About The Efficiency of Energy Production by Recovering the Latent Heat of Vaporization of LNG during Regasification
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ABOUT THE EFFICIENCY OF ENERGY PRODUCTION BY RECOVERING THE LATENT HEAT OF VAPORIZATION OF LNG DURING REGASIFICATION A. I. Dovgyallo,1 D. A. Uglanov,1 K. E. Vorotyntseva,1 and I. A. Arkharov2
UDC 621.5
The questions of the efficiency of energy production by recovering the latent heat of vaporization of LNG during regasification are investigated. A method for evaluating the thermodynamic efficiency of heat-using cycles through the efficiency is proposed, which, taking into account the introduction of entropy as a state parameter, corresponds to the approaches of the entropy-statistical method. The proposed method is considered by the authors as a development of the entropy-statistical method. This method is applicable for all kind of energy generating units and plants. Keywords: latent heat recovering, liquefied natural gas (LNG), efficiency, Rankine cycle, energy systems, regasification, “carnotized” cycle.
The development of technologies for recovering the latent heat of vaporization of cryogenic liquids (part of the energy previously spent on liquefaction [1]) is inextricably connected with the increasing volumes of cryogenic liquids production and the general trend of energy saving. The relevance of recovering the latent heat of vaporization (“Cold Energy” in foreign publications, “heatremoving capacity of a cryoproduct” in some domestic publications) of cryogenic liquids for the production of effective work is due to the possibility of returning a part of energy (up to 15% [2–4]) previously spent on liquefaction of the cryoproduct. It is possible to introduce the latent heat recovering technology by implementing a direct cycle when using a cryogenic liquid with a temperature Tc as a lower heat source, and the ambient heat with a temperature Tg = Ta (either other natural or industrial heat emissions with Tg > Ta) as an upper heat source. One of the options for implementing a direct cycle for generating energy during regasification is a Rankine cycle with a cascade of expansion machines [3–5]. Thermodynamic Aspects of Heat-Using Cycles of Low-Temperature Power Plants This research considers some of the peculiarities of the processes of converting heat into work, provided that a cryoproduct is used simultaneously both as a working fluid and as a lower heat source (sink). Carnot cycles shown in Fig. 1 are usually defined as high-temperature 1–2–3–4–1 “heat-positive” and low-temperature 1′–2′–3′–4′–1′ “heat-negative” cycles (these two terms were introduced in [2] taking into account the generally accepted concept of heat according to Clausius, etc.). Due to disagreements on terminology, it should be noted that heat is considered as a form of energy, which appears in the process of transferring internal energy from one body to another; therefore, the concept of heat can be applied to energy transfer both at low-temperature and high-temperature levels. 1 2
Samara National Research University named after S. P. Korolev, Russia.
Bauman Moscow State Technical University, Russia; e-mail: [email protected], ivanarkharov@yaho
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