Reversed heat engines

Question 1

examples of reverse heat engines simply

Answer 1

heat pump, and refigerators

Question 2

how do reverse heat engines work

Answer 2

• operate between hot and cold resivoirs like any other engines
• difference is direction of energy transfer
  
  • heat energy taken from cold resivoir and trasnferred to the hot resivoir
• heat naturally flows from hotter to colder spaces
  
  • work must be done

Question 3

refrigerators

Answer 3

• aims to extract as much heat energy from the cold space as possible for each joule of work done
• the cold space is the inside of the refrigerator whilst the ht space is the room
• refrigerators keep enclosed spaces cool that can be used to store perishable food fresh for longer

Question 4

heat pump

Answer 4

• aims to pump as much heat as possible into the hot space per joule of work done
• cold space usualyl outdoors
• hot space is inside of house
• used to heat rooms and water

Question 5

Coefficient of performance

Answer 5

• describes how well work is converted into heat transfer

Question 6

what is the max theoretical efficiency for the coefficent of performance for a fridge and a heat pump

Answer 6

• COP_ref = T_C / (T_H - T_C)
• COP_hp =T_H / (T_H - T_C)