Solar Flashcards
When installing a solar collector, what is the best way to place the tilt
15% W plus the latitude facing south
in a temperate region, which side of the house should you install the least number of windows to help keep the cold out in the winter
North
if a solar heating system is not used, how much heat loss shold the auxilary system compensate for
100%
in an all air solar heating system, which of the following is not part of the apparatus
hot water boiler
a solar unit when installed on the ground should
be placed on a concrete pad
solar collectors should be placed facing
latitude south
for the best orientation in order to achieve the greatest efficiency, a solar collector on the ground should be placed
facing south and a little west
when designing a solar system, the first step is
-selection of collector size
-storage capacity
-layout of system
-estimating daily demand
in sizing a solar system, the first item of importance is
determining the BTU/hr load requiremetn
“Life Cycling costing” as related to the design of a solar heating system is
-cost of auxilary energy
-the initial cost of the sytem
-the life expectancy of the system
when installing a solar system, what aspects should be considered
-operating cost
-the gas or liquid system
-the initial cost
-the passive or active system
what climatic conditions shold be considered in solar energy installation
-freezing
-insufficient sunlight
how do you size the solar heating system
for the BTU/hr required
what is the measurement for heat
BTu
in solar heating, where is the heat exchanger placed in relation to the refrigeration or evaportator coil
before the coil
if you have a closed solar water heating system you will need
an expansion tank
if a closed looped piping system is used with the collector, which of the following must also be used
expansion tank
what is the most imporant component in the effiecy of a hot water solar heating system
Solar panels
water type solar flat place collectors use water as the heat transfer medium this is known as
hydronic system
____ CFM of air are required per cubic foot of collector
30.00
collectors mounted above roofing have an allowance of approximately
1-1/2” clearance
most flat plate collectors use ____ as the heat transfer medium
-oil
-antifreeze
-water
-gas
the requiremetn for an 800 sq ft collector is
1200 to 1600 gallon storage capacity
the optimum or ideal tilt angle for the solar collectors for year round hot waer is
30-45
using water as teh heat transfer liquid in the collector loop, what is the gallon flow per hour over a 1 foot square area of collector
1 to 2 gallons
liquid collectors which contain small passages are
susceptible to plugging
the heat transfer fluid most commonly used for a solar sytem is
water
for heat exchanger effectiveness, a heat transfer coefficient of at least ____ should be achieved
10 degrees F
the metal used for an absorber plate (flat plate collector) is usually
-copper
-stainless steel
-mild carbon steel
-aluminium
the surface coating normally used for an absorber plate is
-anodize
-copper oxide
-black chrome or nickel
-black paint - inorganic, acrylic, silicon
the size of the solar hot water storage tank should be approximately
1 to 2 gallons for every sq ft of collector
on a coil in tank heat exchanger, does the coil have to be on the top or on the bottom of the storage tank
bottom of tank
in solar heating the heat exchanger is used to
transfer heat from one material to another
in reference to a solar storage sytem, phase change means
heat of fusion
which of hte following storage sytems requires the smallest storage tank size for solar water heating
phase change (salts)
how do you prevent steam flash from the top of the collector
provide a pressure relief valve
what is the single largest cause of corrosion problems
incompatibility of the piping materials with the transfer fluid
if you have solar collectors mounted in array they should be mounted so that they can
be taken apart easily
what type of heat storage system can you use on an air type of solar heating system
crushed rock or pebbles
what type of storage system for the storage of heat can you used on a liquid type of solar heating system
-water tank
-salts
-crushed rock
-pebbles
the approximate fluid flow rate of gallons per minute over 1 square foot of solar collector is
.02 gallons per minute
if you are getting steam in your hot water system, what do you look for
automatic mixing valve
if the water comes too hot from the collector stroage tank to the hot water tank, what would the automatic mixing valve do
temper the water
in order to prevent water from flashing to steam at teh top of a collector the
balance valves are adjusted
if the water comes too hot from the storage tank to the hot water tank, what would the automatic mixing valve do
add cold water
what do you do to keep scalding water out of your domestic hot water supply
use a thermostatic control mixing valve
anti-freeze solution used in the solar water heating system should be checke
for freezing and ph annually
individual collectors in a series must be
accessible for repairs and replacement
what is the specific heat of water
1 BTU per/lb per degree of F rise
in an air duct, the free space is known as the
K factor
the specific fheat of water equals ____ BTU per/lb per degree of F rise
1
one psi is
2.31 feet in height of water
the main advantage of a passive solar system over an active solar system is
-cost
-number of working parts
-reliablity
what type of thermostat would you have on a solar system
two stages
insulating of pipes is needed in a liquid working fluid solar heating sytem to
transport fluids by conserving heat loss
The ____ determine the mode of operation of a solar air heating system
collectors
the temperature differential between the collector and the storage tank is
10 degrees to 20 degrees
the most common cause of an inefficient solar system is
improperly insulated pipes
____ is not included in a solar system
boiler
air filters in a solar system need to be changed
monthly
a phase-change is
a fusion of heat
which valve is used to control the flow of liquid in one direction only
check
what factors are used to determine to the cost effectiveness of a solar system
-initial cost
-life cycle of the system
-alternate sources of energy
the buildin ____ controls the dampers of a solar air heating system
thermostat
in a solar system, a thermostat governed by an on-off differential control monitors the air temperature in
the collector outlet manifold
what are some of the things to look out for when mounting the collectors on the roof
-ice blockages
-snow drifiting
-leaves
-electric wires
what is the primary in designing a solar system
BTU demand
what creates corrosion in the pipes of the solar system
-dissimilar metals in the piping
-interaction of the metals of the piping and the heat transfer fluid
to avoid boiling, where excessive pressures can develop in a solar system, adequately sized devices are needed such as
pressure relief valves
thermosiphon and bread box solar heating systems are more effective to instll than active pump systems because
-installation is always more difficult in pumped systems
-initial costs are lowered
on a thermosiphon water heater system, where should the water storage tank be located in relation to the solar collector
1 to 2 feet above the collector
solar system corrosion is aused by
-insulation that is not effective durable or compatible for the designed conditions
-pool composition of the metals or alloys
-the type of material specified for the system are not compatible for the fluids
-water composition and leakage
freeze-up and/or lessened operating efficiency may occur in liquid installation if which of the following is overlooked
inadequate pipe insulation
what is the purpose of collector glazing
-it allows for transmission of solar radiation to the collector absorber surface
-it reduces convection heat losses to the surrounding air
-it absorbs the infrared (long wave length) radiation that would otherwise radiate back into the envirnoment from the absorber surface
internal failure in a solar system through corrosion is caused by
incompatibility material with heat transfer fluid
the collectors should be balanced so that the flow rates through them are
plus or minus 20% of design value
insulation of solar hot lines is necessary to prevent
personal injury
what is the specific grvity of water
1
a mass of water compared to the same open air mass of rocks or pebbles will hold how much more heat
five times
collectors should be installed
to minimize ice dams
es should be planted near solar collector panels (t/f)
False
what is the maximum BTU/h per sq ft of surface absorbed by many flatplate collectors
250
what is the most feasible use of solar heating from an energy conservation standpoint in residential aplication
Domestic hot water
how many factors should be considered in determining the feasibility of a residential solar space heating system
5
what percentage of the total heating load is usually practical for the solar heating supplement
50-70
air and liquid are the two most practical methods of transferring heat from the sun to residential spce heating (T/F)
True
what is done with excess solar heat not used immediatly for space heating
it is stored
which occupies mroe space for the same number of BTU stored, rock or water
rock
what is the specific heat of rock
.2
what solution can be used in a liquid system to prevent freeze up
Ethylene glycol
what is the best direction for a residential heating flat-plate collector
Latitude + 15 degrees
low temperature collectors are normally unglazed, flat collectors intended to operate at temperatures of about
15 to 100 degrees above ambient temperature
medium temperature collectors are flat plate collectors enclosed in an insulated case with one or two glazings. The intended temperature range of operation is about
15 to 200 degrees above ambient temperature
high temperature collectors have some overlap from flat plate collectors with selective absorber plates and heavy insulation. some may be enhanced by the installation of a sun tracking system. which of the following best defines the high temperature collector variations
-parabolic dis reflectors
-evacuated tube flat plates
-parabolic through types
unglazed plat-plate liquid collectors are most commonly used for
swimming pools and hot water tanks
solar panels should be placed on a roof at which of the following angles
equal to the latitude
an air solar system can be designed with a pressure drop of how many inches of water
1
with an air movement of 15-25 feet per minute, people are most comfortable in the summer at a temp of
71 degrees
