What are the four primary components of a vapor-compression refrigeration cycle?

Compressor, condenser, expansion valve, and evaporator

True or False: The throttling process through an expansion valve is isenthalpic.

True. The enthalpy remains constant during throttling (h₃ = h₄).

In which component does the refrigerant absorb heat from the refrigerated space?

Evaporator

What is the formula for coefficient of performance (COP) in refrigeration systems?
A) COP = W/Q
B) COP = Q_L/W_net
C) COP = Q_H/Q_L
D) COP = T_H/T_L

B) COP = Q_L/W_net

The refrigeration effect is calculated as _____.

H₁ - h₄

What happens to refrigerant pressure and temperature in the compressor?

Both pressure and temperature increase

One ton of refrigeration equals _____ Btu/hr.

12,000

True or False: Superheating the refrigerant increases the refrigeration effect per unit mass.

False. Superheating prevents liquid from entering the compressor but increases compressor work.

What is the relationship between heat pump COP and refrigeration COP?

COP_HP = COP_R + 1

In the ideal vapor-compression cycle, compression is assumed to be _____.

Isentropic

Which process occurs in the condenser?
A) Constant pressure heat absorption
B) Constant pressure heat rejection
C) Isenthalpic expansion
D) Isentropic compression

B) Constant pressure heat rejection

What is the primary advantage of subcooling refrigerant at the condenser exit?

Increases refrigeration effect per unit mass of refrigerant

The Carnot COP for refrigeration is calculated as _____.

T_L/(T_H - T_L)

True or False: In actual refrigeration cycles, compressor isentropic efficiency is typically 95-100%.

False. Compressor isentropic efficiency is typically 60-85%.

What refrigerant property remains constant during the throttling process?

Enthalpy

In absorption refrigeration systems, what drives the cycle instead of mechanical work?

Heat energy

The intermediate pressure in two-stage compression is approximately _____.

√(P_evap × P_cond)

What is the main working pair in water-lithium bromide absorption systems?

Water (refrigerant) and lithium bromide (absorbent)

True or False: Higher evaporator temperatures result in better COP for refrigeration systems.

True. Smaller temperature lift improves theoretical and actual COP.

EER is calculated as cooling capacity in Btu/hr divided by _____.

Power input in watts

Which refrigerant state typically exists at the evaporator inlet after throttling?
A) Superheated vapor
B) Saturated vapor
C) Two-phase mixture
D) Subcooled liquid

C) Two-phase mixture

What is the primary benefit of using two-stage compression for low-temperature applications?

Reduces compressor discharge temperature and improves volumetric efficiency

The sensible heat ratio (SHR) is defined as _____.

Q_sensible/Q_total

True or False: Cascade refrigeration systems use multiple separate cycles operating in series.

True. Used for very low temperature applications below -40°F.

What environmental factor is measured by ODP in refrigerant selection?

Ozone depletion potential

In psychrometric applications, what does the bypass factor indicate?

Effectiveness of heat transfer in cooling coils

The quality (dryness fraction) at state 4 is calculated as _____.

(h₄ - h_f4)/h_fg4

What is the typical COP range for absorption refrigeration systems?
A) 0.5 - 0.8
B) 2.0 - 3.0
C) 4.0 - 6.0
D) 8.0 - 10.0

A) 0.5 - 0.8

True or False: Ammonia (R-717) has zero ozone depletion potential but is toxic.

True. It's a natural refrigerant used in industrial applications.

Why do large pressure ratios require two-stage compression systems?

Single-stage compression causes excessive discharge temperatures and reduced efficiency

The apparatus dew point (ADP) represents the _____ of the cooling coil.

Effective surface temperature

Which factor most significantly affects the theoretical maximum COP?
A) Refrigerant type
B) Compressor efficiency
C) Temperature difference between reservoirs
D) Mass flow rate

C) Temperature difference between reservoirs

True or False: SEER accounts for varying load conditions throughout the cooling season.

True. It provides seasonal energy efficiency ratio for realistic performance evaluation.