A Similarity Model of Specific Heat Loss Determined by Dimensional Analysis
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Published:2023-07-10
Issue:14
Volume:13
Page:8055
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ISSN:2076-3417
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Container-title:Applied Sciences
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language:en
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Short-container-title:Applied Sciences
Author:
Čarnogurská Mária1, Příhoda Miroslav2, Lázár Marián1ORCID, Jasminská Natália1, Brestovič Tomáš1, Puškár Michal1
Affiliation:
1. Department of Power Engineering, Faculty of Mechanical Engineering, Technical University of Košice, 04200 Košice, Slovakia 2. Department of Thermal Engineering, Faculty of Materials Science and Technology, VSB–Technical University of Ostrava, 70833 Ostrava-Poruba, Czech Republic
Abstract
This article describes an innovative method for the determination of heat flow (specific heat loss; linear heat flow density) from a one-metre length of a twin pipe directly-buried heat network. Such heat losses are currently described by applying analytical procedures based on the heat transfer theory. It is rather complicated to accurately express the heat loss using such procedures, due to the necessity to determine the individual values of thermal resistance. A simpler method to express heat loss is the balance method, as it requires measuring a temperature gradient Δt between the starting point of the heat network and the end point of the heat collection. A suitable measuring device must provide high-accuracy measurements of the temperature. In the case of very well-insulated distribution pipelines and short pipes, the temperature measurements must be accurate to the hundredths of a degree Celsius. It is impossible to install such devices as fixed equipment on every heat distribution network, due to such networks measuring many kilometres and the cost of the appropriate measuring technology. For the aforesaid reasons, the authors created a mathematical model for specific heat losses based on dimensional analysis. This method facilitates the identification of dimensionless criteria based on the relevant dimensional quantities. Functional correlations between the identified criteria may be identified on the basis of the results of physical or numerical experiments. In this study, a database of the results obtained from physical experiments conducted on two heat networks was used. The output of the similarity model was a function describing the heat flow from a one-meter pipe length that was applicable to various alternatives in relation to the geometrical, physical and boundary conditions. The standard deviation of a difference in the heat losses identified by applying the balance method and using the proposed criterial equation for a twin pipe directly-buried pre-insulated heat network was 0.515 W·m−1.
Funder
VEGA granting agency KEGA granting agency APVV granting agency
Subject
Fluid Flow and Transfer Processes,Computer Science Applications,Process Chemistry and Technology,General Engineering,Instrumentation,General Materials Science
Reference26 articles.
1. Measurement of Thermal Conductivity of Sludge and Liquid Materials;Marek;MATEC Web of Conferences,2018 2. Hnizdil, M., Kominek, J., Lee, T.-W., Raudensky, M., Carnogurská, M., and Chabicovsky, M. (2020). Prediction of Leidenfrost Temperature in Spray Cooling for Continuous Casting and Heat Treatment Processes. Metals, 10. 3. Brestovič, T., Čarnogurská, M., Příhoda, M., Lázár, M., Pyszko, R., and Jasminská, N. (2021). A Similarity Model of the Cooling Process of Fluids during Transportation. Processes, 9. 4. Effect of adding copper oxide nanoparticles on the mass/heat transfer in falling film absorption;Hongtao;Appl. Therm. Eng.,2020 5. Two-phase developing laminar mixing layer at supercritical pressures;Davis;Int. J. Heat Mass Transf.,2021
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