Energy Engineering Multiple Choice Questions on “Flat Plate Collectors”.
1. To how many types are flat plate collectors divided depending on type of heat transfer fluid?
A. 2
B. 3
C. 4
D. 5
Answer: A
clarification: Based on the type of heat transfer fluid, flat plate collectors are divided into two types, they are Liquid Heating Collectors and Air or gas heating collectors. And also happens that all other types of collectors come under these two types.
2. For what purpose are Gas heating collectors used?
A. To trap solar radiance
B. To act as a medium to help in conversion of sunlight to electrical energy
C. Employed as solar air heaters
D. They act as alternate panels in case of failure
Answer: C
clarification: Air or Gas heating collectors are employed as solar air heaters. Solar air heater is a type of system driving outdoor air through a sealed, sun heated collector mounted on an exterior wall or roof, returning the warmed air back to the living space.
3. Liquid heating collectors are mainly used for _________
A. heating water
B. generating electricity
C. cooking
D. trapping sunlight
View Answer
Answer: A
clarification: Liquid heating collectors are mainly used for heating water. A liquid based solar collector is a solar collector that uses sunlight to heat a liquid that is circulating in a solar loop. The fluid in the solar loop may be water, an anti freeze mixture or thermal oil.
4. _______ is a glazing which limits the radiation and convection heat losses.
A. Absorber plate
B. Selective surface
C. Insulation
D. Transparent cover
Answer: D
clarification: A transparent cover is glazing which limits the radiation and heat convection losses. It includes one or more sheets of glass or radiation transmitting plastic film or sheet. The glass itself is always a single pane adding to adding the second reduces the collector efficiency.
5. What are provided to minimize heat loss?
A. Absorber plate
B. Surface plate
C. Insulation
D. Casing
View Answer
Answer: C
clarification: Insulation is provided at the back and sides to minimize heat losses. Fiber glass or styro-foam is used for this purpose. And also most modern collectors use standard insulators such as polyurethane or polyisocynurate.
6. Which part of flat plate collectors is coated in black?
A. Transparent cover
B. Absorber plate
C. Insulation
D. Fins
Answer: B
clarification: Absorber plate is usually metallic or coated in black surface which is used for absorbing radiation energy. The absorber plate’s coating directly affects how efficient the collector is. Coatings always have two rating figures: how much they absorb and how much they emit.
7. The frame which contains all the parts is called __________
A. box
B. plate
C. enclose
D. container
Answer: D
clarification: Container is used to enclose the other components to protect them from weather. These containers are made of extruded aluminum which can be quite heavy and thick for heavy duty collectors. There are some collectors which are enclosed by fiber glass too.
8. In which collector does air flow without any obstruction?
A. Porous absorber plate
B. Non-porous absorber plate
C. Over lapped glass absorber
D. Finned absorber
Answer: B
clarification: In a simple flat plate air collector, commonly known as non-porous absorbers, the air stream flow through the absorber plate without any obstruction. An analysis of black painted solar air collectors in conventional design in which the air flows below the absorber plate has been made.
9. In which absorber matrix material is arranged and the back absorber plate is eliminated?
A. Porous absorber plate
B. Non-porous absorber plate
C. Over lapped glass absorber
D. Finned absorber
Answer: A
clarification: In the porous bed air heater, the matrix material is arranged and the back absorber plate is eliminated. A single glazed porous bed collector with a reflecting honey comb, extending above the porous to just under the glass cover have theoretically examined.
10. Which type of absorber increases the heat transfer area over a simple flat plate absorber of the same capacity?
A. Porous absorber plate
B. Non-porous absorber plate
C. Over lapped glass absorber
D. Finned absorber
Answer: D
clarification: The finned plate absorber increases the heat transfer area over a simple flat absorber of same capacity. A good design of a finned absorber can increase the heat transfer rate. The temperature difference between the absorber plate and air is very low.
11. In which type of absorber plate is the overall flow direction is along the absorber glass plate?
A. Overlapped glass absorber
B. Finned absorber
C. Non-porous absorber plate
D. Porous absorber plate
View Answer
Answer: A
clarification: In overlapped absorber plate, overall flow direction is along the absorber glass plate instead of being across the matrix. Plate and air stream temperature increase gradually along the collector length and across from top to bottom.
12. How is heat loss over come in liquid plate collectors?
A. By insulation
B. By casing
C. By the transparent cover
D. From provided tubes
Answer: A
clarification: Heat is transferred from the absorber plate to a point of use by the circulating fluid via water across the solar heated surface. The heat loss from the surface is prevented by placing thermal insulation of 5 to 10cm thickness behind the absorber plate.