Effects of Nozzle Exit Position on Condenser Outlet Split Ejector-Based R600a Household Refrigeration Cycle

Yongseok Jeon,Sanghoon Kim,Hoon Kim,Jae Hwan Ahn

doi:10.3390/en13195160

Yongseok Jeon, Sanghoon Kim + Show 2 more

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https://doi.org/10.3390/en13195160

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Abstract

The objective of this study is to investigate the performance characteristics of a small-sized R600a household refrigeration system that adopts a condenser outlet split (COS) ejector cycle under various operating and ejector geometry conditions. The coefficient of performance and pressure lifting ratio of the COS ejector cycle were analyzed and measured by varying the entrainment ratio, compressor speed, and nozzle exit position. The optimum nozzle exit position in the COS ejector cycle adopted to achieve the maximum cycle performance was proposed as a function of the compressor speed and entrainment ratio. The optimum nozzle exit position was 0 mm when the entrainment ratio and compressor speed were low, and it increased as the entrainment ratio and compressor speed increased owing to the associated internal pressure drop in the suction section.

Highlights

Many household refrigeration cycles such as those used in refrigerators, air conditioners, dehumidifiers, and water purifiers are applied globally; several studies on improving the energy efficiency of household refrigeration cycles have been conducted [1,2,3,4,5,6,7,8,9,10]
As the compressor speed increased, the expansion loss of the total condenser outlet split (COS) ejector cycle was increased; subsequently, the pressure lifting ratio (PLR) increased with the compressor speed owing to the increase in potential ejector effects
An increased nozzle exit position (NXP) implies a greater distance from the inlet of the mixing section; as a result, when the NXP increased beyond the maximum point of the PLR, the PLR

Summary

Introduction

Many household refrigeration cycles such as those used in refrigerators, air conditioners, dehumidifiers, and water purifiers are applied globally; several studies on improving the energy efficiency of household refrigeration cycles have been conducted [1,2,3,4,5,6,7,8,9,10]. A two-phase ejector cycle is considered one of the most effective expansion methods for improving the energy efficiency of the refrigeration cycle through a reduction in the expansion loss [11]; it has been widely applied in high-pressure and high-capacity refrigeration cycles that suffer from significant expansion losses, such as the transcritical cycle [12,13,14,15]. He et al [16] analyzed the exergetic efficiency in a transcritical CO2 cycle using computational fluid dynamics (CFD). The application of a standard two-phase ejector cycle with a phase separator is unsuitable for household refrigeration cycles with a relatively low capacity and low operating pressure

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