Performance optimization of transcritical CO2 cycle with parallel compression economization. Int J Therm Sci

Department of Mechanical Engineering, Dr. B. A. Technological University Lonere, MS-402 103, India
International Journal of Thermal Sciences (Impact Factor: 2.63). 05/2010; 49(5):838-843. DOI: 10.1016/j.ijthermalsci.2009.12.001


Being a low critical temperature fluid, CO2 transcritical system offers low COP for a given application. Parallel compression economization is one of the techniques to improve the COP for transcritical CO2 cycle. An optimization study of transcritical CO2 refrigeration cycle with parallel compression economization is presented in this paper. Further, performance comparisons of three different COP improvement techniques; parallel compression economization alone, parallel compression economization with recooler and multistage compression with flash gas bypass are also presented for chosen operating conditions. Results show that the parallel compression economization is more effective at lower evaporator temperature. The expression for optimum discharge pressure has been developed which offers useful guideline for optimal system design and operation. Study shows that the parallel compression with economizer is promising transcritical CO2 cycle modifications over other studied cycle configurations. A maximum improvement of 47.3% in optimum COP is observed by employing parallel compression economization for the studied ranges.

Download full-text


Available from: Jahar Sarkar, Apr 25, 2014
  • Source
    • "Under the optimal intermediate pressure of 6.5 MPa, cooling COP and heating COP were both at their maximum values, which were 2.5 and 3.5 respectively. Sarkar and Agrawal [57] tested a two-stage compression transcritical cycle with an economizer. The cooling COP improved by 47.3% over a basic conventional transcritical system. "
    [Show abstract] [Hide abstract]
    ABSTRACT: As a natural refrigerant, carbon dioxide is safe, economic and environmentally sustainable which can be used in heat pump and refrigeration systems especially in transcritical cycles. From the early 1990s, in which the carbon dioxide transcritical cycle began, theoretical and experimental researches, as well as commercial system development, has improved to make the transcritical system performance to a level similar to that of conventional heat pump systems. This paper presents an overview of transcritical carbon dioxide heat pump and refrigeration systems. The paper introduces a summary of the history and main application of carbon dioxide's use as a refrigerant firstly. Secondly, the properties of supercritical pure carbon dioxide and that containing polyalkylene glycol (PAG) lubricants are analyzed and reviewed. In Section 3 the paper began with an analysis of some special characteristics of the basic carbon dioxide transcritical cycle such as the optimum system high pressure and so on, and then followed by a performance analysis and comparison of several novel transcritical cycles. The study finally presents a review of research on transcritical carbon dioxide heat pump systems, which covers the main components and research hotspots, such as heat transfer and expander.
    Full-text · Article · Jun 2013 · Energy
  • [Show abstract] [Hide abstract]
    ABSTRACT: We introduce a new practical method of on-line and real-time ARMA modeling. In this method a very high order AR model is used to approach the ARMA model. The multiplication of multi lower order AR models are used to replace the high order AR model, and the cascading linear systems are used to resolve the multiplication of the AR models. The lower order and linear algorithm can achieve the on-line and real-time resolution. The modeling experiments for some systems have proved that the method is effective, and the prediction based on the method also has higher precision. This method has been used to improve GPS positioning precision to achieve some better results
    No preview · Conference Paper · Feb 2000
  • Source

    Preview · Article · Jan 2010
Show more