Universal bounds on cooling power and cooling efficiency for autonomous absorption refrigerators

Area of Science:

• Thermodynamics
• Statistical Mechanics
• Non-equilibrium Systems

Background:

• Autonomous absorption refrigerators are crucial for cooling applications.
• Understanding fluctuation-thermodynamics is key to optimizing device performance.
• Previous work established thermodynamic uncertainty relations for bounds on power and efficiency.

Purpose of the Study:

• To establish a hierarchy of current fluctuations in autonomous absorption refrigerators.
• To derive new universal bounds on cooling power and efficiency.
• To investigate the saturation of these bounds in the tight-coupling limit.

Main Methods:

• Utilized the Onsager reciprocity relation and the refrigeration condition.
• Applied thermodynamic uncertainty relations to derive fluctuation hierarchies.
• Analyzed two paradigmatic absorption refrigerator models (four-level and two-level working fluids).

Main Results:

• Demonstrated a hierarchy in relative current fluctuations for cold, hot, and work terminals.
• Established a hierarchy of universal bounds on mean cooling power.
• Derived a tighter bound on cooling efficiency compared to existing thermodynamic uncertainty relations.
• Showed that all derived bounds saturate in the tight-coupling limit.

Conclusions:

• The identified hierarchy of fluctuations provides tighter performance bounds for absorption refrigerators.
• The work current fluctuation offers the tightest bound on cooling power.
• The findings are robust across different working fluid models and system-bath interaction regimes.