abdul qadir 1, research assistant peter armstrong 2, associate professor mechanical engineering...
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Abdul Qadir1, Research AssistantPeter Armstrong2, Associate Professor
Mechanical Engineering ProgramMasdar Institute of Science and Technology
Abu Dhabi, UAE
IMECE2010-40571Vancouver, BC 17 November 2010
1] [email protected]] [email protected]
Hybrid Liquid-Air Transpired Solar Collector
Model Development and Sensitivity Analysis
Motivation: Dehumidification
UAE urban development in humid coastal regions
Abundant solar resource
Current UAE policies encourage Renewable energyEnergy efficiency
Growth in Peak Demand
4,7905,180
5,910
7,735
8,735
9,705
10,600
11,46012,151
12,71113,139 13,452 13,716 14,089 14,340
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
Gro
ss M
W
Abu Dhabi
Al Ain
Western Region
Total System
Peak electricity demand growth estimates for Abu Dhabi (2007-2012)Recent revised estimates are significantly higher
(Ref: Abu Dhabi Water and Electricity Company, 2007)
Unglazed Hybrid Liquid-Air Collector
Heated water and air to desiccant regenerator
Transpired
air
Fan
Perforated absorber plate
Modeling Assumptions
1. One-Dimensional Flow of Air, Water and Heat
2. Uniform Porosity to Approximate Many Small Holes
3. T(x) Can Be Modeled By Fin EquationFin Boundary Conditions: Fluid Uniform Temperatures; Uniform AbsorbedSolar Flux
4. T(y) Can Be Modeled By Non-Linear ODE
Note That (1-3) Apply to Differential Control Volume
Convective Heat Transfer Relations
Convection Loss From Plate (Kutscher)Face velocity, wind speed, perforation pitch
NTU-Effectiveness Model of Perforations (Kutscher)
Convective coupling of Plate to Airstream BehindNon-uniform temperature difference: bracketing analysisPitch>>BL thickness use standard flat plat Nu=f(Re,Pr,D/L)Pitch<<BL thickness assume no coupling
Sensitivity Analysis
Ratio of Air to Total Thermal Capacitance Rate
Total Thermal Capacitance Rate
Absorber Emissivity
Back Coupling
Sensitivity Analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.2 0.4 0.6 0.8 1
Effici
ency
mdotcp ratio
mdotcptot=25W/m2K mdotcptot=20W/m2K mdotcptot=15W/m2K
mdotcptot=10W/m2K mdotcptot=5W/m2K
Sensitivity Analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.2 0.4 0.6 0.8 1
Effci
ency
mdotcp ratio
mdotcptot=25W/m2K mdotcptot=20W/m2K mdotcptot=15W/m2K
mdotcptot=10W/m2K mdotcptot=5W/m2K
Sensitivity Analysis
300
310
320
330
340
350
360
370
380
390
400
0 0.2 0.4 0.6 0.8 1
Twou
t
mdotcp ratio
mdotcptot=25W/m2K mdotcptot=20W/m2K mdotcptot=15W/m2K
mdotcptot=10W/m2K mdotcptot=5W/m2K
Sensitivity Analysis
300
310
320
330
340
350
360
370
380
390
400
0 0.2 0.4 0.6 0.8 1
Twou
t
mdotcp ratio
mdotcptot=25W/m2K mdotcptot=20W/m2K mdotcptot=15W/m2K
mdotcptot=10W/m2K mdotcptot=5W/m2K
Sensitivity Analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.02 0.04 0.06 0.08 0.1 0.12
effici
ency
(Ti-Ta)/G
e=0.1 e=0.5 e=0.9
Sensitivity Analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.02 0.04 0.06 0.08 0.1 0.12
effici
ency
(Ti-Ta)/G
e=0.1 e=0.5 e=0.9
Sensitivity Analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.02 0.04 0.06 0.08 0.1 0.12
effici
ency
(Ti-Ta)/G
e=0.1 e=0.5 e=0.9
Sensitivity Analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.02 0.04 0.06 0.08 0.1 0.12
effici
ency
(Ti-Ta)/G
e=0.1 e=0.5 e=0.9
Sensitivity Analysis
0
0.2
0.4
0.6
0.8
1
1.2
0 0.02 0.04 0.06 0.08 0.1 0.12
effici
ency
(Ti-Ta)/G
e=0.1 e=0.5 e=0.9
Sensitivity Analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.02 0.04 0.06 0.08 0.1 0.12
effici
ency
(Ti-Ta)/G
e=0.1 e=0.5 e=0.9
Sensitivity Analysis
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
-0.05 0 0.05 0.1 0.15 0.2
Effici
ency
(Ti-Ta)/G
Vw=5m/s Vw=3m/s Vw=0m/s Linear (Vw=5m/s) Linear (Vw=3m/s) Linear (Vw=0m/s)
Sensitivity Analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
-0.05 0 0.05 0.1 0.15 0.2
Effici
ency
(Ti-Ta)/G
Vw=5m/s Vw=3m/s Vw=0m/s Linear (Vw=5m/s) Linear (Vw=3m/s) Linear (Vw=0m/s)
Future Work
Experimental Verification
Regenerator and Absorber Models
System Optimization
Model Refinement and Collector Optimization
Unglazed Transpired Air Collector(UTAC) for Desiccant RegenerationAdvisor: Dr. Peter Armstrong Student: Abdul Qadir
Research Objectives
-Develop through simulation and testing, an UTAC which can deliver an outlet air temperature of 70˚C in order to regenerate a desiccant for desiccant cooling and dehumidification cycles.
- Investigate a hybrid UTAC to produce hot water & air.
- Develop an integrated model and test the performance of a desiccant cooling cycle coupled with a UTAC.
Broader Impacts
- Could replace the gas burners which are currently used to regenerate desiccants.
- Cost effective way to integrate solar technology to an existing cooling infrastructure.
- Can significantly reduce the electricity consumption by removing latent cooling load from the cooling system, especially in humid climates like Abu Dhabi’s.
Figure 2: Initial TRNSYS simulation resultsFigure 1: Schematic of the UTAC configuration
Heated air to desiccant cycle
Transpired Air
FanBuilding Roof
Perforated absorber plate