Question

Entropy is one of the most important and most fundamental concepts in thermal dynamics. It is also one of the most frequently misunderstood. In this assignment, you will research entropy and write a 3-5 page informative essay describing what entropy is and how it relates to the 2^nd law of Thermodynamics. Your description of entropy should be more than a simple definition; the purpose of the paper is for you to demonstrate your own understanding of this concept and how it is applied in the real world. The second part of the paper should describe what the “heat death” of the Universe refers to, and how this relates to entropy. Your discussion should include a statement of whether or not heat death is inevitable and a description of the reasons why/why not.

Answer 1

ANSWER
Entropy is the loss of energy available to do work. Another form of the second law of thermodynamics states that the total entropy of a system either increases or remains constant; it never decreases.
Entropy is zero in a reversible process; it increases in an irreversible process.
Second law of thermodynamics tells about the degradation of energy caused due to entropy generation during heat transfer between system & surrounding through a finite temperature difference.

The entropy is a property of thermodynamic system which is measure of randomness in a system. The change in entropy is caused due to internal as well as external dissipative effects. The change in entropy of the universe is always non-negative i.e.
ΔSuniv≥0
Hence, if there is entropy generation, there is degradation of energy.
The second law of thermodynamics can be stated in terms of entropy. If a reversible process occurs, there is no net change in entropy. In an irreversible process, entropy always increases, so the change in entropy is positive. The total entropy of the universe is continually increasing.

APPLICATION

(1)According to the law, heat always flows from a body at a higher temperature to a body at the lower temperature. This law is applicable to all types of heat engine cycles including Otto, Diesel, etc. for all types of working fluids used in the engines. This law has led to the progress of present-day vehicles.

(2) Another application of this law is refrigerators and heat pumps based on the Reversed Carnot Cycle. If you want to move heat from a body at a lower temperature to a body at a higher temperature, then you have to supply external work. In the original Carnot Cycle, heat produces work while in the Reversed Carnot Cycle work is provided to transfer heat from lower temperature reservoir to a higher temperature reservoir.

(3)Removing heat from the food items in the refrigerator and throwing it away to the higher temperature atmosphere doesn’t happen automatically. We need to supply external work via the compressor to make this happen in the refrigerator.

(4)Air conditioner and heat pump follow the similar law of thermodynamics. The air conditioner removes heat from the room and maintains it at a lower temperature by throwing the absorbed heat into the atmosphere. The heat pump absorbs heat from the atmosphere and supplies it to the room which is cooler in winters.

In both the cases above, external work/energy in the form of electricity has to be supplied; larger the temperature difference, larger is the external work required.

ANSWER

The heat death of the universe, also known as the Big Chill or Big Freeze, is a conjecture on the ultimate fate of the universe, which suggests the universe would evolve to a state of no thermodynamic free energy and would therefore be unable to sustain processes that increase entropy. Heat death does not imply any particular absolute temperature; it only requires that temperature differences or other processes may no longer be exploited to perform work. In the language of physics, this is when the universe reaches thermodynamic equilibrium (maximum entropy).

If the topology of the universe is open or flat, or if dark energy is a positive cosmological constant (both of which are consistent with current data), the universe will continue expanding forever, and a heat death is expected to occur,with the universe cooling to approach equilibrium at a very low temperature after a very long time period.

The hypothesis of heat death stems from the ideas of Lord Kelvin, who in the 1850s took the theory of heat as mechanical energy loss in nature and extrapolated it to larger processes on a universal scale.