Thermodynamics come from the Greek words therme (heat) and dynamis (power). Thermodynamics is indeed the study of heat and power (mass in motion) and the conversion of one to the other. (As it turns out, the conversion is much easier in one direction than the other. Why?) Not surprisingly, the Greeks grasped the basic principle that energy is converted into different forms without being destroyed or created.

"Heat and fire… are themselves begotten by impact and friction"

Plato, anticipating the First Law of Thermodynamics by about 2,200 years.

Since prehistory, humans have known how to convert power to heat: the flint producing the spark, the bow producing flame, rub your hands together, do hard physical labor.

The opposite conversion, heat to power, was found only in natural systems: sun to wind, sun to rain, sun to chemical energy in plants to physical work in animals. Once nature made the conversion from heat to power, humans learned how to convert this power into useful work using windmills, sails, waterwheels and domesticated animals. But the quantity of useful power generated by these machines was small compared to today's standards, and the rate of technological, social and political progress was slow.

The course of human history changed dramatically in the early 1700's when Newcomen invented the first practical engine, converting heat from coal into steam into power to pump water from coal mines. The piston in his engine was 21 inches in diameter and the cylinder was 7 feet long. It generated only 5.5 hp (more than 10 water wheels coupled together) at an efficiency of about 1%. Yet it was enough to begin the industrial revolution that has shaped the modern world.

 Newcomen's steam engine: the first practical machine to transform heat into useful work. 

The science of Thermodynamics followed quickly. Carnot defined the limits of the conversion of heat to power. Joule made the first measurement of the heat equivalent of work (772 ft. lb. of work raises 1 lb. of water 1 F), a number which is barely different from the 778 (ft. lb. / lb. H₂0 F) measured today. Thompson defined a universal scale for measuring temperature based on the volume of gasses. Clausius seized upon Joule's, Carnot's and Thompson's work, derived the concept of entropy (heat/temperature) and formulated explicit mathematical expressions of the first and second laws. Boltzman united Clausius' macroscopic concept of entropy with the new physics of atomic theory by showing that entropy was equivalent to the "logarithim of probability" of the position of gas molecules. The science of thermodynamics was soon extended to all aspects of scientific inquiry and became fundamental to our understanding of the universe and the development of improved technologies.

Many things have changed since Newcomen unleashed the modern era, yet power generation remains much the same. The vast majority our electrical power is generated using Newcomen's model of coal to steam to power. Transportation also relies on Newcomen's model of combustion of fossil fuels to push pistons. Hydroelectric power, in the form of modern water wheels, is by far the biggest source of renewable energy. The efficiencies of conversion have increased, but the basic technologies are the same.

Thermodynamics II traces the progression of heat to power technology from Newcomen to the present. We will study combustion (the generation of heat from chemical energy) and the cycles which covert this heat into useful power (Rankine, Otto, etc.). We will review why this conversion is so difficult (the Second Law of Thermodynamics) and study the application of thermodynamic principles to gases. In essence, we will study the science and technologies that have made the last 300 years of human progress possible.

As we look to the future, we can see the end of the age of combustion. Increasing world population, near total reliance on non-renewable fossil fuels, and the unavoidable production of pollution from combustion necessitate a new generation of power production technologies. The new technologies will be pollutionless and renewable, and are fundamentally different from the energy conversion technologies of the past 300 years. Thus, you will be asked to research and describe one of these technologies (wind turbines, photovoltaic arrays or fuelcells) to the class as a special project.

In sum, the class will develop the skills necessary to analyze and design thermal systems. It will reinforce the basic principles of Thermodynamics I by studying the most important engineering applications of Thermodynamics during the last 300 years. In doing so, we will trace an important arc through technological history, relate our findings to the world around us, and look ahead to the 21^st century.