Chapter 6, Microgeneration

Question 1

Define Microgeneration

Answer 1

“The small scale generation of heat and power”

Question 2

What are the main sources of Microelecticity?

Answer 2

Solar PV

Wind

Question 3

What are the main sources of Microheat?

Answer 3

Solar thermal

Ground source heat pumps

Biomass

Question 4

What are the main benefits of community microgeneration.

Answer 4

Reduced energy costs

Enhanced security if supply

Question 5

Role of expansion valve?

Answer 5

The expansion valve allows the refrigerant to expand and so the refrigerant does work. This causes it to lose energy and so it starts to condense causing it to turn back into a liquid of low temperature.

Question 6

Role of compressor?

Answer 6

The gas enter the compressor at a low temperature, the compressor compresses this gas and in doing so increases the internal energy of the gas further as it does work on it causing it to increase in temperature as it is passed into the condenser.

Question 7

Role of condenser?

Answer 7

As the refrigerant enters the condenser, it is in a gaseous state at a higher temperature than the surroundings of the condenser and so thermal energy transfers from the condenser to the external environment cause if a decrease in the temperature of the gas leading to it slowly condensing and turning into a mixture of gas and liquid but is still at a too high temperature to be directly returned to the evaporator.

Question 8

Role of the Evaporator?

Answer 8

The refrigerant in the evaporator is cooler than the exterior of the house. As such, energy transfers to the refrigerant causing it to evaporate from a liquid into a gas. While this refrigerant has more energy than the before the temperature is still too low to enter the condenser and therefor has to go to the compressor first.

Question 9

Identify the common types of closed loop ground source heat pumps.

Answer 9

Horizontal loop, Vertical loop, Pond loop