Identify the Bell–Coleman refrigeration cycle The Bell–Coleman air refrigeration cycle is thermodynamically equivalent to which reversed power cycle?

Introduction / Context:
The Bell–Coleman cycle (air cycle refrigeration) is used in applications like aircraft cooling and some specialized cryogenic systems. It employs air as the working fluid and standard turbomachinery components rather than phase-change refrigerants.

Given Data / Assumptions:

• Working fluid: air modeled as an ideal gas.
• Basic components: compressor, heat exchanger (aftercooler), expander (turbine), and heat exchanger (refrigerator).
• Idealized processes: adiabatic compression/expansion and constant-pressure heat exchange.

Concept / Approach:
The sequence of processes in Bell–Coleman exactly mirrors the Joule (Brayton) gas-turbine power cycle but operated in reverse: instead of producing net work from heat addition, it consumes work to move heat from cold space to a warm sink. Therefore, the Bell–Coleman cycle is the reversed Joule (Brayton) cycle.

Step-by-Step Solution:

Verification / Alternative check:
Temperature–entropy and pressure–volume diagrams of the air cycle refrigeration align with the reversed Brayton sequence; the device COP expressions also correspond to Brayton relations.

Why Other Options Are Wrong:

Reversed Rankine: involves phase change of a condensable refrigerant, not ideal-gas air.Reversed Otto/Carnot/Diesel: do not match the constant-pressure heat exchange and adiabatic legs of the air cycle used here.

Common Pitfalls:
Assuming all refrigeration cycles are reversed Rankine because most domestic systems use vapor-compression; air cycle is a different family.

Final Answer:

Reversed Joule (Brayton) cycle