Exergoeconomic analysis of an expander-assisted dual-evaporator refrigeration system with internal heat exchange

Dual-evaporator vapor-compression refrigeration systems offer operational flexibility but suffer performance penalties due to throttling losses and off-design conditions. A thermodynamic and exergoeconomic assessment is conducted to evaluate the design feasibility of integrating mechanical expansion work recovery and internal heat exchange. A baseline dual-evaporator configuration is compared with an expander-assisted system incorporating a coupled expander-compressor unit and an internal heat exchanger. Energy, exergy, and cost analyses are performed under identical operating conditions to isolate the effects of work recovery and enhanced subcooling. System performance is examined across a wide range of condenser and evaporator temperatures, cooling-load distribution ratios, and refrigerants (R32, R1234yf, R134a, and R290), representing conventional, low-GWP, and natural options. Results identify the cooling-load distribution ratio between evaporators as the dominant design parameter, directly affecting both recoverable expansion work and economic viability. Mechanical work recovery reduces compressor power consumption by up to 49% and decreases total exergy destruction by 58%. The internal heat exchanger improves performance stability at elevated condenser temperatures. The economic analysis further indicates that the economic advantage of the proposed configuration is most pronounced at low mass flow rate ratios and progressively diminishes as the mass flow rate ratio increases. The refrigerant comparison reveals a distinct design trade-off: R1234yf provides the most favorable thermodynamic performance and total investment cost, R290 offers the highest cooling capacity and lowest payback period, whereas R32 exhibits the lowest exergy efficiency improvement under the investigated conditions.