Experimental study on the improvement of CO2 air conditioning system performance using an ejector

Lee, Jae Seung; Kim, Mo Se; Kim, Min Soo

doi:10.1016/j.ijrefrig.2010.07.025

Cited by 73 publications

(16 citation statements)

References 11 publications

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“…Lee et al [4] experimentally discovered that the COP of the ejector-expansion cycle was approximately 15% higher than that of the reference cycle. Through the experiment, Liu et al [5] found that the maximum COP gain by the introduction of the ejector in a transcritical CO 2 refrigeration cycle could reach 36%.…”

mentioning

confidence: 99%

Effect of Suction Nozzle Pressure Drop on the Performance of an Ejector-Expansion Transcritical CO2 Refrigeration Cycle

Zhang

Tian

2014

Entropy

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Abstract:The basic transcritical CO 2 systems exhibit low energy efficiency due to their large throttling loss. Replacing the throttle valve with an ejector is an effective measure for recovering some of the energy lost in the expansion process. In this paper, a thermodynamic model of the ejector-expansion transcritical CO 2 refrigeration cycle is developed. The effect of the suction nozzle pressure drop (SNPD) on the cycle performance is discussed. The results indicate that the SNPD has little impact on entrainment ratio. There exists an optimum SNPD which gives a maximum recovered pressure and COP under a specified condition. The value of the optimum SNPD mainly depends on the efficiencies of the motive nozzle and the suction nozzle, but it is essentially independent of evaporating temperature and gas cooler outlet temperature. Through optimizing the value of SNPD, the maximum COP of the ejector-expansion cycle can be up to 45.1% higher than that of the basic cycle. The exergy loss of the ejector-expansion cycle is reduced about 43.0% compared with the basic cycle.

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confidence: 99%

Effect of Suction Nozzle Pressure Drop on the Performance of an Ejector-Expansion Transcritical CO2 Refrigeration Cycle

Zhang

Tian

2014

Entropy

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“…As shown in Fig. 11, at the same operating conditions, Lee at al. (2011) found that the system with the ejector caused the pressure in the compressor inlet (point 1′) to be higher than that (point 1) of a SC system.…”

Section: Ejector As An Expansion Devicementioning

confidence: 63%

“…Yan et al (2013) determined that the COP of the combined ejector-vapor compression cycle based on R134a and air-cooled condenser improves by approximately 15.9-21.0 %. Studies on the performance of a CO 2 A/C system using the ejector as an expansion device by Lee et al (2014) also indicated that the cooling capacity and COP in the A/C system using an ejector are higher than those in the conventional system at an 11 p-h diagrams in CO 2 A/C system using and ejector and conventional/SC system (Lee at al. 2011) entrainment ratio greater than 0.76.…”

Section: Ejector As An Expansion Devicementioning

confidence: 99%

Achieving a better energy-efficient automotive air-conditioning system: a review of potential technologies and strategies for vapor compression refrigeration cycle

et al. 2015

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This article presents a review of potential technologies and strategies to develop an energyefficient automotive air-conditioner based on the vapor-compression refrigeration cycle system. This paper is broadly divided into two sections. The first is a review of component optimization (primary and secondary components) that enhances the energy efficiency of the automotive air-conditioning (AAC) system. The second presents a review of operational management and control that efficiently consumes energy in operating the AAC system while maintaining vehicular thermal comfort satisfaction. Some of the technologies and strategies described in this article are still conceptual and are the subject of ongoing research. However, the growing demand to reduce energy consumption by developing a new AAC system has led to an increasing number of related studies aimed at generating alternative conventional systems in the near future. Keywords Automotive air-conditioning system . Efficient component . Energy efficiency improvement . Operational management Nomenclature A/C Air-conditioning AAC Automotive air-conditioning CRC Conventional refrigerant cycle DEAC Dual-evaporator air-conditioning DX Direct expansion EEV Electronic expansion valve EV Electric vehicle EVDC Externally controlled variable capacity compressor FCC Fixed capacity compressor FDC Fixed displacement compressor FSTPID Fuzzy self-tuning proportional integral derivative HVAC Heating, ventilation, and air conditioning MEC Modified ejector cycle RV Revolving vane SC Standard cycle SEC Standard ejector cycle TEV Thermostatic expansion valve TPERC Two-phase ejector refrigerant cycle VAV Variable air volume VCC Variable capacity compressor VCR Vapor compression refrigeration Energy Efficiency

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“…Lee et al [18] presented the experimental results of the R744 ejector expansion refrigeration system, and found that the choked flow appeared when the motive nozzle throat diameter is less than 1.0 mm, but disappeared when the nozzle throat diameter is over 1.0 mm. Chaiwongsa and Wongwises [19] investigated the effects of throat diameter of the motive nozzle on the performance of R134a ejector expansion refrigeration system.…”

Section: Introductionmentioning

confidence: 99%

Choked Flow Characteristics of Subcritical Refrigerant Flowing Through Converging-Diverging Nozzles

Zhang

Tian

Tong

et al. 2014

Entropy

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This paper presents the experimental results the choked flow characteristics of a subcritical refrigerant through a converging-diverging nozzle. A test nozzle with a throat diameter of 2 mm was designed and developed. The influence of operating conditions on the choked flow characteristics, i.e., the pressure profile and mass flow rate under choked flow conditions are investigated. The results indicate that the choked flow occurs in the flow of subcritical refrigerant through nozzles under the normal working conditions of air-conditioners or heat pumps. The pressure drop near the throat is about 80% of the total pressure drop through the nozzle. The critical mass flux is about 19,800 ~ 24,000 kg/(s·m 2 ). The critical mass flow rate increases with increasing the upstream pressure and subcooling. Furthermore, the relative errors between the model predictions and the experimental results for the critical mass flux are also presented. It is found that the deviations of the predictions for homogeneous equilibrium model and Henry-Fauske model from the experimental values are −35% ~ 5% and 15% ~ 35%, respectively.

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Experimental study on the improvement of CO2 air conditioning system performance using an ejector

Cited by 73 publications

References 11 publications

Effect of Suction Nozzle Pressure Drop on the Performance of an Ejector-Expansion Transcritical CO2 Refrigeration Cycle

Effect of Suction Nozzle Pressure Drop on the Performance of an Ejector-Expansion Transcritical CO2 Refrigeration Cycle

Achieving a better energy-efficient automotive air-conditioning system: a review of potential technologies and strategies for vapor compression refrigeration cycle

Choked Flow Characteristics of Subcritical Refrigerant Flowing Through Converging-Diverging Nozzles

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