I have had a long time interest in natural heating and cooling for houses. I hope to be able to have my own place one day, and I’d like this home to be passively heated and cooled, but that situation is out of my reach at present.
To partly satisfy my interest I been building a clothes dryer that is located outside and uses the wind and the sun, but protects the clothes from getting wet when it rains. My hope is that this dryer will be more effective that an ordinary clothes line by trapping infra red and capturing the wind more effectively. Other advantages are that there is no need of pegs, and UV light is blocked. I also intend to power the electronics (which includes the controller, fan and a door activated light) with a battery that is charged with a solar panel.
My current design is only partly successful and I am in the process of doing some improvements, however the first version had the following features that were my first attempt to meet my goals.
1. I used used poly carbonate sheeting which blocks UV but lets IR through.
2. I tried to make sure there are weather seals at every join so air is trapped
3. I made a chimney with hat to utilize the Bernoulli effect to provide a way to draw we air out
4. There is a control system that measures temperature and humidity so that a fan will turn on when the humidity rises above a set point.
5. The controller has Wifi enabling remote monitoring / graphing.
The first version was only partially successful. I do see a temperature and humidity rise above ambient when wet clothes are put into the cabinet. The fan does come on and the humidity then drops. Clothes do dry and come out warm – if there is enough sun to warm the system. The cabinet does protect dry clothes if it rains, and I don’t need to worry about forgetting to bring in the washing.
However for any reasonable amount of wet clothes the humidity overwhelms the fan and the clothes do not dry more quickly than clothes hung out on the ordinary clothes line. In addition it appears that the chimney does not draw very well (or at all). Additionally, measuring the internal humidity is not a good way of determining whether or not to turn on the fan since at night the humidity can often rise quite sharply (probably when the dew falls).
I am in the process of modifying the system to improve it:
1. I have put in a large fan with more airflow and made a proper seal for it.
2. I am modifying the controller by adding an extra sensor channel so I will be able to measure the ambient temperature and humidity so that I can control the fan when the internal humidity rises when the external does not.
3. I will add a detector that senses whether washing is hung inside the system.
4. I will modify the passive chimney extractor to move with the wind and have a double cone shaped wind collector to increase the chimney draw.
My next task is to finish the modifications to the controller software and then do more experiements in order to tune the way the fan works. Once this is done I will make the new chimney pot and again experiment to see how that affects the drying time.
Notes: the embedded controller is a Weimos D1 Mini.