Количество страниц учебной работы: 4,10
“Контрольная работа № 1.
Задача 1.
Произвести расчет термодинамических параметров газовой смеси, совершающей изобарное расширение до объёма V2, если известны начальная температура t1 , начальное давление P1 и масса смеси m.
Определить: газовую постоянную и кажущуюся молекулярную массу, начальный объём ,основные параметры в конечном состоянии, изменение внутренней энергии, энтальпии, энтропии, теплоту и работу расширения в процессе 1-2,
Исходные данные: P1 = 10 МПа, t1 = 120 oC, m = 2 кг, ? = V2/V1 = 3,5.
Средняя характеристика природного газа, % об:
CH4 =94; С2H4 –2,8; С3H8 –0,4; С4H10 – 0,3; С5H12 – 0,1; N2 –2,0; CO2 – 0,4, H2O – 0.

Контрольная работа № 2.
Задача 1. По трубопроводу с внешним диаметром dн и толщиной стенки ? течет газ со средней температурой tг. Коэффициент теплоотдачи от газа к стенке ?1. Снаружи трубопровод охлаждается водой со средней температурой tв. Коэф-фициент теплоотдачи от стенки к воде ?2.
Определить коэффициент теплопередачи от газа к воде, погонный тепловой поток и температуры внутренней и наружной поверхностей трубы.
-Тепловой режим считать стационарным.
-Лучистым теплообменом пренебречь.
Исходные данные:
tг = 800 0C, dн = 190 мм, ? = 7, tв = 60 0C, ?1 = 60 Вт/(м2К), ?2 = 4000 Вт/(м2К).

Стоимость данной учебной работы: 585 руб.


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    Учебная работа № 187628. Контрольная Термодинамика. Вариант 9, контрольная работа №1, задания 1; контрольная работа №2, задание 1

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    Термодинамика и термохимия

    chemical energy, etc. Chemical and physical processes are almost invariably
    accompanied by energy changes, and results of considerable importance have been
    obtained studying the laws underlying these changes. It is this study of energy
    transformation which constitutes the subject matter of thermodynamics. Although
    thermodynamics may appear to be somewhat theoretical in nature, the two laws
    have led to results of fundamental importance to chemistry, as well as to
    of Energy: The First Law of Thermodynamics.
    Many attempts
    have been made from time to time to realize “perpetual motion”, that
    is, the continuous production of mechanical work without supplying an
    equivalent amount of energy from another source. The failure of all such
    efforts has led to the universal acceptance of the principle of conservation of
    energy. This principle has been stated in many forms, but essentially they
    amount to the fact that although energy can be converted from one form to
    another, it cannot be created or destroyed or, alternatively, whenever a
    quantity of one kind of energy is produced, an exactly equivalent amount of
    other kinds must disappear. It is evident that perpetual motion, in the
    generally accepted sense of the term, would be contrary to this principle, for
    it would involve the creation of energy. Further, the exact equivalence of
    mechanical or electrical work and heat, as found by Joule and others, is a
    necessary consequence of the same principle.
    The law of
    conservation of energy is purely the result of experience, no exception to it
    having as yet been found. The assumption that it is of universal applicability
    is the basis of the first law of thermodynamics. This law can be stated in any
    of the ways given above for the principle of the conservation of energy, or
    else it may be put in the following form. The total energy of a system and its
    surroundings must remain constant, although it may be changed from one form, to
    Changes in Chemical Reactions.
    The subject of
    thermochemistry deals with the heat changes accompanying chemical reactions. As
    will be seen shortly the laws of thermochemistry are based-largely on the
    principle of the conservation of energy or the first law of thermodynamics.
    Different substances have different amounts of internal (chemical) energy, and
    so the total energy of the products of a reaction is generally different from
    that of the reactants; hence, the chemical change will be accompanied by the
    liberation or absorption of energy, which may appear in the form of heat. If
    heat is liberated in the reaction the process is said to be exothermic, but if
    heat is absorbed it is described as endothermic. The majority of, although not
    all, chemical reactions which go to virtual completion at ordinary temperatures
    are exothermic in character, since they are accompanied by an evolution of
    heat. If a chemical reaction is associated with a volume change, as is
    particularly the case for many processes involving the combination of gases,
    the magnitude of the heat change will depend on whether the reaction is carried
    out at constant pressure or at constant volume. Since many reactions normally
    occur at constant (atmospheric) pressure it is the usual practice to record
    heat changes by quoting the value of qp, the heat absorbed at
    constant pressure; this may, of course, be identified with ΔH , the
    increase of heat content…