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persia7
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if you hold a pitcher of water under sun you sea cooling of water in it, you transfer heat from hot to cool without do work, how do you explain it according with second law of thermodynamics?
No, the water gets warmer, not cooler. Especially if your pitcher is sealed to prevent evaporation.persia7 said:if you hold a pitcher of water under sun you sea cooling of water in it
Yes, heat goes from the hot body to the cold body without work. That is what the 2nd law of thermo says should happen.persia7 said:you transfer heat from hot to cool without do work, how do you explain it according with second law of thermodynamics?
persia7 said:if there is evaporation it cools and heat transfer from cold to hot how do u explain it?
If there is evaporation then the air is initially too dry, which is a low-entropy state. The evaporation continues until the water vapor in the air is at the vapor pressure, which is a high-entropy state. Thus the entropy can increase even though the temperature decreases.persia7 said:if there is evaporation it cools and heat transfer from cold to hot how do u explain it?
mfb said:In addition, you transfer a lot of energy from a very hot system (the sun) to a cold system (anything on earth).
This is a distortion of Clasius' statement. His statement was "Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time." See p 117 here. Evaporation is "some other change, connected therewith".persia7 said:according to clasius statement there must be work, where is work?
Yes, it is possible for cooling to occur without work under the Sun's heat. This process is known as passive cooling and it involves using natural methods such as radiation, convection, and evaporation to lower the temperature of an object without the use of external energy.
Passive cooling works by utilizing the laws of thermodynamics, specifically the second law which states that heat naturally flows from hotter objects to cooler objects. By using materials with high reflectivity and low thermal conductivity, passive cooling can effectively reflect and dissipate the Sun's heat, causing a decrease in temperature.
Yes, passive cooling is considered to be energy efficient as it does not require any external energy sources to operate. This makes it a sustainable and cost-effective method of cooling, especially in areas with high temperatures and limited access to electricity.
Some examples of passive cooling techniques include shading, thermal insulation, natural ventilation, and evaporative cooling. These methods can be used in buildings, vehicles, and even clothing to reduce the effects of the Sun's heat.
While passive cooling can be effective in lowering temperatures, it is not always suitable for all climates and situations. In extremely hot and humid environments, passive cooling may not be enough to achieve a comfortable temperature. Additionally, passive cooling methods may also be limited by the design and materials used in a building or object.