Course detail

# Thermomechanics

FSI-6TTAcad. year: 2017/2018

The course is concerned with the following topics: Basic quantities of state. Equation of state of an ideal gas. Mixtures of ideal gases. The First Law of Thermodynamics - heat, work, internal energy, enthalpy. The Second Law of thermodynamics, entropy. Reversible and irreversible processes of gases. The thermodynamics of vapours. Vapour tables and diagrams. The Clausius-Clapeyron Equation. Thermodynamic processes in vapours. Thermodynamics of moist air. Definitive quantities, tables, diagram. Isobaric processes of moist air, evaporation from a free surface. Thermodynamics of flow of gases and vapors. Adiabatic flow through nozzles. The cycles of heat gas and heat steam engines. Compressors. The cycles of cooling devices and heat pumps. Fundamentals of heat transfer. Stationary heat conduction. Heat transfer by convection, similarity theory. Overall heat transfer, heat exchangers. Heat transfer by radiation. Radiation between surfaces.

Supervisor

Department

Learning outcomes of the course unit

Students will acquire skills to carry out technical computation in the area of thermodynamics and heat transfer: Computation of heat engines and cooling systems. Heat balance of material and machine systems, in gases, vapors, buildings and technological processes.

Prerequisites

Mathematics, Physics, Hydromechanics

Co-requisites

Not applicable.

Recommended optional programme components

Not applicable.

Recommended or required reading

Not applicable.

Planned learning activities and teaching methods

The course is taught through lectures explaining the basic principles and theory of the discipline. Exercises are focused on practical topics presented in lectures.

Assesment methods and criteria linked to learning outcomes

Exam consits of written and oral parts, the emphasis is put on theory and solution of practical tasks.

Language of instruction

Czech

Work placements

Not applicable.

Aims

The course objective is for students to acquire competency to carry out technical computation in the area of thermodynamics and heat transfer. Students will apply theoretical knowledge to machinery and technological fields.

Specification of controlled education, way of implementation and compensation for absences

Attendance at seminars is required; in a case of absence (in justified cases) students will calculate make up assignments. Students will have to pass a test during a semester.

Classification of course in study plans

#### Type of course unit

Lecture

39 hours, optionally

Teacher / Lecturer

Syllabus

Basic terms. Basic laws and equations of state for an ideal gas. Heat capacity. Mixtures of ideal gases, Dalton’s Law, equations of state for mixtures and their components.

The First Law of Thermodynamics and its two mathematical forms. Heat, volume and technical work, internal energy, enthalpy.

Reversible processes in ideal gases, changes of quantities of state, heat calculation, calculations of internal energy, enthalpy, of volume and technical work, p-v diagrams.

Heat cycles, thermal efficiency, work. The Carnot cycle. The Second Law of Thermodynamics, entropy and general equations for entropy changes. Reversible processes and the Carnot cycle in a T-s diagram. The reversed and irreversible Carnot cycle. Irreversible processes in technical practice.

Van der Waals equations of state for real gases. The thermodynamics of vapour, p-v, T-s and h-s diagrams and vapour tables. The Clausius-Clapeyron Equation. Thermodynamic processes in vapours, changes in quantities of state, heat calculation, calculations of internal energy, enthalpy, of volume and technical work.

Thermodynamics of humid/atmospheric air. The definition of humidity and enthalpy of humid air, the enthalpy-relative humidity diagram. Cooling, heating, mixing and increasing the humidity of air, adiabatic evaporation from a free surface. Psychrometers.

The First Law of Thermodynamics for an open system and its equations. Continuity and Bernoulli’s equations. The Prandtl tube, the speed of sound, the Mach number. Isentropic flow of an ideal gas and steam through a narrowing opening and the Laval nozzle and their calculation. The Laval nozzle with various input conditions and the effect of back pressure.

The cycles of heat gas and heat steam engines. Combustion engines, gas turbines, reaction engines.

The Rankin-Clausius cycle. Compressors. The cycles of cooling devices and heat pumps.

Heat transfer by conduction. 3D differential equations for stationary and transient heat conduction with an internal source using Cartesian and cylindrical coordinates. Heat and temperature conductivity. Stationary heat conduction through a planar and cylindrical single- and multiple-layer wall.

Heat transfer by convection. The 3D Fourier-Kirchoff’s equation, The Navier-Stokes equation, boundary conditions. The Similarity Theory in heat convection. Derivation of the criteria of similarity.

Criterion equations for natural and forced convection.

Stationary overall heat transfer through a planar or cylindrical single- or multiple-layer wall. Heat exchangers, the mean temperature logarithmic gradient, algorithms for calculation.

Heat transfer by radiation. The basic laws (Kirchhoff’s First and Second Law, Planck’s Law, the Stefan-Boltzman Law, Wien’s Law). Radiation between two parallel walls and between mutually surrounding surfaces.

Exercise

26 hours, compulsory

Teacher / Lecturer

Syllabus

Calculations:

State quantities of ideal gas and mixtures of ideal gases. Reversible changes of ideal gases-state quantities, heat, work, changes of internal energy, entropy. The Carnot cycle. Thermodynamic processes in vapours- state quantities, heat, work, changes of internal energy, entropy. Basic properties of humid air and its arrangements (cooling, heating, mixing and increasing the humidity). The cycles of combustion engines and gas turbines. The Rankin-Clausius cycle, the cycles of cooling devices. Compressors. Isentropic flow through a narrowing opening or the Laval nozzle. Calculation of its main dimensions. Stationary heat conduction through a planar or cylindrical single- or multiple-layer wall. Convection heat transfer coefficient and convection heat flow. Stationary overall heat transfer – coefficient of overall heat transfer, heat flow. Basic computation of heat exchanger. Radiation between mutually surrounding surfaces.