Chapter 1 The Intensity of Heat Exchange in Complexes of Organic Waste Disposal
Stanislav Y. Tkachenko, Kseniya O. Ischenko, Nataliya V. Rezydent, and Leonid G. Koval
Vinnytsia National Technical University
Dmitry I. Denesyak
Green Cool LLC
Roman B. Akselrod
Kyiv National University of Construction and Architecture
Konrad Gromaszek
Lublin University of Technology
Serzhan Mirzabayev
Academy of Logistics and Transport
Aigul Tungatarova
M. Kh. Dulaty Taraz Regional University
DOI: 10.1201/9781003177593-1
Contents
- 1.1 Introduction
- 1.2 Material and Research Results
- 1.3 Conclusions
- References
1.1 Introduction
The increase in energy efficiency of biogas plants is slowed down by the drawbacks of the methods, structures and technologies for thermal stabilization of the mixture in the bioreactor, which causes problems with temperature constancy throughout the reactor volume. It is well known that biogas plant (BGP) in the west produces more energy in the form of biogas than is required to maintain the functioning of the BGP itself (pre-heating, transportation, heat stabilization, etc.). Another problem concerns the raw materials for BGP, as it can be animal, agricultural, food and industrial wastes, and usually even mixtures of all of these. The number of variants of mixture compositions is infinite; so the study of each variant is not appropriate. This was confirmed in the conditions announced for scientific works at the XVI Minsk International Forum on Heat and Mass Exchange (http://www.itmo.by/conferences/mif), which clearly indicates that the research of the thermophysical properties of substances is not accepted and has no scientific value. For the qualitative course of the fermentation process, a rather strict compliance with the temperature mode at BGP is required. In this case, under the conditions of acceptable temperature fluctuations in the psychrophilic mode amount to ±2°C, and in thermophilic mode, the accuracy increases to ±0.5°C (Sadchikov and Kokarev, 2016). An important role is played by indirect parameters such as fraction size, substrate moisture in different seasons, and mixing intensity. Devising a rational mixing method contributes to the creation of optimal hydrodynamic and temperature conditions for the existence of the methane-forming bacteria, as well as a more efficient use of a digestion tank volume (Tropin, 2011). This leads to the development of means for evaluating the thermophysical properties and intensity of heat exchange of raw materials at the BGP, directly during the process of fermentation. There are no such plants and experiments that would cover the full range of problems described above. In practice, the methods for assessing the intensity of heat exchange under the conditions of limited information on the thermophysical properties of complex mixtures are required in order to implement both deep fundamental research and rapid analysis at the existing BGP. Such methods have emerged and developed (Tkachenko and Pishenina, 2017), and the convergent results obtained with these methods are available. It is now possible to further improve these techniques using the regular thermal mode (RTM) (Kondratev, 1954; Osipova, 1979).
The purpose of this chapter is to show how to increase the energy efficiency of heat exchange equipment by reducing the uncertainty of estimating the intensity of heat exchange in liquid multiphase mixtures, which are prone to structural changes, by improving the methods and means of implementing the experimental calculation method using the RTM. To achieve this objective, the following tasks were set: analysis of experimental data obtained on a test rig; development of a mathematical model to evaluate the effect of structure cracking and mixing on the intensification of the heat transfer process; development of recommendations to use this technique to estimate heat transfer intensities during the development of full-scale heat exchangers.