Jump to navigation Jump to A first course in heat transfer PDF This article is about a mode of transfer of energy. The Sun and Earth form an ongoing example of a heating process.
This textbook is an introduction to heat transfer based on the understanding of the physical phenomena as well as an introduction to heat transfer engineering. The three transfer modes, by conduction, radiation and convection in single phase are treated and coupled in practical applications. The knowledge of the first principle of thermodynamics and basic notions of mathematics are sufficient for a complete understanding of the course. It is completed by a section “Useful data for design”, which allows a first design of many various systems to be achieved.
A particular care is also brought to the methodology for modeling real thermal systems in application exercises and problems, which illustrate the course: First, by defining a resolution strategy, then by building, from realistic assumptions, simple models, which are introduced in the textbook, by solving this well conditioned problem and finally by validating this modeling.
Application problems deal with the design of a thermal solar collector, the thermal design of a nuclear plant, the atmospheric greenhouse effect, the cryogenic engine of a commercial rocket, in order to highlight the universality of heat transfer. This textbook will be an useful tool for undergraduate students and for generalist engineers, particularly design engineers who are not specialized in heat transfer, but have to face heat transfer phenomena in mechanical, chemical, electrical, building and, more generally, energy engineering.
Some of the Sun’s thermal radiation strikes and heats the Earth. Compared to the Sun, Earth has a much lower temperature and so sends far less thermal radiation back to the Sun. In thermodynamics, heat is energy in transfer to or from a thermodynamic system, by mechanisms other than thermodynamic work or transfer of matter. Like thermodynamic work, heat transfer is a process involving two systems, not a property of any one system. Although heat flows from a hotter body to a cooler one, it is possible to construct a heat pump or refrigeration system that does work to increase the difference in temperature between two systems. In contrast, a heat engine reduces an existing temperature difference to do work on another system. The amount of heat transferred in any process can be defined as the total amount of transferred energy excluding any macroscopic work that was done and any energy contained in matter transferred.
For the precise definition of heat, it is necessary that it occur by a path that does not include transfer of matter. Heat is measured by its effect on the states of interacting bodies, for example, by the amount of ice melted or a change in temperature. The quantification of heat via the temperature change of a body is called calorimetry. In a transfer of energy as heat without work being done, there are changes of entropy in both the surroundings which lose heat and the system which gains it.