Performance of a Single Pass Air Base Photovoltaic/Thermal Solar Collector with and without Hexagonal Honeycomb Heat Exchanger By: Faridah Hussain Senior Metrologist
Background Problem to be solved: Major factor that effect popularity of photovoltaic module is it relatively low in efficiency. Furthermore the rise of PV temperature will result in the drop of module efficiency. In order to minimize PV module losing its efficiency, a simultaneous cooling system using air or water as the heat transfer liquid can be implemented. The heat output from the system can be collected and stored as thermal energy.
PHOTOVOLTAIC/THERMAL (PV/T) COLLECTOR Photovoltaic Module + components Solar thermal A combination of photovoltaic panel (PV) and solar thermal components or system that capable of producing both electrical energy and thermal energy simultaneously and efficiently in one integrated system. Photovoltaic/thermal collector Air in Air out Air in Air out Single pass PV/T collector Double pass PV/T collector
Literature 1991 : Bhargava A.K., Garg H.P., Agarwall R.K. Metal sheet P1 Glass cover PV cell Air in Air out Metal sheet P2 Insulator Single pass PV/T system uses two pieces of metal sheet as heat exchanger
Literature 2000 : Sopian K., Liu H.T., Kakac S., Veziroglu T.N. Glass cover PV cell Air in Metal sheet P1 Air our Metal sheet P2 Insulator Double pass PV/T solar collector suitable for solar drying system using 2 pieces of metal sheet as heat extractor
Literature 2005 : M.Y.Othman, B.Yatim, K.Sopian and M.N.A.Bakar Had been patented PI 2007 1503 A double pass PV/T system with compound parabolic concentrator (CPC) and fins
Literature 2007: M.Y.Othman, B.Yatim, K.Sopian and M.N.A.Bakar A double pass air base PV/T system with fins attached at the back of the absorber plat of the PV module
Literature 2010: Goh Li Jin, Adnan Ibrahim, Yee Kim Chean, Roonak Daghigh, Hafidz Ruslan, Sohif Mat, M.Y.Othman, K.Sopian Aluminium tunnel A single pass air base solar collector with rectangular tunnel heat exchanger. The material of the rectangular tunnel is aluminium.
Literature 2009: M.Y.Othman, Hafidz Ruslan, K.Sopian, Goh Li Jin Photovoltaic module Module Had been patented PI 2010 004880 Aluminium heat absorber A single pass PV/T system with aluminium - grooved absorber plate. The thickness of the aluminium is 0.7 mm attached at the back of the PV module.
Literature 2007: Tripanagnostopoulos For air heat extraction improvement, the modification was done by placing a thin corrugated metallic sheet located in the middle of a channel
Literature 2011: H.G. Teo, P.S. Lee, M.N.A. Hawlader An active cooling system for photovoltaic modules To actively cool the PV cells, a parallel array of ducts with inlet/outlet manifold designed for uniform airflow distribution was attached to the back of the PV panel.
Current Research Photovoltaic Module + components Solar thermal Air Base Single pass PV/T collector Photovoltaic/thermal collector PV A commercially available monocrystalline silicon solar cell photovoltaic module is used to produce electricity. A compact aluminium honeycomb with hexagonal geometry as the heat exchanger was installed horizontally into the channel located at the back of the PV module. Air, as heat removing fluid is made to flow through the honeycomb Hexagonal aluminium honeycomb
Fabrication of Honeycomb Heat Exchanger Aluminium sheet 1 Aluminium sheet 2 Aluminium sheet 3 Aluminium sheet 4 Aluminium sheet 5 5 pieces of aluminium corrugated sheets - joined together to fabricate a compact aluminium honeycomb with hexagonal geometry
How it Works? Convection Conduction Radiation The honeycomb structure enable heat transfer efficiently through radiation, convection and conduction. Capable to enhance thermal efficiency of the system Filed for Patent : PI 2011003877
Structure of Honeycomb The hexagonal honeycomb design has large surface area touching to the back of the PV module. Therefore it will enhance the heat transfer from the back of the PV module to the air, as the moving fluid. Hence the thermal and electrical efficiency of the system will be more efficient.
Installation of Honeycomb Completed fabricated Honeycomb Installed at the back of PV module View from inlet of the channel
Schematic Diagram of the System
( C) Results Thermal efficiency (%) Temperature Difference, T out - T in Temperature Difference, T o - T i 10 9 8 7 6 5 4 3 2 1 With honeycomb Without Honeycomb 0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 Mass flow rate (kg/s) Mass flow rates : 0.021 kg/s, 0.042 kg/s, 0.085 kg/s, 0.110 kg/s and 0.128 kg/s. 100 90 80 70 60 50 40 30 20 10 Testing condition: Indoor : Solar simulator Irradiance : 828 W/m 2 Thermal efficiency of both collectors 0 0.00 0.05 0.10 0.15 Mass flow rate (kg/s) 87% With honeycomb Without Honeycomb 27%
Electrical efficiency (%) Results Electrical Efficiency (%) 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 Electrical efficiency at different flow rate With Honeycomb Without honeycomb 6.7 0.00 0.05 0.10 0.15 Mass flow rate (kg/s) 8.0 7.8 7.6 7.4 7.2 7.0 6.8 6.6 6.4 6.2 Electrical efficiency at different Irradiance With honeycomb Without honeycomb 6.0 500 600 700 800 900 1000 Irradiance (W/m 2 ) The electrical efficiency, for both collectors increase with the increase of the fluid mass flow rate. PV/T collector with honeycomb shows slightly higher electrical efficiency, compared to the collector without honeycomb. The electrical efficiency is lower at higher irradiance due to the increasing temperature of the PV module caused by infrared radiation effect from the halogen lamp of the solar simulator.
Advantages 1. It is a combination of photovoltaic panel (PV) and solar thermal components or system which is capable of producing both electrical energy and thermal energy simultaneously and efficiently in one integrated system. 2. The large surface area of honeycomb heat exchanger touches the back of the PV module able to transfer heat from the PV module efficiently. Therefore the collected thermal energy from the system is very efficient. 3. Besides producing efficient thermal energy, the honeycomb heat exchanger is able to maintain the electrical efficiency of PV module at high temperature. 4. The design of the hexagonal honeycomb is very compact and light. Therefore it is suitable to be installed into a building structure as BIPV/T (roof integrated or façade integrated). As the result, lower cost system can be constructed.
Technology Application
Thank you Name: Faridah Hussain Company: SIRIM Berhad Tel: 603-87781735 Email: faridah_hussain@sirim.my