Abstract
This spring 2011 semester, we constructed a passive thermosyphon solar shower system that utilizes natural temperature stratification to heat and store water without natural gas or electricity. Constructed at the Manila Eco-Hostel, this is an educational piece that seeks to inspire travelers of the area to recreate such a project in their own community.
Background
Continuing on the design for the Samoa Hostel Thermosyphon Solar Shower System, designed by previous Engineering 215 students at Humboldt State University, we have constructed a solar shower at the Manila Eco Hostel. This shower uses a solar water heating panel to heat water for an outdoor, enclosed shower, providing visitors with an ascetically pleasing, functioning way to shower sustainably.
Opportunity Definition
The objective is to demonstrate, educate, and inspire an alternative way of heating water to visitors of the eco-hostel.
Solar Water Heating Basics
Solar water heating is a growing and innovative field that takes advantage of the suns energy to heat water. [1][2]. Solar water heating is a growing market, as Israel, China, Australia, and Austria continue to expand the field.
Types Solar Water Heating
Generally there are two types of solar water heating: passive, and active[3] heating.
Passive Solar Water Heating
- Integrated Collective Storage: This simple and relatively cheap design is a storage tank that also collects heat from the sun. The disadvantage of this tank is that you need to be in a hot climate for it to be effective. [4]
- Convection Heat Storage Unit: Using the properties of convection and thermosyphoning, this system uses a solar water heater panel to collect heat and move water against gravity into a insulated water tank.[5][6]
Active Solar Water Heating
Active solar water heating systems use electricity to pump fluid from the panel to the storage tank.[7] The advantage of an active solar water heating system is that it has the capability to run at higher efficiency with the installation of a pump and controller. [8] These items allow the water to be circulated faster, allows for storage of the water tank lower than the panel, and also reduces the risks of overheating from increased circulation. There are three classifications for Active Solar Water Heating systems[9][10]:
Direct System
Water is the medium which is heated up in a solar collector and is then actively pumped into an insulated storage tank. Concern for freezing should be considered in places with seasonal cold climates.
Indirect System
Anti-freeze circulates through the solar collector, collecting heat. The Anti-freeze is then circulated through a heat exchange device to transfer the heat to water without mixing. This system is a good alternative for the Direct System if freeing is a concern.
Drain-Back System
Similar to that of the Indirect system, except the Drain-back system allows for fluid to drain out of the solar collector when not in use, which allows for variation in design from the Indirect System. This is also a good candidate for cold weather climates.
Implementation Cost
The materials needed for this specific project are listed below. Included is the item name, the quantity needed, the cost per unit item, the cost at which we received the item (at the quantity needed), and an estimated retail cost should someone care to build a system modeled after this page. Several items have been donated and others have been previously obtained by another group working on this project. The variability for the final cost is due to the large range of price a solar water heating panel can have and it should be noted that our range is a modest one.
Materials | Quantity | Unit Cost($) | Actual Cost ($) | Retail Cost ($) |
---|---|---|---|---|
2x4 (8 feet) | 8 | $3.79 | $30.32 | $30.32 |
4x4 (8 feet) pressure treated | 5 | $8.96 | $44.80 | $44.80 |
Redwood Fence Boards | 56 | $3.25 | donated | $182.00 |
Concrete | cubic yard | 1 | $130.00 | $130.00 |
Fencecrete | 5 | $3.99 | $19.95 | $19.95 |
Thompson's Water Sealer | 2 | $15.99 | $31.98 | $31.98 |
Latch | 1 | $1.99 | $1.99 | $1.99 |
Hinges | 2 | $2.99 | $5.98 | $5.98 |
Shower Head | 1 | $12.99 | $12.99 | $12.99 |
2.5" Screws | 5 lbs | $2.99 per lbs | $14.95 | $14.95 |
Shower Pan Drain | 1 | $9.99 | $9.99 | $9.99 |
Hot Water Heater | 1 | $80.00 | donated | $80.00 |
Copper Pipe (feet) | 30 | $3.00 | NA | $90.00 |
Solar Water Heating Pannel | 1 | $500-1,000 | donated | $500-1,000 |
Total Cost | $302.95 | $802.95-$1302.95 |
Evaluation Criteria
This section includes all possible aspects thought up by the group members for this project as well as the director of the Samoa eco-hostel. These criteria were chosen to evaluate the project based on ease of use, educational capacity, and aesthetic. These criteria will help us to determine how much time, money, and effort should be invested in each aspect of the system based on its importance to our client.
Criteria | Constraints | Our weight (0-10) |
---|---|---|
maintainability | must be able to maintain functionality on less then .5 human labor hrs a week | 7 |
safety | must be able to function with out possible injury to users or observers | 9 |
effectiveness | must be able to power a device for the full duration of its intended function | 8 |
ease of use | must be useable for adults without struggle | 7 |
social justice | 50 % of materials must be donated or reused | 5 |
educational value | must be able to provide an understanding of the functionality and use of the device, within a two minute viewing span | 9 |
aesthetics | must be pleasing to the eye and look professional | 6 |
Proposed time line
Week: | Tasks: |
---|---|
Week 6 (3/7/11) | Collect Materials: Fencing Meeting with "Truth Window" Team to Confirm Measurements Meeting with "Water Boys" Team to confirm measurements Confirm Measurements |
Week 7 (3/14/11) | Survery Job Site Data Collection: Solar Pathfinder |
Week 8 (3/21/11) | Solidify Design: Shower Confirm Measurements Create Project Site Map |
Week 9 (3/28/11) | Construction Assembly Create Signage for thanking donaters |
Week 10 (4/4/11) | Construction Assembly Timesheet #5 Due 4/8 |
Week 11 (4/11/11) | Construction Transport Shower, Install Shower Start Final Draft Project Report |
Week 12 (4/18/11) | Construction Transport Greywater, install greywater Work on FDPR |
Week 13 (4/25/11) | Testing, adjustments to System Work on FDPR |
Week 14 (5/2/11) | Testing, adjustments to System Work on FDPR |
Week 15 (5/9/11) | Turn in FDPR |
Next Steps
Over the summer of 2011, a cradle will be constructed at the crest of the shed roof for a gas water heated tank, the solar water heater panel will fastened on the other side, and the permanent plumbing will be installed. After that is done, the Samoa Hostel Truth Tank could be connected for natural grey water treatment and education on grey water treatment.
References
- ↑ Patterson, J. (2010). “Solar Hot Water Basics.” Homepower Magazine. <http://homepower.com/basics/hotwater/>
- ↑ Basics of thermosiphon flow.
- ↑ Ramlow, Bob (2006.) "Solar Water Heating." A Comprehensive Guide to Solar Water and Space Heating Systems, New Society Publishers, Gabriola Island, Canada.
- ↑ Keisling, Bill. (1983). “The homeowner’s handbook of solar water heating systems.” Rodale Press, Emmaus, Pa.
- ↑ J. Cadafalch (2009) A detailed numerical model for flat-plate solar thermal devices. Solar Energy, Volume 83,157-2164
- ↑ W.M. Rohsenow, J.P. Harnett, Y.I Cho (1998). Handbook of heat transfer 3rd Ed.. McGraw-Hill, Chicago, USA.
- ↑ AEF solar water heater
- ↑ RCEA Solar thermal vs Heat pump
- ↑ Findley, David S. (2010). "Solar power for your home" . New York: McGraw-Hill, Print.
- ↑ [[Kang, J., ITT Residential and Commercial Water. "An Introduction to Solar Water Heating". http://www.Bellgossett, PDF.