The refrigerator is a heat engine in which work is done on a refrigerant substance in order to collect energy from a cold region and exhaust in a higher temperature region. It means heat engine operating in reverse direction is a refrigerator. It is also called a heat pump.
The refrigerator extracts heat from low-temperature austin mobile app development company reservoir and discharges heat to high-temperature reservoir with the help of work.
In the household refrigerator, the working substance is a liquid (Freon) gas that circulates within the system. The low-temperature reservoir is the cold chamber in which food is stored and high-temperature reservoir is the room. The external work is performed by a motor that drives the unit.
The refrigerator operates in a cycle. Its cycle operates in reverse direction as that of a heat engine. The heat QL is extracted from LRT at temperature TL, and heat QH is discharged to the HTR at temperature TH with the help of work W.
The change in internal energy is zero for a complete cycle of a refrigerator. Work done is positive and heat is negative because cyclic
the process operates anticlockwise.
First law of thermodynamics is
dEint = Q + W
Under these conditions, first law becomes
0= (-Q) + (W)
Work = Heat
W = QH – QL
W + QL = QH
Calculation Efficiency of Refrigerator
The ratio of work done needed to extract heat from LTR to discharge into HTR and the amount of heat Q extracted from LTR is called the coefficient of performance of the refrigerator.
Efficiency = Desired heat / Required work
K= QL / W
We say that QL=TL and QH = TH
K = TL / TH-TL
Where TH is the enter temperature and TL is exhaust or room temperature. The coefficient of performance of the refrigerators decreases when the temperature of environment is increased. That is why the performance of the refrigerators or AC is affected during hot summer days.