Release:
2020. Vol. 6. № 1 (21)About the authors:
Aleksandr E. Kishalov, Cand. Sci. (Tech.), Associate Professor, Department of Aviation Heat Engineering and Heat Power Engineering, Ufa State Aviation Technical University; kishalov@ufanet.ruAbstract:
Every year, the share of decentralized energy generation in Russia is increasing. The following factors contribute to the development of this scenario: increased wear of the country’s energy system equipment, energy shortages, and lack of centralized energy supply in a number of regions and constantly rising tariffs. One of the methods of decentralized energy generation is the use of low-capacity power plants based on the Rankine cycle with an organic working fluid. The operation of such plants requires cooling and condensation of the working fluid by transferring its heat to the environment.
This study discusses the design of such a power plant and the heat removal system to a cold source. is the authors consider the design of a condenser which is a horizontal pipeline placed in the ground. Seasonal fluctuations of the soil temperatures affect the operation of the condenser. Thereby, to ensure the stable operation of the power plant, it is necessary to quantitatively assess the effect of the annual dynamics of the soil temperature state on cooling and condensation of the coolant.
The study of the temperature fields of the soil, pipeline and working fluid, as well as the lengths required for cooling and condensation of the working fluid, was carried out in the ANSYS CFX software package for numerical hydrodynamic modeling. A homogeneous flow model was chosen to simulate the momentum and condensation of a vapor-liquid medium. Also, the calculations were conducted in a one-dimensional formulation using an engineering method.
A methodology for modeling complex processes of heat transfer to the soil using numerical modeling has been developed and verified. 12 calculations were made; the distributions of the steam dryness and temperature in the simulated region depending on the time of the year were obtained. The functions of the total length of the pipeline, cooling and condensation lengths on the soil temperature are analyzed. It has been established that the harmonic change in the temperature of the soil set as the initial condition determines a similar change in the lengths required for cooling and condensation of the working fluid.
Using this technique, it is possible to calculate pipelines of more complex shapes. The obtained temperature distributions in cross sections allow to establish the optimal distance between the axes of the pipes when designing a condenser in the form of a bundle of horizontal pipes or a bent pipeline.
Keywords:
References:
Babenko A. V., Korelshtein, L. B. 2016. “Hydraulic calculation of two-phase gas-liquid flows: a modern approach”. Truboprovodnaja armatura i oborudovanie (TPA), no. 2 (83), pp. 38-42. [In Russian]
Vargaftik N. B. et al. 1990. Handbook of Thermal Conductivity of Liquids and Gases. Moscow: Ehnergoatomizdat. 352 pp. [In Russian]
Vargaftik N. B. 1963. Handbook of Thermophysical Properties of Gases and Liquids. Moscow: Izdatel’stvo fiziko-matematicheskoj i tekhnicheskoj literatury. 708 pp. [In Russian]
Volkov M. M., Miheev A. L., Konev K. A. 1989. Gas Worker Handbook. 2^{nd} edition. Moscow: Nedra. 286 pp. [In Russian]
Efimov N. N., Popel’ O. S., Baltyan V. N. 2015. “Prospects for the development of small distributed energy”. University News. North-Caucasian Region, no. 1, pp. 60-64. DOI: 10.17213/0321-2653-2015-1-60-64 [In Russian]
Kishalov A. E., Zinnatullin, A. A. 2019. “Mathematical Modelling of the Working Body Condensation in the System of Heat Emission to Cool Source of Low-Capacity Power Plant”. Bulletin of Irkutsk State Technical University, no. 23 (5), pp. 934-949. DOI: 10.21285/1814-3520-2019-5-934-949 [In Russian]
Kishalov A. E., Zarodov, E. A. 2017. “Thermodynamic calculation of the organic Rankine cycle for low-capacity energy plants using biofuels”. Molodezhnyj Vestnik Ufimskogo gosudarstvennogo aviacionnogo tekhnicheskogo universiteta, no. 2 (17), pp. 183-188. [In Russian]
Krylov V. A., Chernoozerskij V. A., Nikitin A. A., Baranov I. V. 2015. “Non-uniformity of geothermal well heat pump temperature field”. Vestnik Mezhdunarodnoj akademii holoda, no. 1 (54), pp. 75-80. [In Russian]
Maksimov V. I., Salum A. 2019. “Features of the use of geothermal energy with the use of heat pump units in conditions of low air temperatures”. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, vol. 330, no. 2, pp 115-123. DOI: 10.18799/24131830/ 2019/2/113 [In Russian]
Industrial production in Russia 2016: a statistical compilation. 2016. Moscow: Federalnaya sluzhba gosudarstvennoj statistiki. 374 pp. [In Russian]
Rating of regions according to the level of energy sufficiency. Regiony Rossii. RIA Rejting. Accessed 24 January 2020. http://vid1.rian.ru/ig/ratings/energodeficit012018.pdf [In Russian]
Russia in numbers. 2019. Electricity and heat production. Federalnaya sluzhba gosudarstvennoj statistiki. Accessed 26 January 2020. https://gks.ru/bgd/regl/b19_11/IssWWW.exe/Stg/d01/16-45.doc [In Russian]
Suchilin V. A., Kochetkov, A. S., Gubanov, N. N. 2018. “Study of the effectiveness of a soil horizontal heat exchanger for a domestic heat pump using Comsol Multiphisics”. Vestnik Evrazijskoj nauki, vol. 10, no. 2. Accessed 20 January 2020. https://esj.today/38SAVN218.html [In Russian]
Suchilin V. A., Kochetkov, A. S., Gubanov, N. N. 2018. “Study of the efficiency of heat exchangers in vertical wells of heat pump units at Comsol Multiphisics”. Vestnik Evrazijskoj nauki, vol. 10, no. 5. Accessed 20 January 2020. https://esj.today/19SAVN518.html [In Russian]
Shein E. V. 2005. Soil Physics Course. Moscow: Moscow State University Publishing House. 432 pp. [In Russian]
ANSYS Inc. 2011. ANSYS CFX-Pre User’s Guide. 368 pp. http://read.pudn.com/downloads500/ebook/2077964/cfx_pre.pdf
Awad M. M., Muzychka Y. S. 2008. “Effective property models for homogeneous two-phase flows”. Experimental Thermal and Fluid Science, vol. 33 (1), pp 106-113. Accessed 21 January 2020. http://www.engr.mun. ca/muzychka/ETFS2008.pdf
Boxcar Function. Wolfram MathWorld: The Web’s Most Extensive Mathematics Resource. Accessed 23 January 2020. http://mathworld.wolfram.com/BoxcarFunction.html
Crowe C. T. 2006. Multiphase Flow Handbook. Boca Raton: Taylor & Francis Group, LLC. 1156 pp.
De Lorenzo M., Lafon Ph., Matteo M. Di, Pelanti M., Seynhaeve J.-M. Bartosiewicz Y. 2017. “Homogeneous two-phase flow models and accurate steam-water table look-up method for fast transient simulations”. International Journal of Multiphase Flow, vol. 95, pp 199-219. DOI: 10.1016/j.ijmultiphaseflow.2017.06.001
Lejon M. 2013. “Wall condensation modelling in convective flow”. Master’s thesis. Stockholm: School of Industrial Engineering and Management.
Wörner M. 2003. Compact Introduction to the Numerical Modeling of Multiphase Flows. Karlsruhe: Institut für Reaktorsicherheit. 38 pp.