Field Test Evaluation of Solar-Heated Evaporators

The cost of disposal of liquid industrial waste is of intense concern to all industrial waste generators, but especially so to smaller generators which are penalized by the economy of scale. As a last resort to on-site treatment or recycling, the smaller generator is forced to depend upon commercial waste disposal at costs approaching $6.00 per gallon. The use of solar energy to evaporate water from aqueous wastes is a potentially viable alternative if the contaminants are salts having low volatility. This paper describes a field test conducted with a small solar evaporator installed in a machine shop. A naturally vented, basin-type evaporator was used to evaporate water from a spent plating solution used to anodize aluminum. Measured evaporation data validated performance predictions made earlier using TRNSYS and TMY weather data. The data also indicated that accepted correlation models for predicting performance of solar stills underpredict evaporator performance by about 20 percent.