PCM thermal storage system for cooling and heating of buildings

Transcription

1 PCM thermal storage system for cooling and heating of buildings University of Ljubljana, Faculty of Mechanical engineering, Laboratory for Heating, Sanitary and Solar technology and Air- conditioning doc. dr. Uroš Stritih univ. dipl. inž.,

2 INTRODUCTION 40% of total final energy consumption presents buildings (priority to minimize) EPB Directive - necessary to choose alternative solutions for heating, cooling option: - thermal energy storage (TES), - using phase change materials (PCMs)

3 INTRODUCTION Latent heat storage - gaining importance Variety of approaches: - storage systems can be integrated into the building s envelope, - into HVAC or - operate as stand-alone units.

4 INTRODUCTION Idea: utilize natural sources within stand-alone active system example: - outdoor cold during summer nights stored and supplied to the indoor environment during the day, when the cooling load increases; - heating load increases after sunset, day-cycle TES can be used. - when available energy exceeds the energy demand energy stored, later released to completely or partially replace conventional systems.

5 The building company Imtech in Hamburg, Germany. Botanic garden in Berlin, Germany.

6 The building company Imtech in Hamburg, Germany: - 5 kilograms PCM material having a melting point at 22 C per square meter of area is embedded - sufficient for the storage of 60 W /m² cooling. - In summer, during the night, when the temperature drops below 18 C, the system is filled. - Throughout the day it is able to maintain the room temperature below 26 C. Botanic garden in Berlin, Germany: - the air due to PCM modules warms up the air and warm air comes to plants. - PCM modules are filled during the day.

7 OUR IDEA Idea: utilize natural sources within stand-alone active system: - To store outdoor cold during summer nights and supply to the indoor environment during the day; - To store heat from solar air collector during winter and supply to the indoor environment during morning and evening. 7

8 The operating principle of LHT - summer, filling OUTDOOR AIR WINDOW PANELS WITH FSS HOT AIR COLLECTOR ROOM

9 The operating principle of LHT - summer, emptying

10 The operating principle of LHT - winter, filling

11 The operating principle of LHT - winter, emptying

12 EXPERIMETAL SETUP Type and quantity of phase change material for the thermal storage are determined by: calculations of office cooling and heating loads. temperature range between 20 and 26 C PCM RT22HC (Rubitherm GmbH) - melting point 22 C

13 EXPERIMENTAL SETUP Experimental system: in room (left), solar air collector outside (right)

14 EXPERIMENTAL SETUP casing made of 5 cm thick EPS internal dimensions: 73 cm 45 cm 39 cm Used PCM macroencapsulated in the form of CSM plates Outer dimensions of plates: 30 cm 45 cm 1,5 cm, horizontally positioned in the storage tank 29 CSM plates (air gap between plates 0,8 cm)

15 EXPERIMENTAL SETUP average mass of filled plate: 1361 g weight of paraffin in the plate: 1003 g volume of each plate: 1,48 liters 12% of the plate s volume empty tube with diameter 110 mm

16 EXPERIMENTAL SETUP Tubes isolated with 20 mm of insulation Fan: installed before the thermal storage tank, 5 speed levels Installed hatch at the output, can direct airflow to the office or out Solar hot air collector is installed on the outer wall of the office

17 EXPERIMENTAL SETUP working of experimental system is different for heating and cooling two cycles COOLING First cycle : during the night, cold air supplied to the thermal storage and its cold is stored (PCM solidifies) Second cycle: during the day, warm air supplied to the thermal storage where it is cooled down (PCM melts) and supplied to the office HEATING Operates from 8 am to 4 pm enough sun radiation collector heats air and that heat is stored in thermal storage (PCM melts) low or no sun radiation, stored heat is used to heat the office (PCM solidifies)

18 MEASURMENTS Measurements of: air temperature, air flow and energy consumption Testing line of PCM storage with measurement points

19 MEASURMENTS electrical power: measured at the connection of system to the electricity grid air speed: measured at the outlet of air from the system temperature sensors put to nine important places precise data of temperature throughout the system

20 RESULTS - Cooling mode Air temperature cooling

21 RESULTS - Cooling mode Air temperature cooling

22 RESULTS - Heating mode Air temperature heating

23 RESULTS - Heating mode Air temperature heating

24 CONCLUSION Systems with phase change technology: promising alternative to conventional systems. PCM thermal storage performs great with air cooling and heating systems delivers outlet air of almost constant temperature.