Day 2 Session VII - 03 Alaa Olama. Consultant

8/18/2019 Day 2 Session VII - 03 Alaa Olama. Consultant

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ABSORPTION SOLUTIONSCAN IT WORK FOR A/C

UNITARY APPLICATIONSESPECIALLY IN HIGH-AMBIENTTEMPERATURE COUNTRIES .

D U B A I , U A E ( 1 0 - 1 1 S E P T . 2 0 1 3 ) B Y : D R . A L A A O L A M A .

The 3rd Regional Symposium on

Alternative Refrigerants for Air-Conditioning Industry in High- Ambient Temperature Countries; Bridging Environment,

Standards and Research


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Absorption SolutionsCan it Work for A/C Unitary Applications especially in High-Ambient Temperature Countries

Contents:

1.0 Introduction.

2.0 Absorption for residential applications.

3.0 Absorption for light commercial applications.4.0 Absorption for commercial applications and solar

cooling.

5.0 Conclusions.


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Absorption SolutionsCan it Work for A/C Unitary Applications especially in High-Ambient Temperature Countries

Three general categories (ASHRAE):

Residential equipment, up to 19 kW (5.5 TR).

Light commercial equipment, up to 40 kW (11.25TR).

Commercial equipment, higher than 40 kW.


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Absorption SolutionsCan it Work for A/C Unitary Applications especially in High-Ambient Temperature

Countries

2.0 Residential Applications: (> 19 kW)

Main obstacle is air cooling. Without air coolingresidential type absorption units are not viable.

H2O-NH3 working solutions are available , air cooled.,two capacities 10 and 18 kW. (3 and 5 TR)

LiBr-H2O solutions are not miscible over their entireconcentration range, creating a crystallisation curve near

operating conditions. With water cooling, operation is close to crystallisation

curve, with air cooling it is in the crystallisation curve.


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Absorption SolutionsCan it Work for A/C Unitary Applications especially in High-Ambient

Temperature Countries

2.0 Residential Applications (cont.)

- Many research were made to resolve problem by either oftwo approaches:

- Mechanical approach.

- Chemical approach.

-Both approaches have to ensure the performanceenhancer ; 2-Ethyl Hexanol (Octyl Alcohol) is preserved.

-Mechanical approach means much improved heat

exchangers to minimize operating too near crystallisationcurve. Available for moderate – Ambient temperaturecountries. Inadequate for High- Ambient countries.


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- Chemical Approach:

. Modify crystallisation line to allow for higher

operation concentrations associated with air cooling without causing crystallisation using additives.

. Additives must keep solution’s viscosity low andpreserve 2-Ethyl Hexanol heat and mass transfer

enhancements.

. This is verified by keeping absorber sub-cooling ataround 1 C.


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- Chemical Approach:

. The discovery of the Carrol solution, LiBr-H2O and

Ethylene Glycol, by Carrier, allowed gains in thecrystallisation curve while keeping absorber sub-cooling performance high and allowing air cooling athigh ambient conditions.

. Prototypes are available, cost of solar collectors inthe 70’s and 80’s prevented commercial production.


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3.0 Light Commercial Applications.(< 40 kW)

- The International Energy Agency task 38 shows thenumber of solar cooling units increased by a factor of

- 6 between 2004 and 2009. Today there are probablyaround 1000 applications.

- Solar cooling units in above figures are divided into:89 % Absorption Units , 8 % Adsorption Units and 3 %Desiccant Units.

- Estimated potential market size is about 50 millioninstallations.


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Number of Installed solar cooling systems in the period 2004

to 2009

89 % Absorption Units , 8 % Adsorption Units and 3 % Desiccant Units Source: Mugnier D., Solar cooling economics workshop, Aarhus, International Energy Agency, task

38


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Absorption machines released to the market (until 2012)

Manufacturer Country Type Working pair Nominal

capacity [kW]

COP Heat Source

[ºC]

Application Coolant

AGO Germany Single eff. NH3-H2O 50 0.61 HW1

(95)

R Water

Broad China Double eff. H20-LiBr 16/23 1.2 GF

PHW (160)

AC Water

Cooltec5 USA GAX NH3-H2O 17.6/35 0.68 GF AC Air

Climatewell Sweden Single effect

,sto.

H20-LiCl 10 0.68 HW

(110)

AC Water

EAW Wergcall Germany Single eff. H20-LiBr 15/30 0.75 HW

(90)

AC Water

Pink

(SolarNext)

Austria

(Germany)

Single eff. NH3-H2O 10/12 0.63 HW

(85)

AC/R Water

Rinnai Osaka

gas

Japan Double eff. H20-LiBr 6.7 1.2 GF AC Water

Robur Italy Single eff. NH3-H2O 17.7

12.8

0.7 0.53 GF

PHW

AC/R Air

Rotartica Spain Single eff. H20-LiBr 4.5 0.67 HW

(90)

AC Water

Air

Solarice Germany Single eff. NH3-H2O 25/40 0.6 HW(80)

R Water

Sonnenklima

(Phonix)

Germany Single eff. H20-LiBr 10 0.78 HW

(75)

AC Water

Termax India Single eff. H20-LiBr 17.5/35 0.7 HW

(90)

AC Water

Yazaki Japan Single eff. H20-LiBr 17.6/35 0.7 HW

(88)

AC Water

Yazaki Japan d. eff . H2O- 28 0.85 GF AC AirLiBr/LiCl/LiI

.


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3.0 Light Commercial Applications.( cont.)

- The industry main drivers are solar thermal cooling

and micro- CCHP technologies.- Those two technologies are the main reason why

there is growing interest in this category ofabsorption cooling.


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Solar thermal fired Absorption System- 35 kW, with thermal

storage


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Typical Energy flow of a Combined Cooling Heating and

Power System (CCHP)


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3.0 Light Commercial Applications.(cont.)• Cost considerations of systems:• 1-Absorption chiller price still high compared to vapour compression• Cost ratio could be as high as 1: 10.• 2- Cost of solar collectors still high, but has gone down considerably over the last

few years.

• In 2010, Dickinson et al* demonstrated the cost of a solar fired absorption coolingsystem of 35 kW refrigeration Capacity for a government building, the cost of thecomponents compared to the system total cost can be analysed as follows;

• Controls, valves, piping : 38 %• Solar collectors : 28 %• Auxiliaries ( cooling• tower and storage tank) : 20%• Chiller : 14 % total : 100%• ( US$ 13,000.- cost per TR) _________* ASME Conference Proceedings, 2010(2010).


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3.0 Light Commercial Applications.(cont.)• Cost Remarks: Even at about US$ 2,000.-/ TR, the chiller cost

constitute only 14 % of the system total cost.•

Total system cost about US$ 130,000.-• If the chiller cost goes down by 50 %, the total system

cost will go down by about US$ 9,000.-• While if the rest of the equipment cost goes down by 50

%, total system cost will go down by over US$ 50,000.-• The main issues of competiveness, apart from high solar

rates and long operating hours, is not so much the cost ofthe chiller but in innovation to the system componentscost.


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4.0 Commercial Applications and solar cooling systems (>40 kW).

• Uses a different construction design, shell and tube

instead of coil and tube to allow for horizontal typemachines.• The most mature category, well established and

competitive.• Commercially marketed systems in Japan, predict that

solar cooling system in this range provide about 20 % 0fthe energy needed for air conditioning, while cutting CO2emissions by about 21 % in a system for a 3 to 4 stories

building with a total floor space area of 4,000 m2,utilising N. Gas fired absorption system.


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4.0 Commercial Applications and solar cooling systems (>40 kW).

• Tokyo Gas and others demonstrate such systems utilising

absorption chillers, hot water fired, high efficiency vacuum tube collectors and specially designed energymanagement system.

• The following slides shows the schematic diagram of

such systems, the roof view for the Tokyo demonstration building and the machine room.


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Commercial solar cooling system in Japan


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Tokyo Gas Nakahara Building (solar cooling system demonstration plant)


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Solar hot water fired chiller, pumps and storagetank


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Chiller, hot water storage and chilled water storagetanks


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4.0 Commercial Applications and solar cooling systems(cont.)

• The largest installed system is claimed to be in a district

cooling plant serving a university campus in Singapore with a total solar cooling capacity of 1,500 kW, built onB.O.O basis.

• System’s economics are viable and will deliver its

calculated return on investment when designed, installedand maintained efficiently.

b i l i


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5.0 Conclusions:5.1 Residential applications( technology not yet mature)

• Must be air cooled. Units exist for moderate-ambient temperaturecountries, but not for high-ambient temperature countries.

•

Two technologies hurdles exist and must be resolved before tech.takes root:

• A- Shifting crystallisation line of LiBr-H2O solutions to allow forhigher concentrations solutions associated with air cooling.

• B- Maintaining small sub-cooling in the absorber while keepinghigh rates of heat and mass transfer for the solution, associated withOctyl Alcohol as a performance enhancer.

Ab i S l i


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5.0 Conclusions ( cont.):5.2 Light commercial applications ( technology semi- mature)

• Two technologies drive this category:Solar thermal cooling and micro-CCHP.

• The high cost of solar thermal systems in this category is animportant factor.Solar collectors price have gone down appreciatively in the

last few years, this improved economics.

Large number of operating hours and high rates of solarradiation associated with high-ambient temperaturescountries improves economics of the system.

• System is viable in those conditions.

Ab i S l i


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5.0 Conclusions ( cont.):5.3 Commercial applications ( technology mature)

• Technologies driven by solar absorption cooling/heatingassisted applications:

• Commercially viable, saving in operating cost of about 20 % foran average size building in Japan of 4,000 m2 and a 21 % savingin CO2 emission compared to N. gas fired system.

• In the Middle Eat, demonstration projects are being prepared both UNIDO and UNEP and others to implement demonstrationprojects to disseminate the technology and help it take root inthe area.

Documents

Day 2 Session VII - 03 Alaa Olama. Consultant