Brunel MSc Thesis-NA Stogiannos-Final

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  • BRUNEL UNIVERSITY LONDON

    PV/Thermal Solar Assisted Heat Pump Systems in Southern Europe: Performance

    Comparison of Different System Configurations Nikolaos Alexandros Stogiannos

    1037560

    MSc Thesis - Building Services Engineering with Sustainable Energy

    2011-2012

    Abstract

    Photovoltaic panels suffer performance degradation when cell temperature increases. PV/Thermal panels address this problem by cooling the cells while also preheating the water in the DHW storage tank. However, at low DHW load and/or high irradiance conditions, the temperature of the water in the tank increases excessively and the cooling advantage diminishes. PV-SAHP systems offer a solution that can deal with all issues, offering high-temperature water output and PV cell cooling simultaneously. In this project various system configurations are tested using TRNSYS simulations under the extreme Greek climate. An optimal design is established that is applicable to domestic buildings and is found to perform remarkably. An average annual COP of 4.4 and an average annual PVT efficiency of 57.3% were estimated by the simulations. The proposed system offers a 23% reduction in electrical energy, CO2 emissions and costs for a typical Greek domestic residence, compared with a conventional DHW electric system.

  • N.A. - Stogiannos

    1

    Table of Contents Notation ............................................................................................................................................ 3

    Glossary and Abbreviations .............................................................................................................. 4

    1. Introduction .............................................................................................................................. 5

    1.1. Context of the project ............................................................................................................. 5

    1.2. Project Aim and Objectives .................................................................................................... 6

    1.3. Brief description of contents ................................................................................................... 6

    2. Technological and Theoretical Background .......................................................................... 7

    2.1. The PVT panel, Past and Present .......................................................................................... 7

    2.2. PVT Basic Theoretical Background ..................................................................................... 8

    2.2.1. PVT Design Aspects ....................................................................................................... 8

    2.2.2. PVT Electrical Performance ............................................................................................ 9

    2.2.3. Flat Plate Solar Collector Thermal Performance............................................................ 11

    2.2.4. The Florschuetz PVT model .......................................................................................... 13

    2.3. The Photovoltaic solar assisted Heat pump system (PV-SAHP) ........................................... 14

    3. Literature Review ................................................................................................................... 16

    3.1. PVT, Research and Development (R&D) ............................................................................. 16

    3.2. PV-SAHP R&D ..................................................................................................................... 18

    3.3. The Spiral sheet-and-tube heat exchanger........................................................................... 21

    4. Data Acquisition Methodology and Result Discussion: Experimental Measurements ..... 25

    4.1. Electrical Part 1: Performance characteristics ..................................................................... 25

    4.1.1. Available data from the group report (Couch, et al., 2012) ............................................ 25

    4.1.2. The new set of measurements ...................................................................................... 26

    4.2. Thermal Part 1: Performance characteristics ....................................................................... 32

    4.3. The correct procedure for proper operation of the System Rig ............................................. 37

    4.4. Electrical Part 2: Pmax panel-temperature coefficient ......................................................... 37

    4.5. Thermal Part 2: Improved ASHRAE curve............................................................................ 39

    5. Theoretical Model Validation ................................................................................................ 45

    6. Data Acquisition Methodology and Result Discussion: TRNSYS Simulations ................. 48

    6.1. Introduction .......................................................................................................................... 48

    6.2. Available PVT and Heat Pump TRNSYS types ................................................................... 48

    6.2.1. PVT types ..................................................................................................................... 48

    6.2.2. Water-to-water Heat Pump types .................................................................................. 49

    6.3. The PVT-Storage Tank configuration .................................................................................. 49

    6.3.1. Weather Data Component ............................................................................................. 49

    6.3.2. Task 35 PVT component, type250 ................................................................................ 51

  • N.A. - Stogiannos

    2

    6.3.3. Pump, Storage Tank and DHW profile components ...................................................... 52

    6.4. The directly connected PV-SAHP configuration .................................................................. 53

    6.4.1. Initial design intention .................................................................................................... 53

    6.4.2. Heat Pump implementation in TRNSYS ........................................................................ 53

    6.4.3. A problematic configuration ........................................................................................... 55

    6.5. The Dual Tank PV-SAHP configuration .............................................................................. 56

    6.6. Simulation Results-Discussion ............................................................................................. 57

    6.6.1. Control Strategy Evaluation ........................................................................................... 57

    6.6.2. System Performance Evaluation ................................................................................... 60

    7. Economic Evaluation............................................................................................................. 68

    8. Concluding Remarks ............................................................................................................. 69

    8.1. Recapitulation ...................................................................................................................... 69

    8.2. Conclusions ......................................................................................................................... 69

    8.3. Recommendations for Future Work ...................................................................................... 70

    9. References ............................................................................................................................. 71

    Appendix A Project Management ................................................................................................. 76

    Original Aim and Broad Objectives ................................................................................................. 76

    Review of Project Management ...................................................................................................... 77

    Appendix B Project Proposal ....................................................................................................... 81

    1. Introduction .............................................................................................................................. 81

    2. Background to the Project ........................................................................................................ 82

    2.1. The PVT panel .................................................................................................................. 82

    2.2. The Photovoltaic solar assisted Heat pump system (PV-SAHP) ....................................... 82

    3. Aims and Broad Objectives ...................................................................................................... 83

    4. Methods to be Adopted ............................................................................................................ 84

    5. Specific Outcomes ................................................................................................................... 84

    6. Time-plan ................................................................................................................................ 85

    7. References .........................................................