FORMATION OF FIELD INDUCED ABSORPTION IN THE PROBE RESPONSE SIGNAL OF A FOUR-LEVEL ‘V’ TYPE ATOMIC SYSTEM: A THEORETICAL STUDY

CO2 (GWP = 1) is considered as a promising natural alternative refrigerant to HFC-134a in mobile air conditioning (MAC) applications. The objective of this study is to investigate the cooling performance characteristics of a CO2 MAC system. A prototype CO2 MAC system, consisting of a CO2 electrical compressor, CO2 parallel flow microchannel heat exchangers, and an electrical expansion valve, was developed and tested. Factor analysis experiments were conducted to reveal the effect of outdoor temperature on the cooling performance of this CO2 MAC system. Compared with a conventional R134a MAC system, the prototype CO2 MAC system achieved comparable cooling capacity, but had COP reductions of 26% and 10% at 27 °C and 45 °C outdoor conditions, respectively. In addition, based on refrigerant properties, theoretical cycle analysis was done to reveal the impact of evaporator, gas cooler and compressor, on the system cooling performance. It is concluded that the increase of overall compressor efficiency or the decrease of gas cooler approaching temperature could greatly improve the COP of this CO2 MAC system.

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Biomass-fired steam power cogeneration system: A theoretical study

Energy Conversion and Management ◽

10.1016/0196-8904(94)00030-4 ◽

1995 ◽

Vol 36 (1) ◽

pp. 65-77 ◽

Cited By ~ 19

Author(s):

Surendra B. Prasad

Keyword(s):

Theoretical Study ◽

Steam Power ◽

System A ◽

Cogeneration System

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Theoretical Study on Instability Boundary of Rotor-Hydrodynamic Bearing Systems: Part II — Rotor With External Flexible Damped Support

Volume 6A: 18th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc2001/vib-21385 ◽

2001 ◽

Author(s):

Zenglin Guo ◽

R. Gordon Kirk

Keyword(s):

Analytical Study ◽

Theoretical Study ◽

System Stability ◽

Hydrodynamic Bearing ◽

System A ◽

Vertical Rotor ◽

Speed Range ◽

Stability Maps ◽

Alternative Means ◽

The Stability

Abstract The situation of a rotor-hydrodynamic bearing system in external flexible damped support is more complicated than that discussed before in Part I but it can become an alternative means to improve the stability of the rotor system. A model for both vertical and horizontal analysis is built first. Then, the analytical study on the vertical rotor is conducted. The results show that there might be up to four threshold speeds in this configuration that form a consecutive regional pattern taken turns by stable or unstable regions. Furthermore, the numerical calculation by MATLAB is carried out to obtain the results of the horizontal system. The stability maps for various parametric configurations are presented. It has been shown that the value of support damping has a strong effect on the first several lower threshold speeds. But it has little effect on the last top threshold speed which is mainly determined by the portion of journal mass. Within a certain range of external damping value, the first several regions of instability can be reduced or eradicated. As far as the entire stability map is concerned, there is an optimum range of value for support damping that can make the rotor have only one top threshold speed over the entire running speed range. When the support stiffness is increased, the system stability map becomes narrow which means a small support stiffness is good for broadening the range of optimum external damping.

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