Heat and Mass Transfer: Fundamentals and Applications (5th Edition)
Yunus Cengel, Afshin Ghajar
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With complete coverage of the basic principles of heat transfer and a broad range of applications in a flexible format, Heat and Mass Transfer: Fundamentals and Applications, by Yunus Cengel and Afshin Ghajar provides the perfect blend of fundamentals and applications. The text provides a highly intuitive and practical understanding of the material by emphasizing the physics and the underlying physical phenomena involved.
This text covers the standard topics of heat transfer with an emphasis on physics and real-world every day applications, while de-emphasizing mathematical aspects. This approach is designed to take advantage of students' intuition, making the learning process easier and more engaging.
formulations for the physical principles and laws by representing the rates of change as derivatives. Therefore, differential equations are used to investigate a wide variety of problems in sciences and engineering (Fig. 1–6). However, many problems encountered in practice can be solved without resorting to differential equations and the complications associated with them. The study of physical phenomena involves two important steps. In the first step, all the variables that affect the phenomena
mechanisms. First the body increases the blood flow and thus heat transport to the skin, causing the temperature of the skin and the subjacent tissues to rise and approach the deep body temperature. Under extreme heat conditions, the heart rate may reach 150 beats per minute in order to maintain adequate blood supply to the brain and the skin. At higher heart rates, the volumetric efficiency of the heart drops because of the very short time between the beats to fill the heart with blood, and the
25°C, and leaves at 50°C. FIGURE P1–31 1–32E Air enters the duct of an air-conditioning system at 15 psia and 50°F at a volume flow rate of 450 ft3/min. The diameter of the duct is 10 inches and heat is transferred to the air in the duct from the surroundings at a rate of 2 Btu/s. Determine (a) the velocity of the air at the duct inlet and (b) the temperature of the air at the exit. Answers: (a) 825 ft/min, (b) 64°F Heat Transfer Mechanisms 1–33C Define thermal conductivity and explain its
through the wall can be determined from T1 2 T2 · Q 5 kavg A L FIGURE 2–65 Schematic for Example 2–21. 114 HEAT CONDUCTION EQUATION where A is the heat conduction area of the wall and kavg 5 k(Tavg) 5 k0 a1 1 b T2 1 T1 2 b is the average thermal conductivity (Eq. 2–80). (b) To determine the temperature distribution in the wall, we begin with Fourier’s law of heat conduction, expressed as dT · Q 5 2k(T) A dx · where the rate of conduction heat transfer Q and the area A are constant.
the rate of change of those quantities with time. For example, if N(t) denotes the population of a bacteria colony at time t, then the first derivative N9 5 dN/dt represents the rate of change of the population, which is the amount the population increases or decreases per unit time. The derivative of the first derivative of a function y is called the second derivative of y, and is denoted by y0 or d 2y/dx2. In general, the derivative of the (n 2 1)st derivative of y is called the nth derivative