Search the Community

I've been doing small experiments with air drying, where essentially the sun is heating air and increasing its capacity to absorb moisture, and in free air (i.e. log standing by itself) and seeing oak dry from green to 20% mc wwb in 44 days. So as heat speeds drying up and solar heat has no fuel cost I started looking at small scale solar drying. I found just using cheap corrugated acrylic sheeting I could make a simple greenhouse where in the last 2 days the temperature has stayed above 40C for much of the day in sunshine with relative humidity falling to 24%. This is consistently more than 10C hotter than outside in the sun. RH is about the same because there is free air flowing and out. Last week I was employed dragging tops and stuffing an ancient chipper on a commercial refurbishment where the previous tenants had allowed the Leylandii and mixed broadleaved hedges run away. I noticed a pair of old cycle racks had been removed and set aside. I mentioned the possibilities of these being the beginnings of a solar log drying kiln for the boss's son, who runs a log round with about 40 customers in his college holiday. Boss being a petrolhead was not at all interested. I made an enquiry and they were available for sale (these things new cost about £5k erected) I sent a photo to the son and explained my thinking and he was interested. At this point father and son took over and bought the shelters. Now I'm not sure if they are going to implement the idea but I estimate placed side by side and south facing they will intercept 18kW(t) in sunshine. This is enough theoretically to evaporate nearly 30kg of water an hour if the air circulation is good enough. With the shelters side by side and south facing and a roofed area behind and the back being a curtain side from a lorry he should be able to stock about 20m^3 of split logs in stillages. I think wit a few low powered circulation fans and a differential thermostatic switch only running them when inside temperature is 10C above outside and a humidistat controlling a vent fan he should get good drying. If I am kept in the loop I will update progress.