A new performance evaluation algorithm for horizontal GCHPs (ground coupled heat pump systems) that considers rainfall infiltration. (1st April 2015)

• Record Type: Journal Article
• Authors: Go, Gyu-Hyun; Lee, Seung-Rae; N.V., Nikhil; Yoon, Seok
• Is Part Of: Energy. Volume 83(2015)
• Page Start: 766
• Page End: 777
• Publication Date: 2015-04-01
• Subjects: Rainfall infiltration -- Horizontal ground heat exchanger -- Numerical simulation -- Groundwater advection -- Performance analysis; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2015.02.086
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: This study presents a novel performance evaluation algorithm for horizontal GCHPs (ground coupled heat pump systems) that considers rainfall infiltration. The influence of rainfall infiltration on the thermal characteristics of shallow trenches is examined using infiltration analyses, and then a numerical analysis study is conducted in order to investigate how rainfall infiltration affects the performance of HGHEs (horizontal ground heat exchangers). According to the thermal performance test results in unsaturated ground with a varying thermal conductivity profile, the rainfall infiltration results in a widening fluid temperature gap between the inlet and outlet, and it increases the thermal efficiency compared with that without rainfall. Furthermore, in fully saturated ground, groundwater advection has a positive influence on the performance of the heat exchanger, and the advection effect varies with the local ground conditions such as hydraulic conductivity and void ratios. In the cooling mode, the free convection phenomenon occurs in shallow trenches, and this fluid circulation attenuates the ground temperature increases due to the heat source, which leads to a significantly faster heat steady state. However, noticeable free convection only occurs if the ground has a high permeability coefficient. Highlights: The influence of rainfall on the thermal characteristics of trenches is examined. Ground thermal conductivity varies with depth and elapsed time during rainfall. Rainfall increases the thermal efficiency of ground coupled heat pump systems. Effect of groundwater advection varies with the local ground conditions. Noticeable free convection tends to occur when the ground has a high permeability.