Stirling cycle is a thermodynamic cycle upon which a Stirling Engine works. Stirling engine is a closed cycle regenerative heat engine. It works on either air or any other gas. Stirling cycle is invented by Robert Stirling with help from his brother (in 1816). Below are P-V and T-S Diagrams of the Stirling Cycle. Stirling… Read More »
Joule Thomson effect Before moving to the topic we should first know that Joule Thomson effect, Joule Thompson effect, Joule kelvin effect, Joule Thomson expansion, Joule kelvin expansion are the different names of the same thing. To understand the Joule Thomson effect, it is very important to first understand Throttling process. Throttling process: Throttling is… Read More »
Second law efficiency We all know the general formula for calculating efficiency of a heat engine. It is a ratio of output work to input heat. This formula for calculating efficiency is in line with first law of thermodynamics. Which deals with the conservation of quantity of energy (not quality). But when it comes to… Read More »
When a system is not in equilibrium (or dead state in this case) with its surroundings there is an opportunity in convert this departure from equilibrium to do some useful work. For example; If there is a difference between the temperature of system and surroundings then this temperature difference can be utilized to produce useful… Read More »
Clausius’ theorem The cyclic integral of ∂Q/T for a reversible cycle is always equal to zero. Proof of Clausius’ theorem: Let’s consider a reversible heat engine. From the absolute thermodynamic scale of temperature, we know that for a reversible process Q1/Q2 = T1/T2 Q1/T1 – Q2/T2 = 0 Q1/T1 + (-Q2)/T2 = 0 ΣCYCLE (Q/T)… Read More »
Birth of Entropy Entropy is the degree of randomness of a thermodynamic system. In this article we will discuss how the concept of Entropy is originated in thermodynamics. Let’s consider a reversible heat engine. From the absolute thermodynamic scale of temperature, we know that. Q1/Q2 = T1/T2 Q1/T1 – Q2/T2 = 0 Q1/T1 + (-Q2)/T2… Read More »
Carnot Cycle Carnot Heat engine (based on Carnot Cycle) was a concept developed by Nicolas Leonard Sadi Carnot (1796-1832, a French Military Engineer and Physicist) so that one can visualize a reversible heat engine in practice. Carnot engine is a reversible heat engine which works on Carnot cycle. Carnot cycle comprises of four processes. Reversible… Read More »
Efficiency of a Heat Engine A heat engine is a device which is used to convert heat into work. Efficiency of a heat engine is defined as the ratio of its work output and heat input. Efficiency of a Heat Engine = Work output/ Heat input η = (Q1-Q2)/Q1 = 1 – (Q2/Q1) For a… Read More »
Absolute thermodynamic scale of temperature Here in this article we are going to define absolute thermodynamic scale of temperature with the help of a reversible heat engine. From the Carnot’s theorem we know that all the reversible heat engines operating between the same temperature limits have the same efficiency. Which means that efficiency of a… Read More »
Carnot theorem No heat engine can be more efficient than a reversible engine operating between the same temperature limits (the temperature of heat addition and the temperature of heat rejection) and all reversible heat engines operating between the same temperature limits have the same efficiency. Proof of Carnot theorem Given: t1: Temperature of the source… Read More »