Biothermodynamics

Principles and Applications

Mustafa Ozilgen, Esra Sorguven Oner

• Publisher: CRC Press
• Year: 2016
• ISBN:
  9781315356587
• Edition: 1
• Topic: Medicine
• Subtopic: Biotechnology in Medicine

Over the past several decades there has been increasing research interest in thermodynamics as applied to biological systems. This concerns topics such as muscle work and internal energy such as fat and starch. Applications of the first and second laws of thermodynamics to the human body are important to dieticians and health science experts, and applications of these concepts to the animal body are a major concern of animal scientists. This book covers these key topics, which are typically not covered in classic or traditional thermodynamics texts used in mechanical and chemical engineering.

1

Energy, Entropy, and Thermodynamics

1.1 Energy

Energy (e) is the capacity for doing work. It may exist in a variety of forms and may be transformed from one type to another.

Kinetic energy (e_k) refers to the energy associated with the motion. It is proportional to the square of the system’s velocity.

Potential energy (e_p) refers to the energy that a system has because of its position or configuration. An object may have the capacity for doing work because of its position in a gravitational field (gravitational potential energy), in an electric field (electric potential energy), or in a magnetic field (magnetic potential energy).

Internal energy (u) refers to the energy associated with the chemical structure of the matter. It includes the energy of the translation, rotation, and vibration of the molecules. It is the energy associated with the static constituents of matter like those of the atoms and their chemical bonds. The internal energy of a matter changes with temperature and the pressure acting on the matter.

Enthalpy (h) is the energy of a fluid in motion. Consider a fluid particle, which is originally at rest and has an internal energy u. If this fluid particle is set to motion, then its internal energy does not change, but its total energy increases because of the flow motion. The energy that the fluid particle possesses to push all the other fluid particles in front of it is called the flow energy, and it may be estimated as the multiplication of the particles’ pressure and specific volume, pv. The total energy of a flowing fluid particle is then the sum of its internal energy and flow energy. Accordingly, enthalpy is defined as

h = u + pv

Enthalpy of formation (Δh_f) is the energy required for the formation of 1 mol of a compound from its elements. If all the substances are in their standard conditions, then it is called the standard enthalpy of formation, which is denoted with ΔhfO. The superscript zero indicates that the process has been carried out under standard conditions. While defining the standard conditions, the most common practice is choosing the temperature as 25°C (298.15 K), pressure as 1 bar, and concentration in a solution as 1 mol, pure liquid or solid state at its most stable structure for a substance.

The total specific energy of a system is the sum of all different types of energy that the system possesses:

e = u + e_k + e_p + pv

The unit of energy in SI is joule (J), which is named after the English physicist James Prescott Joule (1818–1889). He discovered the relationship between heat and the mechanical work, which led to the development of the first law of thermodynamics. Work done by moving an object to a distance of 1 m by applying 1 newton of force is 1 J:

J = N m

Calorie (1 cal = 4.184 J) is a pre-SI metric unit of energy. In some food product labels, kilocalories (kcal) are expressed as Cal, where the first letter is capitalized.

The British thermal unit (BTU) was the traditional unit of energy in England. It is the amount of energy needed to heat 1 pound (454.6 g) of water from 39°F to 40°F (3.8°C to 4.4°C). The BTU unit is still used in the power, steam generation, heating, and air conditioning industries. It may be related with joule as

1 BTU = 1.055 J

Note that the extensive properties depend on the mass of the system. In this book, capital letters are used to denote the extensive properties. For example, the total energy of a sys...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Acknowledgments
• Authors
• 1 Energy, Entropy, and Thermodynamics
• 2 Estimation of Thermodynamic Properties
• 3 Energy Conversion Systems
• 4 Thermodynamic Aspects of Biological Processes
• 5 Thermodynamic Assessment of the Industrial Bioprocesses
• Nomenclature
• References
• Index