A solar still is used to make fresh water from salt water by evaporation. Assume that during a summer day that 1000 BTU/ft sq of solar energy falls on the surface of the salt water. Determine how many inches of water are evaporated in 30 days. Assume that 1040 BTUs is needed to distill one pound of water.
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To determine the number of inches of water evaporated in 30 days using a solar still, we need to consider the following steps:
1. Convert BTUs to pounds of water:
- We are given that 1040 BTUs are needed to distill one pound of water.
- Calculate how many pounds of water can be distilled from 1000 BTUs:
1000 BTUs / 1040 BTUs/pound = 0.9615 pounds of water.
2. Determine the total amount of water distilled in 30 days:
- Multiply the amount of water distilled daily by the number of days:
0.9615 pounds of water/day * 30 days = 28.8462 pounds of water.
3. Convert the pounds of water to inches of water:
- Since we want to determine the depth of water evaporated, we need to convert pounds to inches.
- We know that 1 pound of water covers an area of 1 square foot with a depth of 1 inch.
- Convert pounds of water to cubic feet: 28.8462 pounds of water / 62.4 pounds per cubic foot = 0.4625 cubic feet of water.
- Finally, convert cubic feet of water to inches of water: 0.4625 cubic feet * 12 inches per cubic foot = 5.55 inches of water.
Therefore, approximately 5.55 inches of water will be evaporated in 30 days using a solar still with 1000 BTU/ft sq of solar energy falling on the surface of the salt water.