Optimization and testing of a humidification-dehumidification process using passive solar heating

Produced water treatment is a significant challenge that continues to have significant impacts on the oil and gas industry. The total dissolved solids (TDS) in produced water from oil fields can be higher than 250,000ppm (parts per million) in concentration and may also contain a significant percentage of dissolved organic carbons. Many small oil producing companies operate at the edge of profitability; the cost of treating a barrel of produced water can be a significant expense if the operator has to pay for hauling and disposal and this can make it uneconomical to operate mature producing wells which tend towards high watercuts.;As part of a RPSEA (Research Partnership to Secure Energy for America) research project, a Humidification-Dehumidification (HDH) Unit has been built and tested to treat produced water using co-produced heat and passive solar energy and was designed for low cost and low electricity consumption. The system, utilizing this configuration has been tested to process produced water at a cost of about ;The process works using simple thermodynamic principles. Air (at atmospheric pressure) has the capacity to dramatically increase its water vapor saturation pressure to about 50kPa when the temperature is about 180°F. Consequently, the efficiency of the unit is primarily contingent on the prevailing ambient temperature and relative humidity. The system uses the high solar radiations prevalent in New Mexico to heat produced water to about 180°F which is then pumped into an 80ft3 stainless steel HDH Unit comprised of adjacent evaporation and condensation chambers; ambient air is pumped into the unit opposite to the direction of the input heated produced water, and that air subsequently humidifies at elevated temperatures. The heated and humidified air is then cooled to, or below, dew point to produce fresh water.;This research is focused on the optimization of the HDH process and design, installation, retrofitting, and testing of the process using passive solar array collectors.