1 / 41

Performance Modeling of Low Cost Solar Collectors in Central Asia

Performance Modeling of Low Cost Solar Collectors in Central Asia. Progress Report. Steph Angione, Zach Auger, Adrienne Buell, Suza Gilbert, Emily Kunen, Missy Loureiro, Alex Surasky-Ysasi, Amalia Telbis. Problem Definition.

ganit
Download Presentation

Performance Modeling of Low Cost Solar Collectors in Central Asia

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Performance Modeling of Low Cost Solar Collectors in Central Asia Progress Report Steph Angione, Zach Auger, Adrienne Buell, Suza Gilbert, Emily Kunen, Missy Loureiro, Alex Surasky-Ysasi, Amalia Telbis

  2. Problem Definition • Goal: Design a performance model for a solar collector in central Asia • Specifications: • Heat water for domestic use • Low cost • Local materials • Efficient • Ease of maintenance • Sustainable

  3. Decision Making Process • Background Research: • Region and climate data • Materials and availability • Heat transfer • Testing and modeling process • Specified Situation: • Household size: 7 people • Water usage: 25 liters per person • Region: rural, mountainous • Output Temperature: 60 °C • Functionality: year round • Storage tank Capacity: 1-2 days of water • Delivery system: use existing

  4. Background Research

  5. Geography: Afghanistan • Located in Central Asia, on the Iranian plateau at a longitude of 33°00’N and a latitude of 65°00’E. • Includes three distinct areas: • Central Highlands • Southern Plateau • Northern Plains

  6. Geography: Tajikistan • 93 % of the country is covered in mountains • More than half lies above 3,000 meters • Contains dense river network

  7. Climate: Afghanistan • Highlands similar to lower Himalayas • Temperature range from 50°-60° F • Hottest weather in southwest • Coldest weather in northern regions • Waves of intense cold with temperatures below zero

  8. Lifestyle: Afghanistan ~300 families/village 43 inhabitants/km2 Life Expectancy: • 43.7 male • 43.1 female Children per family: ~7 85% water usage is for agriculture Less than 20% have piped water 4% of population has electricity

  9. Housing: Afghanistan • Construction Materials • Stone, wood, plaster and straw, brick • Terraced Housing • Roof of one in yard of the other • 2 stories • cooking and eating on upper floor • windows with hinged shutters • Post and beam constructions • coniferous wood used

  10. Lifestyle: Tajikistan • 2/3 of population lives in rural areas • 44 inhabitants/km2 • Life expectancy: 67 male • Children per family: ~6 • Natural water system infected with chemicals, bacteria • 20% clean water coverage in rural area • 90% clean water coverage in urban area • 95% of rural population has electricity

  11. Housing: Tajikistan • Varies by Region • Urban Areas: • Apartments • Flat areas: • 1 story, flat roof, covered courtyard • In mountains: • Build into the mountain • Low ceiling • Small openings & rooms • Fire place in central room • Multifamily/ multistory • Construction: • Raw bricks, plaster & cut straw (horizontal layers) • Where available: wood used for roof beams • Cement often used for roof • Area: ~51.4 m2

  12. Materials • What to look for when looking for a material: • Thermal Properties • Durability • Availability • Construction Methods • Maintenance • Costs • Materials Specified by EWB: • Sheet Metal • Wood • Glass • Black Paint • Horsehair • Regional Materials Used: Clay, Cement, Brick, Coniferous Trees Wood, Sheep Wool, Straw, Plaster

  13. Sheet Metal • Used as a conductor • High heat capacity [130-900 J/kg*K] • Variety of metals available • Best heat capacity – Aluminum [903 J/kg*K] • Best conductivity – Copper [401 W/m*K] • Durability and Construction Methods: • Cutting tasks only require aviation snips • Small Pieces are easy to bend • Can be fastened to wood using nails • To fasten two sheets pre-drill holes in each, then join using screws or pop rivets • Aluminum Sheet: • Excellent conductor of heat • Light (about 1/3 weight of copper) • Easily machined • Resists corrosion • Withstands wind, rain, chemicals, pollution • Excellent durability • Can be recycled • Copper Sheet: • Can be shaped into any form easily • Doesn’t not crack when hammered, stamped, forged or pressed. • Resists corrosion and does not rust • Can be recycled

  14. Wood • Used as Insulator • Specific Heat: • Independent of wood species • Dependent of temperature and moisture content of wood • Thermal conductivity • Smaller than value for metals • 2-4 times better than other insulating materials • Conductivity along the grain is 1.5 to 2.8 times greater • Thermal diffusivity is much lower than metal, brick, and stone • Durable insulation • Easily cut for construction • Hand-tools sufficient

  15. Figure 1 Glass: • Used for glazing • Thermal properties: • Coefficient of thermal conductivity ~1.0 W/m*K • Optical properties: • Soda Lime Glass: • Refractive Index (I=435 nm): 1.523 (I=645 nm): 1.513 • Figure 1 shows optical transmission % versus wavelength

  16. Black Paint • Used to improve thermal conductivity of material • Semi-selective black painted surface • Absorptivity = a = 94% • Emissivity = e = 28% • Non-selective coating (matt texture): • Absorbs 90-95% of all solar radiation • Radiates back about 90% of maximum heat energy • Cheap but can be ineffective if not used in proper location • Easily applied and restored

  17. Horsehair and Sheep Wool Horsehair: • Used for insulation • Material readily available • 0.3 million horses in Afghanistan (FREE) • Durable • Lasting for over 200 years • Insulation used for homes • Bousillages – mixture of moss and clay • Outer layer is a mixture of horsehair, water, and clay Sheep Wool: • 11-14 million sheep in Afghanistan

  18. Regional Materials • Positive Aspects of using regional material: • Cheap • Readily available • Training on how to use materials not needed

  19. What is a Solar Collector? • Radiation from the Sun transformed into thermal energy • Used for Heating air or water • Different types: • Batch • Vacuum • Concentrating • Flat Plate

  20. Hot Material Heat Transfer Formulas • Conduction • Fourier’s Law: dQ/dt=-kA(dT/dx) • Through a material • Convection • Newton’s Law of Cooling: dQ/dt=hA(Ts-Tf) • Fluid flowing past a solid • Radiation • Stephan-Boltzman Law: dQ/dt=εσATb4 • Heat emitted by an object

  21. Information Needed: Sunlight Striking Surface Latitude Season Weather Patterns Sun’s Position Temperature Wind Speeds Humidity Some Basic Questions: Will the Collector Storage System Be in the Same Unit? Will the Liquid Circulate Naturally or Be Pumped? Will Back Up Heating and Storage Be in the Same Tank? What Freeze Protection Method will be Implemented? Before You Pick a System

  22. Components of a Solar Collector • Absorber Plate • Absorber Surface Coatings • Glazing • Insulation • Casing

  23. Assumptions: Power from Sun: 1kW/m2 Input Temperature: 0°C Output Temperature: 60°C Household Size- 10 people Hot Water Per Person- 25 Liters per day Hours of Sunlight: 5 per day Outcome: Surface Area of 3.5m2 Issues of Note: Based on Maximum Possible Energy Absorption February Basis Sample Calculation

  24. Testing and Modeling Determine All Variables and Constants Visualized Design/Schematic CAD software: SolidWorks, ProE Free-hand sketches

  25. Calculations • Use of MatLab or Excel • Use of possible simulations • F-chart • TRNSYS

  26. Advantages only 2.5 percent error vs. monitored systems easily determines thermal performance F-Chart

  27. F-chart continued… • Disadvantages • underpredicts system performance in mountainous regions

  28. Solar Heater Types and Designs • Passive vs. Active Solar Heaters • Active • use pumps to circulate water or an antifreeze solution through heat-absorbing solar thermal collectors • Passive • The water is circulated without the aid of pumps or controls • Open Loop vs. Closed Loop • If the liquid that needs to be heated is also the one being circulated:Open Loop • If antifreeze or another solution used in a heat exchanger to heat the water:Closed Loop

  29. Active Solar Heaters

  30. 1. Solar Collector 6. Collector Return  Breaker 11. Tank Drain  2. Vent/Vacuum 7. Collector Supply 12. Tank Drain Fitting 3. Hot Water to Taps 8. Drain Down Valve 13. DHW Electric Tank 4. Cold Feed 9. Circulating Pump 14. Immersion Heater 5. Tempering Valve 10. Drain

  31. Recap: Possibilities and their +/-…what we ended up picking • Active • Open Loop: • (+) cost less • (-) pump controlled • (-) only possibility for freeze protection: manually draining X Second one OUT !!! • Closed Loop: • Drain Down: • (-): not reliable !!! X First one OUT !!! • Drain Back: • (+) good freeze protection • (+) can use water/water instead of antifreeze • (-) pump and 2 different storage tanks • Passive • Batch • (+)easy (can even be a tank painted in black) • (+) offers freeze protection because the water is only present in the tanks and the areas are large; the water cools off slowly • (-) takes long to heat the amount of water • Thermosyphon • (+) no need for pumps • (+) offers good freeze protection • (-) heavy tank placed above the collector • (-) efficiency decreases when using indirect heating • We voted between: Drain Back, Batch and Thermosyphon • Systems chosen • Group I (Suza, Missy, Emily and Zach): Drain Back System • Group II (Stephanie, Adrienne, Alex and Amalia): Thermosyphon

  32. Team Drain Back Team Members: Melissa Loureiro Emily Kunen Suza Gilbert Zach Auger

  33. Drain Back - Description • Solar collector located above storage tank • 2 liquid system • Both can be water • 1liquid water and 1an antifreeze solution • Active closed loop system • Uses pump • Pump circulates water through collectors when collectors are warmer than stored water • Heat exchanger used in storage tank • Heat transfer between circulating fluid and potable water • Circulating solution drains to a 2nd tank when pump shuts off • Tank is placed on a tilt for complete drainage

  34. Positive Aspects: Less likely to freeze Fewer components than other active systems Less likely to break More reliable than antifreeze system Negative Aspects: Requires Energy for Pump Heat loss during transfer If antifreeze used must be replaced every 3 years Pros and Cons

  35. Optimization • Excel spread – sheet to model variables • Optimization parameters: • Cost • Materials • Temperature into/out of collector • Size of collector • Amount of daily solar power • Time required to heat water • Length of piping system • Efficiency

  36. Team Thermosyphon Adrienne Buell Steph Angione Alex Surasky-Ysasi Amalia Telbis

  37. Thermosyphons • Things to address: • Substance for antifreeze • Efficiency of Heat Exchanger in Tank • Pipes in Tank • Flat plate, glazed collector • Liquid Replacement • Storage tank placement & attachment • High Limit Safety Valve

  38. Performance Model • Program in MatLab • Output • Collector Size • Monthly Expected Performance • Optional Maximum Size- Output is Volume of Water • Heat Dissipation in Storage Tank • Data in Excel to be Referenced • F-Chart

  39. Timeline and Future Plans • By Spring Break (3/22) • Gather remaining relevant data • Pricing (in US dollars) and local pricing • Construction techniques • Finalize ideal design to be modeled for each group • Week of 4/10 • Incorporate losses into design and model for each group • Week of 4/17 • Final model completed for each group • May 3rd • Final presentations due

  40. Questions?

More Related