Investigation of thermal flows exchanged by contact moving

Authors

  • В. І. Denhub Department of heat and gas supply, drainage and ventilation. Kryvy Rih National University, st. V. Matusevich 11, Kryvyi Rih, Ukraine, Ukraine https://orcid.org/0000-0003-0380-2466

DOI:

https://doi.org/10.30838/P.CMM.2415.250918.201.152

Keywords:

exergy, mixing heat exchangers, hot water supply, thermal networks

Abstract

Purpose.  The aim of the research is to assess the water and sewage mixing heat exchangers' efficiency in hot water supply systems in the absence of waste water and the use of steam condensate in heat exchangers. From the previously known publications   of other researchers, the results of the estimation of exergent efficiency (EЕ) of heat exchangers for the preparation of hot water supply along the chain are known: energy consumption of fuel  - heat exchanger - the received hot water energy. In this case, cases are co nsidered: a) without the use of waste water; b) using waste water energy; c) using a heat pump.In this case, cases are considered: a) without the use of waste water; b) using waste water energy; c) using a heat pump. But at the same time, the exergy evaluation of the heat transfer process in the heat exchangers itself is not singled out, which was the reason for the writing of this article.  Method. It is constructed on the basis of Carnot's ratios of obtaining the same amount of heat by a cold coolant to a given amount of hot c oolant. But because of the temperature difference in heat exchange, according to the Gui-Stodol's theorem, the loss of exergy occurs in the case of the return of heat, and when it is perceived by the cooler coolant. Taking into account the energy that is exchanged  between "hot" and "cold" media streams in the heat exchanger at the contacts, ЕЕ were calculated. Results. It is established that in the "open" thermal networks the thermal efficiency coincides with the EЕ and equals one. For steam-water mixing machines, the EЕ varies within the range of  0.96-0.98 and depends on the vapor pressure and its saturation temperature.  Scientific novelty.  A thermodynamic model is proposed for estimating the exergent efficiency of directly constructs of heat exchangers with heat fluxes that are intermixed between  them.  Practical  meaningfulness.  If it is possible, it is desirable to switch to open heat networks  for the housing and communal sector with water-water heat exchangers. With the impossibility of switching to open systems for individual heat points, the most exergent advantageous is the use of electric boilers.

Author Biography

В. І. Denhub, Department of heat and gas supply, drainage and ventilation. Kryvy Rih National University, st. V. Matusevich 11, Kryvyi Rih, Ukraine

Ph. D. (Tech.), Assoc. Prof.

References

The Concept of the State Target Program for the Modernization of the Communal Heat Power Engineering (O rder of the Cabinet of Ministers of Ukraine dated April 2, 2009 No. 440-р.-Kyiv.

Kozin V .E. Heat supply: A manual for university students / V.E. Kozin, T.A. Levina, AP Markov, I.B. Pronina, VA Smeszin - M .: Higher school, 1980. - 408 p.

Oleksandryuk A. A. Calculation and design of individual thermal points / AA Aleksandryuk - Makeevka: ДГАСА, 1999. - 103 с.

Technical thermodynamics / Pod. Ed. YOU. Krutov - M.: Mechanical Engineering, 1991. - 384 pp.

Bulandra O. F. Technical thermodynamics: textbook / O.F. Bulandra - 2nd view., vipr. - K .: Technics, 2006. -320 p.

Yenin P.M. Heat supply (part I "Thermal networks and structures") / P. M. Yeinin, N. A. Shvachko. - K.: Condor, 2007. - 241 p.

Tikhomirov K.V. Heat engineering, heat and gas supply and ventilation: study. / K.V. Tikhomirov, E.S. Sergee nko - Moscow: Stroyizdat, 1990. - 480 pp.

Chepurny M. М. Fundamentals of technical thermodynamics: subcategory. for high schools / М.М. Chepurny, S.Y. Tkachenko - Vinnitsa: Podillya - 2000, 2004. - 351 p.

Malkin E.S., Zhuravskaya N. E. Calculations of energy and exergent efficiency of hot water supply systems of housing communal sector / E. S. Malkin, N. E. Zhuravskaya // Ventilation, lighting and heat and gas supply: . save / Kiev National University of Construction and Architecture. - 2016. - Voice over 20. - p. 3-13.

Labay V.Ya., Gerasim D.I. Investigation of exergic efficiency of air conditioning systems of clean rooms // Refrigerating technology and technology - №4 (150), 2014.- C 47-55.

Zadoyanny O. V. Exergy criteria for the estimation of energy efficiency of air conditioning systems of buil dings and structures / O. V. Zadoyanny // Ventilation, lighting and heat and gas supply: save / Kiev National University of Construction and Architecture. - 2014. - Vip. 17. - p. 3-9.

Sokolov E.Ya. Energy basics of heat transformation and cooling processes: study. a manual for high sch ools. -2nd ed., pererab. / E. Ya. Sokolov, VM Brodyansky - Moscow: Energoizdat, 1981. - 320 p.

Exergy calculations of technical systems: cases. allowance / [V.M. Brodyansky, GP Verhivker, Ya.Ya. Karchev et al.]; ed. AA Dolinsky, VM Brodyansky; Institute of Technical Thermophysics, Academy of Sciences of the USSR. -Kiev: Science. opinion, 1991. - 360 p.

Published

2018-09-25

Issue

Section

Life Safety