We studied the heat transfer of finned heat exchanger configurations with a novel design. These novel fin designs use integrated pins to enhance the heat conduction from the fin base to the fin tip as well as the air-side heat transfer on the fin surface. Oval tubes with conventional circular plain fins (CPF) as well as novel circular integrated pin fins (CIPF) and serrated integrated pin fins (SIPF) were additively generated by a Selective Laser Melting (SLM) process and installed at the bottom of a 6.5 m long chimney. All heat exchanger designs were tested in a 2-row and 3-row configuration with Rayleigh numbers between 25,000 and 120,000. We found the average Nusselt number of SIPF to be higher and the Nusselt number of the CIPF to be lower than for the CPF. Moreover, the 2-row configuration achieved a higher Nusselt number compared to the 3-row configuration for all heat exchanger designs. The analysis of the individual tube rows showed the highest Nusselt numbers at the first tube row and the lowest one at the last tube row for both configurations. However, for the SIPF the difference between the first and second tube row is smaller compared to the CPF and CIPF. In order to evaluate the compactness of the heat exchanger, the volumetric heat flux density was considered. Similar to Nusselt number the volumetric heat flux density enhanced for the SIPF and reduced for the CIPF compared to the conventional design. Also the 2-row configuration reached greater thermal performance compared to the 3-row configuration. Additionally, the volume and the surface area of the heat exchanger are 6.9% and 30.7% lower for the SIPF compared to the CPF. The experimental data were used to develop an empirical heat transfer correlation between Nusselt number, Rayleigh number, fin design and tube row number.

我们以新颖的设计研究了翅片式换热器配置的热传递。这些新颖的翅片设计使用集成的销钉来增强从翅片基部到翅片尖端的热传导以及翅片表面上的空气侧传热。通过选择性激光熔化（SLM）工艺相加生成具有常规圆形平翅片（CPF）以及新型圆形一体式针状翅片（CIPF）和锯齿状一体式针状翅片（SIPF）的椭圆形管，并将其安装在6.5 m的底部 长烟囱。所有换热器设计均以2行和3行配置进行测试，瑞利数在25,000和120,000之间。我们发现SIPF的平均Nusselt数高于CPF，CIPF的Nusselt数低于CPF。此外，与所有热交换器设计的3行配置相比，2行配置获得了更高的Nusselt数。对于两种配置，单个管排的分析均显示第一管排的Nusselt数最高，最后一管排的最低。但是，对于SIPF，与CPF和CIPF相比，第一和第二排管之间的差异较小。为了评估热交换器的紧凑性，考虑了体积热通量密度。与Nusselt数类似，与传统设计相比，SIPF的体积热通量密度增加而CIPF的体积热通量密度减小。此外，与3行配置相比，2行配置达到了更高的热性能。另外，与CPF相比，SIPF的热交换器的体积和表面积分别低6.9％和30.7％。实验数据被用于建立努塞尔数，瑞利数，翅片设计和管排数之间的经验传热相关性。