TRNSYS EXTENSIONS FOR - TPG Internet

1 TRNAUS TRNSYS EXTENSIONS FOR SOLAR WATER HEATING Graham L Morrison. February 2014 School of Mechanical Engineering University of New South Wales Sydney Australia E-mail 1 TRNAUS TRNSYS EXTENSIONS for solar water heaters ABSTRACT This report outlines EXTENSIONS of the TRNSYS simulation program for the analysis of a range of solar collectors and solar water heaters that are used or being investigated in Australia. The emphasis is in the area of thermosyphon systems, heat exchangers, evacuated tubular collectors, non-tracking concentrators and solar boosted heat pump water heaters.

2 EXTENSIONS are detailed for TYPE 101 Solar collector TYPE 137 Solar boosted heat pump TYPE 138 Stratified tank model TYPE 145 Thermosyphon solar water heater including collector loop heat exchanger options TYPE 160 Stratified tank model with mantle heat exchanger and falling film heat exchanger options TYPE 176 One-shot user over-ride of boosting TYPE 177 Delay timer TYPE 178 Event detection EXTENSIONS include coded or TRNSYS deck programming for modelling specified energy load delivery in-tank gas boosting for single tank solar/gas systems reverse flow in thermosyphon systems thermosyphon flow over-temperature cut-off valve load quality binning heat pipe coupling between a collector and a storage tank evacuated tube collectors bi-axial incidence angle modifiers heat exchangers in thermosyphon loops serpentine riser solar collectors 2 TRNAUS TRNSYS EXTENSIONS for solar water heaters ABSTRACT.

3 1 1 INTRODUCTION .. 4 2 TRNAUS FEATURES .. 4 Nonlinear solar collector efficiency characterization.. 4 Optical response function .. 4 Theoretical model of an evacuated tubular solar collector.. 4 Collector heat removal via heat pipe.. 4 Thermosyphon systems with collector loop heat exchanger.. 5 Analysis of heat loss due to reverse flow in thermosyphon systems.. 5 Serpentine riser in collector .. 5 Series - parallel connection of collectors.. 5 Thermal cut-off valve in thermosyphon loop .. 5 Over temperature dump valve .. 5 Two auxiliary elements in stratified storage 5 Load quality.

4 6 Energy load specification.. 6 Analysis of conduction in a horizontal tank improved.. 6 3 NONLINEAR SOLAR COLLECTOR CHARACTERIZATION TYPE101 .. 7 Efficiency mode 2 .. 7 Efficiency mode 3 .. 7 Unglazed solar collector .. 7 Theoretical evacuated tubular collector characterization .. 8 Application of Nonlinear Collector Characterisation .. 9 4. INCIDENCE ANGLE MODIFIER EXTENSIONS .. 9 Symmetric Collectors (eg flat plate collectors).. 9 ASHRAE 93-77 9 Data Table of Incidence Angle Modifier Values .. 9 Collectors with North-South and East-West Symmetry .. 9 Bi-axial modifier data table.

5 9 Incidence angle modifier map (optical mode 5) .. 10 Collectors with East-West Symmetry only (optical mode 6) .. 10 Incidence Angle Terminology .. 10 Examples of Data Input .. 11 Bi-axial modifiers .. 11 Optical response map specification .. 11 5 THERMALLY STRATIFIED TANK MODEL 13 Heat pipe coupling between the collector and the 14 Thermal dump valve .. 14 Two position auxiliary input .. 14 Computation sequence .. 15 Load energy binning .. 15 6 THERMOSYPHON ANALYSIS TYPE145 .. 16 Heat exchanger thermosyphon circuits .. 16 Horizontal mantle tank .. 16 Heat exchanger in tank with measured UA.

6 18 Serpentine collectors .. 18 Thermal cut off valve .. 19 Reverse circulation in thermosyphon systems .. 19 7 CONTROLLERS .. 21 USER OVER-RIDE OF BOOSTER OPERATION TYPE176 .. 21 Delay timer TYPE177 .. 22 Event detection TYPE 178 .. 22 Differential controller with three maximum limits TYPE102 .. 22 8. SOLAR BOOSTED HEAT PUMP .. 23 Heat pump model .. 23 Solar-boosted evaporator .. 24 Energy inputs to integral evaporator system .. 26 3 TRNAUS TRNSYS EXTENSIONS for solar water heaters Storage tank and condenser .. 28 Solution procedure .. 28 9. GAS BOOSTED SOLAR WATER HEATERS (in-tank firing).

7 29 10. AUSTRALIAN SOLAR RADIATION DATA (Typical Meteorological Year ) .. 31 Extension of hourly climatic data bank .. 33 Weather data for New Zealand .. 34 11. REFERENCES .. 35 Appendix 1. TRNAUS Solar Collector Component Description TYPE101 .. 37 Appendix 2 Stratified Tank Component Description TYPE138 .. 40 Appendix 3 TYPE145 Thermosyphon Solar Water Heater Component Description .. 43 Appendix 4 TYPE137 Heat Pump with Solar Boosted Evaporator .. 48 Appendix 5 TRNAUS data deck for heat pipe collector modelling .. 49 Appendix 6 TRNAUS data deck for energy load 50 Appendix 7 TYPE 176 User Over-ride of Booster Operation.

8 52 Appendix 8 TYPE 177 Delay timer .. 53 Appendix 9 TYPE 178 Event detection .. 54 Appendix 10 TYPE 102 Differential controller with three maximum limits .. 55 Appendix 11 Gas Boosted Water Heater Simulation .. 56 Appendix 12 TYPE 160 - Modified Type60 detailed storage tank .. 57 4 TRNAUS TRNSYS EXTENSIONS for solar water heaters 1 INTRODUCTION The majority of solar thermal system developments in Australia have been based on experimental evaluation of prototype systems. As the performance of solar devices is strongly seasonally dependent the cost and time involved in long term monitoring of prototype systems is a barrier to the development of innovative designs.

9 To assist with the evaluation of new solar applications this report outlines a set of EXTENSIONS for the TRNSYS [Klein 1999] simulation package to suit the range of solar water heating products in use or being developed in Australia. A Typical Mean Year solar data base for Australia is also outlined. To use the TRNAUS routines the user must have an existing TRNSYS installation. 2 TRNAUS FEATURES TRNAUS extends the range of system configurations that TRNSYS can model as follows Nonlinear solar collector efficiency characterization. Solar collector performance can now be characterized by some of the nonlinear correlation functions recommended in Australian Standard AS 2535.

10 The thermosyphon routine also incorporates nonlinear solar collector characterization. Optical response function The solar collector routine has also been extended to allow optical response functions of concentrating collectors to be specified via a map of optical acceptance. If detailed optical data is available from ray tracing analysis this extension allows a more accurate specification of optical effects than the standard bi-axial optical response product function. Theoretical model of an evacuated tubular solar collector. A model of an evacuated tubular collector with a diffuse reflector has been incorporated.