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We will soon learn how to apply the first law of thermodynamics as the expression of the conservation of energy principle. But, first we study the ways in which energy may be transported across the boundary of a general thermodynamic system. For closed systems (fixed mass systems) energy can cross the boundaries of a closed system only in the form ...

48 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 851 | Lượt tải: 0

INTRODUCTION The study of thermodynamics is concerned with the ways energy is stored within a body and how energy transformations, which involve heat and work, may take place. One of the most fundamental laws of nature is the conservation of energy principle. It simply states that during an energy interaction, energy can change from one form to an...

34 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 809 | Lượt tải: 0

Stagnation Properties Consider a fluid flowing into a diffuser at a velocity , temperature T, pressure P, and enthalpy h, etc. Here the ordinary properties T, P, h, etc. are called the static properties; that is, they are measured relative to the flow at the flow velocity. The diffuser is sufficiently long and the exit area is sufficiently large t...

58 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 728 | Lượt tải: 0

Since the percent theoretical air is known, the N2 balance gives B. The H balance gives G. Then the C and O balances give two equations that relate the remaining three unknowns D, E, and F. Therefore, we need one more equation. To obtain this last equation relating the mole numbers of the products, we assume that the products are in chemical equil...

32 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 864 | Lượt tải: 0

Initially, we shall consider only those reactions that go to completion. The components prior to the reaction are called reactants and the components after the reaction are called products. For more information and animations illustrating this topic visit the Animation Library developed by Professor S. Bhattacharjee, San Diego State University, at...

49 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 796 | Lượt tải: 0

We will be concerned with the mixture of dry air and water vapor. This mixture is often called atmospheric air. The temperature of the atmospheric air in air-conditioning applications ranges from about –10 to about 50oC. Under these conditions, we treat air as an ideal gas with constant specific heats. Taking Cpa = 1.005 kJ/kgK, the enthalpy of ...

38 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 880 | Lượt tải: 0

The discussions in this chapter are restricted to nonreactive ideal-gas mixtures. Those interested in real-gas mixtures are encouraged to study carefully the material presented in Chapter 12. Many thermodynamic applications involve mixtures of ideal gases. That is, each of the gases in the mixture individually behaves as an ideal gas. In this sect...

22 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 732 | Lượt tải: 0

Some thermodynamic properties can be measured directly, but many others cannot. Therefore, it is necessary to develop some relations between these two groups so that the properties that cannot be measured directly can be evaluated. The derivations are based on the fact that properties are point functions, and the state of a simple, compressible sys...

38 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 723 | Lượt tải: 0

The vapor compression refrigeration cycle is a common method for transferring heat from a low temperature to a high temperature. The above figure shows the objectives of refrigerators and heat pumps. The purpose of a refrigerator is the removal of heat, called the cooling load, from a low-temperature medium. The purpose of a heat pump is the trans...

20 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 1008 | Lượt tải: 0

We consider power cycles where the working fluid undergoes a phase change. The best example of this cycle is the steam power cycle where water (steam) is the working fluid. For more information and animations illustrating this topic visit the Animation Library developed by Professor S. Bhattacharjee, San Diego State University, at this link.

51 trang | Chia sẻ: nguyenlinh90 | Ngày: 25/07/2019 | Lượt xem: 812 | Lượt tải: 0