Question 1

Solar energy is quite compatible for a major part of the U.S. because our major energy needs are
For ________ energy.

A) electrical
B) thermal
C) kinetic
D) potential
E) mechanical

B

Accepted Answer

B

Question 2

Commonly used units for solar energy input are&#10;A) watts&#10;B) watts/day&#10;C) watts/day/m2&#10;D) Btu&#10;E) Btu/ft2/day

Accepted Answer

E

Question 3

One can increase the insolation upon a one ft2 horizontal plate by ________.&#10;A) using a fresnel lens of one ft2&#10;B) using two 1 ft2 fresnel lenses, one on top of the other&#10;C) adding reflectors around the plate&#10;D) increasing the temperature of the plate&#10;E) increasing the absorption of the plate

Accepted Answer

By adding reflectors around the plate, the plate will receive more direct and indirect sunlight, increasing the insolation. Using a fresnel lens or increasing the temperature or absorption of the plate may not necessarily increase the amount of sunlight reaching the plate. Using two fresnel lenses on top of each other may actually decrease the insolation as some of the incoming sunlight may be blocked by the second lens.

Question 4

The use of thermal mass on a direct gain passive solar system _______.&#10;A) reduces temperature fluctuations during the day.&#10;B) provides foundation support for the collector superstructure&#10;C) increases the insolation on the south-facing windows&#10;D) increases temperature fluctuations during the night

Accepted Answer

Thermal mass on a direct gain passive solar system helps to absorb and store heat during the day, which then reduces temperature fluctuations inside the building during the night. This is because the thermal mass slowly releases the heat it has stored, keeping the indoor temperature more stable.

Question 5

The optimum angle of tilt (from the horizontal) for a flat plate collector at 35$\degree$ N latitude for the purpose of space heating is ________.&#10;A) 0$\degree$&#10;B) 25$\degree$&#10;C) 35$\degree$&#10;D) 45$\degree$&#10;E) 75$\degree$

Accepted Answer

The optimum angle of tilt for a flat plate collector for space heating purposes is generally recommended to be the latitude of the location plus 15 degrees. Since the given latitude is 35 degrees, adding 15 degrees gives us 50 degrees, which is closest to option D, 45 degrees.

Question 6

If the insolation upon a flat plate collector is 800 Btu/ft2/day, how large must the collector be to provide 30,000 Btu/hr of thermal energy for an entire day? Take the efficiency of the collector
To be 50%.

A) 150
B) 750
C) 1800
D) 4000
E) 7200 ft2

Accepted Answer

To find the required collector area, first calculate the total energy needed per day: 30,000 Btu/hr * 24 hr = 720,000 Btu/day. With 50% efficiency, the collector must capture twice this amount: 1,440,000 Btu/day. Given 800 Btu/ft2/day insolation, the area needed is 1,440,000 Btu/day / 800 Btu/ft2/day = 1800 ft2.

Question 7

An effective way to passively cool a house is to _______.&#10;A) open all the windows&#10;B) use a light colored roofing material&#10;C) use concentrating collectors to provide air conditioning&#10;D) add more insulation on the south side of the house&#10;E) use thermal storage mass

Accepted Answer

Light colored roofing materials reflect more sunlight, which helps to keep the house cooler.

Question 8

The measure of the position of the sun from the horizontal is called the ________.&#10;A) altitude&#10;B) azimuth&#10;C) declination&#10;D) insolation

Accepted Answer

Altitude is the measure of the position of the sun from the horizontal. Azimuth refers to the position of the sun in relation to the observer's location on Earth. Declination is the angle of the sun relative to the celestial equator. Insolation refers to the amount of solar radiation received at a particular location.

Question 9

A Trombe wall in a house uses a large window and ______.&#10;A) R-19 insulation in the walls&#10;B) a vertical thermal mass across the room from the window&#10;C) a vertical thermal mass close to the window&#10;D) a slate floor by the window&#10;E) a vertical flat plate collector using water

Accepted Answer

A Trombe wall uses a large window to absorb sunlight and a thermal mass, which is usually made of a dense material like concrete or brick, to store and release the heat. The thermal mass is typically located near the window to maximize its exposure to the sunlight. Therefore, the best choice is C - a vertical thermal mass close to the window.

Question 10

Water circulates in a thermosiphon, hot water system because ________.&#10;A) a pump is used&#10;B) gravity causes water to flow from the top of the collector to the bottom&#10;C) hot water is less dense than cold water&#10;D) solar energy is used to run the circulating pump

Accepted Answer

Hot water is less dense than cold water, which causes it to rise above the colder water, creating a natural circulation without the need for a pump. This principle is what drives the circulation in a thermosiphon hot water system.

Question 11

One advantage of using air as the working fluid in a solar collector is ________.&#10;A) that freezing will not be a problem&#10;B) that water heats up faster than air&#10;C) a smaller storage facility can be used&#10;D) that one needs hot water for showers

Accepted Answer

The answer of One advantage of using air as the...

Question 12

During which season will more insolation be delivered to a vertical south-facing window on&#10;A clear day?&#10;A) winter&#10;B) fall&#10;C) spring&#10;D) summer&#10;E) depends upon the R-value

Accepted Answer

The answer of During which season will more insolation be...

Deck 4: Solar Energy