatures). Each 1°F reduction in condensing temperature saves approximately 1-2% in compressor energy, making condenser maintenance critical for efficiency.

Question 2

How does floating head pressure control save energy?

Accepted Answer

By allowing condensing pressure to decrease when ambient conditions permit, reducing compressor work

Answer

Floating head pressure allows the system to take advantage of cooler ambient conditions by lowering condensing pressure (and temperature) below the fixed setpoint, reducing compressor energy consumption significantly.

Question 3

What is the benefit of variable frequency drives (VFDs) on compressor motors?

Accepted Answer

VFDs adjust motor speed to match actual load, avoiding the energy waste of running at full speed during partial load conditions

Answer

VFDs allow compressors to operate at reduced speed during partial load, closely matching capacity to actual demand. This can save 20-50% of compressor energy compared to constant-speed operation with slide valve unloading.

Question 4

What impact does evaporator fouling have on system performance?

Accepted Answer

Fouled evaporators reduce heat transfer, lower suction pressure, increase compressor run time, and waste energy

Answer

Ice buildup, oil accumulation, or debris on evaporator surfaces acts as insulation, reducing heat transfer. The system compensates by running longer at lower suction pressures, significantly increasing energy consumption.

Question 5

How does proper insulation of refrigerated piping save energy?

Accepted Answer

Insulation prevents heat gain into cold pipes and moisture condensation, maintaining system efficiency and preventing ice buildup on pipes

Answer

Uninsulated cold piping absorbs heat from the surrounding environment, adding to the cooling load. Proper vapor-barrier insulation prevents both heat gain and moisture condensation, maintaining system efficiency.

CIRO - Certified Industrial Refrigeration Operator Practice Test

CIRO - Certified Industrial Refrigeration Operator Practice Test

CIRO Energy Efficiency & System Optimization