Effect of disturbance on thermal response test, part 2: Numerical study of applicability and limitation of infinite line source model for interpretation under disturbance from outdoor environment

The approximated infinite line source (ILS) model is widely used to interpret thermal response tests (TRTs). It assumes a constant heat flux from the source. However, this assumption is violated in real field conditions by the heat exchange between the circulating fluid and the outdoor environment in an above-ground TRT setup. This results in a fluctuating behavior of sequential estimation and estimation error. In this study, we quantitatively examined the effect of disturbance from outdoor environment on TRTs, especially when TRTs are interpreted by the ILS model, using numerical methods. An analytical model that takes disturbance into account was incorporated as the boundary condition of a numerical model. Using typical synthetic weather data of different seasons and 36 cases of measured weather data, numerical TRTs were conducted and interpreted. Some characteristic behavior of interpretation related to weather conditions was explained and changes in error range with testing duration were analyzed to clarify the applicability and limitation of the interpretation using the ILS model. The results showed that at least 60 h of TRT is required to obtain results within the error range of ±5% compared with the reference case. Additionally, some practical suggestions regarding conducting and interpreting TRTs are provided.

[1]  Saqib Javed.  Thermal Response Testing: Results and Experiences from a Ground Source Heat Pump Test Facility with Multiple Boreholes , 2013 .

[2]  G. Hellström,et al.  Multipole method to compute the conductive heat flows to and between pipes in a composite cylinder , 1987 .

[3]  P. Blum,et al.  Numerical sensitivity study of thermal response tests , 2012 .

[4]  Simon J. Rees,et al.  A transient two-dimensional finite volume model for the simulation of vertical U-tube ground heat exchangers , 1999 .

[5]  Keith A. Woodbury,et al.  Inverse problems and parameter estimation: integration of measurements and analysis , 1998 .

[6]  Jonathan Richard Shewchuk,et al.  Triangle: Engineering a 2D Quality Mesh Generator and Delaunay Triangulator , 1996, WACG.

[8]  B. S. Petukhov.  Heat Transfer and Friction in Turbulent Pipe Flow with Variable Physical Properties , 1970 .

[9]  Jeffrey D. Spitler,et al.  Development of an in-situ system and analysis procedure for measuring ground thermal properties , 2000 .

[10]  Paul Christodoulides,et al.  An analysis of heat flow through a borehole heat exchanger validated model , 2012 .

[11]  Esmail M. A. Mokheimer,et al.  Energy, exergy and uncertainty analyses of the thermal response test for a ground heat exchanger , 2009 .

[12]  Ryozo Ooka,et al.  Interpretation of disturbed data in thermal response tests using the infinite line source model and numerical parameter estimation method , 2015 .

[13]  L. Gosselin,et al.  Borehole temperature evolution during thermal response tests , 2011 .

[14]  L. Schiavi,et al.  Estimation of soil and grout thermal properties through a TSPEP (two-step parameter estimation proce , 2011 .

[15]  L. Gosselin,et al.  Numerical analysis of thermal response tests with a groundwater flow and heat transfer model , 2011 .

[16]  Pingfang Hu,et al.  A method and case study of thermal response test with unstable heat rate , 2012 .

[17]  Gongsheng Huang,et al.  A p(t)-linear average method to estimate the thermal parameters of the borehole heat exchangers for in situ thermal response test , 2014 .

[18]  Signhild Gehlin,et al.  A Mobile Equipment for Thermal Response Test , 1996 .

[19]  Fabio Bozzoli,et al.  Modeling approaches applied to the thermal response test: A critical review of the literature , 2011 .

[20]  O. J. Zobel,et al.  Heat conduction with engineering, geological, and other applications , 1955 .

[21]  Hiroshi Akasaka,et al.  STUDY ON THE METHOD FOR CONSTRUCTING A REFERENCE WEATHER YEAR : A comparison of the EA method and the SHASE method , 2004 .

[22]  B. Palm,et al.  Distributed thermal response tests on pipe-in-pipe borehole heat exchangers , 2013 .

[23]  Hongxian Guo,et al.  In-situ experimental study of heat exchange capacity of CFG pile geothermal exchangers , 2014 .

[24]  A. Busso,et al.  First in situ determination of ground and borehole thermal properties in Latin America , 2004 .

[25]  V. Gnielinski.  New equations for heat and mass transfer in turbulent pipe and channel flow , 1976 .

[26]  J. Beck,et al.  Field Test of a New Method for Determining Soil Formation Thermal Conductivity and Borehole Resistance , 2000 .

[27]  Per Eskilson.  Thermal analysis of heat extraction boreholes , 1987 .

[28]  René Lefebvre,et al.  A Review of Thermal Response Test Analysis Using Pumping Test Concepts , 2011, Ground water.

[29]  Ryozo Ooka,et al.  Effect of disturbance on thermal response test, part 1: Development of disturbance analytical model, parametric study, and sensitivity analysis , 2016 .

[30]  G. Hagen,et al.  Ueber die Bewegung des Wassers in engen cylindrischen Röhren , 1839 .

[31]  Mustafa Inalli,et al.  In-situ thermal response test for ground source heat pump system in Elazığ, Turkey , 2009 .

[32]  G. Hellström,et al.  Comparison of four models for thermal response test evaluation , 2003 .

[33]  Refrigerating.  ASHRAE handbook of fundamentals , 1967 .

[34]  J. C. Jaeger,et al.  Conduction of Heat in Solids , 1952 .

[35]  J. Spitler,et al.  In Situ Measurement of Ground Thermal Conductivity: A Dutch Perspective , 2002 .

[36]  D. Marcotte,et al.  On the estimation of thermal resistance in borehole thermal conductivity test , 2008 .

[37]  G. Florides,et al.  First in situ determination of the thermal performance of a U-pipe borehole heat exchanger, in Cyprus , 2008 .

[38]  Tolga Y. Ozudogru,et al.  3D Numerical Modeling of Vertical Geothermal Heat Exchangers , 2014 .

[39]  Daniel Castro-Fresno,et al.  Borehole thermal response and thermal resistance of four different grouting materials measured with a TRT , 2013 .

[40]  J. Beck,et al.  Determining effective soil formation thermal properties from field data using a parameter estimation technique , 1998 .

[41]  H. S. Carslow,et al.  Conduction of Heat in Solids, Second Edition , 1986 .

[42]  José Acuña,et al.  Distributed thermal response tests on a multi-pipe coaxial borehole heat exchanger , 2011, HVAC&R Research.

[43]  Roland Wagner,et al.  Evaluating thermal response tests using parameter estimation for thermal conductivity and thermal capacity , 2005 .

[44]  P. F. Córdoba,et al.  Improving parameter estimates obtained from thermal response tests: Effect of ambient air temperatur , 2011 .

[45]  Hikari Fujii,et al.  An improved thermal response test for U-tube ground heat exchanger based on optical fiber thermometers , 2009 .

[46]  Daniel Pahud,et al.  Numerical evaluation of thermal response tests , 2007 .