Количество страниц учебной работы: 6,10
“13. Сделайте анализ изобарного процесса.
53. Изобразите в i, s – диаграмме процесс обратимого и не обратимого истечения. Покажите располагаемый и используемый теплоперепад, обусловленную необратимостью процесса истечения. Что такое коэффициент потери энергии, коэффициент скорости и КПД сопла?
13. Определить расход топлива (Q_(p^н ) = 40 000 кДж/кг) для вспомогательного котла производительностью D = 6000 кг/ч (1,67 кг/с), если давление сухого насыщенного пара в котле р_(с.п) = 0,6 МПа, температура питательной воды t_(п.в) = 80°С, КПД котла ?_к = 0,82.13. Определить расход топлива (Q_(p^н ) = 40 000 кДж/кг) для вспомогательного котла производительностью D = 6000 кг/ч (1,67 кг/с), если давление сухого насыщенного пара в котле р_(с.п) = 0,6 МПа, температура питательной воды t_(п.в) = 80°С, КПД котла ?_к = 0,82.
26. Определить скорость адиабатного истечения, диаметры минимального и выходного сечений сопла Лаваля, если начальные параметры перегретого пара р_1 = 3 МПа, t_1 = 400°С, конечное давление р_2= 0,2 МПа, расхода пара G = 5 кг/с.
33. Для идеального никла ДВС со смешанным подводом теплоты определить параметры рабочего тела (воздух) в характерных точках, степень повышения давления ?, степень предварительного расширения ?, количество подводимой и отводимой теплоты, работу цикла и термический КПД, если начальные параметры рабочего тела р_1= 0,14 МПа, t_1 = 35°С, степень сжатия ? =14, максимальные параметры цикла р_4= 6,5 МПа, t_4 = 1600 °С.
Список литературы.”
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    Учебная работа № 187849. Контрольная Термодинамика, 2 вопроса, 2 задачи

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    Термодинамика и термохимия

    to position, heat energy as measured by the temperature, electrical energy,
    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 under the same conditions. This quantity is often
    referred to as the heat of reaction; it represents the difference in the heat
    contents of the reaction products and of the reactants, at constant pressure
    and at definite temperature, with every substance in a definite physical state.
    From the value of qp (or ΔH) the value of gv
    (or ΔE) can be readily determined if the volume change ΔV
    at the constant pressure P is known as will be seen below.
    The heat change
    accompanying a reaction, for example, that between solid carbon (graphite) and
    gaseous oxygen to yield carbon …