Yoann Guinard1,2, Qiyuan Li1, Gonzalo Diarce1, Robert A.Taylor1
1School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
2National Institute of Applied Sciences, Lyon, France
Performance of a Low Profile, Concentrating Solar Thermal
Collector for Industrial Heating Process Applications
1.Introduction
International Conference on Energy, Environment and Economics
16-18th August, 2016, Heriot-Watt University, Edinburgh
©WEENTECH
Recent studies have demonstrated that solar heat has a critical role to play in providing heat for
industrial processes. However, according to a 2014 IEA report, only 132 plants (~100 MW) are
installed around the world to provide heat for industrial processes [1]. Most of the installed solar
systems are based on parabolic troughs, which are not suitable for rooftop installation.
Therefore, the authors believe that market is primed for the development of new rooftop solar
thermal collector technology that can provide heat between 100 °C and 400 °C. As a result, this
work studies the behavior of a novel, low profile, concentrating collector design (developed at
UNSW [2,3,4,5]) – a design which is suitable for rooftop use and which can achieve these
temperatures.
The annual behavior of the collector has been simulated for a metal processing application with
TRNSYS (Transient System Simulation Tool) software in order to study its performance and
economic feasibility.
 The behaviour of a low profile (< 15cm) concentrating solar thermal collector for an industrial
process heating application was investigated. The application is a metal washing and drying
process which requires 180 °C. The daily thermal load is 260 kWh, and the process is assumed
to be continuous (day and night).
 Our simulations indicated that for a collector area of 200 m², a solar fraction of 53 % can be
realised in Sydney. With government subsidies of 50 % of the capital outlay, and with a
reasonable estimation of the gas price escalation (+5 % annually), the system yields a payback
period of 11 years and a net present value of $69,641 for a system with a 20 years life.
 Due to the fact that solar-derived industrial heating is still in its infancy, further research and
development could drastically reduce the capital cost and improve the efficiency of this kind
of system, leading to much more attractive payback time and net present value.
Efficiency of the solar system
Economic and environmental analysis
Sydney Alice Springs Paris
Price of gas constant
Without subsidies Payback Time (years) 99 21 /
With subsidies of
50 %
Payback Time (years) 16 8 30
Net Present Value (AUD) 14, 100 85, 788 -18, 858
Internal Rate of Return
(%) 7% 16 2
Price of gas +5 %
annually
Without subsidies Payback Time (years) 23 14 33
With subsidies of
50 %
Payback Time (years) 11 7 16
Net Present Value (AUD) 69, 641 177, 559 20, 336
Internal Rate of Return
(%) 12 21 7
0,0
0,2
0,4
0,6
0,8
1,0
0 200 400 600 800
Solarfraction(-)
Collector area (m²)
Sydney
Alice Springs
Paris
BestCollectorArea
Parameter Value Unit
Collector Area 200 m²
Cost of collector 800 AUD/m²
160,000 AUD
Installation cost 32,000 AUD
Subsidies 0 - 50 %
Price of gas in Sydney 0.042 AUD/MJ
Price of gas in Paris 0.049 AUD/MJ
Carbon Tax 25 AUD/ton CO2
Discount Rate 5 %
Life span of the system 20 years
Figure 6: Effect of collector area on the solar fraction (tank volume = 4m3; collector flow rate
= 500 kg/hr) for three different cities: Sydney, Alice Springs and Paris
Table 1: Data used for the economic analysis of
the system design
Table 2: Economic feasibility results
The high capital costs make economic
viability questionable without subsidies.
However, in case of 50% government
subsidies, the payback time is reduced
noticeably and the system achieve
satisfactory economic returns.
For the reasonable estimation of a gas
price augmentation of 5 % annually, the
payback time in the three cities are all
achieved during the life span of the
collector leading to a substantial net
present value.
Fresnel Lens
Vacuum glass tube
Vacuum
Tube receiver
CPC
Vacuum glass tube
Figure 1: 3D view of the collector
Figure 2: Cross-sectional view of the collector
The solar fraction is defined as
the ratio between the energy
provided by the solar system
on the total energy required
for the load.
An optimization of the design
options (storage tank sizes,
flow rate in the collector,
control methods) was carried
out to obtain the results
presented in Figure 6.
3.Collector properties
Gb
TaTm
Gb
TaTm )²(
004.064.080.0




0,0
0,2
0,4
0,6
0,8
1,0
0 100 200 300 400
Efficiency(-)
Tm-Ta (°C)
0,0
0,2
0,4
0,6
0,8
1,0
1,2
0 20 40 60 80 100
IncidentAngleModifier(-)
Angle (°)
Longitudinal IAM
Transverse IAM
)0(_
)(_
)(
efficiencyoptical
efficiencyoptical
IAM

 
Figure 4: Transverse and Longitudinal IAM
Figure 3: Efficiency of the collector
(Gb = 900 W/m²)
The non-linear efficiency equation of the
collector was obtained through outdoor
experiments.
IAM (Incident Angle Modifier) is a de-rating
factor to the first term (0.8) of the thermal
efficiency.
4.Industrial process
Figure 5: Schematic of the solar system
[Blue boxes = system components;
Orange boxes = fixed conditions;
Green boxes = variable parameters investigated]
The process consists of a
washing and drying process of
metal pieces modelled by a
thermal load of 260 kWh daily.
The system operates day and
night (24/7).
The outlet temperature of the
solar loop is 180 °C.
The heat transfer fluid used is
the Pirobloc HTF; with a specific
heat of 2.63 kJ/kg.K.
5.Results
6.Conclusion
2.Collector design
References
[1] C. Brunner. Solar Heat for Industrial Production Processes - Latest Research and Large Scale
Installations, in Publication IAE Task 49, 2014.
[2] Q. Li et al. Design and analysis of a low-profile, concentrating solar thermal collector, in: Proceedings of
the 15th International Heat Transfer Conference, Kyoto, Japan, 2014.
[3] Q. Li et al. Experimental investigation of a nanofluid absorber employed in a low-profile, concentrated
solar thermal collector in: Proc. SPIE 9668, Micro+Nano Materials, Devices, and Systems, 2015.
[4] C. Zheng et al. A new optical concentrator design and analysis for rooftop solar applications, in: SPIE
Optical Engineering+Applications, International Society for Optics and Photonics, 2015
[5] C. Zhenq et al. Design and Analysis of Compact Optical Concentrators for Roof-Integrated Solar
Thermal Applications, in: Optics for Solar Energy, Optical Society of America, 2014
For angles greater than 45°, it was found
experimentally that both IAMs approach zero
(e.g. no heat production).