Copy of `Ameco - Solar Terms`

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Ameco - Solar Terms Category: Electronics and Engineering > Glossary of Solar Heating Terms Date & country: 12/08/2008, USA Words: 65

Ultraviolet Radiation
Electromagnetic radiation with wavelengths slightly shorter than visible light.

Tube-Type Collector
A collector in which the heat transfer fluid flows through metal tubes that are fastened to the absorber plate with solder, clamps or other means. (See Collector).

Tube-in-Plate-Absorber
A metal absorber plate in which the heat transfer fluid flows through passages formed in the plate itself.

Trickle Type Collector
A collector in which the heat transfer liquid flows through metal tubes which are fastened to the absorber plate by solder, clamps or other means. (See Collector).

Thermosyphoning
The process that makes water circulate automatically between a warm collector and a cooler storage tank above it. (See Gravity Convection).

Thermistor
Sensing device which changes its electrical resistance according to temperature. Used in the control system to generate input data on collector and storage temperatures.

Thermal Mass or Thermal Inertia
The tendency of a building with large quantities of heavy materials to remain at the same temperature or to fluctuate only very slowly; also the overall heat storage capacity of the building.

Thermal Capacity
The quantity of heat needed to warm a collector up to its operating temperature.

Sun Path Diagram
A circular projection of the sky vault, similar to a map, that can be used to determine solar positions and to calculate shading.

Standby Heat Loss
Heat lost though storage tank and piping walls.

Specific Heat
The quantity of heat, in BTU, needed to raise the temperature of one pound of a material 1°F.

Solar Rights
A legal issue concerning the right of access to sunlight.

Shading Coefficient
The ratio of the solar heat gain through a specific glazing system to the total solar heat gain through a single layer of clear double-strength glass.

Selective Surface
A surface that absorbs radiation of one wavelength (for example, sunlight) but emits little radiation of another wavelength (for example, infrared); used as a coating for absorber plates.

Retrofitting
The application of a solar heating or cooling system to an existing building.

Resistance, or R Value
The tendency of a material to retard the flow of heat.

Refrigerant
A liquid such as Freon that is use in cooling devices to absorb heat from surrounding air or liquids as it evaporates.

Reflected Radiation
Sunlight that is reflected from surrounding trees, terrain or buildings onto a surface exposed to the sky.

Radiant Panels
Panels with integral passages for the flow of warm fluids, either air or liquids. Heat from the fluid is conducted through the metal and transferred to the rooms by thermal radiation.

Photovoltaic Cells
Semi conductor devices that convert solar energy into electricity.

Photosynthesis
The conversion of solar energy to chemical energy, by the action of chlorophyll in plants and algae.

Percentage of Possible Sunshine
The percentage of daytime hours during which there is enough direct solar radiation to cast a shadow.

Passive System
A solar heating or cooling system that uses no external mechanical power to move the collected solar heat.

Nocturnal Cooling
The cooling of a building or heat storage device by the radiation of excess heat into the night sky.

One-Tank Closed-Loop System
A conventional DHW tank, usually electrically heated, is converted to a solar DHW storage tank by installing an external heat exchanger coil. The lower electrical element is removed, leaving the uppermost of the usual two elements to provide auxiliary water heating and to achieve good stratification (layering of hotter water over progressively cold...

Langley
A measure of solar radiation; equal to one calorie per square centimeter.

Insulation
A material with high resistance (R-value) to heat flow.

Insolation
The total amount of solar radiation direct, diffused and reflected-striking a surface exposed to the sky.

Infrared Radiation
Electromagnetic radiation from the sun that has wavelengths slightly longer than visible light.

Indirect System
A solar heating or cooling system in which the solar heat is collected exterior to the building and transferred inside using ducts or piping and, usually fans or ducts.

Hybrid Solar Energy System
A system that uses both active and passive methods in its operation.

Heat Source
A medium or container from which heat flows.

Heat Sink
A medium or container to which heat flows.

Heating Season
The period from early fall to late spring (in the northern hemisphere) during which additional heat is needed to keep a house comfortable for its occupants.

Heat Storage
A device or medium that absorbs collected solar heat and stores it for use during periods of inclement or cold weather.

Heat Capacity
A property of a material denoting its ability to absorb heat.

Gravity Convection
The natural movement of heat that occurs when a warm fluid rises and a cool fluid sinks under the influence of gravity.

Headers
The pipe that runs across the edge of an array of solar collectors, gathering or distributing the heat transfer fluid from, or to the risers in the individual collectors. This insures that equal flow rates and pressure are maintained.

Glaubers Salt
Sodium sulfate a eutectic salt that melts at 90°F. and absorbs about 104 Btu per pound as it does so.

Getters
A column or cartridge containing an active metal which will be sacrificed to protect some other metal in the system against galvanic corrosion.

Galvanic Corrosion
A condition caused as a result of a conducting liquid making contact with two different metal which are not properly isolated physically and/or electrically.

Eutectic Salts
A group of materials that melt at low temperatures, absorbing large quantities of heat.

Emittance
A measure of the propensity of a material to emit thermal radiation.

Drain back System
The solar heat transfer fluid automatically drains into a tank by gravity. Drain back systems are available in one or two tank configurations. A heat exchanger is necessary, because the city inlet pressure would prevent draining. The heat transfer fluid in the collector loop may be distilled or city water if the loop plumbing is copper. If the plum...

Drain down System
Potable water is circulated from the storage tank through the collector loop. Freeze protection is provided by solenoid valves opening and dumping the water at a preset low temperature. Collectors and piping must be pitched so that the system can drain down, and must be assembled carefully to withstand 100 psi. city water line pressures. Pressure r...

Design Temperature
The temperature close to the lowest expected for a location, used to determine the design heat load.

Design Heat Load
The total heat loss from a house under the most severe winter conditions likely to occur.

Degree Day
A unit that represents a 1 degree F. deviation from some fixed reference point (usually 65°F.) in the mean daily outdoor temperature.

Cover Plate
A sheet of glass or transparent plastic placed above the absorber in a flat plate collector.

Conductivity
A measure of the ability of a material to permit conduction of heat flow through it.

Conduction
The flow of heat due to temperature variations within a material.

Concentrating Collector
A device which concentrates the sun's rays on an absorber surface which is significantly smaller than the overall collector area.

Collector Efficiency
The ratio of usable heat energy extracted from a collector to the solar energy striking the cover.

Collector
A device that collects solar radiation and converts it to heat.

Calorie
The quantity of heat needed to raise the temperature of one gram of water one degree Celsius.

British Thermal Unit (BTU)
The quantity of heat needed to raise the temperature of one pound of water one degree Fahrenheit.

Azimuth
The angular distance between true south and the point on the horizon directly below the sun.

ASHRAE
Abbreviation for the American Society of Heating and Air-Conditioning Engineers.

Ambient Temperature
The temperature of the surrounding air.

Altitude
The angular distance from the horizon to the sun.

Air-Type Collector
A collector that uses air as the heat transfer fluid.

Air System
Solar domestic hot water systems employing air-type collectors are available. Hot air generated by these collectors is fan forced through an air-to-liquid heat exchanger with the potable water being pumped through the liquid section of the exchanger. The heated water is then circulated through the storage tank in a similar fashion to the liquid col...

Active System
A solar heating or cooling system that requires external mechanical power to move the collected heat.

Absorptance
The ratio of solar energy absorbed by a surface to the solar energy striking it.

Absorber
The blackened surface in a collector that absorbs the solar radiation and converts it to heat energy.