TY  - EJOU
AU  - Shen, Anxiang 
AU  - Ren, Xinxin 
AU  - Wang, Tao 
AU  - Zhou, Jianqiu 

TI  - Graphical Analysis and 3D Thermodynamic Cycle Construction for Variable-Composition Ejector Refrigeration Cycle
T2  - Frontiers in Heat and Mass Transfer

PY  - 
VL  - 
IS  - 
SN  - 2151-8629

AB  - To address the growing number of variable-composition ejector refrigeration cycles, this study proposes analyzing the matching performance between working fluids and cycles through 3D (Temperature-Entropy-Mass fraction) Thermodynamic Diagrams. The ejector refrigeration cycle is decoupled into a driving module and a refrigeration module, and a theoretical upper-bound model (COP<sub>limiting</sub>) that depends only on working-fluid properties is derived from the <i>T</i>-s diagram. Graph-theoretic analysis yields an explicit relation between COP<sub>limiting</sub> and fluid-specific parameters such as Δ<i>s</i><sub><i>b-b<sup><i>′</i></sup></i></sub>/Δ<i>s</i><sub><i>a-b<sup><i>′</i></sup></i></sub> and Δ<i>s</i><sub><i>e-e<sup><i>′</i></sup></i></sub><i>/</i>Δ<i>s</i><sub><i>d-e<sup><i>′</i></sup></i></sub>. Definition of <i>k</i><sub>1</sub> (Δ<i>T</i><sub>4<i>–</i>7</sub>/Δ<i>s</i><sub><i>e-e<sup><i>′</i></sup></i></sub>) and <i>k</i><sub>2</sub> (Δ<i>T</i><sub>3<i>–</i>4</sub>/Δ<i>s</i><sub><i>b-b</i><sup><i>′</i></sup></sub>) reveals that wet fluids favour the refrigeration module, whereas dry fluids favour the driving module. The influence of different mixtures has been also analyzed. The mixture of R227ea/R152a, R245fa/R134a, and Isobutane/pentane achieved their maximum COP<sub>limiting</sub> values at <i>x</i> = 0.5, 0.4, and 0.2, respectively. These optimal compositions all falling within the high-slope region of <i>k</i><sub>2</sub>. Additional parameters (<i>x, t</i><sub><i>g</i></sub>, <i>t</i><sub><i>c</i></sub>) are evaluated: At <i>MF</i><sub><i>t</i></sub> = 0.5, increasing <i>x</i> from 0.1 to 0.2 raises the limiting cycle COP from 0.08 to 0.18 and elevates <i>t</i><sub>e</sub> from −79.24°C to −35.15°C. Raising <i>t</i><sub><i>g</i></sub> from 85°C to 95°C lowers the limiting cycle COP from 0.1269 to 0.1235 while lifting <i>t</i><sub><i>e</i></sub> from −56.00°C to −49.18°C. Increasing <i>t</i><sub><i>c</i></sub> from 30°C to 40°C boosts the limiting cycle COP from 0.1216 to 0.1285 and raises <i>t</i><sub><i>e</i></sub> from −60.84°C to −44.26°C.
KW  - Ejector refrigeration cycle; limiting cycle; zeotropic mixture; graph theory

DO  - 10.32604/fhmt.2026.082573