{"title":"Generic modelling to develop thermal yield nomograms for coaxial deep borehole heat exchangers (DBHE)","authors":"D. Banks, C. Brown, I. Kolo, G. Falcone","doi":"10.1144/qjegh2023-162","DOIUrl":null,"url":null,"abstract":"\n Numerical modelling of coaxial deep borehole heat exchangers (DBHE) can be resource-intensive. Simpler, transparent analytical models and nomograms would be valuable to developers and geologists for evaluating thermal output. An analytical computational model by Beier (2020) was used to produce nomograms of geothermal heat yield by systematically varying DBHE depth and rock thermal conductivity, while assuming two generic simplified DBHE designs, a geothermal gradient of 25°C/km and a fluid circulation rate of 5 L/s. Continuous 25-year heat yields from a 1000 m DBHE range from 27.3 to 54.8 kW for thermal conductivities of 1.6 to 3.6 W/m/K. For a 3000 m DBHE, they range from 165 kW to 281 kW. Effective borehole thermal resistance (\n \n R\n b,eff\n \n ) increases strongly as DBHE depth increases, due to internal heat transfer between upflow and downflow elements. Simulations correspond well with results from industry-standard Earth Energy Designer software for shallow 200 m coaxial BHE. They modestly underestimate OpenGeoSys numerical modelled thermal yields by 2-4% for DBHE in the range 1000 to 3000 m depth. Modelled temperature evolution closely approximates an analytical “line heat source” approach, implying that simpler analytical approaches are plausible for DBHE simulation. Future research should focus on methods for forward quantification of\n \n R\n b,eff\n \n .\n \n \n Supplementary material:\n https://doi.org/10.6084/m9.figshare.c.7237887\n","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":"17 12","pages":""},"PeriodicalIF":16.4000,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Accounts of Chemical Research","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1144/qjegh2023-162","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Numerical modelling of coaxial deep borehole heat exchangers (DBHE) can be resource-intensive. Simpler, transparent analytical models and nomograms would be valuable to developers and geologists for evaluating thermal output. An analytical computational model by Beier (2020) was used to produce nomograms of geothermal heat yield by systematically varying DBHE depth and rock thermal conductivity, while assuming two generic simplified DBHE designs, a geothermal gradient of 25°C/km and a fluid circulation rate of 5 L/s. Continuous 25-year heat yields from a 1000 m DBHE range from 27.3 to 54.8 kW for thermal conductivities of 1.6 to 3.6 W/m/K. For a 3000 m DBHE, they range from 165 kW to 281 kW. Effective borehole thermal resistance (
R
b,eff
) increases strongly as DBHE depth increases, due to internal heat transfer between upflow and downflow elements. Simulations correspond well with results from industry-standard Earth Energy Designer software for shallow 200 m coaxial BHE. They modestly underestimate OpenGeoSys numerical modelled thermal yields by 2-4% for DBHE in the range 1000 to 3000 m depth. Modelled temperature evolution closely approximates an analytical “line heat source” approach, implying that simpler analytical approaches are plausible for DBHE simulation. Future research should focus on methods for forward quantification of
R
b,eff
.
Supplementary material:
https://doi.org/10.6084/m9.figshare.c.7237887
期刊介绍:
Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance.
Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.