Integrated Desert Building Technologies

(IDBT)

Ezzat Fahmy

Amr Serag-Eldin

Ehab Abdel-Rahman

THE AMERICAN UNIVERSITY IN CAIRO

THE AMERICAN UNIVERSITY IN CAIRO

Integrated Desert Building Technologies is a joint project between the American University in Cairo (AUC) and King Abdullah University for Science and Technology (KAUST)

The Project Aims at Transfer, Development, Adaptation, And Integration Of technologies in such fields as: Architecture, Structure, Materials And Construction, Energy Generation And Conservation, Water Management And Re-use, And Life Cost Analysis.

THE AMERICAN UNIVERSITY IN CAIRO

CURRENT AND FUTURE PHASES OF

THE PROJECT

CURRENT AND FUTURE PHASES OF

THE PROJECT

Phase IDevelopmental

Studies

Phase IIDemonstration

and Monitoring

Phase IIDemonstration

and Monitoring

Saudi Arabia, Egypt, and the

Arab World

Saudi Arabia, Egypt, and the

Arab WorldKAUSTKAUSTAUC/KAUST

Phase IIIPractical

Implementation

Phase IIIPractical

Implementation

THE AMERICAN UNIVERSITY IN CAIRO

ASPECTS OF EFFICIENT DESERT BUILDING DEVELOPMENT

ASPECTS OF EFFICIENT DESERT BUILDING DEVELOPMENT

Stru

ctur

al, M

ater

ials

and

Cons

truc

tion

Aspe

cts

Stru

ctur

al, M

ater

ials

and

Cons

truc

tion

Aspe

cts

Ener

gy G

ener

ation

and

Co

nser

vatio

n M

etho

dolo

gies

Ener

gy G

ener

ation

and

Co

nser

vatio

n M

etho

dolo

gies

Sust

aina

ble

Was

tew

ater

Man

agem

ent

Sust

aina

ble

Was

tew

ater

Man

agem

ent

Life

Cyc

le C

ost A

naly

sis

And

Opti

miz

ation

Life

Cyc

le C

ost A

naly

sis

And

Opti

miz

ation

Arch

itect

ural

Asp

ects

Arch

itect

ural

Asp

ects

Elements of the First Phase

Integrated Energy Systems in IDBT

Amr Serag-Eldin

THE AMERICAN UNIVERSITY IN CAIRO

Sustainability

• The IDBT project pays special consideration to Sustainability.

• Sustainability implies that future generations will be able to continue enjoying current living standards despite the reduction of fossil fuels and non-renewable energy resources.

• Like most future building technologies it aims at reducing energy consumption without compromising indoor quality.

• However, it goes one step further; it considers localized energy conversion from available RE resources.

• The desert environment offers both challenges and opportunities, which the proposed design addresses

Classification of Energy Loads

• Heat Loads:– Cooling loads: Air-conditioning– Cooling loads: Refrigeration for preservation & cooling of

food and beverage– Heating loads: Cooking– Heating loads: Occasional indoor heating (winter nights?)– Heating Loads: Domestic hot water (bathrooms, kitchen,

dish/clothes-washers)

• Electrical Loads:– Lighting– Appliances (computer, TV and multimedia, hair-dryers,

dish/clothes washer motor, etc.. ; refrigerator and ovens have been added to heat loads)

• Mechanical Loads:– Air circulation (ventilation & fans)– Water circulation and deep-well pumping.

Special DBT Features

• A/C load is expected to be the highest, particularly in summer daylight hrs.

• Minimum water consumption is allowed.

• Hostile environment (sand storms)

• Most abundant source of RE is Solar

• Night time temperatures much lower than daytime temperatures

• Day time hours don’t vary much year round

• Wind energy is site dependent and should not be depended upon entirely.

• Biogas, if available, is ideal for cooking load; can also be used as alternate heat source for TAHE.

• A/C loads and Solar energy are in phase, thus reducing thermal storage requirements)

Energy Design Criteria

1. Reduce loads and conserve energy : particularly A/C loads.

2. Exploit locally available RE resources, particularly Solar (attempt zero conventional).

3. Extend use of available RE resources by introducing both thermal and electrical energy storage.

4. Design should not be too site specific; it should reflect the most common features of ME desserts. Thus biogas and desalination ruled out.

5. Design should provide a healthy, comfortable, and productive environment at minimum cost.

6. It should be reliable, durable, user friendly, as well as environmentally friendly.

The Proposed Conceptual Design

• Designed for Energy:– Conservation: Double-cavity-walls,

smart windows– Conversion: Fresnel-mirrors/Absorption

refrigeration, WECS, Photovoltaics, Wind-ventilator, Parabolic-dish/ Thermoacoustic-engine/refrigerator

– Storage : Chiller water storage, Hot water storage, Battery

Fresnel collector principle

A Fresnel Mirrors System

A/C Absorption Chillers: Ammonia/water

A/C Absorption Chillers :H2/Ammonia

Parabolic Dish/Thermo-acoustic Engine

Displacement .vs. Dilution Ventilation

CO2(ppm) in cross-planes

T(oC) in cross-planes

WIND DRIVEN VENTURI-VENTILATOR

DEVELOPED EMPLOYING CFD

A Model was built

Tested and validated in W.T.

The Full Scale Prototype is Built

1. Develop prototype to operate under field conditions : introduction of a self-alignment mechanism.

2. Test prototype under varying wind speed and direction.

3. Long term testing on a roof-top under actual/near-desert operating-conditions.

4. Integrate Wind ventilator in the architectural design .

5. Integrate it in the energy system, e.g. with thermal storage and passive cooling and heating systems.

With transparent Side Walls

and Mobile too!

Discussion of Some Features

• Conventional wisdom in architectural design is to increase building height in order to reduce A/C load, because most of heat losses/gains occur from roof.

• In proposed design, the roof is a collector of energy, hence a one floor building is most efficient from energy collection point of view.

• Moreover , proportion of side wall areas (source of heat gains/losses) is smaller in case of one floor building thus reducing A/C loads.

• Plenty of roof overhangs should be introduced to increase collection area and provide shading.

• Use of two cold water storage tanks is efficient.

Energy Management

• Energy system management is controlled by a central processor, connected to appropriate sensors.

• Computer control includes sun tracking of Fresnel mirrors, operation of evaporative cooler according to air relative-humidity, control of air exchanges according to room air-quality, closing down of inlet dampers in case of sandstorms (sensors may yet have to be designed!), daily start-up and shut-down of absorption refrigeration chiller and thermo-acoustic engines, automatic lighting, various pumps operations , fire-sprays, and regulation of electrical energy supply.

• It should also issue warnings when system is unable to meet its design criteria and automatically operate a back-up engine-generator under such conditions.

• It should attempt optimization of resources, taking into consideration the instantaneous energy conversion rates, available thermal and electrical energy storage, instantaneous environmental conditions, as well as system characteristics and the user preferred settings.

Needs & Alternative Design

• Appliances may need to be modified or adapted to exploit heat sources, e.g. dishwasher, refrigerator, Absorption-chiller. This will be one of the tasks of the present research.

• From a thermodynamic point of view, it is NOT efficient to convert EE into HE; however from an economic /practicality point this may not be so.

• Comparison will be made between an energy system based entirely on photovoltaic cells (converting some of EE into heat) and the one proposed here.

• Comparison includes life cycle costs, projected reliability, ease of maintenance and repair and local manufacturing opportunities

Summary & Conclusion

• An investigation was conducted to examine typical energy needs of a desert building. Special desert features were identified and a conceptual integrated energy system design presented.

• The design in addition to being efficient in energy conservation, will also produce its own energy needs by converting readily available local solar energy, supplemented by any available wind energy.

• Future developments will see detailed calculations, equipment selection and specification as well as performance estimates. Moreover, the proposed design, which employs novel techniques and non-conventional technologies, will be compared against one which relies only on photovoltaic cells to meet its energy requirements.

CFD Simulation of Thermo-acoustic engine/refrigerator

Amr Serag-Eldin

THE AMERICAN UNIVERSITY IN CAIRO

CFD Simulation : background

• Thermo-acoustic engines/refrigerators are currently designed using simple thermo-acoustic theory subject to Rott’s acoustic approximations; which are justified for weak pressure waves (small amplitudes) and semi one dimensional geometries.

• Our research is investigating applications with 10% or higher pressure amplitudes in 2/3 -dimensional geometries, and large dimensions with possibility of flow turbulence (requiring turbulence models).

• We don’t want our designs to be constrained by the capabilities of our prediction models. Thus we need to go to the most general computational tools, namely CFD commercial S/W.

• CFD solves sets of multi-dimension, partial-differential, non-linear eqns.; very different from Rott’s wave equations. Solution time and computational requirements are several orders of magnitude higher.

CFD Solutions : Challenges

• CFD computations resort to domain discretization. Thus very fine and large spatial grids are required to capture the phenomena occurring over a fraction of the thermal penetration lengths within the stack( order of fractions of m.m.) and spanning half the acoustic wave length (order of several m) . In addition computations need to be conducted over several cycles to reach a cyclic steady repetition; each cycle requiring many solution time steps (of the order of 100)

• Formulation of boundary conditions requires special attention in order to reflect the physical situation as close as possible.

• Reported experience with CFD simulations is very limited . No existing commercial CFD package appears to have been optimized or used extensively for thermo-acoustic engine/refrigeration predictions. A recent paper (2008) reports results of using FLUENT for a single thermo-acoustic couple (a very small idealized fraction of an actual refrigerator). Yet integration domain did not extend all the way to the loud speaker; instead, an acoustic solution was prescribed at the inlet to the domain!

CFD Simulation : Plan-I

In the present research it is intended to simulate an entire engine /refrigerator hence the following steps are planned/executed:

- Use parallel processors and parallelized CFD S/W. A single user version PHOENICS is temporarily set-up, until cluster of computers are connected.

- Use of higher order discretization methods in order to get high accuracy with a reasonable grid size. Ongoing attempts to introduce in code.

- Optimize B.C. formulations for high accuracy with reasonable calculation time. Four different formulations are currently being considered, e.g. use of a direct loud-speaker piston motion simulation rather than the universally adopted sinusoidal pressure fluctuation. Even this may be implemented employing two different methods, moving grids or unsteady porosities.

CFD Simulations: Plan-II

- Prior to simulating the complicated configurations to be investigated, we are currently experimenting with predicting simple known flows, in order to gain experience with the characteristics of thermo-acoustic CFD flow predictions (e.g. time step requirements and stability constraints)

- Special diagnostics and displays are being introduced in the code. Among these are automatic calculations of the local time-variation of the thermo-acoustic cooling/heating during the cycle and its cycle average; mean and time-dependent temperature difference across the stack, and variation between corresponding temperatures with cycle repetition (measure of steady cycle repetitions).

Thermoacoustic Devices for Harvesting Energy from Solar

Energy & Waste Heat

Ehab Abdel-Rahman

Department of Physics, AUC

&

Yousef Jameel Science and Technology Research Center, AUC

THE AMERICAN UNIVERSITY IN CAIRO

What is Thermoacoustic?

• Thermoacoustics (TA) is the study of the conversion of acoustic energy into heat energy and vice versa

• Acoustic energy can be harnessed in sealed systems and used to create powerful heat engines, heat pumps, and refrigerators.

Components of Heat Pump &

Prime Movers

Components of Heat Pump &

Prime Movers

• Thermoacoustics is the study of temperature fluctuations in an acoustic field

• A Thermoacoustic refrigerator harnesses the thermoacoustic effect to move heat

1

3

4

What a Gas Parcel Does

1) Expands and Cools2) Draws Heat from Plate3) Contracts and Heats4) Expels Heat to Plate

2

Plate

How does it work?

Application

How does it work?

History of Thermoacoustic

Byron Higgins, 1777

Sondhauss, 1850

Rijke, 1859

Lord Rayleigh

Rott, 1969

Wheatley and Swift, 1983

Symko and Abdel-Rahman 2002

Glass Blowers

The first successful theory of

thermoacoustic

If heat to be given to the air at the moment of greatest condensation or

taken from it at the moment of greatest

refraction, the vibration is encouraged (1887)

built the first TAR

Harvesting Energy!!

• TA Devices can use Solar Energy to Produce cooling

• TA Devices can use waster heat / solar energy to produce electricity

Solar Energy Driven TA Refrigerator

Concentrator

Prime MoverSunlight Heat

SO

UN

D

TA Refrigerator/ linear Alternator

Cooling/

Electrical

Pow

er

Solar Energy Driven TARefrigerator / Concentrator

Solar Energy Driven TARefrigerator / Concentrator

0

0.2

0.4

0.6

0 0.005 0.01 0.015 0.02

(Tin-Tamb)/ (Ieff) ( oC m2/ W)

Eff

icie

nc

y

CRI

TTFUF

eff

ambinRLRo

)(

Solar Energy Driven TARefrigerator / Prime Mover

Time (sec)

-0.002 -0.001 0.000 0.001 0.002

Sound P

ressure

(V

)

-6

-4

-2

0

2

4

6

Fluctuations Coherent Oscillations

Time (sec)

-2 -1 0 1 2

So

un

d P

re

ssu

re

(V

)

-6

-4

-2

0

2

4

6

Solar Energy Driven TARefrigerator / Prime Mover

15

25

35

45

0 0.1 0.2 0.3 0.4 0.5 0.6

Filling Factor

Aco

ust

ic P

ow

er (

Wat

ts)

St. Steel (Th.)

Mylar (Th.)

Glass wool (Exp.)

St. Steel (Exp.)

Cotton (Exp.)

Solar Energy Driven TARefrigerator / Refrigerator

-20

-10

0

0 4 8 12

P1/Pm=0.2%P1/Pm=0.35%P1/Pm=0.6%P1/Pm=1%P1/Pm=3%

T(oC

)

Time (sec)

Conversion of Waste Heat / Solar Energy into Electricity

Conversion of Waste Heat / Solar Energy into Electricity

Dreams and Reality

• Several devices have been developed

• New designs are under study

Achievements

SIZES!!!

Summary

Harvesting Waste Heat and Solar Energy

Via Thermoacoustic Devicesis a promising technology

ENERGY CONSERVATION

Tunable Photonic Smart Windows

29 Layers

ENERGY CONSERVATION

Tunable Photonic Smart Windows

9 Layers

AcknowledgementAcknowledgement

• KAUST

• Prof. Amr Shaarawi, AUC, Egypt