The Performance Analysis of a Quantum Brayton Refrigeration Cycle with an Ideal Bose Gas

2003 ◽  
Vol 10 (02) ◽  
pp. 147-157 ◽  
Author(s):  
Bihong Lin ◽  
Jincan Chen
Keyword(s):  
Constant Pressure ◽  
Pressure Ratio ◽  
Bose Gas ◽  
Ideal Gas ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Special Cases ◽  
Work Input ◽  
Brayton Refrigeration Cycle ◽  
Ideal Bose Gas

A Brayton refrigeration cycle using an ideal Bose gas as the working substance is simply referred to as a quantum Brayton refrigeration cycle, which consists of two constant-pressure and two adiabatic processes. The influence of quantum degeneracy on the performance of the cycle is investigated, based on the correction equation of state of an ideal Bose gas. The general expressions of the coefficient of performance, refrigeration load and work input of the cycle are calculated. The lowest temperature of the working substance and the minimum pressure ratio of the two constant-pressure processes for a quantum Brayton refrigeration cycle are determined. The variations of the relative refrigeration load with the temperature of the cooled space and the pressure of the low constant-pressure process are discussed for three special cases. Some curves related to the important performance parameters are given. The results obtained here are compared with those of a classical Brayton refrigeration cycle using an ideal gas as the working substance. Some significant conclusions are obtained.

Parametric analysis of a gas turbine cycle coupled to a Brayton refrigeration cycle

2009 ◽  
Vol 223 (5) ◽  
pp. 497-503 ◽  
Author(s):  
L Chen ◽  
W Zhang ◽  
F Sun
Keyword(s):  
Gas Turbine ◽  
Power Efficiency ◽  
Pressure Ratio ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Refrigeration Cycle ◽  
Fluid Temperature ◽  
Optimal Power ◽  
Brayton Refrigeration Cycle

Performance analysis and optimization of an endoreversible Brayton cycle coupled to a Brayton refrigeration cycle has been performed using finite-time thermodynamics. The analy-tical formulae are derived with respect to power, efficiency, optimal extracted pressure ratio of air refrigeration cycle corresponding to optimal power, optimal power and the corresponding efficiency. The influences of various parameters on the cycle performances are analysed by numerical examples. The results show that there exists one optimal pressure ratio of the compressor corresponding to maximum power and another optimal pressure ratio of the compressor corresponding to maximum efficiency; the compressor inlet temperature is reduced by mixing the chilled working fluid from the Brayton refrigeration cycle and the main intake working fluid streams; the intake working fluid temperature could be controlled even below the temperature of the heat sink and the gas turbine performance can be improved.

Research on the Application of Alternative Refrigerants R407C and R410A in Refrigeration-Type Compressed-Air Dryers

2014 ◽  
Vol 672-674 ◽  
pp. 1739-1742
Author(s):  
Hui Liu ◽  
Jin Hua Li ◽  
Hong Xiao
Keyword(s):  
Working Condition ◽  
Pressure Ratio ◽  
Environmentally Friendly ◽  
Compressed Air ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Alternative Refrigerants ◽  
Percentage Points ◽  
Refrigeration Capacity ◽  
Air Dryer

The coefficient of performance (COP), the volumetric refrigeration capacity and the pressure ratio of refrigeration cycle were studied in a refrigeration-type compressed-air dryer using environmentally friendly refrigerants R410A and R407C and compared with those using R22. Study indicates that under the working condition of a refrigeration-type compressed-air dryer, COP using R410A is 3% higher than that using R407C, the volumetric refrigeration capacity using R410A is 50 percentage points higher than that using R407C and the pressure ratio of R410A is 10% less than that of R407C. COP using R410A equals 96% of that using R22 and the volumetric refrigerating capacity equals 147% of that using R22. COP using R407C is equal to 93% of that using R22 and the volumetric refrigerating capacity is equal to 97% of that using R22. R410A is a more appropriate alternative to R22 than R407C in a refrigeration-type compressed-air dryer.

Performance Analysis of the Regenerative Brayton Refrigeration Cycle Using Gd0.94Er0.06 as the Working Substance

2013 ◽  
Vol 631-632 ◽  
pp. 318-321
Author(s):  
Wang Yuan ◽  
Gildas Diguet ◽  
Guo Xing Lin ◽  
Jin Can Chen
Keyword(s):  
Magnetic Field ◽  
Room Temperature ◽  
Entropy Change ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Analysis Method ◽  
Magnetic Field Change ◽  
Effects Of Temperature ◽  
Brayton Refrigeration Cycle ◽  
Set Up

Based on the experimental data of entropy change varying with temperature, the regenerative Brayton refrigeration cycle using Gd0.94Er0.06 as the working substance is set up for magnetic field changes with 0-1T and 0-2T. By using thermodynamic analysis method, some parameters such as the non-perfect regeneration, net cooling quantity, coefficient of performance (COP), and so on, are analyzed and calculated. The effects of temperature of the heat reservoir, regeneration and external magnetic field are also discussed. The results obtained in the present paper show that the refrigeration cycle operating in TC=T0, TH= T0+7K and 0-2T magnetic field change has not only maximum cooling quantity but also maximum COP in all the established magnetic refrigeration cycles, and can provide some new guide for the optimal design of real room-temperature magnetic refrigerators.

The Influence of Quantum Degeneracy on the Performance of a Fermi Brayton Engine

2004 ◽  
Vol 11 (01) ◽  
pp. 87-99 ◽  
Author(s):  
Bihong Lin ◽  
Jincan Chen
Keyword(s):  
Constant Pressure ◽  
Pressure Ratio ◽  
Fermi Gas ◽  
Work Output ◽  
Quantum Degeneracy ◽  
Special Cases ◽  
Output Ratio ◽  
Maximum Work ◽  
Engine Cycle ◽  
Maximum Work Output

The influence of quantum degeneracy on the performance of a Brayton engine using an ideal Fermi gas as the working substance is investigated, based on the theory of statistical mechanics. The general expressions of the efficiency and work output of the engine cycle are derived. The maximum work output and the corresponding efficiency are calculated. The bound of the pressure ratio of the two constant-pressure processes that the Brayton engine cycle can be operated normally is determined. Some important characteristic curves of the cycle, such as the work output versus pressure ratio curves, the efficiency versus pressure ratio curves, the maximum work output ratio versus temperature of the heat reservoirs curves, and so on, are presented. Three special cases are discussed in detail. The results obtained may reveal the general performance characteristics of a Brayton engine working with an ideal Fermi gas.

Study on Performances of Refrigeration-Type Compressed-Air Dryers Using Environmentally-Friendly Refrigerants R717, R290 and R600a

2014 ◽  
Vol 672-674 ◽  
pp. 1708-1711
Author(s):  
Hui Liu ◽  
Hong Xiao
Keyword(s):  
Working Condition ◽  
Pressure Ratio ◽  
Environmentally Friendly ◽  
Compressed Air ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Refrigeration Capacity ◽  
Air Dryer

The coefficient of performance (COP), the volumetric refrigeration capacity and the pressure ratio of the refrigeration cycle were calculated for a refrigeration-type compressed-air dryer using natural environmentally friendly refrigerants R717, R290 and R610a and compared with those using R22. Study shows that in the working condition of a refrigeration-type compressed-air dryer the COP and volumetric refrigeration capacity using R717 are 5% and 11% higher than those using R22 respectively and COP using R290 is equal to 98% of COP using R22 and the volumetric refrigeration capacity is equal to 85% of that using R22. Although COP using R600a is 2% higher than that using R22, the volumetric refrigeration capacity is much lower than that using other refrigerants above mentioned. R717 and R290 are recommended as appropriate substitute refrigerants for R22 in a refrigeration-type compressed-air dryer.

Experimental Evaluation of Window-Type Air-Conditioning Unit with New Expansion Device and R404A Alternative Refrigerant

2020 ◽  
Vol 28 (04) ◽  
pp. 2050031
Author(s):  
Ali K. Shaker Al-Sayyab
Keyword(s):  
Experimental Evaluation ◽  
Air Conditioning ◽  
Capillary Tube ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Cycle Model ◽  
Ansys Fluent ◽  
Compressor Power

In this study, the performance of a window-type air-conditioning unit with an alternative, ozone-friendly refrigerant was enhanced by incorporating a nozzle instead of a capillary tube as an expansion device. An experimental evaluation was adopted on a 1.5 RT window-type air-conditioning unit with a controlled environmental zone. According to operating conditions, an ANSYS-Fluent program was used to predict an appropriate nozzle size for a lower pressure ratio. The refrigeration cycle model was simulated using the Engineering Equation Solver (EES).27 The results showed that using a nozzle of 30[Formula: see text]mm length and inner and outer diameters of 9 and 2[Formula: see text]mm, respectively instead of the capillary tube with R404A reduces compressor power consumption by 7.7% and increases the coefficient of performance (COP) by 7.4%.

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

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Candeniz Seckin
Keyword(s):  
Parametric Analysis ◽  
Constant Pressure ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Operational Parameters ◽  
Entrainment Ratio ◽  
Evaporator Temperature ◽  
Constant Area ◽  
Condenser Temperature

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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