Solar Solar Cooling Cooling for Agriculture for Agriculture Do It Yourself! Do It Yourself! Technical Training Promotion Conference March 18 th – 22 nd 2019 Nairobi, Kenya In cooperation with: Media Partner: Institute of Agricultural Engineering│Tropics and Subtropics Group 1
Get your soft copy of all materials presented during the day http://solar-cooling-engineering.com/details-training-and-conference-kenya-2019 Institute of Agricultural Engineering│Tropics and Subtropics Group 2
DAY 1 Monday March 18th Academia Institute of Agricultural Engineering│Tropics and Subtropics Group 3
DAY 2 Tusday March 19th Companies Institute of Agricultural Engineering│Tropics and Subtropics Group 4
Where is Hohenheim? Institute of Agricultural Engineering│Tropics and Subtropics Group 5
Who are we? Tropics/Subtropics group of the Institute of Agricultural Engineering • 5 Departments (Professors) • 150 Staff members Attached to the multidisciplinary: Institute of Agricultural Sciences University of Hohenheim in the Tropics (Hans-Ruthenberg) 9,500 Students(15% international) • 10 Departments (Professors) 40 Degrees, 2,000 Staff members • 100 Researchers Institute of Agricultural Engineering│Tropics and Subtropics Group 6
Tropics/Subtropics group (Prof. Dr. Joachim Müller) ■ Solar Drying ■ Irrigation (Solar) ■ Plant oil extraction (Solar) ■ Use of biogas/biomass 20 PhD Students ■ Postharvest technologies 6 Post. Docs. 5 Technical staff ■ Solar cooling 2 administrative staff From 15 countries! Institute of Agricultural Engineering│Tropics and Subtropics Group 7
Solar Cooling Team Juliet Farah Victor Florian Julian Muaz Ana Kilian Institute of Agricultural Engineering│Tropics and Subtropics Group 8
Facilities of the Institute of Agricultural Engineering Metal Workshop Wood Workshop Electric/Electronic Laboratories Research hall Greenhouse Institute of Agricultural Engineering│Tropics and Subtropics Group 9
Solar cooling testing facilities Weather profile Solar Power profile Climate chamber PV Simulator Institute of Agricultural Engineering│Tropics and Subtropics Group 10
Our work since 2014 with commercial available solar refrigerators Institute of Agricultural Engineering│Tropics and Subtropics Group 11
Small scale milk cooling Institute of Agricultural Engineering│Tropics and Subtropics Group 12
Institute of Agricultural Engineering│Tropics and Subtropics Group 13
Institute of Agricultural Engineering│Tropics and Subtropics Group 14
Implemented projects Tunisia 2016 10 systems Colombia 2018 4 systems Kenya Kenya 2018 2016 2 systems 3 systems Institute of Agricultural Engineering│Tropics and Subtropics Group 15
Even though a technical solution is economically feasible, that doesn't mean this will be adopted by the industry Institute of Agricultural Engineering│Tropics and Subtropics Group 16
Business models Farmer / Cooperative Technology supplier New Marketing markets Processing Distribution Storage Production Increase production Testing Preserve quality Product development Challenges • No quality based pricing • High transportation cost • Seasonal fluctuations • Lack of investments for R&D • Strong informal market • Expensive distribution and • Unreliable customers maintenance in rural areas Institute of Agricultural Engineering│Tropics and Subtropics Group 17
Business models Farmer / Cooperative Technology supplier „This technology is not 100% „I can not invest in innovations to adapted to my needs and too my farmer customers“ expensive“ Institute of Agricultural Engineering│Tropics and Subtropics Group 18
Farmers often don´t have access to the technology they need and would be ready to pay for Institute of Agricultural Engineering│Tropics and Subtropics Group 19
Promote key components instead of key systems Locally produced Solar cooling units + solar cooling systems Electronics and sensors + Know-how Institute of Agricultural Engineering│Tropics and Subtropics Group 20
Example for solar refrigerator Insulated box (Suitable for local production ) Battery free solar refrigerator Solar Cooling Unit (Final System) (Key component) + = + Ice-packs Institute of Agricultural Engineering│Tropics and Subtropics Group 21
One key component … many options Institute of Agricultural Engineering│Tropics and Subtropics Group 22
Refrigeration machines Thermoelectric (Peltier) Refrigerant free Thermomagnetic Air compression Refrigeration methods Without phase Vórtex tube change Stirling engines With refrigerant Open circuit Evaporative cooling Vapor compression With phase change (heat pumps) Closed circuit Absorption (cycle) Adsorption Institute of Agricultural Engineering│Tropics and Subtropics Group 23
Heat pumps theory ■ The efficiency of refrigeration systems is measured by the Coefficient Of Performance (COP) which indicates the ratio between extracted heat and energy input. In the case of vapor compression systems, the ratio between refrigeration effect and mechanical or electrical work. The maximal COP of a refrigeration cycle is defined by the second law of thermodynamics and depends on the temperature of the warm and cold source as described by Carnot (1824) in following equation: Where Q is the thermal energy, P the mechanical work, α the ideality factor of the refrigeration cycle and T the temperature of the warm and cold source respectively Institute of Agricultural Engineering│Tropics and Subtropics Group 24
Coefficient of Performance (COP) Source: https: / / www.dimplex.co.uk ■ ■ COP Carnot (Ideal) COP Refrigeration cycle (real) * T warm (°C) T warm (°C) 20 30 40 20 30 40 4 4 17.3 10.7 7.7 2.6 2.1 1.8 T cold T cold (°C) (°C) -10 -10 8.8 6.6 5.3 1.6 1.4 1.1 * Different for each refrigeration system Institute of Agricultural Engineering│Tropics and Subtropics Group 25
Importance of climate friendly refrigerants ■ R134a has Global Warming Potential (GWP) of 1400 kg CO 2 equivalent per kg ■ Natural refrigerants as R290(Propane) or R600a(Isobutane) have GWP of around 3 kg CO 2 equivalent per kg. Good to know! The refrigerant of a typical solar refrigerator with R134a implies the Co 2 eq. emissions that are saved through the use of PV-Panels during almost 7 years! Therefore, Solar always with natural refrigerants! Institute of Agricultural Engineering│Tropics and Subtropics Group 26
Cost comparison -68% -42% -48% Institute of Agricultural Engineering│Tropics and Subtropics Group 27
Better cost efficiency Tailored to customers Higher local added value Promising performance Institute of Agricultural Engineering│Tropics and Subtropics Group 28
Get into the market with several system configurations! Household Refrigerator Water chiller for Cold rooms or Milk tanks Institute of Agricultural Engineering│Tropics and Subtropics Group 29
3 Example Systems Example System 1 : Example System 2 : Example System 3 : Solar ice-maker Refrigerator battery-free Water Chiller for cold rooms And water bath milk cooling Institute of Agricultural Engineering│Tropics and Subtropics Group 30
Construction Materials Solar cooling unit Wooden box Technology Stability Insulation Water proof Polystyrene plates Acryl glass plates Institute of Agricultural Engineering│Tropics and Subtropics Group 31
Solar ice-maker ● 2 cooling units ● Power: 140 W ● 2 fans for increased heat transfer (x3) ● Space for nominal 54 kg ice (max. capacity: 72 kg) ● 3 chambers 20 °C 30 °C 40 °C 0 kWh/m 2 day -2.4 kg -3.5 kg -4.7 kg 2 kWh/m 2 day 10.3 kg 5.6 kg 0.6 kg Daily ice production in kg/day 4 kWh/m 2 day 23.3 kg 15.8 kg 6.7 kg powered by 400 Wp 6 kWh/m 2 day 30.4 kg 23.2 kg 14.1 kg and 2 x 40 Ah Batteries 8 kWh/m 2 day 31.4 kg 24.2 kg 15.1 kg Institute of Agricultural Engineering│Tropics and Subtropics Group 32
Solar ice-maker (Performance) • 23 kg ice within 24 hours at 30°C ambient • Faster cooling in the middle chamber • 3 Days autonomy through ice stored in the side chambers Temperature (°C) Air Evaporator Institute of Agricultural Engineering│Tropics and Subtropics Group 33 Time (hh:mm)
Battery free refrigerator ● Directly connected to PV ● icepacks around the evaporator → Energy storage in ice Institute of Agricultural Engineering│Tropics and Subtropics Group 34
Battery free refrigerator (Stages during Assembly) Case with Insulation and Solar Cooling Unit is installed ● ● acrylic glass box Ice Storage is beeing installed ● Top is removed to allow Solar on both sides of Evaporator ● Cooling Unit assembly plate Institute of Agricultural Engineering│Tropics and Subtropics Group 35
Battery free refrigerator (Performance) • 30 Liter Water per day 25°C-> 4°C • Autonomy of 24 hours at 35°C ambient temperature Institute of Agricultural Engineering│Tropics and Subtropics Group 36
Water chiller ● Evaporator plate directly immersed in water ● Ice storage for fast cooling or as substitute of electrical batteries Institute of Agricultural Engineering│Tropics and Subtropics Group 37
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