INTRO 2004

Low Energy Air Conditioning

Inventors: Chua Kian Jon Ernest; Ng Kim Choon

Chou Siaw KiangHo Ghim Wei

Richard Kwok (STK)

October 24, 2012

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Trends in kW/Rton of chillers at ARI conditions (exclude cooling towers and pumps)

Most likely combined system efficiency in kW/Rton

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Existing Problems• Conventional air-conditioning in hot-humid climates has to cool and dehumidify air. • If cooling and dehumidification are decoupled, cooling energy is markedly reduced. • Commercial desiccant (Silica-gel) wheels used in existing HVAC require high temperature

heat to regenerate and causes large pressure drop – High operating cost.

Novel nano-woven membrane + low temperature regenerative composite desiccants

Proposed Solution

Higher temperature chilled water system with lower heat losses.

Greener Cooling Technology for Buildings

orLarge Scale District Cooling

** Energy efficiency of cooling technology defined by amount of electrical power (kW) required to deliver one refrigeration ton (RT) of cooling. The lower the value, the more energy savings.

Dehumidification Cooling

Breakthrough air-conditioning technology with low kW of energy input per ton of cooling (towards 0.65 to 0.5 kW/ton**)

Technology Overview

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Cooling Coil

Conventional HVAC – Chilled water dehumidification and reheat

Dehumidification and chilled water decoupled

•Decoupling moisture removal and cooling improves chiller performance by at least 40%.

•NO reheating required.

•Chilled water temperature can be raised from 5/10 oC to 12/18 oC.

•Hybrid membrane/composite desiccant dehumidification would easily add another 5 to 10% improvement in efficiency.

Technology Overview

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• Composite desiccant system

• Membrane

Silica Gel

Clay/Calcium Chloride Composite

Technology Overview

Control desired pore structure and tune pore size

Structured pores increased mass transport.

Synthesis technique: Film uniformity, low-temperature

fabrication, and high reproducibility.

Adsorption capacity of the composite desiccant material is approximately 3 to 4 X times higher than that of silica gel at high relative humidity.

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Relative humidity (%)

Ads

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Cap

acity

(kg/

kg)

Silica GelComposite Desiccant

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Thin membranes sieving water from air – a combination transport mechanisms: enhanced hydrophilicity, molecular sieving and capillary condensation.

Control key properties – tune pore sizes, control pore distributions andimprove mechanical strength/durability.

Compared to Prior Art – Energy efficient dehumidification, Pollutant Monitoring and Disinfection.

Impregnated with photocatalytic particles with UV light to administer air disinfection.

A non-invasive air dehumidifiers rejunevates new or existing HVAC systems.

Easy integration to the proposed co-generation/district cooling systems.

To employ new knowledge on nano-science/nano-technology to weave the state-of- the-art membranes for air dehumidificationMembrane Technology Development ‐ 1

To employ nano-science/nano-technology to produce membranes for air dehumidification

Natural sunlight feasible light source for photocatalytic disinfectant of organic pollutantsSensing capability of Pollutants such as VOC

Schematic of testing rector (extension of existing set-up).7

To employ new knowledge on nano-science/nano-technology to weave the state-of- the-art membranes for air dehumidificationMembrane Technology – Sensing and Disinfection

To employ new knowledge on nano-science/nano-technology to weave the state-of- the-art membranes for air dehumidificationMembrane Technology Development ‐ 2

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• Membrane

ARPA‐E Project Selections (July 12, 2010) – Ceramic Membrane*

Advanced Research Projects Agency - Energy

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Core Innovation:•Hybrid mesoporous inorganic TiO2 framework with polymeric support membrane. •Mesoporous framework loaded with nanoparticles for enhanced UV-Vis light disinfectant, anti-biofouling (self-cleaning) and sensing.

Development of Membrane Dehumidification for Large Commercial Application

Scalable process: sol-gel dip coating

Scalable process: cast films

Scalability: Commercial large scale dip coater

Table shows wide range of respective physical filtration capabilities.

Mesophase ordering and structuring to attain tunable pore size.

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Effect of inlet air humidity on the outlet air humidity (Sam1; Sam2; Sam3; PTFE membrane; temperature: 298-302K; inlet air flow rate: 1.3m/s; at 1 atmospheric condition; uncertainty:2%).

Sam 1: Sol‐H (TiO2) gel  submerge twiceSam 2: Sol‐H (TiO2) gel  submerge once

Sam 3: Sol‐H (TiO2) gel  submerge thrice

Sam 1: Sol‐H (TiO2)  gel submerge twice

Insert: Membrane samples

Feed sidePermeate side

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Scale-up commercial membrane fabrication

Lab test facility Excellent Results ~ 10% RH reduction for single membrane

To employ new knowledge on nano-science/nano-technology to weave the state-of- the-art membranes for air dehumidificationFrom Lab to Commercial Application

Sensible cooling

12/18 deg C Nation-wide CWS network

Latent cooling

Development of HYBRID-based dehumidifier

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Engineering/Science research:- AD chillers for waste heat utilization and HYBRID dehumidifier for moisture removal

Integration of electric, AB and AD chillers at centralized power plants

Existing Power plants

Electricity production

Steam fired AHP-excess steam

System integration optimization

New Paradigm Change in Cooling

Waste heat utilization

To employ new knowledge on nano-science/nano-technology to weave the state-of- the-art membranes for air dehumidificationLatest News on Efficient Cooling Technology in Singapore

NUS-designed system helps Hyatt slash energy use, emission01 August 2012

The desiccant dehumidifier, jointly patented by Grand Hyatt Singapore and NUS, dehumidifies outdoor air for the hotel lobby and dining room.

The Grand Hyatt Singapore has won the 2012 National Energy Global Award for Singapore as well as Achievement of Excellence in the Green Technology Awards winners at the Singapore Sustainability Awards 2012, thanks to a new eco- friendly trigeneration plant it jointly developed with NUS.

The first hotel in the world with such a retrofitted implementation, the system is set to cut the hotel's energy consumption by 22 per cent, helping it save S$800,000 in electricity bill. More importantly, its daily carbon dioxide emission of 5.72 tons will be slashed by 3.52 tons, which would amount to that discharged from 300 cars for a year.

The only engine in the world that operates on town gas and is capable of switching to natural gas when it becomes available

Residual heat generated by the new system is harnessed to produce steam and hot water for the hotel's laundry plant. The remaining heat is captured for dehumidifying the outdoor air introduced to the lobby and dining room. A silica gel-based dehumidifier unit was built for this purpose. Hyatt and NUS have jointly filed for a patent in the waste heat-driven dehumidifier developed.

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Cogeneration- based cooling plants

Primary fuel

Industrial complex/factories

Commercial complexes/Offices

Townships/ housing estates

hospitals/ schools/colleges

Commercial centers

Moisture removal by HYBRID technology

Moisture removal by HYBRID technology

Moisture removal by HYBRID technology

Moisture removal by HYBRID technology

Moisture removal by HYBRID technology Moisture removal by HYBRID technology

moisture removal by HYBRID technology moisture removal by HYBRID technology

Moisture removal by HYBRID technology

Moisture removal by HYBRID technology

Chilled-water distribution grid at 12/18oC

Electricity production for national grid

Can be employed for Co-generation based cooling plants.

Can be employed for District Cooling Systems.

More realizable energy savings for district cooling due to ECONOMIC of SCALE.

To employ new knowledge on nano-science/nano-technology to weave the state-of- the-art membranes for air dehumidificationMotivation: System Versatility

AD Technology – Beyond Proven Concept( PCT/SG2009/ 000223, filing No. 61/226,783, No.: 61/297,347, PCT/SG2012/000076)

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3 prototypes in Saudi Arabia and Singapore.

4 commercial prototypes in Singapore

and Poland (Wroclaw University of Technology) .

Test data shows that cooling capacity from 24 to 40

Rton and 8 to 28 tonne of water per tonne of adsorbent.

3 large ADCs (>3000 Rtons, 250 m3/d) planned for SA.

Saudi Arabia –KAUST, 10Rtons Solar Powered Singapore ‐45Rtons Each, Solar Powered Singapore –NUS 10Rtons, Waste Heat Prototype

Reaction bed tower

Evaporator

Condenser

Purified water

storage tankReaction bed tower

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An example of Common Services  Tunnel (CST) at Marina Bay, Singapore

August 12th, 2012, Straight Times

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Team members

Professor Chou Siaw Kiang, works on air-conditioning and thermal engineering for many years. He is a consultant on renewable energy applications to the Tianjin Eco-City project. He has rich experience in energy performance studies of large buildings, clean and renewable energy systems and thermal power generation.

Professor Ng Kim Choon, works on chillers and heat pumps, adsorption cooling and desalination, co-generation systems analysis and testing. He has worked on several hybrid cogeneration-based district cooling (HCDC) for island-wide implementation. He has won numerous local and international awards for his works on heat-driven cooling systems for large-scale applications.

Co-PI, Dr. Ho Ghim Wei, has been a specialist in nano-technology research. She has extensive knowledge of top-down and bottom-up fabrication of nano- structures. She is an expert in synthesizing and characterization of nano-structures with simultaneous control of the dimensions, properties, and morphology for the development of any nano-structure based device.

Industrial Co-I Dr. Richard Kwok the Chief Technical Officer (CTO) of STK is a highly regarded technical officer with invaluable experience in conducting high-end research. He is an engineer, a technologist, an academia, and a researcher. Dr. Richard is very active in many Ministry of Defence projects and is a champion of renewable clean energy technologies. He is in many governmental review panels on innovative energy technologies and future energy landscape.

Hybrid systems – marked improved performance compared with commercial silica desiccant – (1) lower regenerative temp (2) greater moisture absorption; and (3) lower ∆P.

Quantum leap towards the realization of present 0.9 kW/ton of cooling towards ultimate target of 0.65 to 0.5 kW/ton.

Intangible benefits: footprint/space savings to building owners, lower operating cost; District Cooling - no system maintenance.

Closure

Thank You

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For further enquiries, please email

NUS Principle Investigator : Chua Kian Jon Ernest (Email: mpeckje@nus.edu.sg; Tel: 6516 2558)