Enhancing geothermal heat pump efficiency with fin creation and microencapsulated PCM: A numerical study

Abstract

The main cause of global warming is the emission of carbon dioxide from fossil fuels. Several methods to reduce CO2 emissions have been explored to ensure energy conservation. Many researchers have focused on renewable energy sources for this reason. Ground-source heat pumps (GSHPs) have emerged as a popular alternative in various sectors that utilize shallow geothermal energy sources for heating and cooling. This study presents a novel approach to enhancing the efficiency of geothermal heat exchangers, a critical component of GSHPs, through numerical simulation using computational fluid dynamics (CFD) with Ansys Fluent software. The research investigates the impact of adding four models of spiral fins to the exterior body of the heat exchanger: single spiral and double spiral configurations with pitches of 60 mm and 40 mm, respectively. Additionally, the study explores the effect of incorporating microencapsulated phase change materials (PCMs) with volume fractions of 0 %, 10 %, 30 %, and 50 % into the backfill material surrounding the heat exchanger. The results demonstrate that the double spiral fins with a 40 mm pitch significantly enhance thermal efficiency by reducing the output temperature by up to 1 °C compared to the model without fins. Furthermore, the addition of 50 % microencapsulated PCM by volume to the backfill material can further decrease the output temperature by up to 4 °K. The combined use of double spiral fins and microencapsulated PCMs results in a 7.5 % improvement in the efficiency of the heat exchanger and the coefficient of performance of the heat pump. This study highlights the potential of innovative design modifications and material enhancements to significantly improve GSHP performance for more efficient and sustainable heating and cooling solutions.