| Line 82: | Line 82: | ||
*Thermosyphon system | *Thermosyphon system | ||
**The collector is positioned underneath the water storage tank. Water from the collector is heated up and then naturally flows into the water storage tank. From there, the cold water sinks to refill the collector. This is an open loop system.<ref name=Energy.gov/> | **The collector is positioned underneath the water storage tank. Water from the collector is heated up and then naturally flows into the water storage tank. From there, the cold water sinks to refill the collector. This is an open loop system.<ref name=Energy.gov/> | ||
==Costs== | |||
{| class="wikitable sortable" | |||
! Quantity !! Material !! Source !! Total ($) | |||
|- | |||
| 6 || PVC pipes and parts || Hensel's Ace Hardware | |||
|align="right"| 32 | |||
|- | |||
| 1 || Another thing - 3' x 2', Yellow|| The OT Store | |||
|align="right"| 240 | |||
|-class="sortbottom" | |||
|colspan="4" align="right" | '''Total Cost: 272''' | |||
|} | |||
==References== | ==References== | ||
Revision as of 04:48, 28 February 2014
Background
Bayside Park Farm is a local CSA, (Community-Supported Agriculture establishment) which is supported by the community and provides fresh organic produce to members and shareholders. Bayside was formed by Humboldt State Professors, started farming in 1993 and was the first CSA in Arcata. It is also a community park and demonstration site for permaculture farming and appropriate technology. Bayside Park Farm is located on 930 Old Arcata Road.
Our ENGR305 team (Trevor, John, and Annika) chooses to help the farm rebuild their solar hot water heater for the outdoor sink and vegetable washing station. It was disassembled and never rebuilt; we will determine what parts are in working order and possibly improve the system if it is easy to get back in working condition.
Problem statement
The objective of this project is to reassemble the Bayside Park Farm solar hot water heater and connect it to the sink in the new wash station in a way that it will be easy to maintain and will be effective to the farm's needs.
Criteria
The following criteria are based off of a scale from 1 to 5, 5 being the most crucial and 1 being the least.
| Criteria | Constraint | Weight |
|---|---|---|
| Water temperature | Warm enough to wash vegetables with, not hot enough to scald hands | 5 |
| Hot water duration /
Total heat capacity |
At least 30 minutes of continual usage | 5 |
| Washing station
efficiency |
Must be more efficient than the current kitchen sink | 2 |
| Maintenance /
documentation |
Must be easy to understand by farm staff with no prior solar hot water experience and provide some trouble shooting information | 5 |
| Educational physical infrastructure | Should provide signs and additional information on the project that the farmers can reference when giving tours. | 4 |
| Cost | Should remain within budget. | 3 |
Literature Review
This is a review of the available literature pertinent to the solar hot water heater at the Bayside Park Farm.
Solar hot water basics
Solar water heating collectors capture and retain heat from the sun and transfer this heat to a liquid. Solar thermal heat is trapped using the “greenhouse effect,” which is the ability of a reflective surface to transmit short wave radiation and reflect long wave radiation. Heat and infrared radiation (IR) are produced when short wave radiation light hits a collector’s absorber, which is then trapped inside the collector. Fluid, usually water, in contact with the absorber collects the trapped heat to transfer it to storage. [1] The core of a solar water heater is a solar collector and a storage tank. A solar collector is basically a glazed, insulated box with a dark-colored interior and, usually, a bunch of tubes or passageways for water flow. The solar collector turns the sun's radiation into heat. The storage tank does the job of holding the water. [2]
Solar hot water concerns
There are a few concerns with the use of solar hot water, the main one being that you are not always guaranteed hot water. The sun does all the heating so without sun your water will not be heated up. Cloudy days can still produce warm water but it will not be hot. Also early in the morning your water will not be hot, the tank could still have retained some heat from the previous day but it will not be hot. Solar hot water had a peak in use in the 1980s but with the cost of energy going down people opted for the traditional water heater. The solar hot water heater is still not making much of a come back, but their are really high quality systems being made. A problem is that the systems worth owning are not cheap, they are expensive, and requires a skilled crew to install. They cost more then a traditional water heater and the initial investment is hard for people to pay. With the combination of efficiency and the cost of energy relatively cheap the market for solar hot water in United States is not as big as it could be.[3]
Types of solar hot water heaters
All solar hot water heaters use collectors, which are the "panel-like" components of the system that are heated by the sun, and storage tanks, which hold the domestic water. Solar hot water heaters have these basic components, but otherwise are separated into active and passive. Active systems use circulating pumps, while passive systems do not. [4] Systems can also be closed loop or open loop. Closed loop systems "continuously circulate an isolated fluid... from which heat is extracted via a heat exchanger" and open loop systems run the same water that would come through your tap through the collector. [5] Open loop systems should only be used in warmer climates, due to fear of the water freezing up in the collector. [6] However, collectors can also be mounted inside the house to prevent freezing, while in warmer climates solar collectors can be placed on the roof. [7]
Type 1: Active
There are two types of active solar hot water heaters:
- Direct circulation system
- Pumps circulate water directly through collector to be heated up and then hot water is passed on to the house/faucet. This is considered an open loop system.
- Indirect circulation system
- Pumps circulate a "heat transfer fluid" through the collector to be heated up. This can be a variety of fluids such as, water, refrigerants, silicones, and even air can be used. After the heat transfer fluid is warmed by the sun, it is carried into the storage tank to heat the domestic water itself. The transfer fluid does this by traveling through a "heat exchanger", which is normally made of copper or another good conductor. Within the heat exchanger, the heat transfer fluid is passed by the potable water so as to transfer thermal energy. This is accomplished through multiple means; by running a coil through the water storage tank, and shell-in-tube/tube-in-tube designs. The shell/tube-in-tube designs run the transfer fluid and potable water past each other in tubing so that they are in thermal contact with one another. This is a closed loop system.[4]
Type 2: Passive
Passive solar hot water heaters do not use pumps and therefore are cheaper, but possibly less efficient. There are two types of passive solar hot water heaters:
- Integral collector-storage passive system
- Also known as a batch system, the integral collector-storage system has domestic water run straight through the collector and into a storage tank. This is often used alongside a normal gas/electric water heater and may have to be drained and out of commission during cold winter months. This is an open loop system. [5]
- Thermosyphon system
- The collector is positioned underneath the water storage tank. Water from the collector is heated up and then naturally flows into the water storage tank. From there, the cold water sinks to refill the collector. This is an open loop system.[4]
Costs
| Quantity | Material | Source | Total ($) |
|---|---|---|---|
| 6 | PVC pipes and parts | Hensel's Ace Hardware | 32 |
| 1 | Another thing - 3' x 2', Yellow | The OT Store | 240 |
| Total Cost: 272 | |||
References
- ↑ "What is Solar Water Heating?." Solar Water Heating System Basics. http://www.homepower.com/articles/solar-water-heating/basics/what-solar-water-heating (accessed February 8, 2014).
- ↑ Layton, Julia. "How Solar Water Heaters Work." HowStuffWorks. http://science.howstuffworks.com/environmental/green-tech/sustainable/solar-water-heater1.htm (accessed February 8, 2014).
- ↑ Jennifer Runyon "What Is Holding Back Solar Hot Water in the US?" Renewable Energy World. http://www.renewableenergyworld.com/rea/blog/post/2012/05/what-is-holding-back-solar-hot-water-in-the-us. (accessed february 9, 2014)
- ↑ 4.0 4.1 4.2 US Department of Energy 2012. "Solar Water Heaters." Energy.gov. Accessed February, 8th. http://energy.gov/energysaver/articles/solar-water-heaters
- ↑ 5.0 5.1 Ewing, Rex. 2011. "Two Solar Hot Water Heaters You Can (Probably) Do By Yourself." Country Side and Small Stock Journal 56-8
- ↑ Davidson, Jane and Wood, Byard 1996. "Solar Hot Water for the Home." Mechanical Engineering 118,8:60-3
- ↑ Laughton, Chris 2010. Solar Domestic Water Heating. Earthscan.