ausSCIG Conference Apr 2013 - 12a - Systems - David Whaley · Australian Solar Cooling Interest Group (ausSCIG) Conference 2013 6 Day 2 – Solar Cooling Conference - 12/04/2013 Venue:

Australian Solar Cooling Interest Group (ausSCIG) Conference 2013 www.ausSCIG.org

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Day 2 – Solar Cooling Conference - 12/04/2013Venue: CSIRO, North Ryde, Sydney

D.M. Whaley, W.Y. Saman, A. Alemu,Barbara Hardy Institute,

University of South Australia,Mawson Lakes,

South Australia, 5095 [email protected]


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Overview

• Introduction / Justification of research• Solar thermal air conditioner prototype:

– Overview of system,– System components.

• Preliminary Results:• Preliminary Results:– Moisture absorption, – Cooling modes,– Heating mode,– Regenerator mode – not in paper!

• Future Work:– Evaluation of 12 month performance,– Model validation.

• Conclusions


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Introduction

• Air conditioning energy in residential sector increasing over last 2 decades.

• Average residential energy demand:– Space heating & cooling: 41%,– Domestic hot water: 30%.

Space

heating /

cooling

Other

– Domestic hot water: 30%.

• Residential buildings account for 20% Australia’s GHG emissions:– Space heating & cooling: 30-40%

• Number of houses and their size increasing– Heating / cooling requirements increase,– Peak electrical demand is escalating and adding to electricity costs.

• New housing trend: use RC AC– Monitored data shows 90% of summer peak demand linked to AC’s.

Domestic

hot

water


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What To Do?

Use renewable / clean energy and low power appliances?• Cooling not using vapour compression, e.g. evaporative

– Don’t work in humid regions!

• Solar water heaters– Well established technology,– Well established technology,– Numbers doubled between 2005-08,

now 7% of Australian homes,– Oversized for Summer usage (cover Winter demand).

• Integrated approach? Combining these and other components, to provide:– space and water heating, – space cooling and dehumidification??


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System Overview

HW

tank

Regenerator Absorber

Direct

Evap.

Pad

Continuous

gas booster

Hot water

Warm waterCollector inlet water

Warm air

Dehumidified air

Continuous

gas booster Low conc.

desiccant

High conc.

desiccantFresh air

gas booster

Return air

• Figure does not include:– Water inlet and outlet of heat exchangers,– Dampers, fans and pumps,– Controller and other electronics,– Gas supply.


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System Components

• Solar water heater– 5 * Flat plate collectors,– 500L vented tank (2 HE coils).

• Absorber (HE)• Regenerator (HE)• Regenerator (HE)• Liquid desiccant

– Lithium Chloride

• Controller– PCI-1710U,– Feedback based on outside

and indoor temperatures & relative humidity.


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Absorber

Indirect water and air to air heat exchanger, used for two modes:• Direct and indirect cooling,• Direct, indirect cooling and

dehumidification.dehumidification.

Absorber

Outside Air

Outside Air Exhaust Air

Cooled +

Dehumidified Air

High Conc.

Desiccant

Low Conc.

Desiccant

Water

In (mist)

Water Out


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Regenerator

Indirect water to air heat exchanger, used for two modes:• Heating,• Regeneration

(reconcentrate desiccant).(reconcentrate desiccant).

Regenerator

Return / Outside Air

Heated /

Exhaust Air

Low Conc.

Desiccant

High Conc.

Desiccant

Hot Water

Out

Hot Water In


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Test Arrangement


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Preliminary Test Results:

• Test rig inside an open shed, Mawson Lakes Campus– Dry Adelaide heat!

Absorber modes:• Moisture absorption,• Cooling Mode.• Cooling Mode.

– Direct and indirect cooling,– Direct, indirect cooling and

dehumidification.

Regenerator modes:• Heating,• Regeneration.


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Moisture Absorption

• Moisture absorption capacity– Function of desiccant concentration, temperature and flow rate

If outside air has less Moisture than theequilibrium moisture... 8

10

12

14

16

Eq

uil

ibri

um

fil

m a

ir m

ois

ture

(g

/kg

)

• Results for 2 Adelaide summer day conditions:Inlet

Temp. (°C)Inlet Specific

Humidity (g/kg)Outlet

Temp. (°C)Outlet Specific

Humidity (g/kg)31.8 9.1 28.6 7.436.0 7.3 30.0 6.2

equilibrium moisture...

Absorber acts as anEvaporator!

0

2

4

6

8

28 30 32 34 36 38 40E

qu

ilib

riu

m f

ilm

air

mo

istu

re (

g/k

g)

Desiccant temperature (oC)


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Cooling Modes

• Direct + Indirect Cooling:

• Direct and Indirect Cooling + Dehumidification (limited data):

Outside Air dry bulb temp. (°C)

Outside air wet bulb

temp. (°C)

Indirect evaporator outlet air (°C)

Direct evaporator outlet air temp. (°C)

Direct evaporator saturation

efficiency (%)

Indirect evaporator

effectiveness

42.0 20.0 32.0 19.1 89 0.42

• Direct and Indirect Cooling + Dehumidification (limited data):

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18

20

22

24

26

28

30

32

34

36

38

16

:34

16

:35

16

:36

16

:37

16

:38

16

:39

16

:40

16

:41

16

:42

16

:43

Tem

pe

ratu

re (

oC

)

Local time

Outside Dry Bulb Outside Wet Bulb Absorber Outlet Direct Evap Outlet


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Heating

Design for 60°C air temperature• Test conditions:

– Ambient air temperature = 19.5°C, – Hot water flow rate = 328L/h,– Flow rate tripled at 13:30. – Flow rate tripled at 13:30.

0

10

20

30

40

50

60

70

80

90

09

:00

09

:30

10

:00

10

:30

11

:00

11

:30

12

:00

12

:30

13

:00

13

:30

14

:00

14

:30

15

:00

15

:30

16

:00

Tem

pe

ratu

re (

°C)

Local time

Regen HW In Regen HW Out Regen AIR In Regen AIR Out


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Regenerator (not in paper!)

Tested over 4 days, where:• Ambient air: 31.7 – 39.0°C, • Specific humidity: 10.4 – 12.5 g/kg

– Maintain desiccant inlet concentration and flow rate,– Vary hot water temperature. – Vary hot water temperature.

y = 0.18997x + 25.93774

R² = 0.93806

34

35

36

37

38

39

40

41

40 45 50 55 60 65 70 75

En

d c

on

cen

tra

tio

n (

%)

AVG HW in & ou t T (°C)


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Summary & Conclusions

Summary:• Overview of a combined approach for solar water

heating, space heating, cooling and dehumidification,• Preliminary test results, for various modes.

Conclusions: • System can cool air to below wet bulb temp, using

ordinary evaporative cooling, when used with indirect cooler and dehumidifier,

• Air moisture absorption and desiccant concentrating (regeneration) dependent on desiccant initial concentration and temperature.


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Future Work

• Install prototype in Adelaide House for 12 month trial:– Northern suburbs house: 4 bedroom, 168m2,

• Automatic operating mode and zones.

– Evaluate performance for 12 month period.• Compare to TRNSYS models developed.

• Test absorber to humid conditions• Test absorber to humid conditions– e.g. specific humidity of 18+ g/kg

• Adjust controller– Allow user controllability

• Zones,• Control mode,


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TRNSYS Model


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Thank you

Acknowledgement: • The Department for Manufacturing,

Innovation, Trade, Resources and Energy (Renewables SA)

• Barbara Hardy Institute members:

http://c3dmm.csiro.au/SA_ASTER/images/dmitre_cmyk_h.jpg

• Barbara Hardy Institute members:– Academic and professional staff,– Technical (workshop) staff,– Interns, and local and international

students.

• Questions?

http://images.hollywood.com/site/homer-simpson.jpg

http://www.truthdig.com/images/eartothegrounduploads/Bush_confused_iarm300.jpg

Documents

ausSCIG Conference Apr 2013 - 12a - Systems - David Whaley · Australian Solar Cooling Interest Group (ausSCIG) Conference 2013 6 Day 2 – Solar Cooling Conference - 12/04/2013 Venue: