Thermodynamic insights and comparative evaluation of R22, R410A, R32, R290, and R1234ze(E) in air source heat pump systems: A theoretical study

Abstract

Air source heat pumps (ASHPs), particularly split air conditioners, are widely favored for their energy efficiency, ease of application, and capacity to provide both seasonal heating and cooling. However, their performance and environmental impact are largely determined by the refrigerants they use. This study examines the performance and operating parameters of an ASHP retrofitted with five different refrigerants—R22, R410A, R32, R290, and R1234ze(E)—using a physics-based model. R22 and R410A were considered phased-out refrigerants due to their environmental impact, while R32, R290, and R1234ze(E) were evaluated as eco-friendly pure refrigerant alternatives. Refrigerants were analyzed at outdoor temperatures of 0°C, 7°C, and 15°C, with evaporator and condenser pressure drops included to improve model accuracy. R32 demonstrated superior coefficient of performance (COP) at lower outdoor temperatures, while R1234ze(E) outperformed other refrigerants at 15°C. R1234ze(E) exhibited the highest refrigerant flow rate, nearly twice that of R290 and R32, increasing charging costs. However, its low condensing pressure allows for more economical equipment. R290 showed the lowest pressures, facilitating safer sealing despite its high flammability. Pressure drop and pipe diameter requirements are critical in system design. R1234ze(E) requires larger pipes to mitigate pressure losses, increasing system costs and refrigerant charge. R32, with minimal pressure loss, allows smaller pipes, making it cost-effective. R290, though needing slightly larger pipes than R32, operates at lower condenser and evaporator pressures, improving safety and reducing sealing challenges. This feature, combined with its low GWP, makes R290 a promising next-generation refrigerant, though its high flammability remains a concern. R32 consistently achieves the lowest condensing temperatures at lower outdoor conditions. These findings provide insights into the trade-offs between environmental benefits, performance, and operational considerations of various refrigerants.

Keywords

• Air source heat pump
• Refrigerant performance analysis
• Low GWP refrigerants
• Thermodynamic model

Kaynakça

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