Final answer:
In a refrigeration cycle with a coefficient of performance (K_R) of 3.0, a refrigerator removing 200 J of work will extract 600 J from the cold reservoir and discard 800 J to the hot reservoir. Recovering refrigerants such as HCFCs and HFCs before system disposal is crucial for environmental protection.
Step-by-step explanation:
The question pertains to the refrigeration cycle and the coefficient of performance (KR) of a refrigerator. In a refrigeration cycle, a refrigerator must remove heat from its cold reservoir and expel heat to its hot reservoir while requiring work to operate.
For a refrigerator with a coefficient of performance of 3.0 that requires 200 J of work per cycle, the amount of heat removed from the cold reservoir (Qc) can be calculated.
- Calculate the heat removed (Qc): The coefficient of performance (KR) is given by KR = Qc / W, where W is the work done.
- Substitute the known values: With KR = 3.0 and W = 200 J, Qc = KR × W = 3.0 × 200 J = 600 J. So, 600 J of heat is removed from the cold reservoir per cycle.
- Calculate the heat discarded (Qh): We know that Qh = Qc + W. Thus, Qh = 600 J + 200 J = 800 J. This means 800 J of heat is discarded to the hot reservoir per cycle.
The refrigerants that need to be recovered before opening or disposing of a system include substances such as hydrochlorofluorocarbons (HCFCs) like HCFC-22, HCFC-123, and HCFC-124, as well as hydrofluorocarbons (HFCs) like HFC-134a. These are important to prevent environmental damage as some refrigerants deplete the ozone layer or contribute to global warming.