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
Paragraph on the basics. [1]
Solar hot water concerns
Short paragraph on the concerns.[2]
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. [3]
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.
- 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.
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. [4]
- 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.
References
Designing interpretive materials
According to ______ interpretive materials for composting should include....