Tài liệu PROBLEMS AND SOLUTIONS IN MECHANICAL ENGINEERING doc

[...]... thermodynamics in thermal engineering Sol: Thermal engineering is a very important associate branch of mechanical, chemical, metallurgical, aerospace, marine, automobile, environmental, textile engineering, energy technology, process engineering of pharmaceutical, refinery, fertilizer, organic and inorganic chemical plants Wherever there is combustion, heating or cooling, exchange of heat for carrying out... reactions, conversion of heat into work for producing mechanical or electrical power; propulsion of rockets, railway engines, ships, etc., application of thermal engineering is required Thermodynamics is the basic science of thermal engineering Q 3: Discuss the applications of thermodynamics in the field of energy technology 2 / Problems and Solutions in Mechanical Engineering with Concept Sol: Thermodynamics... thermoelectric engines (vi) Air conditioning, heating, cooling, ventilation plants (vii) Domestic, commercial and industrial lighting (viii) Agricultural, transport and industrial machines All the above engines and power consuming plants are designed using laws of thermodynamics Q 4: Explain thermodynamic system, surrounding and universe Differentiate among open system, closed system and an isolated... relevance in thermodynamics Define density and pressure using this concept (June, 01, March– 02, Jan–03) Or Discuss the concept of continuum and its relevance (Dec–01) Or Discuss the concept of continuum and its relevance in engineering thermodynamics (May–02) Or What is the importance of the concept of continuum in engineering thermodynamics (May–03) Sol: Even the simplification of matter into molecules,... various intermediate states passed through by a system during a process CYCLE refers to a typical sequence of processes in such a fashion that the initial and final states are identical Thus, a cycle is the one in which the processes occur one after the other so as to finally, land 10 / Problems and Solutions in Mechanical Engineering with Concept the system at the same state Thermodynamic path in a cycle... of its pressure 18 / Problems and Solutions in Mechanical Engineering with Concept X Y P X Y L Fig 1.10 Let us consider any two normal sec-tions XX and YY of a pipe line through which a fluid is flowing in the direction as shown in Fig 1.10 Let L = distance between sections XX and YY A = cross–sectional area of the pipe line p = intensity of pressure at section l Then, force acting on the volume of... changes in the system 3 The properties like velocity, momentum, impulse, kinetic energy, and instruments cannot easily measure force of impact etc that describe the molecule Our senses cannot feel them 4 Large numbers of variables are needed to describe a system So the approach is complicated 6 / Problems and Solutions in Mechanical Engineering with Concept Q 8: Explain the concept of continuum and its... are infinitely large Quasi–static process is presumed to remain in thermodynamic equilibrium just because of infinitesimal state change taking place during the occurrence of the process Quasi–static process can be understood from the following example W Weight Lid p Gas 1 = Initial state 2 = Final state ××××××××××× Intermediate equilibrium states Heating Fig 1.9 Quasi static process v 12 / Problems and. .. Problems and Solutions in Mechanical Engineering with Concept Let us consider the locating of gas in a container with certain mass ‘W’ kept on the top lid (lid is such that it does not permit leakage across its interface with vessel wall) of the vessel as shown in Fig 1.9 After certain amount of heat being added to the gas it is found that the lid gets raised up Thermodynamic state change is shown in figure... of thermal engineering Almost all process and engineering industries, agriculture, transport, commercial and domestic activities use thermal engineering But energy technology and power sector are fully dependent on the laws of thermodynamics For example: (i) Central thermal power plants, captive power plants based on coal (ii) Nuclear power plants (iii) Gas turbine power plants (iv) Engines for automobiles, . is complicated. 6 / Problems and Solutions in Mechanical Engineering with Concept Q. 8: Explain the concept of continuum and its relevance in thermodynamics. Define density. thermal engineering. Almost all process and engineering industries, agriculture, transport, commercial and domestic activities use thermal engineering. But