Finite Volume Based Computer Programs for Ground Source Heat Pump Systems

Transcription

1 Finite Volume Based Computer s for Ground Source Heat Pump Systems Presented by: Jim Menart Director of at Wright State University Research Scientist: Shiva Prasad Graduate Students: Paul Gross and Kyle Hughes IGSHPA Technical Conference & Expo Baltimore, MD October 15 16, 2014

2 Outline Objective of work Computer programs GEO2D GEO3D Demonstration Additional Results Summary Acknowledgements

3 Geothermal Energy Objective Develop a computer simulation tool to size a GSHP (ground source heat pump) system We have developed two codes: GEO2D GEO3D Wanted to produce temperature profiles in the ground and ground loop Project sponsored by DOE Use for design and analysis purposes Horizontal Loop (from ) Vertical Loop (from )

4 Brief Description of GEO2D Detailed building heating and cooling loads determined Capable of doing heat load calculations via DOE s program EnergyPlus Solve detailed form of energy equation using finite volume numerical routine No g-factors are used Two-dimensional (radial and axial directions) Unsteady Model heat transfer in fluid flow, grout, and tube wall No heat transfer coefficients are required Includes model for heat pump Use manufacturer s heat pump performance curves Produces all heat transfer rates and complete temperature profiles Takes about 5 minutes of CUP time for a 20 year simulation on an hourly basis Very easy to use graphical user interface

5 Brief Description of GEO3D Solve detailed form of energy equation using finite volume numerical routine No g-factors are used Three-dimensional (radial, axial, and circumferential directions) Unsteady Model heat transfer in fluid flow, grout, and tube wall No heat transfer coefficients are required Includes model for heat pump Use manufacturer s heat pump performance curves Produces all heat transfer rates and complete temperature profiles Takes about 30 hours of CUP time for a 20 year simulation on an hourly basis

6 GEO2D User Interface Novice or Expert User Novice user allows one to use standard home designs for heating and cooling loads. Expert user allows user to do a detailed heating and cooling load calculation

7 GEO2D Coupling with EnergyPlus WSU Geothermal GUI CAD Model Building Specifics Converts to EnergyPlus input file Novice User Load Calculator Expert User/ Designer to EnergyPlus Editor Hourly Load Data

8 GEO2D User Interface Novice User Home Information

9 GEO2D User Interface Expert User Interface to Energy Plus Expert user will make a detailed EnergyPlus input file Allows for complete flexibility in home or building design This takes a good deal of time Good for professional designers

10 GEO2D User Interface Heat Pump Selection

11 GEO2D User Interface Fluid Property Selection

12 GEO2D User Interface Ground Tube Selection

13 GEO2D User Interface Soil Properties Selection

14 GEO2D User Interface Simulation Parameters

15 GEO2D User Interface Summary Screen

16 Accuracy of Results Have checked the solution against a number of simple analytical solutions and other numerical solutions One-dimensional conduction in both directions Two-dimensional, unsteady exact solution Two dimension convective and conduction problem Have made comparisons to commercial codes The average fluid temperature from GEO2D and GS2000 for a 10 year period.

17 Accuracy of Results Results from EED (Earth Energy Design) Average Temperature for 5 Year Period with Realistic Heating and Cooling Loads Average Temperature for 10 Year Period with Constant Heating and Heating Cooling Load

18 GEO2D Results Yearly Heating and Cooling Loads

19 GEO2D Temperature Profile Year 20 In St. Paul, MN

20 GEO2D Inputs Temperature Profiles for Year 2 In St. Paul, MN

21 GEO2D Inputs Temperature Profiles for Year 2 In St. Paul, MN

22 GEO2D Results Fluid Temperature at Exit from Ground Loop

23 Fluid Exit Temperature at Exit From Ground Loop for a Shorter Ground Loop For Orlando, Florida with k = 0.8 W/m-K and L = 200 m

24 GEO2D Results Heat Transfer with Ground

25 GEO2D Results COP

26 GEO2D Results COP

27 GEO2D Results Economic Results

28 GEO3D Geometry Geometry

29 GEO3D Results Temperature Profiles in Horizontal Planes at Different Depths Depth = 0 m Depth = 0.22 m Depth = 13.6 m

30 GEO3D Results Temperature Profiles in Horizontal Planes at Different Depths Depth = 49.1 m Depth = 93.6 m Depth = m

31 GEO3D Results Zoomed in View of Temperature Profiles in Horizontal Plane at 13.6 m

32 GEO3D Results Temperatures and Heat Flows Bulk temperature of working fluid exiting the ground loop Heat flows

33 Summary Wright State has developed two GSHP computer tools GEO2D GEO3D These are available from the DOE websites: or GEO2D can also be obtained from the Wright State web site It is believed that good computer models can help speed the development of renewable energy technologies

34 Acknowledgements We would like to thank the Department of Energy and Wright State University for funding this work