Application of 2nd Law of Thermodynamics
Another industry related to the second law of thermodynamics is the air-conditioner. As the weather in this country, Malaysia is always hot and humid, air-conditioners are used to cool down the surrounding inside the house. In fact, the concept of air-conditioner is one of the applications of the second law of thermodynamics which stated that for any process occurring in a closed system, the entropy increases for an irreversible system and remains constant for a reversible system, but never decreases.
An air-conditioner functioned by using a working fluid to transfer heat from the colder indoor air to the hotter outside air. So the indoor air will be cooled down to a favorable temperature for indoor activities. Second law of thermodynamics defines as the entropy of an isolated system never decreases due to isolated systems spontaneously evolve towards thermodynamics equilibrium. Air conditioners apply it during its function. Air conditioners are made up of three main components which are evaporator, condenser and compressor.
Evaporator located inside used to transfer heat from the indoor atmosphere to the working fluid. Condenser located outdoor will transfer heat from the working fluid to atmosphere outside and lastly compressor do works on the working fluid and provide additional thermal energy so that the total entropy of the system do not reduced. From the diagram above, it is clear to show how second law of thermodynamics apply on the process of air conditioners. At first, the working fluid arrives at the evaporator as a warm and high pressure liquid and it passes through a constrictor which causes a large drop in pressure.
It thus enters the evaporator as a warm and low pressure liquid. Because of the low pressure, the working fluid changes its state from liquid to become a gas. Breaking the bonds between the particles requires some thermal energy. Therefore, the working fluid which is in gaseous state becomes quite cold which its temperature less than indoor temperature. Then, heat begins to flow in from the room air with the help of the metal fins that decorates the evaporator. Next, the working fluid leaves the evaporator as a cool and low pressure gas.
It absorbed a lot of thermal energy from the inside air, leaving evaporator stay in low temperature. The compressor receives the low pressure gaseous working fluid, compresses it to a much higher density and sends it to the condenser. Then, the additional energy the working fluid get from the compressor is stored as thermal energy. Thus, the high pressure working fluid enters the condenser at a much higher temperature. Same with the evaporator, the condenser is decorated with metal fins.
These fins help heat to flow from the hot working fluid to the outside air which has lower in temperature. Finally, the working fluid cools and condenses to a warm and high pressure liquid while the temperature atmosphere outside getting higher. To sum up, the second law of thermodynamics indeed brings some impacts to this world in industrial aspects such as heat engines, internal combustion engines and air-conditioner. In fact, this law is also being researched for more usage in our future life.