Building Services Engineering CHALMERS Akademiska Hus Carrier CTC / Enertech OPTIMIZATION OF Donghua University Fastighetsägarna GROUND SOURCE HEAT PUMP Geotec Grundfos SYSTEMS IVT LTH Saqib Javed (PhD Researcher) NCC Nibe Per Fahlén (Research Leader) SWECO TAC Johan Claesson (Supervisor) Thermia Värme Wilo ÅF-Infrastruktur EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS OBJECTIVE Identifying key optimization factors for Ground Source Heat Pump (GSHP) systems using modelling and simulations, field studies and experiments. • Developing simple and user-friendly models and calculation tools to facilitate the work of designers and researchers interested in the complete system optimization . EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS LITERATURE REVIEW Long-Term Response Short-Term Response Borehole Resistance - - - Classical line source Numerical solution of Drake and Eckert’s solution (LS) Yavuzturk method - - - Classical cylindrical Buried electric cable Gu and O’Neal’s method source solution (CS) analogy - Paul’s empirical method - - Superposition borehole Lamarche and - model (SBM) Beauchamp’s solution Hellström’s approach - - - Finite-length line Virtual solid solution Multipole method source solutions - Quassi 3D methods EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS LITERATURE REVIEW • Long-term response: � Existing solutions to model single borehole systems Shortage of solutions to model multiple borehole systems � • Short-term response solutions: � Use simplifying assumptions. � Check for consistency and accuracy. EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS ANALYTICAL SOLUTIONS: LONG-TERM RESPONSE OF MULTIPLE BOREHOLES CS (borehole interaction with infinite LS) CS (borehole interaction with finite LS) 9 16 Maximum mean fluid temperature [deg C] Minimum mean fluid temperature [deg C] Infinite LS (borehole interaction with infinite LS) Finite LS (borehole interaction with finite LS) 15 7 SBM 14 5 Maximum mean fluid temperature → 13 3 12 11 1 10 ‐ 1 ← Minimum mean fluid temperature 9 ‐ 3 8 0 5 10 15 Year EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS ANALYTICAL SOLUTIONS: SHORT-TERM BOREHOLE RESPONSE 0.40 Temperature Increase (K) 0.30 0.20 BFTM solution 0.10 L & B solution VS solution New Analytical solution 0.00 0 5 10 15 20 Time (hours) EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS NEW ANALYTICAL SOLUTION • Laplace transformation based approach. • Considers capacities, resistances and properties of all borehole elements. • Use of thermal network to model any physical or thermal setting of the borehole. • Very concise formulas to obtain time dependent solutions. EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS NEW NUMERICAL SOLUTION • Studies one dimensional heat conduction problem. • Transforms the radial coordinate to a conformal coordinate. � 0 0, 1, �1, , � � � � � � � � � � � � � � , 0, 1, 2, �1, , �1, , x x x x x x x x 1 2 ... n ‐ 1 n n + 1 ... N 1 ∆ ∆ EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS VALIDATION: INTER-MODEL COMPARISON 0.004 Temperature Difference (K) 0.003 0.002 0.001 0 0 25 50 75 100 Time (hours) EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS VALIDATION: EXPERIMENTAL DATA 0.25 Temperature Difference (K) 0.20 0.15 0.10 0.05 0.00 0 10 20 30 40 50 Time (hours) EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS LABORATORY DEVELOPMENT EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS LABORATORY DEVELOPMENT EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS NEW GSHP TEST FACILITY EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS NEW GSHP TEST FACILITY Borehole system From DC1 To DC1 To HP2 HX1 + AT2 AT1 HP1 EH1 +5--+15 -10--+10 From HP2 Process cooling agent (Brine) Process cooling water EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS NEW GSHP TEST FACILITY From DC2 HX2 To DC2 From AT2 AT3 AT4 HP2 HP3 +20--+55 +20--+55 Return HW1 HW1 heating system To AT2 HW1 process heating water EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS NEW GSHP TEST FACILITY HX2 RC AT3 AT4 AT5 EP1 +20--+55 +20--+55 +20--+80 +20--+80 HW1 heating system HW2 process heating water HW1 process heating water EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS NEW GSHP TEST FACILITY • New GSHP test facility consisting of: � Nine borehole ground system, � Three heat pumps, � Five storage tanks, � Dry coolers. • New test facility can be used to: � Develop and validate models, � Study optimization parameters for simple & hybrid GSHP systems, � Conduct thermal response tests (TRTs). EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS TRTS: SEQUENCE AND DURATION Undisturbed ground No. Thermal response test temperature BH1 2009-12-03 (45 minutes) 2009-12-03 – 2009-12-07 (75 hours) BH9 2009-12-10 (35 minutes) 2009-12-10 – 2009-12-15 (98 hours) BH2 2009-12-18 (75 minutes) 2009-12-18 – 2009-12-21 (54 hours) BH3 2009-12-24 (30 minutes) 2009-12-24 – 2010-01-07 (267 hours) BH6 2010-01-14 (60 minutes) 2010-01-14 – 2010-01-18 (91 hours) BH4 2010-02-02 (60 minutes) 2010-02-02 – 2010-02-04 (48 hours) BH8 2010-02-05 (40 minutes) 2010-02-05 – 2010-02-08 (69 hours) BH7 2010-02-09 (30 minutes) 2010-02-09 – 2010-02-11 (48 hours) BH5 2010-02-12 (45 minutes) 2010-02-12 – 2010-02-15 (68 hours) EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS TRTS: RESULTS • Undisturbed Ground Temperature: 8.2 → 9.2 °C • Ground Thermal Conductivity: 3.01 ± 7% W/(m·K) • Borehole Thermal Resistance: 0.056 ± 0.012 (m·K)/W EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS TRTS: UNCERTAINTY ANALYSIS Uncertainty in Uncertainty in Factors estimated λ s estimated R b Test duration between 50 and 100 hours ± 4 % ± 3 % Power fluctuations of ± 1 % ± 1 % ± 1 % Temperature measurement uncertainty of ± 0.15 K < ± 1 % < ± 1 % Uncertainty of ± 0.9 K in undisturbed ground - ± 25 % temperature measurement Uncertainty of ± 15 % in the volumetric heat - ± 8 % capacity Borehole geometry ± 1 % uncertainty in borehole depth ± 1 % < ± 1 % ± 1 % uncertainty in borehole radius - ± 8 % Estimation method ± 2.5 % ± 10 % EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS TRT ESTIMATIONS: EFFECTS ON BOREHOLE SYSTEM DESIGN 35 16 Mean Fluid Temperature (deg C) BH6 BH8 Fluid Temperature (deg C) Maximum mean fluid temperature 12 30 8 25 Minimum mean fluid temperature 4 Set 1A Set 2A Set 3A Set 4A Set 5A Set 6A Set 7A Set 8A Set 9A 0 20 0 5 10 15 20 25 0 5 10 15 20 25 Years Years Single Borehole System Multiple Borehole System EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS CONCLUSIONS � Conducted a state-of-the-art literature review. � Presented different approaches to model multiple borehole systems. � Developed new analytical and numerical methods. � Conducted TRTs and uncertainty analysis. EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS PLANNED FUTURE WORK • Optimize operation and performance of GSHP systems. • Develop new TRT evaluation method to shorten test duration. • Investigate of new operation and control strategies for simple and hybrid GSHP systems. • Study long and short term borehole response of laboratory borehole system . EFFSYS 2 meeting 2010-06-10
Building Services Engineering CHALMERS PUBLICATIONS • Javed, S, 2010. Design of ground source heat pump systems – Thermal modelling and evaluation of boreholes. Licentiate thesis, Building service engineering, Chalmers university of technology, Sweden. • Javed, S and Fahlén, P, 2010. Development and planned operation of a ground source heat pump test facility. Newsletter IEA heat pump centre , vol. 28, no. 1/2010, pp. 32-35. • Javed, S, Claesson, J and Fahlén, P, 2010. Analytical modelling of short-term response of ground heat exchangers in ground source heat pump systems. 10th REHVA world congress; Clima 2010 , May 9-12, Antalya, Turkey. • Javed, S., Fahlén, P. and Holmberg, H., 2009. Modelling for optimization of brine temperature in ground source heat pump systems . Proceedings of 8th international conference on sustainable energy technologies; SET2009, Aachen, Germany. August 31- September 3. • Javed, S., Fahlén, P. and Claesson, J., 2009. Vertical ground heat exchangers: A review of heat flow models . Proceedings of 11th international conference on thermal energy storage; Effstock 2009, Stockholm, Sweden. June 14-17. EFFSYS 2 meeting 2010-06-10
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