Solar Desalination for Isolated Areas Technique

Low Cost Solar Desalination Prototype Development for Isolated Communities

Eng. Raul Gonzalez-Acuna, M.S.

RGA INGENIERÍA Y PROYECTOS, C.A.

RIF: J-31097757-7

I m p r o v i n g y o u r F u t u r e !

Raul Gonzalez-Acuna. [email protected]

RIF: J-31097757-7 www.rga-ip.com

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Contenido

Addressing Future Water Shortage 1

2

3 MEH Solar Desalination

4 Construction Challenges

5 Desalination plant Technical Information

Desalination Technologies



Page 3

Million of people Affected by water shortage(a) in 2050

Arnell, 2004 Alcamo et al.,

2007

Population Baseline

(1995) 1,368 1,601

2050: A2 emission

scenario

5,050 (4,351 to

5,747)

6,676 (6,432 to

6,920)

2050: B2 emission

scenario

3,362 (2,766 to

3,958)

5,037 (4,909 to

5,166)

(a) For this case it is defined as per capita water resources of less than 1000 m3/year

Source: L.. J. Mata,

Presentación del día del

ambiente, USB, 5 de junio

2008

Number of People Affected by 2050 Water Shortage

Addressing Future Water Shortage



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Global Warming

The World

This scenario is impelling major

investigation projects in the

desalination area, especially in

those destined to satisfy isolated

areas’ needs.

Upcoming Water

Shortage

Increasing number of

Conventional desalination

plants

Environmental Impact

Increasing vulnerability of

entire Countries, specially Isolated

Communities



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Source: GoogleEarth

Venezuela’s Water Resource Reality

Venezuela, in spite of being located in the Amazonian region, it has

serious water problems, especially in coastal and insular areas where

distribution is problematic due to the lack of this resource. In these areas,

solar irradiance is very high and relatively constant throughout the year,

so it can be used to provide fresh water and energy.



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State Population

Anzoátegui 796,519

Aragua 33,094

Carabobo 166,467

Delta Amacuro 58,070

Falcón 761,246

Miranda 107,335

Monagas 15,722

Nueva Esparta 456,454

Sucre 805,001

Trujillo 16,123

Vargas 296,461

Yaracuy 11,223

Zulia 3,128,184

Total 6,651,899

2010 Resident Population in Venezuela’s Coastline

Source: Self made

INE’s projection

2010




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Salt water desalination is an energy intensive consumption process,

normally fossil fuel driven. Reverse Osmosis and Multi-Flash Evaporation

are among the most common principles used. For isolated demands, a

principle with fewer technical requirements called Multi-Effect

Humidification (MEH) can be employed.

Hybrid energy proposal for a RO

desalination plant



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Parameter Reverse Osmosis Solar MEH Desalination

Distilled product for the

same size of the

installation

High production Low production

Energy Consumption

High energy consumption needed to exceed the sea

water osmotic pressure. Primary energy requirements

can be reduced by placing a turbine in the output of

the rejected water

Low. The fluid displacements can be

forced in the air and water cycles by

thermosyphon and hydrostatic pressure

respectively

Training manpower for

operation and

maintenance

It requires a qualified personnel to operate the

complex control systems that the installation has; and

who can perform regular maintenance of the high

pressure pump and semi-permeable membranes

It does not require skilled labor as the

system requires almost no moving parts

and maintenance simply consist on

cleaning

Flexibility in operation Low. Membranes working out of the normal operating

range decrease its life rapidly High

Brine Disposal It must have a system for disposal of brine in which it

is diluted to pour it into the sea

The brine practically don’t change its

concentration

Specialization of

Components High

Low. The components can

be made with commercial materials

(copper, aluminum, etc.)




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Research branch initiated to solve the water

problems of isolated populations, starting with the

fishermen communities that work near Dos

Mosquises cay in Los Roques National Park, a set

of cays located in the Caribbean Sea at 86 miles

from Vargas State’s coast.

Dos Mosquises cay. Source: R. Gonzalez-Acuna

MEH Solar Desalination



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• Low initial and maintenance costs.

• Easy transportation.

• Replicability.

• Low energy consumption.

• The utilization of as many homemade

components as possible.


Main Objective

Construction of a prototype that could distill 25 liters (6.6 US gal) of drinking water

per day. This prototype was designed considering the following:

Design Criteria

Sunset at Dos Mosquises Cay. Fuente: R. Gonzalez-Acuna



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Desalination Research Branch Phases

1

Theoretical Design &

Sensitivity Analysis

2 3

Construction & System

Performance Testing

Water Properties

Testing



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MEH Desalination System Configuration

Configuration Selection

According to the design

considerations, and taking into

account the applicable process

types, the configuration of the

prototype was decided to be a

single stage, open water –

closed air cycle with a flow of air

due to natural convection.

Schematic of a MEH Unit Source: R. Gonzalez-Acuna

Advantage: Using water vapor latent

heat of condensation for preheating

the salt water in the Condenser and

reduce the main energy input

required in the Solar Collector



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Most Important Activities

1. Mathematical model development to simulate the plant’s operation and

equipment sizing

2. 3D CAD design of the desalination plant, material selection and caliber.

Resistance analysis.

3. Procurement and construction of cupper equipment for the condenser

and solar collector.

4. Stagnation and hydrostatic resistance tests of the cupper ducts made.

5. Casing construction of the different equipments, air ducts and structural

support.

6. On site transportation, and foundation works for the installation of the

desalination unit.

7. Design and construction of a testing rig to characterize the built solar

collector

Fuente: R. Gonzalez-Acuna

Construction Challenges



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Most Important Activities (Cont.)

8. Solar collector characterization according with ANSI/ASHRAE 93-2003

Standard requirements. Determination of its maximum exergetic gain

operation criteria, and establish start and stop criteria. Master in

Science thesis awarded with the Honorable Mention of the ASME’s

Solar Energy Division Graduate Student Award.

9. Design and construction of a testing rig to characterize the desalination

plant

10. Assembly and commissioning of the desalination plant.

11. Desalination plant start-up, preliminary test and development of

performance indicators

8

10




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Casing Construction

Solar

Collector

Internal

Casing

Condenser

Internal

Casing

Humidifier

Internal

Casing

Brine and

Distillate

Collection

System

Fuente: R. Gonzalez-Acuna




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Structural System Construction

Desalination

Base

Solar

Collector

Base

Zinc

Chromate

Coating

Final

Alumina

Coating




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Stagnation Tests




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Solar Collector Coating, Isolation and Assembly

High

temperature

resistent varnish

coating

Assembly test 1:

Absorber –

Internal Casing

Absorber

Pre-Assembly:

Black paint

Assembly test 2:

Absorber,

Isolation

(High density PE)

and casings




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Solar Collector On Site Installation

Adjustable Tilt

base

Installation

Final Assembly:

Transparent

cover Installation

On site final

installation and

stagnation tests




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Characterization of the Solar Collector and Determination of the Exergetic Operation Point

Solar Collector

Testing Rig Desalination plant

operation point

(m) using USB

environmental

data




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On site Assembly and Construction of the the Desalination plant Testing Rig for Performance Analysis

Left: Structure Installation. Center: Humidifier packing material. Right: Desalination plant final Assembly. Source: R. Gonzalez-Acuna




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Final Product:

Left: Assembly test at Simon Bolivar University E Lab. Center: Desalination Plant Render. Right: Desalination Plant Commisioning. Source: R. González-Acuna




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Desalination Plant Tech Details

Technical Information Tests Information Financial Information

Cycle Type

Single Stage

(Open Water –

Closed Air)

Test performed/

N° of tests

Production

Capacity/ 2

Labor Hours

Invested 9,500

Rated

Capacity;

Operation time

per day

25 L/day;

11.5 h

Average

production

reported

0.7 L/h Project

Duration 2007-2012

Condenser,

Solar Collector

Type/

Material

Sandwich type/

Cupper

Test period/month

year

9 am – 4 pm /

October 2012

Average

inflation rate 30%

Plant’s

dimensions

Length: 1.1 m;

wide: 1.5 m;

height: 2.,3 m

Test Place

Sartenejas Valley

Simón Bolívar

University (USB),

Caracas, Vzla.

Monetary

resources

invested

(equipment,

labor, etc)

Bs. 45,000.00

($6,428.57)

average

exchange

rate of 7 Bs/$

Solar collector

area

Apert.: 1.68 m2;

Capt.: 1.25 m2 Stopping cause

Condenser ducts’

failure. Lack of

resources to repair

them

-- --

The SC aperture area was enough

to produce de required fluid output

temperature

Steady State test Not performed -- --



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Most Relevant Awards



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Thank you for your

attention, Questions?

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Technology

Solar Desalination for Isolated Areas Technique