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IEA HPP Annex 28 Calculation of compact units

IEA HPP Annex 28 Calculation of compact units

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IEA HPP Annex 28 Calculation of compact units

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  1. IEA HPP Annex 28 N 140 IEA HPP Annex 28Calculation of compact units Workshop IEA HPP Annex 28 8th International Heat Pump Conference, Las Vegas, 30 May 2005 Thomas Afjei, Institute of Energy, University of Applied Sciences Basel

  2. Outline of the presentation • Introduction compact units • System layout of compact units • Approach for the calculation

  3. Introduction compact units • Background • In low- and ultra-low energy dwellings, significantly reduced heating energy requirement • Share of domestic hot water energy requirement increasing up to 50% (ultra-low energy houses) • Air-tight buildings => usually equipped with mechanical ventilation system with heat recovery • High insulation and high passive solar gains => eventually comfort cooling demand in summertime

  4. Conclusion system layout • Compact unit • Highly integrated system layout with core elements • Heat pump • Domestic hot water storage • Ventilation heat recovery system • Optional solar collector • Optional cooling function in summertime • Air heating systems and/or systems with hydronic distribution

  5. Principle of system layout Source: Viessmann

  6. Consequences calculation • Heat recovery Energy requirement: • Reduction of energy demand by recovery of ventilation losses • Electrical expense for the operation of the ventilation system Source temperature: • heat recovery influences source temperature of the heat pump • ground-to-air heat exchanger influences source temperature

  7. Assumptions calculation • Operation Heating energy requirement is covered in the order: • heat recovery (running through in the heating period) • heat pump • back-up heater Domestic hot water energy requirement is covered in the order: • solar collector (optional) • heat pump • back-up heater

  8. temperature difference outside-supply air temperature difference return-outside air OA = Temperature change coefficient Additional input data for compact units • Heat recovery: • key value: temperature change coefficient • mass flow rates • electricity input for ventilation

  9. Additional input data for compact units • Solar energy system: • solar collector characteristics, meteo data • Ground-air heat exchanger: • outlet temperature (if not already considered in performance characteristics, see testing method HTA Lucerne)

  10. Design indoor temperature HP HP S HR HP OP3 S HP Balance point temperature Balance point temperature HR HP design outdoor temperature HP HR S BU BU calculation method compact units Upper ambient temperature for heating OP4 • Domestic hot water covered by heat pump and back-up • Heating requirement covered by heat pump and back-up • heat recovery • Reduction of heating energy requirement • lower inlet temperature to heat pump • domestic hot water energy requirement partly covered by solar contribution (optional) OP2 OP1 HP ambient dry bulb temperature [°C] DHW Space Heating

  11. Thank you for your attention!