Essco

Heat and thermodynamics

100

• Heat that changes temperature on

• What is sensible heat

200

• Heat added with no temp change

• What is latent heat? 

300

• Heat added after evaporation

• What is superheat

400

• Heat transfer by fluid movement

• What is convection

500

• Heat transfer by direct contact

• What is conduction

Refrigeration Cycle

100

• First step in the cycle

What is compression 

200

The part of the cycle that rejects heat 

• what is the condeser 

300

•  Correct cycle order

• What is compression → condensation → expansion → vaporization? 

400

Evaporator function is 

→ What is absorb heat from space? 

500

• First stage inside condenser

What is de-superheating

Metering devices

100

• Fixed orifice systems rely on this instead of superheat control

• What is load matching / pressure differential?

200

• TXV bulb senses this

What is suction line temp 

300

A automatic expansion valve is used when 

What is maintain consistent evap pressure 

400

Hunting TXV is caused by

• What is improper superheat control / overshooting?

500

A decrease in super heat causes the txv to begin to 

What is close 

Compressors

100

Mechanical shaft seal is necessary on 

Open drive compressor 

200

Liquid slugging is 

What is liquid refrigerant in the compressor clearance space 

300

An accumulator is for 

To prevent liquid slugging in the compressor 

400

• What causes high discharge 

What is low suction

500

List all 5 types of compressor 

1. Reciprocating (piston)
2. Scroll
3. Rotary (rolling piston / vane)
4. Screw (helical)
5. Centrifugal

System Faults

100

• Saturation temp is directly related to this

What is pressure 

200

• High superheat + low suction indicates

• What is underfeeding / restriction?

300

• Low head + low suction indicates

• What is undercharge?

400

High head + normal suction suggests

• What is dirty condenser / overcharge?

500

• System with high superheat + high subcooling

• What is liquid line restriction