Guidelines on how to successfully implement solar cooling systems and lesson learned from Adriacold case studies
Renewable solar energy and thermally-driven technologies, Dubrovnik, 28.8.2015.
Boris Ćosić, Neven Duić University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture
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.
Solar cooling technologies - absorption cooling, - adsorption cooling - closed cycles - open cycles (desiccant cooling) - PV driven vapour compression chiller - solar driven Rankinecycle (mechanical systems)
Generally types of thermally driven cooling technologies
COP=Qcold/Qheat – Number used to quantify the thermal process quality in thermal driven chilled water systems
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
Heat rejection technologies
Predesign methodology for solar cooling systems Predesign methodology consists of following steps
Basic decision scheme to identify a technology path
General schema of complete system
ADRIACOLD case studies(1) Study
Number
Case Study Croatia Hotel Berulia
1.
Case Study Croatia Hotel Maestral
Case Study Croatia Hotel Marina Case Study Croatia school Ivan Gundulić Case Study Slovenia elderly home Podsabotin Case Study Slovenia hospital of Izola Case Study Italy wellness centre Nadir-Putignano
Case Study Italy winery Santa Margherita
2.
3. 4.
5.
6.
7.
8.
Case Study B&H Hotel Aćimović
9.
Case Study B&H Hotel Zepter
10.
ADRIACOLD case studies(2)
Scenario 1 is designed to cover basic and peak loads
Scenario 2 is designed only to cover basic load
Dubrovnik pilot plant – operating condition Absorber power at cold side
Heat pump
Absorber power at hot side
20 18 16 12
10 8 6 4 2 0 0
100
200
300
400
500
600
700
800
900 1000 1100 1200 1300 1400 1500
Minutes [21.7.2015.]
Room temp.
Outside temp.
40 35 Temperature [°C]
Power [kW]
14
30 25 20
15 10 5 0 0
200
400
600
800
1000
Minutes [21.7.2015.]
1200
1400
1600
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 CO2emissions. • 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.
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.
Thank you for your attention !
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