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ASEE Paper 2005-1408-234

Extending Thermodynamic Concepts from the microscopic nonliving system to the macroscopic living system

Ernest W. Tollner and David Gattie

Abstract

This paper summarizes some key questions arising in a seminar discussion of thermodynamics and its application to living systems. The seminar began with a discussion of fundamental questions related to: thermodynamic systems, energy, temperature, heat, exergy, entropy, work and state equations. The seminar considered thermodynamic laws and thermodynamic equilibrium from classical and modern viewpoints. The context of the discussion was focused around living systems. Referenced resources comprised the readings list.

Introduction

This discussion seminar stemmed from the proposition that thermodynamic laws guiding nonliving and living processes drive ecological processes. We set about to review and refresh ourselves on the thermodynamics of nonliving processes in order to provide orientation from which to begin an inquiry into the thermodynamics of living systems. Several questions were surfaced and the answers that evolved over the course of the discussion are presented.

A. What is a thermodynamic system?

A thermodynamic system, or system, from a macroscopic viewpoint is defined as a quantity of matter or a region in space chosen for study. The mass or region outside the system is called the surroundings (Cengel and Bowles, 2002, page 8-9, 168) or the environs (Patten, 1978). The real or imaginary surface or line that separates the system from its surroundings is called the boundary, which may be fixed or moveable.

A closed system, known also as a control mass, consists of a fixed amount of mass and no mass can cross its boundary. Energy in the form of work or heat can cross the boundary. If energy is not allowed to cross the boundary, the system is referred to as an isolated system.

The closed system does not allow mass transport through boundaries but may allow energy transport. Closed systems with no chemical reactions or phase changes, whose velocity and elevation of the center of mass remains constant are referred to as stationary systems. In a stationary system, a change of energy represents a change in sensible internal energy, with kinetic energy changes requiring complementary changes in potential energy. In the event of chemical reactions and phase changes, one must consider latent energy and chemical internal energy as contributors to the energy state. System boundaries allowing no heat transfer are known as adiabatic boundaries.

Presented at the 2005 American Society of Engineering Education National Conference Portland, Oregon.

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Tollner, E., & Gattie, D. (2005, June), Extending Thermodynamic Concepts From The Microscopic Nonliving System To The Macroscopic Living System Paper presented at 2005 Annual Conference, Portland, Oregon. 10.18260/1-2--14979