Transcritical CO2 Ejector Lift Calculator
Refrigeration Efficiency: Calculate two-phase ejector expansion work recovery, suction pressure lift ($Delta P_{lift}$), entrainment ratio ($omega$), and compressor energy savings.
Ejector Operating State & Pressures
Pressure Lift & Energy Savings Output
Recommended Tools & Equipment
Tested hardware and components for high reliability
Two-Phase Ejectors in Transcritical R744 Systems
Multi-ejector blocks represent the pinnacle of modern supermarket and industrial CO2 refrigeration, eliminating the historical "CO2 equator" efficiency barrier in warm climates.
1. Ejector Efficiency Definition
The thermodynamic efficiency of expansion work recovery is defined by Elbel and Hrnjak:
η_ej = ω · [ h( P_diff, s_suc ) - h_suc ] / [ h_mot - h( P_diff, s_mot ) ]
where $\omega = \dot{m}_{suc} / \dot{m}_{mot}$ is the entrainment mass ratio.
Frequently Asked Questions
How does an ejector recover expansion work in transcritical CO2 refrigeration?
In conventional refrigeration, high-pressure liquid throttles through an expansion valve where mechanical pressure energy is completely destroyed as friction. In an ejector, this high pressure (80–100 bar) accelerates fluid through a converging-diverging motive nozzle into a supersonic jet, entraining low-pressure vapor and converting kinetic energy in a diffuser into 2 to 6 bar of suction pressure lift.
Why does a 3 to 5 bar pressure lift deliver substantial energy savings?
Compressor power consumption scales with the pressure ratio $P_{discharge} / P_{suction}$. Raising compressor suction pressure from 28 bar up to 33 bar reduces the compression ratio from 3.2 down to 2.7, reducing compressor electrical power by 12% to 20% during warm summer operating hours.
What is the difference between vapor ejectors and liquid ejectors?
Vapor ejectors entrain low-pressure gas from evaporator outlets, directly lifting suction pressure into parallel compressors. Liquid ejectors entrain unevaporated liquid from overfed evaporators back into the receiver tank, eliminating superheat requirements in evaporator coils and allowing evaporation temperatures to rise by 2–4 K.