Analytical modeling and heat transfer analysis of deep-buried pipe groups under typical multi-pipe layouts

This study investigates heat transfer in deep-buried pipe groups, with a particular emphasis on the challenges associated with non-regularly arranged configurations. An analytical method is proposed that effectively addresses the complexities of modeling and computational intensity of existing numerical methods. Experimental and numerical validation demonstrates that beyond the first 8 h, the maximum relative error is only 2.28 %. This model is used to analyze the heat transfer characteristics of various typical pipe group layouts over 20 years. The results indicate that the heat transfer intensity of a 3 × 3 staggered layout is 0.75 % higher than that of an aligned layout. Furthermore, increasing the pipe group spacing from 20 to 80 m significantly enhances heat transfer performance, with 80 m identified as the suggested spacing in this study. The study also examines three 5-pipe layouts; namely, right-angled, vertical, and cross-shaped. The results show that the vertical layout achieves the highest heat transfer efficiency, with a 20-year average heat transfer intensity of 345.757 kW. This research advances solution methods for heat transfer in deep-buried pipe groups and provides reliable tools for engineering applications.