Wednesday, April 27, 2011

Boiling Temperature of Water At Different Altitudes

Approximate Boiling Temperatures of Water

Altitude........Temperature
Sea Level.......212 degrees F
984 ft............210 degrees F
2,000 ft........208 degrees F
3,000 ft........206 degrees F
5,000 ft........203 degrees F
7,500 ft........198 degrees F
10,000 ft.......194 degrees F
20,000 ft.......178 degrees F
26,000 ft.......168 degrees F

Note: Each 500 foot increase in altitude causes a drop of about 1° in the boiling point.

Boiling Temperature Of Water At Different Altitudes

Approximate Boiling Temperatures of Water

Altitude TemperatureSea Level 212 degrees F
984 ft. 210 degrees F
2,000 ft. 208 degrees F
3,000 ft. 206 degrees F
5,000 ft. 203 degrees F
7,500 ft. 198 degrees F
10,000 ft. 194 degrees F
20,000 ft. 178 degrees F
26,000 ft. 168 degrees F

Note: Each 500 foot increase in altitude causes a drop of about 1° in the boiling point.

Wednesday, April 20, 2011

Home Energy Conservation and Tips

Saving energy means more dollars in your pocket, but it is also a powerful way to save our valuable resources. Energy conservation is the most important green initiative that we should take to heart and practice.

We can start with small steps to lighten the "footprints" we leave behind for future generations like the simple changing of a light bulb which can make a dramatic difference in energy efficiency and cost savings (standard incandescent light bulbs with compact fluorescent light bulbs (CFLs) can save 75% of lighting cost).

A surprisingly large number of electrical products—TVs to microwave ovens to air conditioners—cannot be switched off completely without being unplugged. These products draw power 24 hours a day, often without the knowledge of the consumer. We call this power consumption "standby power."

An individual product draws relatively little standby power but a typical American home has forty products constantly drawing power. Together these amount to almost 10% of residential electricity use.

Identify and reduce these energy drains by using smart strips or unplugging when not in use.


Energy Saving Tips

Turn off the lights when you leave a room.

Replace energy-hungry incandescent lights with fluorescent lighting.

Check with your utility company for energy conservation tips.

Use a programmable thermostat that automatically turns off

the air conditioner or heater when you don't need them.

Add insulation to your home.

Use a fan instead of air conditioning.

Use an EPA-approved wood burning stove or fireplace insert

Insulate your water heater or buy a tankless unit.

Install low-flow showerheads.

Tuesday, April 12, 2011

Solar Collectors

EVACUATED TUBE COLLECTORS:
Another type of active solar collector consists of several
glass tubes, each of which has concentric inner and outer
walls. The annular space between these glass tubes has
been evacuated of air and thus acts like a Thermos®
bottle. Convective heat transfer between the inner and
outer glass tubes is essentially eliminated. A coated
copper absorber strip with attached tubing is located
within the inner glass tube, as shown in figure 12.
Most current-generation evacuated tubes have a
specialized fluid sealed within the internal copper tubing.
When heated, this fluid changes from liquid to vapor
and rises toward the top of the tube. It then passes into
a small copper capsule that fits tightly into a manifold
assembly at the top of the collector. Heat conducts
though this copper capsule into fluid circulating along
the manifold. The fluid sealed within the evacuated
tubes never contacts the fluid in the manifold. As heat
is released from the fluid within the evacuated tube, it
condenses back to a liquid and flows back to the bottom
of the tube ready to repeat the cycle.


FLAT PLATE COLLECTORS:
The principal component in this type of collector is the
absorber plate, which is usually an assembly of copper
sheet and copper tubing. The top surface of the absorber
plate is coated with dark colored paint or electroplated
“selective surface” coating that absorbs the vast majority
of solar radiation striking it. The instant solar radiation
strikes this surface it is converted to thermal energy
(e.g., heat). The copper sheet acts as a wick to conduct
this heat toward the copper tubing that is welded or
otherwise bonded to the sheet. Heat moves across the
copper sheet toward the tubes because the fluid flowing
through the tubes is cooler than the absorber sheet. This
fluid absorbs the heat and carries it out of the collector.
To minimize heat loss, the absorber plate is usually
housed in an enclosure made of aluminum and capable of
withstanding many years of exterior exposure. The sides
and back of this enclosure are insulated with materials
capable of withstanding temperatures in excess of 350ºF,
which might occur if the collector is exposed to intense
sunlight without fluid flow through its absorber plate.
The upper surface of the enclosure is usually tempered
glass with a low iron oxide content. Tempered glass can
withstand high thermal stress as well as potential impact
from hailstones or other objects. Low iron oxide content
glass minimizes absorption of solar radiation as it passes
through on its way to the absorber plate.