Thermodynamic Cycles – Check the Process Types Both the Ericsson cycle and the Joule (Brayton) cycle each contain two constant-pressure (isobaric) heat-transfer processes, used respectively for heat addition and heat rejection in their ideal representations.

Introduction / Context:
Engineering thermodynamics uses ideal cycles to model real machines. The Ericsson and the Joule (Brayton) cycles are both gas-turbine–type cycles. A frequent point of confusion is which processes are isobaric, isentropic, or isothermal. This question asks whether both cycles include two constant-pressure processes. Understanding this helps with drawing correct p–v and T–s diagrams and applying the proper equations for work and heat.

Given Data / Assumptions:

• Idealized cycles with negligible pressure losses in heat exchangers and ducts.
• Internally reversible compression and expansion unless otherwise noted.
• Perfect-gas behavior with nearly constant specific heats for introductory analysis.

Concept / Approach:

The ideal Joule (Brayton) cycle has two isentropic processes (compression in the compressor and expansion in the turbine) and two isobaric processes (heat addition in the combustor/heater and heat rejection in the cooler/exhaust). The ideal Ericsson cycle consists of two isothermal processes (compression at the low temperature and expansion at the high temperature) combined with two isobaric regenerative processes that transfer heat internally. Thus, in both cycles the heat-transfer segments occur at essentially constant pressure, justifying the statement.

Step-by-Step Solution:

Verification / Alternative check:

T–s diagrams show horizontal isobars for the heat-transfer portions in both cycles; the remaining legs are isentropic (Joule) or isothermal (Ericsson). Regeneration in Ericsson shifts heat between the two isobars and enables high efficiency when idealized.

Why Other Options Are Wrong:

“False because they are isothermal” confuses Ericsson’s isothermal legs with its additional isobaric legs; Joule is not isothermal. “True only for open cycles” is incorrect because closed versions also use isobaric heat exchangers. “True only if regeneration is used” is wrong since Joule does not require regeneration to have isobars.

Common Pitfalls:

Mixing up Ericsson with Stirling (which uses isochoric regeneration), or assuming all constant-pressure segments imply open-cycle combustion. Pressure losses in real heat exchangers modify but do not negate the ideal isobaric model.

Final Answer:

True