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The thermal performance of a single slope (SS) solar still integrated with a condenser supplied with cooled water from an evaporative cooling system under hot and humid climatic conditions were studied and analyzed. Results of this study shows that the solar energy available inside the still with and without condenser resulted in an increase in the brackish water temperatures of 8.1 ºC. It also increased the temperature of the water vapor inside the still by 12.7 ºC. Due to increase in the intensity of solar radiation and consequently the heat energy stored inside the single slope solar still, the productivity of distilled water was 5941.4 ml/m 2 day. The thermal efficiency of the (SS) still without using condenser was on, an average, 54.4%. Connecting the solar still to a condenser led to an increase in the productivity and thermal efficiency to 55.41% and 30.1%, respectively. The obtained data also revealed that the pH (7.9), EC (43.4 μs/cm), and TDS (30.9 ppm) values were lower than those of the brackish water (8.1, 1,436 μs/cm, and 1,370 ppm, respectively).

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The goal of this project was to evaluate the feasibility of using a solar greenhouse as a solar dryer for drying dates. We attempted to analyze the thermal performance and thermal balance of the solar greenhouse. An experimental gable-even span greenhouse (solar greenhouse) was installed at the experimental research station at King Faisal University (latitude 25.4ºN, longitude 49.6ºE, and altitude 142 m above sea level) and functioned during October 2010. We evaluated the thermal performance analysis of the solar greenhouse (active or dynamic system) based on the thermal balance equations. The obtained results revealed that the daily average solar energy available outside the solar dryers was 15.921 kWh, and 12.335 kWh was available inside the solar greenhouse for an average effective transmittance of 77.48%. Of the 12.335 kWh available inside the solar greenhouse, 7.414 kWh was converted into useful heat gain that could be used for the drying process, 3.947 kWh was lost by conduction and convection, and 0.686 kWh was lost by thermal radiation. The solar energy available inside the solar greenhouse produced a 14.1°C increase in the inside air temperatures versus the outside temperature (33.6°C) and reduced the relative humidity of the inside air versus the outside air (35.3%) by 9.6%. The daily average overall thermal efficiency of the solar greenhouse during the experimental period was 57.2%. Consequently, 42.8% of the solar energy available inside the solar greenhouse was lost. The predicted thermal balance for the solar greenhouse was well validated with that measured during the experimental period (r= 0.999) indicating an excellent agreement.

Dustfall is a major threat to agricultural and industrial infrastructures, as well as to other aspects of livelihood. Dustfall associated to a severe dust storm that hit the Al-Ahsa Oasis of Saudi Arabia during 12-13 March 2014 is discussed in this paper. The storm caused widespread and heavy dust deposition. A dramatic decrease in the visibility coincided with the storm, and the average dust concentrations recorded during a peak 10-hour period were 6772, 5862.4 and 451.1 µg/m 3 for total suspended particles (TSP), particulate matter smaller than or equal to 10 µm (PM10) and those smaller than or equal to 2.5 µm (PM2.5), respectively. The lowest visibility was 200 m, and the wind speed increased to 17.5 m/s from the north. The average daily dust deposited in the study area during the event was 12.84 (SD = 1.2) g/(m 2 •d). The dust samples comprised insoluble dust (48.5%) and soluble dust (51.5%). Based on the Munsell color system, the final color description of the falling dust was 10 YR/6/3. A microphotograph of the dustfall (settleable particulate matter) captured by a stereo dissection microscope shows that the dust particles had various colors and sizes, and they contained fibers and vegetative debris).

A prototype electrostatically assisted particulate wet scrubber (EPWS) for controlling dust in livestock buildings was developed and tested under laboratory and field conditions. Under laboratory conditions, the EPWS with the negatively-charged water spray had significantly higher particle removal efficiency (79%) than either the uncharged wet scrubber (58%) or the control (i.e., only the fan was operated; 21%). There was no significant difference in removal efficiency between the negatively-charged EPWS (79%) and the positively-charged EPWS (73%). For the negatively-charged EPWS, an optimum ratio between the air flow rate and amount of water spray for each specific mixing volume existed in which the removal efficiency decreased as the air flow rate increased. Field tests in a swine building proved that the EPWS was effective in removing airborne dust.

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