کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1742191 1017673 2016 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Numerical model for non-grouted borehole heat exchangers, Part 2—Evaluation
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Numerical model for non-grouted borehole heat exchangers, Part 2—Evaluation
چکیده انگلیسی


• Detailed DTRT and heat pump measurement of a 261 m water filled BHE are presented.
• The numerical model accurately replicates the detailed experimental measurements.
• Transient effects during heat pump cycles and response test are analyzed.
• Model predicts distinct changes in borehole resistance related to natural convection.
• Natural convection dramatically reduces the internal resistance.

In this paper a simplified and not fully discretized numerical model is used to simulate the performance of a non-grouted (water filled) borehole heat exchanger (BHE). The model enables simulation of the initial transient behavior of a BHE and gives transparent insight into the heat transfer mechanism acting during the startup and operation of the BHE installation. To account for the thermal effect of natural convection that arises in non-grouted BHEs, the model is complemented with a Nusselt-correlation. The model is presented in detail in Holmberg et al. (2014) and in the present paper it is evaluated based on distributed temperature measurements from Acuña (2010). The measurements were obtained during a distributed thermal response test (DTRT) and during heat pump operation, both on a 261 m deep borehole equipped with a U-tube collector and a distributed temperature sensing system. Despite the simplifications involved with the model, it agrees well with the measured data even on a time scale on the order of minutes. The Nusselt number related to natural convection in the borehole was found to be 6.4 during the DTRT and 3.68 during heat pump operation. This indicates the large differences in the borehole thermal resistance during heat injection and heat extraction.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geothermics - Volume 59, Part A, January 2016, Pages 134–144
نویسندگان
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