Study of capillary tubes in a transcritical CO2 refrigeration system

Madsen, Kenneth B.; Poulsen, Claus S.; Wiesenfarth, Maike

doi:10.1016/j.ijrefrig.2005.09.009

Cited by 32 publications

(13 citation statements)

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“…Parametric study for cooling pressure, evaporating temperature, ambient heat transfer coefficient and capillary size was presented. Recently Madsen et al (2005) investigated an adiabatic capillary tube in a transcritical CO 2 refrigeration system. However, the expansion was assumed to be isenthalpic; critical explanation on the mathematical model and related assumptions were not reported and the testing was performed for a limited range of operating conditions.…”

Section: Introductionmentioning

confidence: 99%

Adiabatic capillary tube flow of carbon dioxide in a transcritical heat pump cycle

Agrawal

Bhattacharyya

2007

Int. J. Energy Res.

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SUMMARYFlow characteristics of an adiabatic capillary tube in a transcritical CO 2 heat pump system have been investigated employing the homogeneous model. The model is based on fundamental equations of mass, energy and momentum which are solved simultaneously. Two friction factor empirical correlations (Churchill, Lin et al., Int. J. Multiphase Flow 1991; 17(1):95-102) and four viscosity models (Mcadams, Cicchitti, Dukler and Lin) are comparatively used to investigate the flow characteristics. Choked condition at the outlet is also investigated for maximum mass flow rate. Subcritical and supercritical thermodynamic and transport properties of CO 2 are calculated employing a precision property code. Choice of viscosity model causes minor variation in results unlike in chlorofluorocarbons (CFCs) refrigerants.Relationships between cooling capacity with capillary tube diameter, length and maximum mass flow rate are presented. A lower evaporating temperature yields a larger cooling capacity due to the unique thermodynamic properties of CO 2 . It is also observed that an optimum cooling capacity exists for a specified capillary tube.

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Section: Introductionmentioning

confidence: 99%

Adiabatic capillary tube flow of carbon dioxide in a transcritical heat pump cycle

Agrawal

Bhattacharyya

2007

Int. J. Energy Res.

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“…More recently, Agrawal and Bhattacharyya (2008a,b) proposed a numerical model for predicting the transcritical carbon dioxide capillary tube flow for heat pump applications. The results were compared with the numerical results of Chen and Gu (2005) and the experimental results of Madsen et al (2005), showing a good level of agreement.…”

Section: Introductionmentioning

confidence: 79%

“…Chen and Gu (2005) developed a model for simulating the R-744 flow through non-adiabatic capillary tubes, but their results were not compared with experimental data. In the same year, Madsen et al (2005) investigated the high-side pressure control of CO 2 refrigeration systems using capillary tubes. Experimental and theoretical studies were carried out and a reasonable level of agreement between measured data and model predictions was achieved.…”

Section: Introductionmentioning

confidence: 99%

A study of transcritical carbon dioxide flow through adiabatic capillary tubes

Silva

Hermes

Melo

et al. 2009

International Journal of Refrigeration

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“…Then the effects of parameters such as refrigerant temperature output of gas cooler, isentropic efficiency of compressors, the presence or absence of internal heat exchanger (SGHX), mean pressure between the two compression stages, the intercooler value, compressors consumption and energy consumption have been investigated. Operating parameters to simulate operating conditions are shown in Table 1 [11][12][13][14]. In addition, using parameters obtained by Ozgur [15], the mean optimized pressure by equation (1) is estimated.…”

Section: Statement Of the Problem And Numerical Simulationmentioning

confidence: 99%

Numerical analysis of transcritical carbon dioxide compression cycle: a case study

Keshtkar¹

2018

JACST

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This study deals with thermodynamic investigation of a refrigeration compression cycle with carbon dioxide refrigerant and two stage compression. In this paper, the effect of intercooler in the two-stage compression system at different pressures of gas cooler is investigated. In addition, the performance of one stage compression cycle and two-stage compression cycle are compared and eventually, the performance of system is investigated under the influence of the change of variables such as gas cooler pressure, isentropic efficiency of the compressors, the intercooling rate between the two stages of compression, the refrigerant gas cooler outlet temperature is examined. Due to evaporation temperature in the evaporator   C and refrigeration capacity (kW) results show that the coefficient of performance in the two-stage compression with intercooler is increased compared to the single-stage compression cycle.

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Study of capillary tubes in a transcritical CO2 refrigeration system

Cited by 32 publications

References 1 publication

Adiabatic capillary tube flow of carbon dioxide in a transcritical heat pump cycle

Adiabatic capillary tube flow of carbon dioxide in a transcritical heat pump cycle

A study of transcritical carbon dioxide flow through adiabatic capillary tubes

Numerical analysis of transcritical carbon dioxide compression cycle: a case study

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