Feasibility of a Practical Carnot Engine – Statement Check Is it possible to construct and operate a real, practical engine that exactly follows the ideal, perfectly reversible Carnot cycle between two reservoirs?

Introduction / Context:
The Carnot cycle defines the theoretical upper bound on efficiency for any heat engine operating between two fixed temperatures. It comprises perfectly reversible isothermal and adiabatic steps. This question probes whether such a cycle can be realized exactly in a real engine, not merely approximated.

Given Data / Assumptions:

• Carnot cycle requires zero entropy generation (fully reversible processes).
• Heat transfer must occur with infinitesimal temperature differences.
• No pressure drops, no friction, no leakage, and perfectly slow (quasi-static) operation.

Concept / Approach:

Real devices inevitably have irreversibilities: mechanical friction, finite temperature gradients for practical heat transfer, fluid flow losses, valve and seal leakage, and finite-rate processes. Eliminating these entirely is impossible. While some laboratory setups can approach reversible behavior at vanishing power, an engine that exactly executes a Carnot cycle in finite time with finite power cannot exist. Therefore, the statement about making an engine working exactly on the Carnot cycle is judged impossible in practice, though it remains a useful ideal for benchmarking.

Step-by-Step Solution:

Verification / Alternative check:

Exergy analyses of any functioning engine show nonzero exergy destruction T0 * S_gen > 0. Only in the limit of infinitely slow, zero-power operation can processes approach reversibility—still not an exact, usable engine.

Why Other Options Are Wrong:

Claims of possibility (with exotic media or huge heat exchangers) overlook the requirement of zero entropy generation. “Zero power output” or “infinite exchangers” still do not yield an exact Carnot engine; they only approach it in limiting cases.

Common Pitfalls:

Confusing “approach Carnot efficiency” with “achieve Carnot exactly”; ignoring the power-efficiency trade-off in near-reversible operation.

Final Answer:

impossible