PCM thermal storage system for cooling and heating of ...kgh-kongres.rs/images/2016/doc/ppt/88-Stritih.pdf · PCM thermal storage system for cooling and heating of buildings University

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

47. Međunarodni kongres i izložba o KGH, Beograd, 30.11–2.12.2016 47th International HVAC&R Congress and Exhibition, Belgrade, Nov.30–Dec.2 2016

doc. dr. Uroš Stritih univ. dipl. inž.,

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)


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.

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.

The building company Imtech in Hamburg, Germany.


Botanic garden in Berlin, Germany.

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.


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

The operating principle of LHT - summer, filling

OUTDOOR AIR

WINDOW

ROOM

PANELS WITH FSS

HOT AIR COLLECTOR

The operating principle of LHT - summer, emptying

The operating principle of LHT - winter, filling

The operating principle of LHT - winter, emptying

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

EXPERIMENTAL SETUP


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

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)

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

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

EXPERIMENTAL SETUP


 working of experimental system is different for heating and cooling

COOLING › two cycles

› 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)

MEASURMENTS


› Measurements of: air temperature, air flow and energy consumption

Testing line of PCM storage with measurement points

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

RESULTS - Cooling mode


Air temperature cooling
Chart1

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41918.4300462963 41918.4300462963

41918.4314351852 41918.4314351852

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41918.434212963 41918.434212963

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41918.4383796296 41918.4383796296

41918.4397685185 41918.4397685185

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41918.446712963 41918.446712963

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41918.4494907407 41918.4494907407

41918.4508796296 41918.4508796296

41918.4522685185 41918.4522685185

41918.4536574074 41918.4536574074

41918.4550462963 41918.4550462963

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41918.459212963 41918.459212963

41918.4606018519 41918.4606018519

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41918.4633796296 41918.4633796296

41918.4647685185 41918.4647685185

41918.4661574074 41918.4661574074

41918.4675462963 41918.4675462963

41918.4689351852 4

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PCM thermal storage system for cooling and heating of ...kgh-kongres.rs/images/2016/doc/ppt/88-Stritih.pdf · PCM thermal storage system for cooling and heating of buildings University