Voluntary team targets achievement gap
By Austin Bogues, Times Staff Writer
Published Friday, February 20, 2009
ST. PETERSBURG — The goal is ambitious for all parties involved.
It includes recruiting 100 people for each of three schools in Pinellas County to "stand in the gap."
The "Dream Team" goal is to help schools with high minority enrollments close the achievement gap by providing community assistance. In Pinellas last year, 42 percent of black students graduated in four years with a standard diploma. In contrast, the graduation rate for Hispanic students was 57 percent, and more than 70 percent for Asian and white students.
Thursday night more than 100 volunteers gathered at Pinellas Technical Institute to discuss the program's goals for the next year. The project, organized by the PACT, a Pinellas-based group that focuses on closing the achievement gap, has representatives from some 110 community organizations. The idea is to help students at all levels. Schools participating in the initial program are Maximo Elementary, Baypoint Middle and Gibbs High School.
Success will depend on the mobilization of a huge volunteer effort from businesses, clergy, educational groups and other community organizations.
Michelle Dennard, one of the "Dream Team's" founders and a former president of the Pinellas County Teachers Association, said the group will rely on an expansive database of community organizations to fit individual students' needs.
Some volunteers will be tutors and mentors while others will give families one-on-one support to identify specific needs and provide encouragement.
Right now, there is no county funding for the program. It will rely on community sponsors, although the group is looking into fundraising options. Families will be contacted through targeted direct mail and phone calls.
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http://www.tampabay.com/news/education/k12/article977830.ece
1 of 1 2/23/2009 10:18 AM
Monday, February 23, 2009
Saturday, February 21, 2009
NYU Student Protest Over Financial Transparency Getting Heated - wcbstv.com
NYU Student Protest Over Financial Transparency Getting Heated - wcbstv.com: "Feb 20, 2009 6:46 am US/Eastern
NYU Student Protest Takes Violent Turn Overnight
Demonstrators Blow Off 1 a.m. Deadline To Vacate Barricaded Cafeteria; Cops Scuffle With Crowd Outside
Students Want Back-And-Forth On Financial Transparency
Security Guard Carried Away On Stretcher"
Dozens of students who barricaded themselves inside a New York University cafeteria have rejected the possibility of leaving the building as negotiations with school officials continue into Friday morning.
Members of the coalition Take Back NYU! have been occupying the cafeteria of the Helen & Martin Kimmel Center for University Life for more than 24 hours.
A spokeswoman for the students said that NYU told them that they could face expulsion or arrest if they didn't leave the building by 1 a.m. Friday.
A crowd outside the building scuffled with police officers about a half hour after the deadline.
The students are calling for a series of changes, including increased transparency of the school's finances. They want full budget and endowment disclosure, affordable education, and increased student participation in the university's operation.
The university has offered to dialogue with the students. NYU spokesman John Beckman said the students rejected the offer.
It has been a battle of wills in Greenwich Village as the students try to force a face-to-face discussion with the university. The students have been holed up inside the third-floor room since late Wednesday night.
The school had said if its deadline expired it may use force, but now it looks like the two sides may negotiate.
The student occupiers, who chanted for the television news cameras on Thursday night, have said repeatedly said they have no intention of going anywhere, despite the university-imposed deadline.
The occupation began to turn ugly Thursday night when an NYU security guard was wheeled out on a stretcher after claiming she was pushed by a student.
It came on a night of defiance and solidarity for the student revolutionaries who've barricaded themselves in an upstairs cafeteria claiming NYU won't come to the bargaining table.
"We're here until they negotiate with us," demonstrator Julie Kliger told CBS 2 HD.
Kliger is one of the occupants and sent to CBS 2 HD pictures of her fellow occupants, a group of students who said they won't bend to what they call the shady scare tactics of the administration.
"They're resorting to things to like these mental scare games like calling your parents to say you know this could lead to expulsion or this could lead to their arrest," Kliger said.
Webcam video is also allowing supporters to follow the drama, which centers on more than a dozen demands that centers on financial transparency. However, not everyone is buying in.
"You know a laundry list of demands and none of them seem like they have a chance of being implemented by anything other than actual negotiation rather than going for the political theater aspect of it," NYU student Ken Nisbet said.
The political theater has attracted police throughout the building, with the school saying, "We value reasoned debate and forceful argument. We do not honor, however, forms of expression that disrupt the university's academic mission, it's operations, or it's students pursuit of their education."
But students said they're not asking for much.
"The NYU has flat-out not responded. It's not even that their demands have been denied, it's that they're not responded at all," student Dacia Mitchell said.
Added student Raphael Mishler, "I think making the university more accountable to its students is something that's realistic for us to expect."
Tuition at NYU annually is about $50,000, including room and board. Some students told CBS 2 HD they had no idea the cost was so high; they just want to know where their money is going.
The budget demands seem to be the top order of business on Take Back NYU!'s mind.
"Most important to me is the budget demands," student Jane Bird said. "I think it's gotten out of hand at this point."
There are also other demands that don't concern the budget. The group wants 13 scholarships a year provided for students of the Gaza Strip, and to give surplus supplies to the Islamic university in Gaza.
Though the students are sticking to their guns, many in the NYU community didn't necessarily think action was warranted.
"I don't agree with them on the issue of Gaza, even though I agree with them on the majority of their demands," student Gabriel Schoenberg said.
"I don't like the fact that, through this action, they're taking away legitimacy from the student senate," Constantino Rago added.
Please stay with CBS 2 HD and wcbstv.com for more on this developing story.
CBS 2 HD's John Slattery contributed to this report.
NYU Student Protest Takes Violent Turn Overnight
Demonstrators Blow Off 1 a.m. Deadline To Vacate Barricaded Cafeteria; Cops Scuffle With Crowd Outside
Students Want Back-And-Forth On Financial Transparency
Security Guard Carried Away On Stretcher"
Dozens of students who barricaded themselves inside a New York University cafeteria have rejected the possibility of leaving the building as negotiations with school officials continue into Friday morning.
Members of the coalition Take Back NYU! have been occupying the cafeteria of the Helen & Martin Kimmel Center for University Life for more than 24 hours.
A spokeswoman for the students said that NYU told them that they could face expulsion or arrest if they didn't leave the building by 1 a.m. Friday.
A crowd outside the building scuffled with police officers about a half hour after the deadline.
The students are calling for a series of changes, including increased transparency of the school's finances. They want full budget and endowment disclosure, affordable education, and increased student participation in the university's operation.
The university has offered to dialogue with the students. NYU spokesman John Beckman said the students rejected the offer.
It has been a battle of wills in Greenwich Village as the students try to force a face-to-face discussion with the university. The students have been holed up inside the third-floor room since late Wednesday night.
The school had said if its deadline expired it may use force, but now it looks like the two sides may negotiate.
The student occupiers, who chanted for the television news cameras on Thursday night, have said repeatedly said they have no intention of going anywhere, despite the university-imposed deadline.
The occupation began to turn ugly Thursday night when an NYU security guard was wheeled out on a stretcher after claiming she was pushed by a student.
It came on a night of defiance and solidarity for the student revolutionaries who've barricaded themselves in an upstairs cafeteria claiming NYU won't come to the bargaining table.
"We're here until they negotiate with us," demonstrator Julie Kliger told CBS 2 HD.
Kliger is one of the occupants and sent to CBS 2 HD pictures of her fellow occupants, a group of students who said they won't bend to what they call the shady scare tactics of the administration.
"They're resorting to things to like these mental scare games like calling your parents to say you know this could lead to expulsion or this could lead to their arrest," Kliger said.
Webcam video is also allowing supporters to follow the drama, which centers on more than a dozen demands that centers on financial transparency. However, not everyone is buying in.
"You know a laundry list of demands and none of them seem like they have a chance of being implemented by anything other than actual negotiation rather than going for the political theater aspect of it," NYU student Ken Nisbet said.
The political theater has attracted police throughout the building, with the school saying, "We value reasoned debate and forceful argument. We do not honor, however, forms of expression that disrupt the university's academic mission, it's operations, or it's students pursuit of their education."
But students said they're not asking for much.
"The NYU has flat-out not responded. It's not even that their demands have been denied, it's that they're not responded at all," student Dacia Mitchell said.
Added student Raphael Mishler, "I think making the university more accountable to its students is something that's realistic for us to expect."
Tuition at NYU annually is about $50,000, including room and board. Some students told CBS 2 HD they had no idea the cost was so high; they just want to know where their money is going.
The budget demands seem to be the top order of business on Take Back NYU!'s mind.
"Most important to me is the budget demands," student Jane Bird said. "I think it's gotten out of hand at this point."
There are also other demands that don't concern the budget. The group wants 13 scholarships a year provided for students of the Gaza Strip, and to give surplus supplies to the Islamic university in Gaza.
Though the students are sticking to their guns, many in the NYU community didn't necessarily think action was warranted.
"I don't agree with them on the issue of Gaza, even though I agree with them on the majority of their demands," student Gabriel Schoenberg said.
"I don't like the fact that, through this action, they're taking away legitimacy from the student senate," Constantino Rago added.
Please stay with CBS 2 HD and wcbstv.com for more on this developing story.
CBS 2 HD's John Slattery contributed to this report.
Friday, February 20, 2009
THE ART OF BEING PRESENT : Looking Inside
eric has sent you a link to a blog:
Great stuff to enjoy!!!
Blog: THE ART OF BEING PRESENT
Post: Looking Inside
Link: http://art-of-being-present.lightomega.org/2009/02/looking-inside.html
--
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Great stuff to enjoy!!!
Blog: THE ART OF BEING PRESENT
Post: Looking Inside
Link: http://art-of-being-present.lightomega.org/2009/02/looking-inside.html
Friday, February 20, 2009
Looking Inside
It is often easier to see beauty outside of oneself than inside.
Pride gets in the way,
fear gets in the way,
blame gets in the way.
Next time you look inside, look not for what is yours
but for what is God's.
Then you will not have to worry about pride or fear.
All that you will see will belong
to the One
who created you.
Pride gets in the way,
fear gets in the way,
blame gets in the way.
Next time you look inside, look not for what is yours
but for what is God's.
Then you will not have to worry about pride or fear.
All that you will see will belong
to the One
who created you.
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http://www.blogger.com/
Wednesday, February 18, 2009
Understanding Evolution
 |  | What is evolution and how does it work? Detailed explanations of the mechanisms of evolution and the history of life on Earth
| ||
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 | | How does evolution impact my life? The relevance of evolutionary theory to our everyday lives
| ||
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 | | What is the evidence for evolution? Multiple lines of scientific evidence relating to evolution
| ||
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 | | What is the history of evolutionary theory? The history of ideas, research, and contributors in the study of evolution | ||
Sunday, February 8, 2009
New Alchemy And Green Center Archives - Falmouth, MA
New Alchemy And Green Center Archives - Falmouth, MA: "'Among our major tasks is the creation of ecologically derived human support systems - renewable energy, agriculture aquaculture, housing and landscapes. The strategies we research emphasize a minimal reliance on fossil fuels and operate on a scale accessible to individuals, families, and small groups. It is our belief that ecological and social transformations must take place at the lowest functional levels of society if humankind is to direct its course towards a greener, saner world.'
Fall 1970
Bulletin of the New Alchemists"
Fall 1970
Bulletin of the New Alchemists"
Wednesday, February 4, 2009
Sustainable Civilization
Oilcrash.com: Sustainable Civilization:
Water Technology
Water Collection from "Dry" Air. Before modern dehumidifiers, there were methods shown usefull in precipitating water from the air.
Dew ponds appear to predate history. They are large but shallow artificial pools, smooth rock to protect the water tight layer, with the entire pond insulated from the ground below and around.
A pond described in Popular Science (September 1922 is a concrete cistern about 5 feet deep, with sloping concrete roof, above which is a protective fence of corrugated iron said to aid in collecting and condensing vapor on the roof and prevent evaporation by the wind. The floor of the cistern is flush with the ground, while sloping banks of earth around the sides lead up to the roof. Moisture draining into the reservoir from the low side of the roof maintains the roof at a lower temperature than the atmosphere, thus assuring continuous condensation. At one side of the reservoir is a concrete basin set in the ground. By means of a ball valve, this basin is automatically kept full of water drawn from the reservoir.
In 1932, Achille Knapen built an "air well" in France . The structure was described in Popular Mechanics Magazine to be about 45 feet tall with walls 8 to 10 feet thick. The claim is the aerial well will yield 7,500 gallons of water per 900 square feet of condensation surface.
At night, cold air pours down the central pipe and circulates through the core... By morning the whole inner mass is so thoroughly chilled that it will maintain its reduced temperature for a good part of the day. The well is now ready to function. Warm, moist outdoor air enters the central chamber, as the daytime temperature rises, through the upper ducts in the outer wall. It immediately strikes the chilled core, which is studded with rows of slates to increase the cooling surface. The air, chilled by the contact, gives up its moisture upon the slates. As it cools, it gets heavier and descends, finally leaving the chamber by way of the lower ducts. Meanwhile the moisture trickles from the slates and falls into a collecting basin at the bottom of the
well.
The French inventor L. Chaptal built a small air well near Montpellier in 1929. The pyramidal concrete structure was 3 meters square and 2.5 meter in height (10 x 10 x 8 ft), with rings of small vent holes at the top and bottom. Its 8 cubic meters of volume was filled with pieces of limestone (5-10 cm) that condensed the atmospheric vapor and collected it in a reservoir. The yield ranged from 1-2.5 liters/day from March to September. The total weight of water was 190 lb; the maximum yield was 5.5 lb/day. Chaptal found that the condensing surface must be rough, and the surface tension sufficiently low that the condensed water can drip. The incoming air must be moist and damp. The low interior temperature is established by
reradiation at night and by the lower temperature of the soil. Air flow was controlled by plugging or opening the vent holes as necessary.
Calice Courneya patented an air well in 1982 (USP #4,351,651): A heat exchanger at or near subsurface temperature. .. is in air communication with the atmosphere for allowing atmospheric moisture-laden air to enter, pass through, cool, arrive at its dew point, allow the moisture to precipitate out, and allow the air to pass outward to the atmosphere again. Suitable apparatus may be provided to restrict air flow and allow sufficient residence time of the air in the heat exchanger to allow sufficient precipitation. Furthermore, filtration may be provided on the air input, and a means for creating a [negative] movement pressure, in the preferred form of a turbine, may be provided on the output... The air well is buried about 9 feet deep. The entrance pipe is 3-inch diameter PVC pipe (10 ft
long), terminating just near the ground... This is an advantage because the greatest humidity in the atmosphere is near the surface." (7, 8) (Figure 4)
Air flows through the pipes at 2,000 cubic feet per hour at 45oF with a 5 mph wind. This translates to about 48,000 ft3/day (over 3,000 lb of air daily). Courneya’s first air well used a turbine fan to pull air through the pipes. Later designs employed an electric fan for greater airflow. At 90oF and 80% Relative Humidity (RH), the air well yields about 60 lb water daily. At 20% RH, the yield is only about 3 lb/day. The yield is even lower at lower temperatures. The yield depends on the amount of air and its relative and specific humidity, and the soil temperature, thermal conductivity, and moisture.
Acoustic resonance within the pipes might enhance condensation. The more recent invention of acoustic refrigeration could be used to advantage, as well as the Hilsch-Ranque vortex tube.
It is necessary to cool the air to the "Dewpoint". All of the preceding devices appear to rely on night cooled mass to provide the needed temperature difference, yet leave the device open to daytime heating by the sun. I find indications that even in the daytime in certain conditions it might be possible to radiate to the sky 100 to 200 BTU per hour, which strictly in math could represent 1 pint or so of operation for every 10 square foot or radiation area.
Once the water has condensed the "dry" air, now cool, needs to be exhausted. This points out the flaw in all of the above. None of the above low-tech devices provide for heat exchange directly between the incoming and outgoing air[i], therefore
the "coolness", essential to precipitation, imparted to the incoming air is directly exhausted, and rapidly eroded.
Ideally, there should be sufficient heat exchange between intake and exhaust air that at the pipe open ends, they are virtually at the same temperature, despite being cycled thru a chilled spot. The transition between liquid and vapor water is, absent unknown science or magic, a matter of the transfer of 970 BTU per each pint condensed. (7760 BTU per gallon)
Using a sky radiation approach[ii] to cooling your condenser core, if the latent heat of vaporization of water is 2.26 × 106 J/kg a 1 m2 radiator can provide 50 W/m2 of cooling, enough to condense 1 g of water in 45 s; 1 kg in 12.6 hr; or 1.9 kg per day. Reportedly production rates in the Southwest U.S. can average about 2 liters per day in the winter to over 6 liters per day during the summer, per square meter.” At the low end 10 m2 (1/4 acre) of radiators cooling humid air could produce 19 L of water per day. The humid air must of course be moved thru the cooling unit, and the “coolness” used to change air temperature recovered during expulsion of the “dried” air.
A commercial, powered water condenser is sold under the name Aqua-Cycle, invented by William Madison, introduced in 1992. It resembles a drinking fountain and functions as such, but it is not connected to any plumbing. It contains a refridgerated dehumidifier and a triple-purification system (carbon, deionization, and UV light) that produces water as pure as triple-distilled. Under optimal operating conditions (80o/60% humidity) the unit claims to produce up to 5 gallons daily.
ATMOSPHERIC CONDENSER DISCUSSION
At any given pressure and temperature, in a fixed volume only a limited amount of water will evaporate into vapor, the limit is referred to as the dew/saturation point. A cubic meter of normal sea level air has a mass of 1.292 kilo. A cubic meter of water vapor at sea level pressure has a mass of .804 kilo, this would occur at a temperature of 100C (212F).
At 0 C (32 F), saturation point is about 1.1 gm of water per cubic meter. A rule of thumb is that raising the air temperature 18°F (10°C) doubles its moisture capacity. This means that air at 86°F (30°C) can hold eight times as much water as air at 32°F.
Degrees C Degrees F Gram H2O
0 32 1.1
10 50 2.2
20 68 4.4
30 86 8.8
40 104 17.6
50 122 35.2
60 140 70.4
70 158 140.8
80 176 281.6
90 194 563.2
100 212 1126.4
Relative humidity is the percentage of water vapor present as compared to how much there could be at the present temperature.
Take a typical Tucson fall day of 84 F and relative humidity of 7%. There is roughly 7% of 8.8 grams of water in each cubic meter of air (.616 gram). Lower the temperature to 66 F, and relative humidity doubles to 14%. Lower the temperature to 48 F, and relative humidity again doubles, now to 28%.
If we cool air without changing its moisture content, eventually we'll reach a temperature at which the air can no longer hold the moisture it contains. Then water will have to condense out of the air, forming dew or fog. The dewpoint is this critical temperature at which condensation occurs.
But, water does not immediately change state as the temperature reaches the "right" point. The "Latent heat of condensation" (Lc) refers to the heat that must be removed from water vapor for it to change into a liquid. Lc=2500 Joules per gram (J/g) of water or about 600 calories per gram (cal/g) of water.
Specific heat is defined as the amount of heat energy required to raise 1 g of a substance by 1° Celsius. If the specific heat of air is .25 calories per gram of air per degree C change, then each degree C change in a cubic meter represents 323 calories. The specific heat of water is 1 calorie per gram per degree C. In our Tucson fall day above there was .616 grams of water in a cubic meter of air. Air and water vapor together take a change of about 324 calories per degree C. We need to lower the temperature by around 40 C, or get rid of 12,960 calories of heat to reach the dew point. An additional 379 calories of heat needs to be removed to compensate for the latent heat of condensation, for a total of 13,339 calories.
Assume a daily water need of 174 gallons (658.6 liters) - 658,660 grams of water. In a Tucson fall day, each of us would need to "wring" all of the water out of more than a million cubic meters of air (1,069,252) - a cube 100 meters on a side.
The heat to be moved is about 14 billion calories. The water portion of this number is about 450 million calories. Depending on device efficiency, SOME part of the other 1 billion calories should be able to be conserved in a heat exchanger.
Increasing the pressure also changes the dew point. Double the pressure and relative humidity doubles. Assume normal atmospheric pressure of 14 PSI. Pump the fall Tucson air into a tank at 28 PSI and the relative humidity inside is now 14%. Make it 56 PSI - 28%. 102 PSI - 56%. 204 PSI - 102%, and you've got water accumulating in the bottom of the tank.
[i] See chapter 7 of the book "Passive Annual Heat Storage", by John Hait
[ii] Radiative Cooling in Hot Humid Climates
Aubrey Jaffer February 2006
Ronald Frederick Greek
Moderator (Electronic Janitor)
Sustainable Tucson
"Stabilization of human numbers is no solution... To speak of an actual reduction of human population - exactly what is needed if the world is to avoid unprecedented human dieoff through famine, pestilence, and war - is unthinkable and unspeakable, at least in polite company. Not just Catholics and conservatives, but liberals as awll become positively apoplectic if the subject is broached. And so the discussion necessary to understanding our econlogical dilemma, and dealing effectively with it, never occurs."
- Richard Heinberg, Power Down
Water Technology
Water Collection from "Dry" Air. Before modern dehumidifiers, there were methods shown usefull in precipitating water from the air.
Dew ponds appear to predate history. They are large but shallow artificial pools, smooth rock to protect the water tight layer, with the entire pond insulated from the ground below and around.
A pond described in Popular Science (September 1922 is a concrete cistern about 5 feet deep, with sloping concrete roof, above which is a protective fence of corrugated iron said to aid in collecting and condensing vapor on the roof and prevent evaporation by the wind. The floor of the cistern is flush with the ground, while sloping banks of earth around the sides lead up to the roof. Moisture draining into the reservoir from the low side of the roof maintains the roof at a lower temperature than the atmosphere, thus assuring continuous condensation. At one side of the reservoir is a concrete basin set in the ground. By means of a ball valve, this basin is automatically kept full of water drawn from the reservoir.
In 1932, Achille Knapen built an "air well" in France . The structure was described in Popular Mechanics Magazine to be about 45 feet tall with walls 8 to 10 feet thick. The claim is the aerial well will yield 7,500 gallons of water per 900 square feet of condensation surface.
At night, cold air pours down the central pipe and circulates through the core... By morning the whole inner mass is so thoroughly chilled that it will maintain its reduced temperature for a good part of the day. The well is now ready to function. Warm, moist outdoor air enters the central chamber, as the daytime temperature rises, through the upper ducts in the outer wall. It immediately strikes the chilled core, which is studded with rows of slates to increase the cooling surface. The air, chilled by the contact, gives up its moisture upon the slates. As it cools, it gets heavier and descends, finally leaving the chamber by way of the lower ducts. Meanwhile the moisture trickles from the slates and falls into a collecting basin at the bottom of the
well.
The French inventor L. Chaptal built a small air well near Montpellier in 1929. The pyramidal concrete structure was 3 meters square and 2.5 meter in height (10 x 10 x 8 ft), with rings of small vent holes at the top and bottom. Its 8 cubic meters of volume was filled with pieces of limestone (5-10 cm) that condensed the atmospheric vapor and collected it in a reservoir. The yield ranged from 1-2.5 liters/day from March to September. The total weight of water was 190 lb; the maximum yield was 5.5 lb/day. Chaptal found that the condensing surface must be rough, and the surface tension sufficiently low that the condensed water can drip. The incoming air must be moist and damp. The low interior temperature is established by
reradiation at night and by the lower temperature of the soil. Air flow was controlled by plugging or opening the vent holes as necessary.
Calice Courneya patented an air well in 1982 (USP #4,351,651): A heat exchanger at or near subsurface temperature. .. is in air communication with the atmosphere for allowing atmospheric moisture-laden air to enter, pass through, cool, arrive at its dew point, allow the moisture to precipitate out, and allow the air to pass outward to the atmosphere again. Suitable apparatus may be provided to restrict air flow and allow sufficient residence time of the air in the heat exchanger to allow sufficient precipitation. Furthermore, filtration may be provided on the air input, and a means for creating a [negative] movement pressure, in the preferred form of a turbine, may be provided on the output... The air well is buried about 9 feet deep. The entrance pipe is 3-inch diameter PVC pipe (10 ft
long), terminating just near the ground... This is an advantage because the greatest humidity in the atmosphere is near the surface." (7, 8) (Figure 4)
Air flows through the pipes at 2,000 cubic feet per hour at 45oF with a 5 mph wind. This translates to about 48,000 ft3/day (over 3,000 lb of air daily). Courneya’s first air well used a turbine fan to pull air through the pipes. Later designs employed an electric fan for greater airflow. At 90oF and 80% Relative Humidity (RH), the air well yields about 60 lb water daily. At 20% RH, the yield is only about 3 lb/day. The yield is even lower at lower temperatures. The yield depends on the amount of air and its relative and specific humidity, and the soil temperature, thermal conductivity, and moisture.
Acoustic resonance within the pipes might enhance condensation. The more recent invention of acoustic refrigeration could be used to advantage, as well as the Hilsch-Ranque vortex tube.
It is necessary to cool the air to the "Dewpoint". All of the preceding devices appear to rely on night cooled mass to provide the needed temperature difference, yet leave the device open to daytime heating by the sun. I find indications that even in the daytime in certain conditions it might be possible to radiate to the sky 100 to 200 BTU per hour, which strictly in math could represent 1 pint or so of operation for every 10 square foot or radiation area.
Once the water has condensed the "dry" air, now cool, needs to be exhausted. This points out the flaw in all of the above. None of the above low-tech devices provide for heat exchange directly between the incoming and outgoing air[i], therefore
the "coolness", essential to precipitation, imparted to the incoming air is directly exhausted, and rapidly eroded.
Ideally, there should be sufficient heat exchange between intake and exhaust air that at the pipe open ends, they are virtually at the same temperature, despite being cycled thru a chilled spot. The transition between liquid and vapor water is, absent unknown science or magic, a matter of the transfer of 970 BTU per each pint condensed. (7760 BTU per gallon)
Using a sky radiation approach[ii] to cooling your condenser core, if the latent heat of vaporization of water is 2.26 × 106 J/kg a 1 m2 radiator can provide 50 W/m2 of cooling, enough to condense 1 g of water in 45 s; 1 kg in 12.6 hr; or 1.9 kg per day. Reportedly production rates in the Southwest U.S. can average about 2 liters per day in the winter to over 6 liters per day during the summer, per square meter.” At the low end 10 m2 (1/4 acre) of radiators cooling humid air could produce 19 L of water per day. The humid air must of course be moved thru the cooling unit, and the “coolness” used to change air temperature recovered during expulsion of the “dried” air.
A commercial, powered water condenser is sold under the name Aqua-Cycle, invented by William Madison, introduced in 1992. It resembles a drinking fountain and functions as such, but it is not connected to any plumbing. It contains a refridgerated dehumidifier and a triple-purification system (carbon, deionization, and UV light) that produces water as pure as triple-distilled. Under optimal operating conditions (80o/60% humidity) the unit claims to produce up to 5 gallons daily.
ATMOSPHERIC CONDENSER DISCUSSION
At any given pressure and temperature, in a fixed volume only a limited amount of water will evaporate into vapor, the limit is referred to as the dew/saturation point. A cubic meter of normal sea level air has a mass of 1.292 kilo. A cubic meter of water vapor at sea level pressure has a mass of .804 kilo, this would occur at a temperature of 100C (212F).
At 0 C (32 F), saturation point is about 1.1 gm of water per cubic meter. A rule of thumb is that raising the air temperature 18°F (10°C) doubles its moisture capacity. This means that air at 86°F (30°C) can hold eight times as much water as air at 32°F.
Degrees C Degrees F Gram H2O
0 32 1.1
10 50 2.2
20 68 4.4
30 86 8.8
40 104 17.6
50 122 35.2
60 140 70.4
70 158 140.8
80 176 281.6
90 194 563.2
100 212 1126.4
Relative humidity is the percentage of water vapor present as compared to how much there could be at the present temperature.
Take a typical Tucson fall day of 84 F and relative humidity of 7%. There is roughly 7% of 8.8 grams of water in each cubic meter of air (.616 gram). Lower the temperature to 66 F, and relative humidity doubles to 14%. Lower the temperature to 48 F, and relative humidity again doubles, now to 28%.
If we cool air without changing its moisture content, eventually we'll reach a temperature at which the air can no longer hold the moisture it contains. Then water will have to condense out of the air, forming dew or fog. The dewpoint is this critical temperature at which condensation occurs.
But, water does not immediately change state as the temperature reaches the "right" point. The "Latent heat of condensation" (Lc) refers to the heat that must be removed from water vapor for it to change into a liquid. Lc=2500 Joules per gram (J/g) of water or about 600 calories per gram (cal/g) of water.
Specific heat is defined as the amount of heat energy required to raise 1 g of a substance by 1° Celsius. If the specific heat of air is .25 calories per gram of air per degree C change, then each degree C change in a cubic meter represents 323 calories. The specific heat of water is 1 calorie per gram per degree C. In our Tucson fall day above there was .616 grams of water in a cubic meter of air. Air and water vapor together take a change of about 324 calories per degree C. We need to lower the temperature by around 40 C, or get rid of 12,960 calories of heat to reach the dew point. An additional 379 calories of heat needs to be removed to compensate for the latent heat of condensation, for a total of 13,339 calories.
Assume a daily water need of 174 gallons (658.6 liters) - 658,660 grams of water. In a Tucson fall day, each of us would need to "wring" all of the water out of more than a million cubic meters of air (1,069,252) - a cube 100 meters on a side.
The heat to be moved is about 14 billion calories. The water portion of this number is about 450 million calories. Depending on device efficiency, SOME part of the other 1 billion calories should be able to be conserved in a heat exchanger.
Increasing the pressure also changes the dew point. Double the pressure and relative humidity doubles. Assume normal atmospheric pressure of 14 PSI. Pump the fall Tucson air into a tank at 28 PSI and the relative humidity inside is now 14%. Make it 56 PSI - 28%. 102 PSI - 56%. 204 PSI - 102%, and you've got water accumulating in the bottom of the tank.
[i] See chapter 7 of the book "Passive Annual Heat Storage", by John Hait
[ii] Radiative Cooling in Hot Humid Climates
Aubrey Jaffer February 2006
Ronald Frederick Greek
Moderator (Electronic Janitor)
Sustainable Tucson
"Stabilization of human numbers is no solution... To speak of an actual reduction of human population - exactly what is needed if the world is to avoid unprecedented human dieoff through famine, pestilence, and war - is unthinkable and unspeakable, at least in polite company. Not just Catholics and conservatives, but liberals as awll become positively apoplectic if the subject is broached. And so the discussion necessary to understanding our econlogical dilemma, and dealing effectively with it, never occurs."
- Richard Heinberg, Power Down
World heads for 'water bankruptcy', says Davos report - Yahoo! News
AFP/File – An Egyptian resident of the Nile Delta town of Borg Al-Borollos, 300 kms north of Cairo, fills a bucket … DAVOS, Switzerland (AFP) – The world is heading toward "water bankruptcy" as demand for the precious commodity outstrips even high population growth, a new report warned Friday.
In less than 20 years water scarcity could lose the equivalent of the entire grain crops of India and the United States, said the World Economic Forum report, which added that food demand is expected to sky-rocket in coming decades.
"The world simply cannot manage water in the future in the same way as in the past or the economic web will collapse," said the report.
Water has been consistently under-priced in many regions and has been wasted and overused, the report said.
Many places in the world are on the verge of "water bankruptcy" following a series of regional water "bubbles" over the past 50 years.
The report said that energy production accounts for about 39 percent of all water used in the United States and 31 percent of water withdrawals in the EU. Only three percent is actually consumed, but competition for access to water will intensify over the next two decades.
Water requirements for energy are expected to grow by as much as 165 percent in the United States and 130 percent in the EU, putting a major "squeeze" on water for agriculture, said the WEF.
The report said most glaciers in the Himalayas and Tibet will be gone by 2100 at the current rate of melting, but they provide water for two billion people. About 70 major rivers around the world are close to being totally drained in order to supply water for irrigation and reservoirs.
The WEF said that within two decades water will become a mainstream theme for investors -- even better than oil.
Speaking at the Davos forum on Thursday, UN Secretary General Ban Ki-moon said: "The water problem is broad and systemic. Our work to deal with it must be so as well."
Corporate chiefs at the forum have also expressed concern. "I am convinced that, under present conditions and considering the way water is being currently managed, we will run out of water long before we run out of fuel," said Peter Brabeck-Letmathe, chairman of Swiss food conglomerate Nestle.
"The only way to measurably and sustainably improve this dire situation is through broad-scale collaborative efforts between governments, industry, academic, and other stakeholders around the world," said Indra Nooyi, chairman and chief executive of PepsiCo Inc, the US drinks major that makes huge use of water.
Dominic Waughray, the WEF head of environmental initiatives, said "management of future water needs stands out as an urgent, tangible and fully resolvable issue for multiple stakeholders to engage in."
Permaculturist David Blume
Permaculturist David Blume says 100 percent of domestic fuel consumption could be made from cattails grown in city sewage. Audio interview: http://www.coyotene tworknews. com/productcart/ pc/radioshow. htm
It's true. I studied the Blume book for an environmental physics class (had to remember a lot of math from 40 years ago!) and if we had enough space to turn into swamps, we could grow all we need from a cattail-willow polyculture. The cattails only produce their astounding 10,000 gallons/acre if they have sewage to drink. (Corn ethanol is around 30, algae and sugar cane around 5000.) We can also reclaim deserts while making ethanol, harvesting just the pods from mesquite plants, or adding polycultures to improve the system and increase production. What about all those roadside lawns?
It's true. I studied the Blume book for an environmental physics class (had to remember a lot of math from 40 years ago!) and if we had enough space to turn into swamps, we could grow all we need from a cattail-willow polyculture. The cattails only produce their astounding 10,000 gallons/acre if they have sewage to drink. (Corn ethanol is around 30, algae and sugar cane around 5000.) We can also reclaim deserts while making ethanol, harvesting just the pods from mesquite plants, or adding polycultures to improve the system and increase production. What about all those roadside lawns?
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