T=33°C Question of the Day Consider a person who emits 100W of heat in a house. The temperature outside is on average 33°C. He turns on the AC to keep the indoor temperature at Tc = 23°C for 8 hours a day. Question: 100W T (a) If the AC is running a Carnot cycle, find the COP of the AC operates at (i) T = 23°C; and (ii) TC = 25°C (b) Estimate how much energy in percentage he can save per day if he sets the indoor temperature to 25°C instead. Energy saved in % = Energy spent at 23°C – Energy spent at 25°C Energy spent at 23°C Hints: 1. The answer actually depends on how efficient the AC device is, but we can assume the AC is the most efficient AC which runs in Carnot Cycle. 2. Assume that electricity power convert 100% to power in the compressor of the AC.

T=33°C Question of the Day Consider a person who emits 100W of heat in a house. The temperature outside is on average 33°C. He turns on the AC to keep the indoor temperature at Tc = 23°C for 8 hours a day. Question: 100W T (a) If the AC is running a Carnot cycle, find the COP of the AC operates at (i) T = 23°C; and (ii) TC = 25°C (b) Estimate how much energy in percentage he can save per day if he sets the indoor temperature to 25°C instead. Energy saved in % = Energy spent at 23°C – Energy spent at 25°C Energy spent at 23°C Hints: 1. The answer actually depends on how efficient the AC device is, but we can assume the AC is the most efficient AC which runs in Carnot Cycle. 2. Assume that electricity power convert 100% to power in the compressor of the AC.