Hiroaki Terasaki

Cost and production performance of a Tubular Solar Still

In this paper, the design, fabrication, cost and distilled water production (production) performance of a Tubular Solar Still (TSS) is presented. Since the TSS cover and trough are made of cheap and locally acquisitioned lightweight materials, the TSS can be formed into a desirable size easily. Thus, the weight per unit length is 0.65kg/m and it is expected that the production cost is about 484/m3(~US

Effects of Gravel and Date-Palm Mulch on Heat Moisture and Salt Movement in a Desert Soil

5/m3). A field experiment on the production performance of the TSS was carried out in the United Arab Emirates and the effects of initial saline water volume (water depth) in the trough on the daily production were examined in terms of the use and management of the TSS. The daily production is inversely proportional to the water depth, as far as the water depth is 0.04m or less. The main reason is attributed to the production performance after the evening or sunset due to remaining solar heat (designated as “production inertia”). It is seen that contribution of the production inertia to the daily production cannot be disregarded and that the water depth is one of key parameters to control the production performance of the TSS.

EXPERIMENTAL STUDY ON WATER BALANCE IN A NEGATIVE PRESSURE DIFFERENCE IRRIGATION SYSTEM

The control performance of evaporation from the soil surface and of the soil surface temperature by gravel mulch (GM) and date-palm mulch (DM) was discussed in this paper. A heat, moisture and salt movement experiment was carried out using soil columns in the United Arab Emirates. Elapsed time, when 50% of irrigation water was lost due to evaporation, was remarkably prolonged by mulching, e.g. 2.3 times for the GM and 3.4 times for the DM, respectively, compared with that for bare soil (BS). The daily maximum soil surface temperature was 5.0°C lower for the DM than the BS, but there was little difference between the GM and the BS. The time rate of salt accumulation near the soil surface was reduced by mulching. For example, the salt mass content of the soil surface, S c surf , for the BS became higher than the initial S c surf (=0.4%) 48 hours after watering. On the other hand, S c for the DM was lower than the initial one at the same elapsed time. It was concluded that the reduction of evaporation by mulching with date-palm chips and gravels is effective in delay of the salt accumulation near the soil surface.