Solar heating and cooling solutions for buildings Stephen White - - PowerPoint PPT Presentation

Solar heating and cooling solutions for buildings

Stephen White July 2017

ENERGY FLAGSHIP

Solar cooling

Using solar radiation to drive a cooling process. Displacing the use of fossil fuel derived electricity that would otherwise be used in a conventional vapour compression airconditioner.

 Solar thermal heat driving a thermal cooling process  Solar photovoltaics driving a conventional vapour compression cooling process

Cooling Demand Matches Solar Availability

Why solar cooling? - Policy perspective

• 1. Reduce greenhouse gas emissions
• 2. Lower energy costs/ benefit the electricity system

(higher load factor/ lower tariffs) Demand (MW) Time of Day

Why solar cooling?

– Owner perspective

• 1. Reduce greenhouse gas emissions/

lower energy costs

• 2. Increase asset value
• Access to environmentally aware (CSR)

tenants

• Point of sale rating disclosure
• 3. Response to government policy
• Compliance with minimum renewable

energy targets (development permission)

• Eligibility for incentives

2010 2008 2011 2012 2014 2009 Year of Study 2013 Percentage increase in sale price for green buildings compared with conventional code-compliant buildings (%)

• 15%
• 10%

0%

• 20%

10%

• 5%

20%

• 5%

25% 35% 15% 30%

IPEEC, 2014

Mugnier, & Jakob, 2012

Solar cooling market

Total amount of installed Solar Cooling systems in Europe & the World

Source: Solem Consulting / TECSOL

IEA Roadmap vision of solar heating and cooling (2012)

Solar cooling accounts for ~17% of TFE cooling in 2050

Technology Approach

ENERGY FLAGSHIP

Routes to delivering solar heat

Solar Electric Solar Thermal

Transpired Glazed air heater Solar PV Roof cavity Mechanical heat pump

• Split system
• DX Unit

Combi System Thermal heat pump

Combi-systems beget solar cooling systems?

Solar collector panels Thermal storage tank Backup heater Hot water Thermally Activated Cooling Machine

Solar PV or solar thermal – integration and backup

Routes to delivering active solar cold

Solar Electric Solar Thermal

Evacuated Tube Parabolic Trough Solar PV Flat Plate Parabolic Dish Mechanical compressor driven

• Split system
• DX Unit
• Chiller

Double- effect absorption chiller Single- effect absorption chiller Rankine Cycle Desiccant dehumidification Adsorption chiller Stirling cycle

“Solar [thermal/vapour compression] hybrid” cooling?

Free (Solar?) Cooling

ENERGY FLAGSHIP

Free cooling approaches

• Economizer cycle
• Economizer cycle with direct
• r indirect evaporative cooling
• Night purge ventilation
• Evaporatively cooled water

circulation

• Night sky radiant cooling
• Geo-exchange

Water Air

? Sealed well insulated buildings ? Ventilated adaptive comfort

Dew point cooler

Gives enthalpy reduction; not just sensible - latent switch

Source: Oxycom

Extending the economy cycle season

Perth Brisbane

Dew point coolers entering the market

Implications

• Smaller temperature differentials = larger air flows
• Better suited to applications such as
• Tempered air
• Underfloor cooling
• Chilled beams/ceilings (for evaporatively cooled water)
• What level of duplication of infrastructure is

required for peak demand?

Solar PV Driven Cooling

ENERGY FLAGSHIP

Systems emerging on the market

Some indicative (only) information

Adapted from Mugnier and Mopty, IEA Task 53, 2016

Separate PV and AC (grid acting as buffer)

vs Connected PV and AC (off-grid/ self consumption)?

Is this “Solar Airconditioning” or ”Solar AND Airconditioning” ?

Potential benefits (beyond simple energy savings)

Electricity system benefit 100% off grid solar PV/AC with separate AC backup

• Reduced peak

demand

• No reverse

power flow

• Safety
• Voltage
• Slow ramp rates

100% Solar PV self consumption with grid backup

• Reduced peak

demand

• No reverse

power flow Solar PV self consumption with grid export/import Reduced peak demand Consumer benefit Residential:

• leave it permanently
• n = guilt free luxury

Commercial

• Solar cooling efficiency

increase at part load I don’t need to inform my electricity utility I don’t need to inform my electricity utility Get full value for electricity Disadvantages

• Wasted

electricity if airconditioning is not required

• Needs batteries

to manage fluctuations Wasted electricity if airconditioning is not required Lack of advantages

Solar thermal driven cooling

ENERGY FLAGSHIP

Solar thermal technology options

(By heat source temperature)

Performance

Water at Patm

Solar thermal collector efficiency

Absorption chillers (predominantly LiBr/water)

(Mature technology, chilled water output)

Chiller Coefficient of Performance (COP) Required Heat Source Temperature Availability Single Stage 0.6-0.75 80-120ºC

• Good. Also ammonia

Two Stage 1-1.3 160-180ºC Large systems (>100kW) Three Stage 1.6-1.8 200-240ºC limited

Broad Carrier Thermax York Century Kawasaki Shuangliang Yazaki, Japan (35 - 175 kW) Robur, Italy (35 - 88 kW) EAW, Germany (30 - 200 kW) AGO, Germany (50 - 500 kW) NH3 /water

Adsorption Chillers

Sortech (8 - 15 kW) Invensor (7 - 10 kW) Mayekawa (50 - 350 kW) Mitsubishi Plastics (10,5 kW)

Bryair (35 - 1180 kW)

Desiccant dehumidification

Electric heater or Gas heater  Suitable for solar pre-heat 35°C 14g/kg 60°C 7.0 g/kg 35°C 14g/kg 56°C 21g/kg 80°C ~200Pa

Selection considerations

Absorption Adsorption Desiccant

Hazards  Corrosive fluid  Crystallization  Inert solid media  Inert solid media Performance  Best COP  Poor at low temperatures  Works at lower temperature  Lower COP  Works at lower temperature  Free part load cooling ? Depends on conditions Heat rejection  Cooling tower ? Cooling tower preferred  No cooling tower Size/weight  More compact  Bulky and heavy ? Bulky but light Maintenance  Solution chemistry  Cooling tower  Easy  Cooling tower  Atmospheric pressure  Robust Cost  Comparable with conventional (at scale)  Expensive ? Probably most economic Co-benefits ? Ventilation

Some likely combos

Air collectors →

• Heating and desiccant dehumidification

Flat plate collectors →

• Desiccant or adsorption system

Evacuated tubes →

• Single effect absorption chiller

Concentrating collectors → - Double effect absorption chiller

• Air cooled food refrigeration

Indicative Performance 1 unit of Sun Driving Energy Cold (heat)

Electric Thermal

Low Efficiency (air cooled) High Efficiency (water cooled) Low Efficiency (single effect) High Efficiency (double effect)

0.2 0.2 0.5 0.5 0.6 (0.8) 1.2 (1.4) 0.35 (0.85) 0.6 (1.1)

Thermal systems are ideally integrated

Large Hotel

2% 14% 1% 29% 54% Air Conditioning Lighting Laundry Other Hot w ater

Large Office Buidling

13% 37% 49% 1% Air Conditioning Lighting Office equipment Other

Medium Size Hospital

18% 8% 15% 39% 20% Air Conditioning Lighting Laundry Other Hot w ater

Cost competitiveness (example installed systems)

Neyer, Mugnier and White, 2015

Cost of energy savings compared with PV

Hotel in Madrid (3050 m2 floor area), “advanced” flat plate collectors and single effect absorption chiller Sensitivity to buffer tank size , collector area and chiller size

Technical Integration

ENERGY FLAGSHIP

Average Hobart diurnal profile

Winter Summer

Average Townsville diurnal profile

Winter Summer

But every day and every hour is different

Storage and/or backup required

Generic flow-sheet for matching an intermittent heat source and a variable demand for cooling

Solar Collector Evaporator (+possible backup AC) Cooling Tower

Ten Key Principles

Principle 1: Choose applications where high annual solar utilization can be achieved

• Is there a load in the shoulder season?
• Can solar be the lead with

conventional peaking? Principle 2: Avoid using fossil fuels as a backup for single effect ab/adsorption chillers Principle 3: Design to run the absorption chiller in long bursts

• If in doubt oversize the field not the chiller

Principle 4: Use a wet cooling tower where possible

The Key Principles (con)

Principle 5: Select solar collectors that achieve temperature even at modest radiation levels Principle 6: Keep the process flowsheet simple and compact Principle 7: Match storage temperature and hydraulics with the application Principle 8: Minimise parasitic power Principle 9: Minimise heat losses Principle 10: Apply appropriate resources to design, monitoring and commissioning

Building Integration

ENERGY FLAGSHIP

Bolt on or fabric integrated?

• Reduced materials

duplication

• Improved aesthetics
• Achieving core building

functionality

• Maintaining performance
• Diverse product range

Lichtblau et al 2010

IEA Task41 categorization

Farkas, 2013 Source: Monier Source: SOLID

And other functions

IEA Task41

Transpired air collectors

The attic

• To suck or blow? That is the question

Impacts of orientation and tilt angle

Output per kW of panel purchased vs Output per m2 floor plate area

Near horizontal panels don’t care about

• rientation

Precinct Integration

ENERGY FLAGSHIP

Zero Energy Precinct Example

• 151 Units
• 11kV connection

– Private network – No backflow

• Residential demand

– 550 kVA peak demand – 780 MWh/annum

• PV potential from available roof area

– 2740 MWh/annum

Normalised Power Normalised Power

Winter

• Nett daily shortfall
• Export at midday is approximately

the same as average demand

Summer

• Nett daily surplus
• Exporting (shifting to my neighbours)

around 3 times more electricity than average demand at midday

Export

Needs to be transported somewhere or stored

? More generation capacity , Add battery storage, or Shift demand

Going 100% solar electricity

Examples

ENERGY FLAGSHIP

SolaMate air heater example

BlueScope PV/T example

SW Orientation NE Orientation

Sproul and Farschimonfared, 2016

CSIRO residential hot water, heating and cooling product

 Provides cooling even when the sun is not shining  Low temperature heat source requirement  No cooling tower required (but does require water)  Positive pressurization of building

Observations: Rowes Bay operating by itself

Observations: Operating in tandem with peak smart

Around the cities

Total solution as is Partial/hybrid cooling

Total comfort solution (% of hours)

Large ESCO systems make economic sense

• Wide variety of reported capital cost numbers
• lets say ~US$2,500 / kWcooling installed
• Even better when there is a high DHW load

United World College, Singapore

• 1575kW single effect

absorption chiller

• 3900m2 flat plate collectors

with transparent teflon sheet

• 60m3 storage at ~88°C
• ESCO financing

S.O.L.I.D

. =2.5 m2/kW =15 L/m2

Some absorption chiller installations in Australia

Source: ECS

District heating and cooling Building A : 11 000 m² - offices and shops Building B : 10 600 m² with 167 dwellings

Montpellier Heating and System net utilities => System owner

TECSOL: engineering company

Buildings situation

AXIMA : Company in charge

• f the works

SERM building, Montpellier (France), 2010

• 900 kW gas heating
• 700 kW chiller

System selection

Selection

• 240 m² double glazed flat plate collectors (Block A, limited by roof area)
• solar circuit in drainback mode (with water glycol + HX)
• 35 kW absorption chiller
• 1500 liter hot buffer storage tank for the chiller (Block A)
• + 10 m3 DHW storage capacity in Building B for dwellings)

Application

• Hot water preheat (all year round)
• Autonomous solar cooling (when

hot water temperature is high enough)

=6.9 m2/kW =43 L/m2

Schematic

Hot water gives year round solar utilization

Month Solar Heat Collected/ DHW Heat Demand

Solar Irradiation (kWh) Collected solar heat (kWh) Solar DHW Production (kWh) Solar Cooling Production (kWh) Parasitic electricity consumption (kWh) Electrical Seasonal Performance Factor* (-) Jan-14 14,214 4,092 3,734 190 19.7 Feb-14 21,409 6,789 6,435 218 29.5 Mar-13/14 37,977 13,153 12,504 308 40.6 Apr-13 33,255 12,236 11,588 290 40.0 May-13 47,124 17,350 16,478 380 43.4 Jun-13 53,349 13,236 7,497 2,765 902 13.4 Jul-13 55,769 16,639 11,311 3,983 1190 13.6 Aug-13 48,656 12,467 8,628 1,970 840 14.2 Sep-13 37,744 10,513 9,316 676 554 18.9 Oct-13 24,645 8,541 7,843 240 32.7 Nov-13 17,309 5,133 4,789 220 21.8 Dec-13 15,164 4,341 3,851 157 24.6 TOTAL 406,616 124,490 103,974 9,394 5,489 21.5

Case study performance

TAFE commercial kitchens demonstration

• Unique solar desiccant cooling design
• Flat plate/ 2-rotor desiccant cooling
• Solar hot water
• Worlds largest solar desiccant cooling system
• 80 kWth
• 400m2 collectors, 9000 litres

=5 m2/kW =23 L/m2

Preheating water and precooling air

Pre-cooled air out Ambient air in

Novel two wheel intercooled desiccant wheel system

Solar hot water heating contribution

• Preheating cant

heat the ring main

Solar space heating and cooling contribution

• Evaporative

cooling not included/ valued

(despite doing the bulk of the cooling)

• Temperature not

always available to run the DEC

Conclusion

• Solar cooling makes intuitive supply/demand sense
• It can add to the value of the building asset
• Solar PV driven systems are emerging on the market

but manufacturers and electricity utilities need to work together

• A wide variety of thermal technologies and solar

thermal collectors have been demonstrated but work best satisfying integrated building thermal needs

Conclusion

• 10 Principles for good integration
• Year round solar utilization
• Integration with backup systems
• Good quality solar collectors
• Energy only economics are ok at large scale and for

hot water lead

• Desiccant cooling has cost, maintenance and part

load advantages, but is probably not well suited to providing a 100% solution (but nor would you expect a

100% solution from intermittent solar)

• But don’t forget low-cost building-integrated solar

air heating options too

ENERGY TECHNOLOGY

Thank you

Energy Technology Stephen White Energy for Buildings Manager t +61 2 4960 6070 e stephen.d.white@csiro.au w www.csiro.au/