Lecture # 7 Solar Thermal Energy 1. Low Potential Heat презентация

collectors, troughs, vacuum pipes
implementation of solar ponds
Solar desiccant cooling
Integration with PV
Acquaintance with AUA solar hot water and desiccant cooling system

a state of temperature homeostasis as the heat imparted by the sun is offset by the heat given off through reflection, radiation, and convection.

Visible

Visible

Infrared (IR)

IR

IR

Convection

Contact heat transfer

because the most important variables are characteristics of the surface: - reflectance, - emissivity, - convection, - surface area.

Slowly but surely an extinct glacier in a remote corner of the Peruvian Andes is being returned to its former colour, not by falling snow or regenerated ice sheets, but by whitewash.

Real snow on Chalon Sombrero - not paint

RESULT ?

it reflects light from light sources such as the Sun. It is therefore a more specific form of the  reflectivity term.
Albedo is defined as the ratio of total-reflected to incident electromagnetic radiation. It is a unitless measure indicative of a surface's or body's diffuse reflectivity.

excellent reflectors because they are very poor in heat emission. Human skin, and many other living surfaces, like tree leaves, have near perfect emissivity (~1.0), and so stay pretty cool.
Black people in Africa emit more IR than white people.
A perfect sunscreen is a dye that perfectly absorbs, with high emissivity, or perfectly reflects, ultraviolet and infrared while being transparent in visible light.

both sides with a heat-reflective metallic surface.
It is ideal for treating or preventing hypothermia after first aid has been administered. The emergency foil blanket retains most radiated body heat while protecting against wind and rain.

Foil Survival Blanket reflective thermal first aid

outside dwellings, typically on the roof or nearby.
Many models are the direct-gain type, consisting of flat panels in which water circulates.
Other types may use dish or trough mirrors to concentrate sunlight on a collector tube filled with water, brine or other heat transfer fluid. A storage tank is placed indoors or out.
Circulation is caused by natural convection or by a small electric pump. At night, or when insufficient sunlight is present, circulation through the panel can be stopped by closing a valve and/or stopping the circulating pump, to keep hot water in the storage tank from cooling.
Depending on the local climate, freeze protection, as well as prevention of overheating, must be addressed in their design, installation, and operation.

using the sun's power to cook. There are mainly two types of solar cookers: concentrating and solar box cookers (usually known as solar ovens because of the way they are used).
Since they use no fuel they are free to run, humanitarian organizations are promoting their use worldwide to help slow deforestation and desertification caused by the need for firewood with which to cook.

production technology.

production technology.

built from material that can act as a thermal mass (such as stone, concrete, adobe or water tanks), combined with an air space, insulated glazing and vents to form a large solar thermal collector. Adobe wall ? (not a Trombe wall)

and warm the surface of the thermal mass. At night, heat would escape from the thermal mass, primarily to the outside. Because of the insulating glazing, the average temperature of the thermal mass can be significantly above the average outdoor temperature. If the glazing insulates well enough, and outdoor temperatures are not too low, the average temperature of the thermal mass will be significantly higher than room temperature, and heat will flow into the house interior.

bottom of the air gap between the glazing and the thermal mass. Heated air flows via convection into the building interior. The vents have one-way flaps which prevent convection at night, thereby making heat flow strongly directional. This kind of design is an isolated passive thermal collector. By moving the heat away from the collection surface, it greatly reduces thermal losses at night and improves overall heat gain. Generally, the vents to the interior are closed in summer months when heat gain is not wanted.

Trombe walls
Use controllable windows
Use integrated PV
Provide Aesthetics

too.
Need to prevent losses
Provide comfort of use through engineering
Provide best price per peak watt.

energy,
transparent cover(s) - allows solar energy to pass through but reduces heat loss from the absorber,
heat-transport body - air, water or antifreeze, flowing through tubes to remove heat from the absorber
heat insulating backing

a state of temperature homeostasis as the heat imparted by the sun is offset by the heat given off through reflection, radiation, and convection.

Visible

Visible

Infrared (IR)

IR

IR

Convection

Contact heat transfer

liquid

AIR

a thin layer of either finely divided nickel (black nickel) or chromium (black chrome) is formed on the surface usually by electrolysis.
Such a layer has the property that it absorbs solar energy almost as well as a matt black surface but it is a poor emitter of energy at the temperature of the base metal. The net result is that, other things being equal, a selectively coated absorber exposed to sunlight will get hotter than a simple matt black one.
This in turn means that the lower conductivity of an aluminum sheet can be compensated by having it run hotter so that the copper water tubes do not have to be put closer together and the sheet does not have to be made thicker.
A second advantage of selective coatings is that they enable the collector to work better in poor conditions (weak sunshine.

a2 = 0.0085 W/(m2K2)

G - insolation level in Watts/m2,
Ta - ambient temperatures
Tm - average manifold temperature (average panel temperature).
Tm = (Tinlet+Texit)/2

inlet and outlet liquid, ΔT, depending on your working cycle.
Ability to isolate the convection through air.
Ability to block the infrared (IR) radiation.

on forced circulation via pumps

in antifreeze
Double or triple contour - freezing temperatures in the environment, need in antifreeze, certain hygiene norms.

to the atmosphere.
Solar energy is used to regenerate the media that absorbs humidity.
Pre-desiccated room inlet air is humidified, low temperatures and acceptable humidity levels are attained.
The system is usually coupled with a heat-recovery system, that returns energy back to the room from the exhaust channel.

the energy delivered by the system divided by the electrical or gas energy put into the system. The higher the number, the more energy efficient. Solar energy factors range from 1.0 to 11. Systems with solar energy factors of 2 or 3 are the most common.
Another solar water heater performance metric is the solar fraction. The solar fraction is the solar portion of the total conventional hot water heating load (delivered energy and tank standby losses). The higher the solar fraction, the greater the solar contribution to water heating, which reduces the energy required by the backup water heater. The solar fraction varies from 0 to 1.0. Typical solar factors are 0.5–0.75.

solar but is sometimes set up in a "solar assisted" manner, is the heat-pump.
A heat pump is essentially a refrigeration system working in reverse. Instead of pumping heat from an evaporator inside the refrigerator to a condenser in the room the heat pump pumps heat from an evaporator in the atmosphere to a condenser attached to the hot water cylinder.
For convenience the evaporator is sometimes mounted on the roof of the house where the sun helps to provide input to the evaporator.
Despite the appearance of roof mounted heat pump evaporators, the heat pumps are really electrical heating systems which use electricity in a much more energy efficient way than simple conventional resistance heaters.
There is not a lot to distinguish between a good solar system and a heatpump in terms of overall net consumer savings over a year.

capacity installed. Copy paste the reference link.
Imagine your home has a south looking wall of a specific size (e.g. 3 x 6 m). Now you plan to build a Trombe wall on it. Roughly estimate the budget based on the bill of materials to construct it.