An Ejector Transient Performance Model for Application in a Pulse Refrigeration System

Clou, Sven du; Brooks, Michael J.; Lear, W. E.; Sherif, S. A.; Khalil, Essam E.

doi:10.2514/6.2011-5804

Cited by 4 publications

(1 citation statement)

References 16 publications

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“…With the deepening of the research on ejector, some scholars have begun to study the transient process. Clou et al proposed a 1D ejector transient model to investigate the performance in a pulse refrigeration system (PRS). Their model can accurately describe the geometry required for steady flow conditions and can meet the response requirements.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of ejector transient characteristics for a 130‐kW PEMFC system

et al. 2020

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Summary Improvement of fuel utilization is an important issue for proton exchange membrane fuel cell (PEMFC) system. As a promising anode recirculation method, ejector has attracted great attention because it does not require additional power consumption. However, some transient processes such as the suck, diffusion, and mix of fluids are still not thoroughly revealed, which significantly influence ejector performances. In this study, a dynamic three‐dimensional (3D) multicomponent ejector model for a 130‐kW PEMFC system is developed. The model is validated against experimental data, including the entrainment ratio and mass flow rates. The effects of operating conditions (eg, pressure, water vapor, and nitrogen mass fraction) are investigated. The results show that the fuel supply can be controlled by the primary flow pressure. When the pressure difference between the primary and secondary flow is less than 10 kPa, the secondary flow cannot be sucked into the ejector. The transient response of ejector during stack power variations can be classified into two periods: the primary flow impact period and the mixed flow impact period. Under normal fuel cell system operating conditions, when the inlet relative humidity of the secondary flow is higher than 85%, the water vapor condensation is possible to happen at the ejector outlet region, leading to fuel supply instability. Besides, the hydrogen entrainment ratio decreases with the increase of nitrogen mass fraction. The effects of geometric parameters (eg, nozzle convergence angle, secondary flow tube diameter, mixing tube length, and diffuser angle) on ejector performances are also studied. It is found that the relatively short tube leads to pressure fluctuations in the vacuum region. Increasing the tube length is beneficial to creating a stable vacuum region. However, excessive tube length can increase the friction loss. Increasing the secondary flow inlet tube diameter is beneficial to the entrainment ratio. However, further enlarging the diameter contributes negligibly to the increase of entrainment ratio once the secondary flow mass rate depends on pressure.

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Section: Introductionmentioning

confidence: 99%

Numerical investigation of ejector transient characteristics for a 130‐kW PEMFC system

et al. 2020

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Parametric Analysis and Comparison of Ejector Expansion Refrigeration Cycles With Constant Area and Constant Pressure Ejectors

Seçkin

2017

Journal of Energy Resources Technology

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In this work, parametric analysis of ejector expansion refrigeration cycles (EERC) with two different types of ejectors (constant area (CA) ejector and constant pressure (CP) ejector) is performed, and comparison of the results is presented. Effects of variation in operational parameters (condenser temperature, evaporator temperature, and cooling capacity) on coefficient of performance (COP), entrainment ratio (w), and pressure lift factor (Plf) are investigated. The range of variation for evaporator temperature, condenser temperature, and cooling capacity are −5 to 15 °C, 50–70 °C, and 10–80 kW, respectively. The ejector refrigeration cycle is simulated by ees software. The obtained results are validated by the experimental data available in the literature. The refrigerant R134a is selected based on the merit of its environmental and performance characteristics. The results show that the effect of evaporator temperature is much higher than that of condenser temperature on Plf. In contrast, the influence of condenser temperature on COP is much stronger than that of evaporator temperature. It is seen that COP and Plf of ejector expansion refrigeration cycle with constant pressure ejector (CP-EERC) are higher than those of refrigeration cycle with constant area ejector.

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Performance and Control of a Pulse Thermal Loop Heat Transport System

Clou¹,

Brooks²,

Lear³

et al. 2015

Journal of Thermophysics and Heat Transfer

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An Ejector Transient Performance Model for Application in a Pulse Refrigeration System

Cited by 4 publications

References 16 publications

Numerical investigation of ejector transient characteristics for a 130‐kW PEMFC system

Numerical investigation of ejector transient characteristics for a 130‐kW PEMFC system

Parametric Analysis and Comparison of Ejector Expansion Refrigeration Cycles With Constant Area and Constant Pressure Ejectors

Performance and Control of a Pulse Thermal Loop Heat Transport System

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