Active and Passive Solar Energy System

ENERGY RESOURCES
(ME-302)
GROUP-10
MEMBERS:-
HAMMAD AHMED JAVAID (2011-ME-25)
ALI SHAN AJMAL (2011-ME-29)
USMAN KHALID (2011-ME-39)
MUHAMMAD UMAIR AHSAN (2011-ME-19)
AAMIR ALI IDREES (2011-ME-11)
DEPARTMENT OF MECHANICAL ENGINEERING
UCE&T, BZU, MULTAN

TOPICS TO BE DISCUSSED
 What Is Solar Energy System?
 Types Of Solar Energy System.
 Passive Solar Energy System.
 Active Solar Energy System.
 Solar Heating Of Buildings (Active System)
 Passive Solar Heating And Cooling Of Buildings
 Five Elements Of Passive Solar Home Design
 Advantages And Disadvantages
 Active Solar Heating
 Passive Solar Heating

SOLAR ENERDGY SYSTEM
Solar Energy System or Solar Power System, is a stand-alone system,
entirely powered by solar energy to harness different types of energies.
Solar Energy System are broadly characterized as either Passive Solar or
Active Solar depending on the way they capture, convert and distribute
solar energy.
 Active Solar Energy Systems include the use of photovoltaic panels
and solar thermal collectors to harness the energy.
 Passive Solar Energy Systems include orienting a building to the Sun,
selecting materials with favorable thermal mass or light dispersing
properties, and designing spaces that naturally circulate air.

PASSIVE SOLAR ENERGY
SYSTEMSAncient people used passive solar energy systems. They build their houses out of
stone or clay, which absorbed the sun’s heat during the day and stayed warm
after dark, providing heat throughout the night.
Builders today use similar methods for passively capturing solar energy. For
example, they construct houses with large double- or triple-paned windows that
get direct sunlight to capture and magnify the sun’s warmth. The effect is similar to
but more powerful than what happens to your car on a sunny day: The air inside
becomes much warmer than the air outside because the windows let in the sun’s
energy and trap it, gradually raising the temperature.
Other effective methods of passive solar energy capture include using stone
flooring and walls with thick insulation to keep the energy in buildings. With
carefully placed windows and other architectural techniques, passive solar energy
systems can be an effective way to heat buildings

ACTIVE SOLAR ENERGY
SYSTEMSActive Solar Energy Systems use the same principles as passive systems except
that they use a fluid (such as water to absorb the heat) and some electrical or
mechanical equipment (such as pumps and fans) to increase the usable heat in a
system. A solar collector positioned on the roofs of buildings heats the fluid and
then pumps it through a system of pipes to heat the whole building.
Photovoltaic Cells, or Solar Panels, are slightly more involved than active solar
energy systems. They convert sunlight to electricity by using thin sheets of silicon.
These thin sheets are inexpensive and can be added to roof tiles. People in
remote areas such as mountain tops and islands often use photovoltaic cells to
generate electricity in their homes and businesses.
This figure illustrates how solar panels capture sunlight and generate electricity.

SOLAR HEATING OF BUILDINGS
(ACTIVE SYSTEM)

SOLAR HEATING OF BUILDINGS (ACTIVE
SYSTEM)Active Solar Heating Systems use solar energy to heat a fluid -- either liquid or air --
and then transfer the solar heat directly to the interior space or to a storage system
for later use.
Most solar water heaters use heat exchangers to absorb sunlight with glycol and
transfer the warmth to water. But glycol is difficult to work with, as it is very viscous,
easily leaks and contaminates, and turns into dangerous acid if it oxidizes with
aluminum and other metals.
A very cheap and easy way to use the sun to heat incoming water is to simply run
the pipes outdoors through insulated glass. Copper pipes zigzag through an
insulated box with a glass top and black bottom, maintaining the same water
pressure. These pipes are painted black to absorb the heat that gets trapped in the
box.

SYSTEM)

SYSTEM)
Evacuated Tube Collectors use a vacuum between the pipe and a tube around it to
insulate heat from escaping. But a much cheaper way is to stack plastic soda
bottles, trapping air pockets as with the soda can solar chimney. Aluminum cans
can be cut into broad arcs and placed at the bottom to reflect heat to the pipes.
The amount of heat that can be
absorbed when the sun is shining is
incredible, so include a pressure
release valve. Drain the pipes in the
winter and bypass the water directly
to the water heater when it gets too
cold outside to be effective. By
supplementing a water heater with a
solar heated water first, a lot less
energy is needed to get the water
hot.

SYSTEM)Liquid-Based Active Solar Heating
Solar Liquid Collectors are most appropriate for central heating. They are the same
as those used in solar domestic water heating systems. Flat-plate Collectors are
the most common, but evacuated tube and concentrating collectors are also
available. In the collector, a heat transfer or "working" fluid such as water,
antifreeze (usually non-toxic propylene glycol), or other type of liquid absorbs the
solar heat. At the appropriate time, a controller operates a circulating pump to move
the fluid through the collector.
The liquid flows rapidly, so its temperature only increases 10° to 20°F (5.6° to 11°C
) as it moves through the collector. Heating a smaller volume of liquid to a higher
temperature increases heat loss from the collector and decreases the efficiency of
the system. The liquid flows to either a storage tank or a heat exchanger for
immediate use. Other system components include piping, pumps, valves, an
expansion tank, a heat exchanger, a storage tank, and controls. The flow rate
depends on the heat transfer fluid.

SYSTEM)Storing Heat in Liquid Systems
If the solar system cannot provide adequate space heating, an auxiliary or back-up system provides the
additional heat. Liquid systems store solar heat in tanks of water or in the masonry mass of a radiant slab
system. In tank type storage systems, heat from the working fluid transfers to a distribution fluid in a heat
exchanger exterior to or within the tank.
Tanks are pressurized or unpressurized, depending on overall system design. Before choosing a storage
tank, consider cost, size, durability, where to place it (in the basement or outside), and how to install it. You
should also note how much insulation is necessary to prevent excessive heat loss, and what kind of protective
coating or sealing is necessary to avoid corrosion or leaks.
Specialty or custom tanks may be necessary in systems with very large storage requirements. They are
usually stainless steel, fiberglass, or high temperature plastic. Concrete and wood (hot tub) tanks are also
options. Each type of tank has its advantages and disadvantages, and all types require careful placement
because of their size and weight. It may be more practical to use several smaller tanks rather than one large
one.
The simplest storage system option is to use standard domestic water heaters. They meet building codes for
pressure vessel requirements, are lined to inhibit corrosion, and are easy to install.

SYSTEM)Distributing Heat for Liquid Systems
You can use a radiant floor, hot water baseboards or radiators, or a central forced-air system to
distribute the solar heat.
In a radiant floor system, solar-heated liquid circulates through pipes embedded in a thin concrete slab
floor, which then radiates heat to the room. Radiant floor heating is ideal for liquid solar systems
because it performs well at relatively low temperatures. A carefully designed system may not need a
separate heat storage tank, although most systems include them for temperature control.
Hot-water baseboards and radiators require water between 160° and 180°F (71° and 82°C) to effectively
heat a room. Generally, flat-plate liquid collectors heat the transfer and distribution fluids to between 90°
and 120°F (32° and 49°C). Therefore, using baseboards or radiators with a solar heating system
requires that the surface area of the baseboard or radiators be larger, temperature of the solar-heated
liquid be increased by the backup system, or a medium-temperature solar collector (such as an
evacuated tube collector) be substituted for a flat-plate collector.
There are several options for incorporating a liquid system into a forced-air heating system. The basic
design is to place a liquid-to-air heat exchanger, or heating coil, in the main room-air return duct before it
reaches the furnace. Air returning from the living space is heated as it passes over the solar heated
liquid in the heat exchanger. Additional heat is supplied as necessary by the furnace. The coil must be
large enough to transfer sufficient heat to the air at the lowest operating temperature of the collector.

PASSIVE SOLAR HEATING AND
COOLING OF BUILDINGS

SOLAR HEATING OF BUILDINGS (PASSIVE
SYSTEM)
The amount of energy spent on heating
and cooling homes can be severely
reduced by using simple design
techniques. Building materials and
structural design greatly impact the
temperature inside a space. A building
can use the power of the sun to heat or
cool itself, with techniques that were
developed over thousands of years in
distant parts of the world. These
techniques are cheap, saves money, and
helps the environment.

SYSTEM)FIVE ELEMENTS OF PASSIVE SOLAR HOME DESIGN
The following five elements constitute a complete passive solar home design. Each
performs a separate function, but all five must work together for the design to be
successful.
APERTURE (Collector)
The large glass (window) area through which sunlight enters the building.
Typically, the aperture(s) should face within 30 degrees of true south and
should not be shaded by other buildings or trees from 9 a.m. to 3 p.m. each
day during the heating season.
ABSORBER
The hard, darkened surface of the storage element. This surface—which could
be that of a masonry wall, floor, or partition (phase change material), or that of
a water container—sits in the direct path of sunlight. Sunlight hits the surface
and is absorbed as heat.

SYSTEM)FIVE ELEMENTS OF PASSIVE SOLAR HOME DESIGN
THERMAL MASS
The materials that retain or store the heat produced by sunlight. The difference between the
absorber and thermal mass, although they often form the same wall or floor, is that the
absorber is an exposed surface whereas thermal mass is the material below or behind that
surface.
DISTRIBUTION
The method by which solar heat circulates from the collection and storage points to different
areas of the house. A strictly passive design will use the three natural heat transfer modes—
conduction, convection, and radiation—exclusively. In some applications, however, fans,
ducts, and blowers may help with the distribution of heat through the house.
CONTROL
Roof overhangs can be used to shade the aperture area during summer months. Other
elements that control under- and/or overheating include electronic sensing devices, such as
a differential thermostat that signals a fan to turn on; operable vents and dampers that allow
or restrict heat flow; low-emissivity binds; and awnings.

SYSTEM)Overhangs:
Size roof overhangs so that the summer sun is blocked but so that the lower winter sun is let
through. Consider the height of the sun in these seasons for the length of your roof eaves.
The height of the sun in summer and winter depends on your elevation. This direct sunlight
will heat spaces considerably in the winter. But unless you live in a very cold climate, you
don't want this heat gain in the summer.

SYSTEM)Horizontal Shades South/North & Vertical Shades East/West:
Space out horizontal louvers as you would an overhang, so that summer sun is
blocked and winter sun is let through. Most louvers are rigid, but if you can get
louvers that are adjustable like interior shades that would probably prove handy.
The rising and setting sun is low to the horizon, so vertical louvers are probably
best on the East and West.

SYSTEM)Outside Objects Shade Sun:
Outside elements such as mountains and structures help block the sun. Trees and
bushes are excellent for filtering sunlight. Deciduous trees drop their leaves in the
winter, allowing sun in the winter but blocking sun in the summer.

SYSTEM)
Inside Objects Filter Sun : Objects in the
room can likewise block or filter sunlight.
Water elements like fish tanks are great
because they soak up heat and mitigate
temperatures.
Indirect Lighting: Indirect lighting sources
provide healthy bright sunlight with less
heat gain. The exterior of the building
should use such reflections to illuminate
interior spaces.

SYSTEM)Courtyards :
Thermal mass materials work best in use
together with courtyards or porches. A
central outside space provides a way for
the material to shed its heat. The heat
stack effect literally sucks heat out of the
building and up into the courtyard.
Conversely, cold regions should not have
courtyards and the building's shape
should be as compact as possible. A
cube-shaped building will conserve
energy much better than a long flat
building.

SYSTEM)
SOLAR TOWERS FOR NATURAL DRAFTS & HEATING
Many homes have tall front entrances. They naturally provide cooler temperatures.
If the insulation at this tall space is thinner than everywhere else, sunlight radiation
will heat up the ceiling. As this hot air vents through an upper window it will suck up
cooler air from below, creating a natural draft and cooling the entire house. This is
known as the Stack Effect.

SYSTEM)
But what about the winter?
Even with the upper window closed, this warmer air will suck up air and create an
unwanted draft. The best thing to do is isolate this solar tower to its own room that
can be opened or closed with a door. It can provide a cooling draft in the summer
and be isolated away behind closed doors in the winter.

SYSTEM)
SOLAR CHIMNEY
A very effective and low-cost device that
rarely gets used is the solar chimney. It is
particularly effective for creating a draft in
humid, hot climates that have very few options
for cooling. A long flat chimney faces the sun
and is painted black so that the air inside
heats up. This air vents out the top and sucks
out the air below.
The important thing to make this work is to
make these chimneys long and thin. The
important principles behind the stack effect is
area of air flow and height of the chimney.

SYSTEM)It could also heat the house in the winter. Close off the upper chimney with a
damper and allow the heated air to enter back into the room. A popular variation of
this is the soda can heater. Air flows from can to can in little pockets, which gives it
a chance to really heat up before it vents out of the top.

SYSTEM)

SYSTEM)The most important thing to prevent heat loss or gain in any roof is insulation. But
with the cold roof, the attic is ventilated to shed any heat that does escape from the
house and prevent ice dams and icicles on the roof.
Continuous inlet vents at the eave soffits allow cool air to enter the space and warm
up as heat is leaked out of the house and vents out continuous ridges at the top.

ADVANTAGES AND DISADVANTAGES
ACTIVE SOLAR HEATING
Advantages:
Renewable resource that is environmentally friendly
Available anywhere on Earth
Used to provide heat, lighting, mechanical power and electricity
Source is Free – significantly reduced gas bills

ACTIVE SOLAR HEATING
Disadvantages:
Array of Solar collectors takes up a lot of space
Dust, smoke, and weather conditions affect the performance of solar collectors
Dependent upon time, season, and latitude
Silicon used for making photovoltaic cells is not in large supply

PASSIVE SOLAR HEATING
Advantages:
Passive solar design is highly energy efficient, reducing a building's energy
demands for lighting, winter heating, and summer cooling.
Energy from the sun is free. Strictly passive designs capture it without additional
investments in mechanical and electrical "active solar" devices such as pumps,
fans and electrical controls.
Passive solar design also helps conserve valuable fossil fuel resources so that
they can be directed toward other uses.
Passive solar design also reduces greenhouse gases that contribute to global
warming because it relies on solar energy, a renewable, nonpolluting resource.

PASSIVE SOLAR HEATING
Disadvantages:
 Passive solar design costs little more than conventional building design and
saves money over the long run.
 In addition, room and furniture layouts need to be planned carefully to avoid glare
on equipment such as computers and televisions.
 And along with daylight comes heat. During the summer or in consistently warm
climates, daylight could actually increase energy use in a building by adding to its
air-conditioning load.

Active and Passive Solar Energy System

Active and Passive Solar Energy System

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