A general distributed parameter model for ground heat exchangers with arbitrary shape and type of heat sources. (15th May 2018)

• Record Type: Journal Article
• Authors: You, Tian; Wang, Baolong; Li, Xianting; Shi, Wenxing; Yang, Hongxing
• Is Part Of: Energy conversion and management. Volume 164(2018)
• Page Start: 667
• Page End: 679
• Publication Date: 2018-05-15
• Subjects: Ground-coupled heat pump -- Ground heat exchanger -- Distributed parametermodel -- Response factor -- Simulation; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2018.03.059
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: A general distributed parameter model for a ground heat exchanger is proposed. The proposed model has similar accuracy to the numerical solutions and experiments. This model can calculate distributed temperatures and short-term heat transfer. This model is suitable for different types of ground heat exchangers. Abstract: The heat and mass transfer simulation model of a ground heat exchanger (GHE) directly affects the design and operation performance of a ground-coupled heat pump system. The GHE models based on the response function (like the Green function and g-function) can achieve a fast calculation speed. However, the heat sources in these models are limited to points or whole boreholes, leading to low calculation accuracy in heat transfer during a short time period and limitation to a certain GHE. A general distributed parameter model for a ground heat exchanger (RF model) is proposed based on the principle of response factors in this paper. A sandbox experimental platform is then built to test the temperatures of typical points in the double-layered soil and to validate the RF model. After that, the calculation of the RF model is simplified by determining suitable positions for the soil boundaries and the numbers of sub pipes and sub soil boundaries. Finally, the RF model is applied in different scenarios to demonstrate its characteristics. The results show that: (1) the RF model is suitable for different kinds of GHEs with arbitrary shape and type of heat sources releasing heat in arbitrary time steps; (2) the RF model has only 0.01 °C and 0.23 °C temperature response errors compared to those from numerical solutions and experiments, respectively; (3) the general RF model has similar accuracy to the numerical solution in calculating the distributed temperatures of the borehole and pipes, heat transfer in the short term, and heat transfer of borehole groups and the energy pile.