Vortex Tube Expansion Two-Stage Transcritical CO2 Refrigeration Cycle

2012 ◽  
Vol 516-517 ◽  
pp. 1219-1223 ◽  
Author(s):  
Ying Fu Liu ◽  
Guang Ya Jin
Keyword(s):  
Mass Fraction ◽  
Vortex Tube ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Outlet Temperature ◽  
Two Stage ◽  
Evaporation Temperature ◽  
Optimum Heat ◽  
Tube Expansion ◽  
Cold Mass

Use of vortex tube as an expansion device in transcritical CO2 cycle could reduce the throttle loss and improve the coefficient of performance. In this paper, a vortex tube expansion two-stage transcritical CO2 refrigeration cycle(VTTC) is established and compared to that of the two-stage transcritical CO2 refrigeration cycle with throttle valve(TVTC). Thermodynamic analysis results indicate that there is also an optimum heat rejection pressure for the vortex tube cycle, and the COP improvement is 2.4%~16.3% at given conditions. Decrease in evaporation temperature or increase in gas-cooler outlet temperature decrease the COP, but the COP improvement will increase. The effect of cold mass fraction on the COP is negligible, but the COP improvement will increase fast with the increase of cold mass fraction.

CO2 Trans-Critical Two Stage Compression Refrigeration Cycle with Vortex Tube

2011 ◽  
Vol 52-54 ◽  
pp. 255-260 ◽  
Author(s):  
Ying Bai Xie ◽  
Kui Kui Cui ◽  
Zhi Chao Wang ◽  
Jian Lin Liu
Keyword(s):  
Mass Fraction ◽  
Vortex Tube ◽  
Refrigeration Cycle ◽  
Two Stage ◽  
Fluid Mass ◽  
Cold Fluid ◽  
Exit Temperature ◽  
Discharge Pressure ◽  
Tube Expansion ◽  
Cold Gas

The paper analyses CO2 trans-critical two stage compression refrigeration cycle with vortex tube expansion by thermodynamics method. And compare with CO2 trans-critical two stage compression refrigeration cycle with expansion value. The results show that in the calculated conditions of the paper, the performance of the cycle with vortex tube improves 2.4%~16.3% than the cycle with expansion value. The optimal discharge pressure maximizing COP of the cycle with vortex tube exists. With lower evaporating temperature or higher gas cooler exit temperature, COP of system decreases and COP improvement increases. The effect of cold fluid mass fraction on COP is not significant, but COP improvement increases more quickly with cold gas mass fraction increasing.

scholarly journals Experimental study and CFD analysis of energy separation in a counter flow vortex tube

2019 ◽  
pp. 418-418
Author(s):  
Lizan Zangana ◽  
Ramzi Barwari
Keyword(s):  
Mass Fraction ◽  
Vortex Tube ◽  
Coefficient Of Performance ◽  
Energy Separation ◽  
Outlet Temperature ◽  
Cfd Analysis ◽  
Counter Flow ◽  
Radial Profiles ◽  
Swirl Velocity ◽  
Flow Vortex

In this manuscript, both experimental and numerical investigations have been carried out to study the mechanism of separation energy and flow phenomena in the counter flow vortex tube. This manuscript presents a complete comparison between the experimental investigation and CFD analysis. The experimental model was manufactured with (total length of 104 mm and the inner diameter of 8 mm, and made of cast iron) tested under different inlet pressures (4, 5 and 6 bar). The thermal performance has been studied for hot and cold outlet temperature as a function of mass fraction ? (0.3- 0.8). Three-dimensional numerical modeling using the k-? model used with code (Fluent 6.3.26). Two types of velocity components are studied (axial and swirl). The results show any increase in both cold mass fraction and inlet pressure caused to increase ?Tc, and the maximum ?Tc value occurs at P = 6 bar. The coefficient of performance (COP) of two important factors in the vortex tube which are a heat pump and a refrigerator have been evaluated, which ranged from 0.25 to 0.74. A different axial location (Z/L = 0.2, 0.5, and 0.8) was modeled to evaluate swirl velocity and radial profiles, where the swirl velocity has the highest value. The maximum axial velocity is 93, where it occurs at the tube axis close to the inlet exit (Z/L=0.2). The results showed a good agreement for experimental and numerical analysis.

Performance Assessment of Blends of CO2 With Eco-Friendly Working Fluids for Heat Pump Applications

2013 ◽  
Author(s):  
Xiaowei Fan ◽  
Xianping Zhang ◽  
Xinli Wei ◽  
Fang Wang ◽  
Xiaojing Zhang
Keyword(s):  
Heat Pump ◽  
Mass Fraction ◽  
Experimental Results ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Outlet Temperature ◽  
Pump System ◽  
Heat Rejection ◽  
Working Fluids ◽  
Optimum Heat

Since pure CO2 as refrigerant has some disadvantages failing to meet requirements, binary blends of CO2 (or R744) with other eco-friendly working fluids, R290, R1270, R170, RE170 and HFC134a are proposed in this paper to be used for medium temperature heat pump systems. The eco-friendly refrigerant mixtures can reduce the heat rejection pressure as that for pure CO2, and meanwhile suppress the flammability, explosivity as that for pure HCs or RE170. Based on the pinch point of heat transfer, the numerical models of heat pump cycle using CO2-based mixture are developed. With a comprehensive consideration of heating coefficient of performance (COPh), optimum heat rejection pressure, volumetric heating capacity, discharge temperature, the binary mixture CO2/R290 is determined as the most suitable working fluid for the given heat pump application. Compared to pure CO2, the optimum heat rejection pressure of mixture for 95/5, 90/10, 85/15 and 80/20 is decreased by 0.82, 0.94, 1.06 and 1.86MPa respectively for heat sink outlet temperature of 65°C. The experimental testrig is designed and set up for the transcritical heat pump system. The experimental study with different CO2 mass fraction has been carried out, which conducts a study on the variations of heat pump performance, component’s mass fraction and working fluid charge. The experimental results validated the CO2/R290 natural mixture proposed in theory. The experimental results provide useful references on the optimization and improvement of CO2/R290 heat pump testrig.

Experimental study of the impacts of cold mass fraction on internal parameters of a vortex tube

2019 ◽  
Vol 104 ◽  
pp. 151-160 ◽  
Author(s):  
Nian Li ◽  
Guannan Jiang ◽  
Lichen Fu ◽  
Liming Tang ◽  
Guangming Chen
Keyword(s):  
Experimental Study ◽  
Mass Fraction ◽  
Vortex Tube ◽  
Internal Parameters ◽  
Cold Mass

scholarly journals Thermodynamic Analysis of Transcritical CO2 Ejector Expansion Refrigeration Cycle with Dedicated Mechanical Subcooling

Entropy ◽  
2019 ◽  
Vol 21 (9) ◽  
pp. 874
Author(s):  
Fu ◽  
Wang ◽  
Zheng ◽  
Yu ◽  
Liu ◽  
...  
Keyword(s):  
Thermodynamic Analysis ◽  
Environmental Temperature ◽  
Exergy Efficiency ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Evaporation Temperature ◽  
Mass Ratios ◽  
Environmental Temperatures

: The new configuration of a transcritical CO2 ejector expansion refrigeration cycle combined with a dedicated mechanical subcooling cycle (EMS) is proposed. Three mass ratios of R32/R1234ze(Z) (0.4/0.6, 0.6/0.4, and 0.8/0.2) were selected as the refrigerants of the mechanical subcooling cycle (MS) to further explore the possibility of improving the EMS cycle’s performance. The thermodynamic performances of the new cycle were evaluated using energetic and exergetic methods and compared with those of the transcritical CO2 ejector expansion cycle integrated with a thermoelectric subcooling system (ETS). The results showed that the proposed cycle presents significant advantages over the ETS cycle in terms of the ejector performance and the system energetic and exergetic performances. Taking the EMS cycle using R32/R1234ze(Z) (0.6/0.4) as the MS refrigerant as an example, the improvements in the coefficient of performance and system exergy efficiency were able to reach up to 10.27% and 15.56%, respectively, at an environmental temperature of 35 C and evaporation temperature of −5 C. Additionally, the advantages of the EMS cycle were more pronounced at higher environmental temperatures.

An Experimental Investigation of the Cold Mass Fraction, Nozzle Number, and Inlet Pressure Effects on Performance of Counter Flow Vortex Tube

2009 ◽  
Vol 131 (8) ◽  
Author(s):  
Volkan Kırmacı ◽  
Onuralp Uluer
Keyword(s):  
Experimental Investigation ◽  
Mass Fraction ◽  
Vortex Tube ◽  
Plastic Material ◽  
Momentum Conservation ◽  
Pressure Effects ◽  
Inlet Pressure ◽  
Frictional Heat ◽  
Energy Separation ◽  
Cold Mass

This paper discusses the experimental investigation of vortex tube performance as it relates to cold mass fraction, inlet pressure, and nozzle number. The orifices have been made of the polyamide plastic material. Five different orifices, each with two, three, four, five and six nozzles, respectively, were manufactured and used during the test. The experiments have been conducted with each one of those orifices shown above, and the performance of the vortex tube has been tested with air inlet pressures varying from 150 kPa to 700 kPa with 50 kPa increments and the cold mass fractions of 0.5–0.7 with 0.02 increments. The energy separation has been investigated by use of the experimentally obtained data. The results of the experimental study have shown that the inlet pressure was the most effective parameter on heating and the cooling performance of the vortex tube. This occurs due to the higher angular velocities and angular momentum conservation inside the vortex tube. The higher the inlet pressure produces, the higher the angular velocity difference between the center flow and the peripheral flow in the tube. Furthermore, the higher velocity also means a higher frictional heat formation between the wall and the flow at the wall surface of the tube. This results in lower cold outlet temperatures and higher hot outlet temperatures.

Numerical Investigation of the Thermo-Hydraulic Characteristics for Annular Vortex Tube: A Comparison With Ranque–Hilsch Vortex Tube

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Milad Khosravi ◽  
Meisam Sadi ◽  
Ahmad Arabkoohsar ◽  
Amir Ebrahimi-Moghadam
Keyword(s):  
Mass Fraction ◽  
Vortex Tube ◽  
Secondary Circulation ◽  
Outlet Section ◽  
Separation Performance ◽  
Outlet Temperature ◽  
Hydraulic Characteristics ◽  
Temperature Separation ◽  
Mass Fractions ◽  
Higher Temperature

Abstract In this work, a new configuration of the vortex tubes (VTs), called annular VTs, is proposed to improve the temperature separation performance. In the proposed configuration, a compartment has been added on the top of the tube wall that the separated hot outlet is repassed inside it over the hot tube. An axisymmetric swirl model of the Ranque–Hilsch (RH) and annual VTs is numerically simulated, and the thermo-hydraulic characteristics of them are compared for cold mass fractions ranging 0.2–0.8. The results illustrated that a small secondary circulation is created near the cold outlet of the RHVT that is not observed in the annular model. This secondary circulation is a destructive mechanism in VTs that results in more mixing and higher temperature in the cold outlet section. Analyzing the results indicates that using annular VT causes up to 12.51% increment of the hot outlet temperature compared to the RHVT model (which occurs at a mass fraction of 0.23). Also, up to 9.23% reduction of the cold outlet temperature is occurred (which occurs at a mass fraction of 0.37). These explanations prove the improvement of the annular VT compared to that of the conventional VTs.

Investigations of Energy Separation Effect in Vortex Tube for Natural Gases

2013 ◽  
Vol 397-400 ◽  
pp. 205-208
Author(s):  
Wen Chuan Wang ◽  
Xiang Jun Fang ◽  
Shi Long Liu ◽  
Wen Long Sun
Keyword(s):  
Mass Fraction ◽  
Vortex Tube ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Energy Separation ◽  
Separation Effect ◽  
Natural Gases ◽  
Temperature Separation ◽  
Total Temperature ◽  
Cold Mass

This paper aims to investigate fixed composition natural gases including N2, CH4 and C2H4 energy separation effect in vortex tube. Energy separation phenomena of those gases were investigated by means of three-dimensional Computational Fluid Dynamics (CFD) method. Flow fields of natural gases in fixed inlet boundary conditions were simulated. The results main factors were found that affect the energy separation with cold mass fraction being 0.7 and pressure drop ratio being 3.90. At the same time, this paper has illustrated the effects and tendencies of energy separation with gases in the tube under the same cold mass flow fraction and cold pressure ratio. The results show mixture gases total temperature difference effect is unchanged varied with the cold mass fraction; CH4% has no effect on the vortex cold end temperature separation, but varied of CH4% has an influence in total temperature and hot end separation effect; total temperature separation effect of CH4% was divided into two sections, one is0%-80%, and the other 80%-100%.

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