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Lecture Objectives:

Lecture Objectives:. Modeling procedure Learn about weather data base Design vs. energy consumption weather data Analyze an examples solar collector study Introduce eQUEST Energy Simulation Tool http://www.doe2.com/equest/

harper-johnston
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Lecture Objectives:

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  1. Lecture Objectives: • Modeling procedure • Learn about weather data base Design vs. energy consumption weather data • Analyze an examples solar collector study • Introduce eQUEST Energy Simulation Tool • http://www.doe2.com/equest/ • Learn about major differences between common energy simulation tool

  2. Modeling steps • Define the domain • Analyze the most important phenomena and define the most important elements • Discretize the elements and define the connection • Write energy and mass balance equations • Solve the equations (use numeric methods or solver) • Present the result

  3. Input data • Geometry • Material and surface properties • Internal set point temperatures and RH • Period and use of internal sources • Weather data for specific location

  4. Weather data Design condition vs. Operation condition Design whether parameters Winter • Temperature Summer • Temperature and RH - Solar radiation – clear sky no pollution

  5. Weather data for ES analyses • Representative (typical) data • Characteristic for the location and longer period of time • TMY , TMY2, TMY3 database • Typical Meteorological Year 2 (TMY2) • data files are created from the National Solar Radiation Data Base (NSRDB) • a solar radiation and meteorological database (1961-1990 for TMY2 and 1991-2005 for TMY3)

  6. Typical Meteorological Year • http://rredc.nrel.gov/solar/old_data/nsrdb/tmy2/ • Large number of locations • http://rredc.nrel.gov/solar/old_data/nsrdb/tmy2/State.html • Very compact data base • http://rredc.nrel.gov/solar/pubs/tmy2/fig3-1.html • You need to use data reader (write your one ore use already developed) • http://www.eere.energy.gov/buildings/energyplus/

  7. Typical Meteorological Year • Structure (many weather parameters) • Real data (no averaging) 1960 1961 1962 ………………….. 1990 January February December August

  8. Example of TMY2 Database Use for Solar Collector Analysis

  9. Example:Pecan Street Project Demo House Residential House in Austin

  10. Production SystemsPV and Hot Water Solar Collectors Goal: Match annual production and consumption Production

  11. Design ProblemPV and Hot Water Solar Collectors Surrounding building • 1) Case without shading (for example two-story building on the south side): • Annual production 7030 kWh. • 2) Casewith a three-story building on the south side: • Annual production with single inverter 4511 kWh - 35% loss • Annual production with inverter integrated into each panel 5870 kWh - 17% loss • Case when partial shading of PV panels does not affect other panels (more expensive equipment) Used software: • http://www.doe2.com/equest/

  12. Differences in various energy simulation programs

  13. Methods for conduction calculation • Finite difference or finite volume method • Weighting factor method • Response factor method or Response function method

  14. q Building Q HVAC Weighting factor methods The simplest method T external air T internal air Q solar Orientation and Wall (or element) structure Heat flux on internal surface database q

  15. Response function methods Used in eQUEST program

  16. Conduction equations in the matrix Example room

  17. System with the finite difference method for conduction calculation

  18. System when we know the fluxes thought building walls We need to find other way to calculate fluxes

  19. Response function methods NOTATION: θ(x,t)=T(x,)

  20. Laplace transformation Laplace transform is given by Where p is a complex number whose real part is positive and large enough to cause the integral to converge.

  21. Laplace transformation table

  22. Principles of Response function methods The basic strategy is to predetermine the response of a system to some unit excitation relating to the boundary conditions anticipated in reality. Reference: JA Clarke Book form the Reference List

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