Guidelines on how to successfully implement solar cooling systems and lesson learned from Adriacold case studies

Transcription

1 Guidelines on how to successfully implement solar cooling systems and lesson learned from Adriacold case studies Renewable solar energy and thermally-driven technologies, Dubrovnik, Boris Ćosić, Neven Duić University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture

2 ADRIACOLD Hands-on guidelines Main goal of the ADRIACOLD handbook to provide practical information about application of solar cooling systems in buildings First part comprises basics on solar energy such us solar radiation and solar collectors and its utilization in hot water systems for conversion into useful thermal energy. Second part deals with thermally driven cooling systems including all auxiliary components and design guidelines based on knowledge and experiences gained from design and monitoring of installed systems.

3 Solar cooling technologies - absorption cooling, - adsorption cooling - closed cycles - open cycles (desiccant cooling) - PV driven vapour compression chiller - solar driven Rankinecycle (mechanical systems)

4 Generally types of thermally driven cooling technologies COP=Qcold/Qheat Number used to quantify the thermal process quality in thermal driven chilled water systems

5 Solar collectors FK-ST Flat-plate collector, standard product FK-AR Flat-plate collector, 1-cover glass, anti-reflective coated FK-HT Flat-plate collector, 1-cover glass, convection barrier foil, improved insulation VRK-CPC Evacuated tube collector, direct mass flow, Sydney type with external CPC-reflector

6 Heat rejection technologies

7 Predesign methodology for solar cooling systems Predesign methodology consists of following steps

8 Basic decision scheme to identify a technology path

9 General schema of complete system

10 ADRIACOLD case studies(1) Study Number Case Study Croatia Hotel Berulia 1. Case Study Croatia Hotel Maestral 2. Case Study Croatia Hotel Marina 3. Case Study Croatia school Ivan Gundulić 4. Case Study Slovenia elderly home Podsabotin 5. Case Study Slovenia hospital of Izola 6. Case Study Italy wellness centre Nadir-Putignano 7. Case Study Italy winery Santa Margherita 8. Case Study B&H Hotel Aćimović 9. Case Study B&H Hotel Zepter 10.

11 ADRIACOLD case studies(2) Scenario 1 is designed to cover basic and peak loads Scenario 2 is designed only to cover basic load

12 Temperature [ C] Power [kw] Dubrovnik pilot plant operating condition Absorber power at cold side Heat pump Absorber power at hot side Minutes [ ] 40 Room temp. Outside temp Minutes [ ]

13 Overview of design recommendation and guidelines (1) Before solar cooling system is considered and sized, the building cooling load should be carefully assessed and reduced by passive cooling strategies, like reduction of solar gains by sunblind, implementation of thermal mass, night ventilation, orientation and size of windows etc. In applications/climates with heating and cooling demand, combined systems (solar heating and cooling) should be considered. Keep systems as simple as possible in order to minimize risk of failures during installation, operation and maintenance. Comparisons/assessment of the environmental impact of solar heating and cooling systems should be done on the primary energy level and on CO 2 - emissions. For economic reasons, the system and its components should not be sized to cover peak loads, as they account for only a few hours of the year.

14 Overview of design recommendation and guidelines (2) Min. 70% cooling fraction with solar cooling systems is recommended. 100% cooling fraction is technically and economically rarely feasible. In these cases a back-up source provides cooling when the solar irradiation cannot cover the current load. Autonomous solar systems without back-up for cooling can be implemented in building of a large thermal inertia (thermally activated concrete slabs or storage rooms in food and agro industry) For solar cooling only highly efficient collectors with a selective absorber coating should employed. For the Mediterranean, solar cooling systems can yield to 40-50% decrease of primary energy. Related cost of saved primary energy is about 0.07 /kwh. Small cooling capacities and tracking solar collectors for two stage systems increase the cost significantly.

15 Thank you for your attention!