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| − | = Description =
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| − | [[File:Solar milk cooling system with isolated cans and adaptive ice-maker.jpg|border|right|300px|Solar Milk Cooling System for 60 liter per day ( PV-Panels, Batteries, Adaptive control unit, Ice-maker and 2 Isolated milk cans)]]
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| − | The milk cooling solution developed by the University of Hohenheim is based on a commercially available DC Refrigerator equipped with an adaptive control unit for its conversion to a smart ice-maker that operates depending on the availability of solar energy. The ice-maker has a volume of 160l and is capable of producing approx. 8-13 kg ice per day. One system includes 25 reusable plastic blocks of 2 kg capacity and two 30l isolated milk cans with removable ice compartment. To cool down 30l of milk from 36°C to 15°C in one of the supplied milk cans, the systems needs 6kg of ice and 90 minutes.<br/>
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| − | The smart ice-maker is powered by 600 Wp solar PV modules together with two batteries with a total capacity of around 1.5kWh. Thanks to the thermal energy storage, in form of the 25 2kg-Ice-blocks, the system is able to run autonomously for up to 7 days even during periods of low solar radiation and high ambient temperatures. | + | = Description<br/> = |
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| | + | [[File:Solar Milk Cooling System Overview.jpg|border|right|300px|Solar Milk Cooling System for 60 liter per day ( PV-Panels, Batteries, Adaptive control unit, Ice-maker and 2 Isolated milk cans)|alt=Solar Milk Cooling System for 60 liter per day ( PV-Panels, Batteries, Adaptive control unit, Ice-maker and 2 Isolated milk cans)]] The milk cooling solution developed by the University of Hohenheim is based on a commercially available DC Refrigerator equipped with an adaptive control unit for its conversion to a smart ice-maker that operates depending on the availability of solar energy. The ice-maker has a volume of 160l and is capable of producing approx. 8-13 kg ice per day. One system includes 25 reusable plastic blocks of 2 kg capacity and two 30l isolated milk cans with removable ice compartment. To cool down 30l of milk from 36°C to 15°C in one of the supplied milk cans, the systems needs 6kg of ice and 90 minutes.<br/> |
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| | + | The smart ice-maker is powered by 600 Wp solar PV modules together with two batteries with a total capacity of around 1.5kWh. Thanks to the thermal energy storage, in form of the 25 2kg-Ice-blocks, the system is able to run autonomously for up to 7 days even during periods of low solar radiation and high ambient temperatures.<br/> |
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| | = Ice-Maker with Adaptive Control Unit = | | = Ice-Maker with Adaptive Control Unit = |
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| − | Ice making rate is adapted to solar energy availability. During night or rainy days, the total of 50 kg ice stored are kept frozen and ready for its use in the isolated milk cans.<br/>
| + | The implemented adaptive control unit allows the efficient use of conventional DC-Refrigerators for a intensive and reliable production of ice all over the year. The ice-maker is equipped with following features:<br/> |
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| | + | *Variable compressor speed in dependence of solar radiation and state of charge of the batteries. |
| | + | *Operation of a fan in the inner chamber in order to increase freezing rate. |
| | + | *Energy saving mode during night and rainy days. |
| | + | *Use of batteries to increase daily ice production up to 30%.<br/> |
| | + | *Storage of 50 kg ice blocks to assure a autonomy of at least 5 days under low radiation or high ambient temperatures.<br/> |
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| | + | https://energypedia.info/images/d/de/Adaptive_control_unit_for_solar_ice_maker.jpg |
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| | = Isolated Milk Cans = | | = Isolated Milk Cans = |
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| − | Capacity: 30 liter milk and 8 Kg Ice<br/>
| + | The milk-cans implemented are made of stainless-steel and have a capacity of 30 liter milk and 8 kg Ice. This allows a flexible use of them depending on the cooling requirements. The milk-can has been design to operate for two modes as described in following table. |
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| − | Material: Stainless steel<br/>
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| − | Weight: 10 kg including ice-compartment and isolation<br/>
| + | {| border="0" cellspacing="0" cellpadding="0" |
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| | + | | style="width: 205px;" | |
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| − | Thermal isolation: Milk increases its temperature 0.2 °C/hour (Ambient temperature 35°C, Milk temperature 15°C)<br/>
| + | | style="width: 205px;" | |
| | + | '''30 Liter milk + 6kg Ice''' |
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| − | <br/>
| + | | style="width: 205px;" | |
| | + | '''20 Liter milk + 8kg Ice''' |
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| − | = Preservation of Milk Quality through Cooling = | + | |- |
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| | + | '''Cooling temperature''' |
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| − | *For 6 hours during transportation to milk collecting center<br/>
| + | | style="width: 205px;" | |
| | + | 17°C after 90 min. |
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| − | - At 15°C for a maximum of 30 L Milk (6 kg ice needed)<br/>
| + | | style="width: 205px;" | |
| | + | Under 10°C after 150 min. |
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| − | - Milk quality*: Around 15% bacterial growth after 4h ( compared to 120% bacterial growth of uncooled milk in the same time)<br/> | + | |- |
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| | + | '''Used for''' |
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| − | <br/>
| + | | style="width: 205px;" | |
| | + | Transport of morning milk |
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| − | *For 12 hours for on-farm storage of evening milk<br/>
| + | | style="width: 205px;" | |
| | + | Storage of evening milk |
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| − | - At 8°C for a maximum of 20 L Milk (8 kg ice needed)<br/> | + | |- |
| | + | | style="width: 205px;" | |
| | + | '''Milk quality preservation''' |
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| − | - Milk quality*: Around 90% bacterial growth after 12h ( uncooled milk spoiled after around 7 h)<br/>
| + | | style="width: 205px;" | |
| | + | At least 6 hours |
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| − | ''*Orientative values based on laboratory measurements <ref>V. Torres-Toledo, 2016, Research at the Institute of Agriculture Engineering of the University of Hohenheim, Stuttgart, Germany</ref> ''
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| | + | At least 12 hours<br/> |
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| | <br/> | | <br/> |
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| | + | The cooling performance and bacterial growth were measured with real milk under lab conditions in a climate chamber. On-field milk quality assessments are currently carried out in order to confirm the potential of the system to retard bacterial growth depending on milk temperature and transport time under real working conditions.<br/> |
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| − | = Collaboration partners = | + | [[File:Isolated milk cans cooling performance.jpg|center|600px]] |
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| | + | = Collaboration partners<br/> = |
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| | Institute of Agriculture Engineering of the University of Hohenheim<br/> | | Institute of Agriculture Engineering of the University of Hohenheim<br/> |
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| − | = On-field implementations = | + | = On-field implementations<br/> = |
| − | [[File:Solar Milk Cooling Tunisia OnField.jpg|border|right|300px|One Farm in Sidi Bouzid(Tunisia) equipped with two solar milk cooling systems for 120 L/day]]
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| | *Tunisia, July 2015 until December 2017:<br/> | | *Tunisia, July 2015 until December 2017:<br/> |
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| | [[Field Testing of an Innovative Solar Powered Milk Cooling Solution for the higher Efficiency of the Dairy Subsector in Tunisia (PA Project)|Field Testing of an Innovative Solar Powered Milk Cooling Solution for the higher Efficiency of the Dairy Subsector in Tunisia]]<br/> | | [[Field Testing of an Innovative Solar Powered Milk Cooling Solution for the higher Efficiency of the Dairy Subsector in Tunisia (PA Project)|Field Testing of an Innovative Solar Powered Milk Cooling Solution for the higher Efficiency of the Dairy Subsector in Tunisia]]<br/> |
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| | + | 10 solar systems of the presented milk cooling solution were installed in 7 farms in the region of Sidi Bouzid by the end of April 2016. Each system has a capacity of 60l per day while 3 farms were equipped with two system due to higher production volumes up to 120 liter milk per day.<br/> |
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| − | = Overview of solar milk cooling systems = | + | The performance of the solar ice-makers is currently monitored in order to confirm the right use of the system by the farmers and the daily availability of 12kg ice. Additionally experts interviews are carried out for farmers and dairy industry to assets the acceptance of the milk-cans by daily use together with the social impact in terms of gender and labor organization.<br/> |
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| | + | From the economical side, the potential of the system to increase productivity and preserve milk quality will be analyzed as main pillars to support the milk value chain and generate business opportunities. Furthermore the system cost will be reduced by the development of milk-cans able to be produced locally.<br/> |
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| | + | https://energypedia.info/images/c/c6/Solar_Milk_Cooling_On_the_Field_in_Tunisia.jpg<br/> |
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| | + | = Overview of solar milk cooling systems<br/> = |
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| | *[[Solar Milk Cooling|Solar Milk Cooling]] | | *[[Solar Milk Cooling|Solar Milk Cooling]] |
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| | = References = | | = References = |
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| − | <references /> | + | <references /><br/> |
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| | + | Torres-Toledo, Victor, Klaus Meissner, Alberto Coronas, and Joachim Müller. 2015. “Performance Characterisation of a Small Milk Cooling System with Ice Storage for PV Applications.” International Journal of Refrigeration 60. 81–91. doi:10.1016/j.ijrefrig.2015.06.025.<br/> |
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| | + | Torres-Toledo, Victor. 2013. “MSc. Thesis: Design Methodology of Cost Optimized Solar Chillers for Milk Cooling in Rural Areas.” University Rovira i Virgilli, Tarragona, Spain.<br/> |
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| | For further information, please contact the author of this article.<br/> | | For further information, please contact the author of this article.<br/> |
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| − | [https://www.uni-hohenheim.de/projekt/field-testing-of-an-innovative-solar-powered-milk-cooling-solution-for-the-higher-efficiency-of-the-dairy-subsector-in-tunisia https://www.uni-hohenheim.de/projekt/field-testing-of-an-innovative-solar-powered-milk-cooling-solution-for-the-higher-efficiency-of-the-dairy-subsector-in-tunisia] | + | [https://www.uni-hohenheim.de/projekt/field-testing-of-an-innovative-solar-powered-milk-cooling-solution-for-the-higher-efficiency-of-the-dairy-subsector-in-tunisia https://www.uni-hohenheim.de/projekt/field-testing-of-an-innovative-solar-powered-milk-cooling-solution-for-the-higher-efficiency-of-the-dairy-subsector-in-tunisia]<br/> |
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| − | [[Category:Photovoltaic_(PV)]]
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| − | [[Category:Productive_Use]]
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| − | [[Category:Cooling]]
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| | [[Category:Powering_Agriculture]] | | [[Category:Powering_Agriculture]] |
| | + | [[Category:Cooling]] |
| | + | [[Category:Productive_Use]] |
| | + | [[Category:Photovoltaic_(PV)]] |
The milk cooling solution developed by the University of Hohenheim is based on a commercially available DC Refrigerator equipped with an adaptive control unit for its conversion to a smart ice-maker that operates depending on the availability of solar energy. The ice-maker has a volume of 160l and is capable of producing approx. 8-13 kg ice per day. One system includes 25 reusable plastic blocks of 2 kg capacity and two 30l isolated milk cans with removable ice compartment. To cool down 30l of milk from 36°C to 15°C in one of the supplied milk cans, the systems needs 6kg of ice and 90 minutes.
The smart ice-maker is powered by 600 Wp solar PV modules together with two batteries with a total capacity of around 1.5kWh. Thanks to the thermal energy storage, in form of the 25 2kg-Ice-blocks, the system is able to run autonomously for up to 7 days even during periods of low solar radiation and high ambient temperatures.
The implemented adaptive control unit allows the efficient use of conventional DC-Refrigerators for a intensive and reliable production of ice all over the year. The ice-maker is equipped with following features:
The milk-cans implemented are made of stainless-steel and have a capacity of 30 liter milk and 8 kg Ice. This allows a flexible use of them depending on the cooling requirements. The milk-can has been design to operate for two modes as described in following table.
The cooling performance and bacterial growth were measured with real milk under lab conditions in a climate chamber. On-field milk quality assessments are currently carried out in order to confirm the potential of the system to retard bacterial growth depending on milk temperature and transport time under real working conditions.
10 solar systems of the presented milk cooling solution were installed in 7 farms in the region of Sidi Bouzid by the end of April 2016. Each system has a capacity of 60l per day while 3 farms were equipped with two system due to higher production volumes up to 120 liter milk per day.
The performance of the solar ice-makers is currently monitored in order to confirm the right use of the system by the farmers and the daily availability of 12kg ice. Additionally experts interviews are carried out for farmers and dairy industry to assets the acceptance of the milk-cans by daily use together with the social impact in terms of gender and labor organization.
From the economical side, the potential of the system to increase productivity and preserve milk quality will be analyzed as main pillars to support the milk value chain and generate business opportunities. Furthermore the system cost will be reduced by the development of milk-cans able to be produced locally.
Torres-Toledo, Victor, Klaus Meissner, Alberto Coronas, and Joachim Müller. 2015. “Performance Characterisation of a Small Milk Cooling System with Ice Storage for PV Applications.” International Journal of Refrigeration 60. 81–91. doi:10.1016/j.ijrefrig.2015.06.025.
Torres-Toledo, Victor. 2013. “MSc. Thesis: Design Methodology of Cost Optimized Solar Chillers for Milk Cooling in Rural Areas.” University Rovira i Virgilli, Tarragona, Spain.
For further information, please contact the author of this article.
