Numerical investigation of heat transfer enhancement in shell-and-tube heat exchangers with helically coiled tube for low-temperature cold-start applications

IF 5.4 3区工程技术 Q2 ENERGY & FUELS

Thermal Science and Engineering Progress Pub Date : 2025-10-03 DOI:10.1016/j.tsep.2025.104176

Siyu Zheng , Zengxin Qiao , Mingshan Wei , Ran Tian , Xiaoxia Sun

{"title":"Numerical investigation of heat transfer enhancement in shell-and-tube heat exchangers with helically coiled tube for low-temperature cold-start applications","authors":"Siyu Zheng , Zengxin Qiao , Mingshan Wei , Ran Tian , Xiaoxia Sun","doi":"10.1016/j.tsep.2025.104176","DOIUrl":null,"url":null,"abstract":"<div><div>Shell-and-helically coiled tube heat exchangers (SHCTHEs) are widely used in industry, yet limited research exists on natural convection and heat transfer enhancement strategies for such exchangers. This study presents a numerical investigation of thermal performance and associated oil natural convection behavior in a SHCTHE for a diesel engine lubricant tank under low-temperature cold-start conditions. The accuracy of numerical method was validated experimentally. For the baseline finless tube, the influence of coil pitch on heating performance was analyzed, elucidating natural convection mechanisms in low-viscosity oils at varying pitches. Subsequently, Annular coil fins were then added to optimize heat transfer. Parametric studies focused on fin geometry, height, and fin cycles, with Rayleigh and Nusselt number correlations identifying the enhancement mechanisms. Lastly, the optimal fin structure was obtained through the overall performance factor. Results showed that closely spaced smooth coils promoted the development of the thermal boundary layer, which inhibited heat transfer. As coil pitch increased from 1.05 to 1.2, the average oil temperature rose from 18.89 °C to 34.41 °C, with heat transfer power improving by 23.2 %. Further increases in coil pitch had minimal effect on the performance, with the optimal result at a coil pitch of 1.8. This increase weakened the thermal boundary layer on the tube wall, enhancing natural convection and improving heat transfer. For the tube with annular coil fins, fin shape had little effect on heat transfer, while increasing fin cycles and height improved performance by improving thermal conductivity. Additionally, excessive fin length suppressed the occurrence of natural convection in the oil. The optimal fin configuration was found to be a fin height-to-pitch ratio of 0.8 and 200 fin cycles, balancing heat transfer efficiency and material consumption.</div></div>","PeriodicalId":23062,"journal":{"name":"Thermal Science and Engineering Progress","volume":"67 ","pages":"Article 104176"},"PeriodicalIF":5.4000,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Thermal Science and Engineering Progress","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2451904925009679","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENERGY & FUELS","Score":null,"Total":0}

引用次数: 0

Abstract

Shell-and-helically coiled tube heat exchangers (SHCTHEs) are widely used in industry, yet limited research exists on natural convection and heat transfer enhancement strategies for such exchangers. This study presents a numerical investigation of thermal performance and associated oil natural convection behavior in a SHCTHE for a diesel engine lubricant tank under low-temperature cold-start conditions. The accuracy of numerical method was validated experimentally. For the baseline finless tube, the influence of coil pitch on heating performance was analyzed, elucidating natural convection mechanisms in low-viscosity oils at varying pitches. Subsequently, Annular coil fins were then added to optimize heat transfer. Parametric studies focused on fin geometry, height, and fin cycles, with Rayleigh and Nusselt number correlations identifying the enhancement mechanisms. Lastly, the optimal fin structure was obtained through the overall performance factor. Results showed that closely spaced smooth coils promoted the development of the thermal boundary layer, which inhibited heat transfer. As coil pitch increased from 1.05 to 1.2, the average oil temperature rose from 18.89 °C to 34.41 °C, with heat transfer power improving by 23.2 %. Further increases in coil pitch had minimal effect on the performance, with the optimal result at a coil pitch of 1.8. This increase weakened the thermal boundary layer on the tube wall, enhancing natural convection and improving heat transfer. For the tube with annular coil fins, fin shape had little effect on heat transfer, while increasing fin cycles and height improved performance by improving thermal conductivity. Additionally, excessive fin length suppressed the occurrence of natural convection in the oil. The optimal fin configuration was found to be a fin height-to-pitch ratio of 0.8 and 200 fin cycles, balancing heat transfer efficiency and material consumption.

查看原文本刊更多论文

低温冷启动用螺旋盘管壳管换热器强化传热的数值研究

壳-螺旋盘管换热器在工业上应用广泛，但对其自然对流和强化换热策略的研究有限。在低温冷启动条件下，对柴油机润滑油箱SHCTHE的热性能和油的自然对流行为进行了数值研究。实验验证了数值方法的准确性。以无翅片基准管为研究对象，分析了不同螺距对加热性能的影响，阐明了不同螺距下低粘度油的自然对流机理。随后，增加环形盘管翅片以优化传热。参数化研究的重点是鳍的几何形状、高度和鳍的循环，利用瑞利数和努塞尔数的相关性来确定增强机制。最后，通过综合性能因子得到最优的翅片结构。结果表明，密集的光滑线圈促进了热边界层的发展，从而抑制了换热。当线圈螺距从1.05增加到1.2时，平均油温从18.89℃提高到34.41℃，换热功率提高23.2%。进一步增加线圈螺距对性能的影响最小，在线圈螺距为1.8时效果最佳。这种增加削弱了管壁上的热边界层，增强了自然对流，改善了换热。对于环形翅片管，翅片形状对换热影响不大，增加翅片循环次数和高度可通过提高导热系数提高性能。此外，过大的翅片长度抑制了油中自然对流的发生。最佳的翅片配置是0.8和200个翅片循环，平衡传热效率和材料消耗。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Thermal Science and Engineering Progress Chemical Engineering-Fluid Flow and Transfer Processes

CiteScore

7.20

自引率

10.40%

发文量

327

审稿时长

41 days

期刊介绍： Thermal Science and Engineering Progress (TSEP) publishes original, high-quality research articles that span activities ranging from fundamental scientific research and discussion of the more controversial thermodynamic theories, to developments in thermal engineering that are in many instances examples of the way scientists and engineers are addressing the challenges facing a growing population – smart cities and global warming – maximising thermodynamic efficiencies and minimising all heat losses. It is intended that these will be of current relevance and interest to industry, academia and other practitioners. It is evident that many specialised journals in thermal and, to some extent, in fluid disciplines tend to focus on topics that can be classified as fundamental in nature, or are ‘applied’ and near-market. Thermal Science and Engineering Progress will bridge the gap between these two areas, allowing authors to make an easy choice, should they or a journal editor feel that their papers are ‘out of scope’ when considering other journals. The range of topics covered by Thermal Science and Engineering Progress addresses the rapid rate of development being made in thermal transfer processes as they affect traditional fields, and important growth in the topical research areas of aerospace, thermal biological and medical systems, electronics and nano-technologies, renewable energy systems, food production (including agriculture), and the need to minimise man-made thermal impacts on climate change. Review articles on appropriate topics for TSEP are encouraged, although until TSEP is fully established, these will be limited in number. Before submitting such articles, please contact one of the Editors, or a member of the Editorial Advisory Board with an outline of your proposal and your expertise in the area of your review.