Seawater Air ConditioningHezi Gildor

TheInstituteofEarthSciencesTheHebrewUniversityofJerusalem,Israel

Acknowledgement:Yakov Nazichovski,YossiAshkenazy,Hezi Yizhak,RafaelAharoni

Motivation• Conventional air conditioning in Eilat consumes up to 40% of

the total electricity use during the summer.

IRENAreport,2014

Motivation• Conventional air conditioning in Eilat consumes up to 40% of

the total electricity use during the summer.• Using seawater to chill a conventional AC system condenser

can save up to 30% of the electricity used for AC in public buildings, depending on the seawater temperature.

• SWAC is restricted due to the concerns from thermal and chemical pollution.

• We aim to conduct an analysis of the economic viability of SWAC systems and estimate the thermal pollution.

• Introduction to SWAC; variants of SWAC.• Environmental benefits and challenges.• Design of SWAC systems.• Preliminary analysis of feasibility for Eilat.• Conclusions.

Outline

The technology goes by many different names–basically same principle

• SWAC - Seawater Air Conditioning• Deep Lake Water Cooling• Lake Source Cooling• Seawater District Cooling • Water source heat pump • ….

Makai Ocean Engineering, Inc

Conventional air-conditioning system

A/Ccondensersuselargeamountsofelectricitytocompressrefrigerant(~80%)

A simple diagram of a heat pump's vapor-compression refrigeration cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor

Wikipedia

Conventional air-conditioning system

Makai Ocean Engineering, Inc

• Coldwaterispumpedtoaheatexchanger,andusedtochillfreshwater.Withouttheuseofheatpump.

• Watertemperatureupto13OC(someclaims18OC).• Themaincomponentsofthisbasicseawaterairconditioningsystem:(1)seawatersupplypipe;(2)thepumpstation;(3)theheatexchanger(coolingstation);(4)thechilledwaterdistributionsystem;and(5)theeffluentpipe.

Makai Ocean Engineering, Inc

Direct water cooling system

• Whenitistoocostlyorimpracticaltosupplyseawateratthenecessarylowtemperatures.

• Useauxiliarychillerstosupplementthecoolingprovidedbytheseawaterexposure.

• Canbeusedforbothcoolingandheating.• Waterprovidesagoodheatexchangemedium,asitisgenerallycoolerthanambientairwhencoolingisneeded,andwarmerthanambientairwhenheatingisneeded.

Seawater heat pump systems

• Reductions in electricity consumption –> it reduces air pollution and greenhouse gas emission.

• Secondary applications for the used seawater: • Aquaculture• Desalination• Spa

• In direct systems, no hazardous refrigerants.• Solution available 24/7.• Thermal pollution; thermal shock.• Nutrient load – if we use deep and relatively cold (and

nutrient-rich) seawater. • Suction of marine organisms into the pipes.

Environmental benefits and impacts

• Toronto: 3,200,000 m2 (46 buildings), pipe length – 5000 m, 4.4 m3/s, Tin=4Oc, Tout=12OC.

• Cornel: pipe length – 3200 m, 2.2 m3/s, Tin=4OC, Tout=14OC.

• Hawaii: pipe length – 7600 m, 2.02 m3/s, Tin=11.7OC, Tout=18OC.

Systems around the world

• Data collection:• Meteorological data (temperature, relative humidity, daily range, wind speed).• Ocean data: bathymetry, temperature depth profile, current, tides, nutrients.

• Economical analysis:• Distance to cold water.• Local cost of electricity.• Access to fuel.• Total A/C demands.

• Optimizing the flow rate of sea water and chilled water.• Pipes and pump station planning.• Distribution system.

Design of a SWAC system

• BathymetryEilat - characteristics

• Bathymetry• Hydrographic characteristics: surface water vs. 200 m water

Eilat - characteristics

St. A

Black – observations (taken from NMP)Red – Model

Biton andGildor,2011

• Bathymetry• Hydrographic characteristics: surface water vs. 200 m water

Eilat - characteristics

Eilat - characteristics• Bathymetry• Hydrographic characteristics• Meteorological characteristics

Eilat - characteristics• Bathymetry• Hydrographic characteristics• Meteorological characteristics• Hotels and other consumers

48hotels,additional2000roomsareplannedClosetotheseaSeaisrelativelycalm

• Use ground water from 135 m, at temperature of 27-31OC• Pumping flux is about 170 m3/h (permit allows a maximum of

200 m3/h)• Reduces ~15% of the total electricity consumption compared

to conventional AC systems

U-Suits (formerly Meridian)

• SWAC is not technically complex. Systems exist around the world (Toronto, Halifax, Cornel, Bora Bora, Hawaii, …).

• Has the potential to save a significant amount of electricity in Eilat. Electricity is required only to run the pumps (~20%).

• The costs are primarily related to the initial capital expenditure. This, in turn, is related to the distance to cold water, to air and sea temperature, required A/C load, etc…

• Auxiliary chillers will be needed.• The effect of thermal pollution has yet to be studied.• Various scenarios should be explored.

Conclusions

Thank you!