Англ Enthalpy

Text 5. ENTHALPY

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What is enthalpy? This is a term that is often used in thermodynamic calculations.
Enthalpy is the same as heat content, or the amount of heat contained in unit weight of a substance. It is measured fr om some arbitrarily chosen condition taken as zero. This is not strictly correct and it is accurately defined by the equation: H = I + PV/J, wh ere H = enthalpy, I = internal (molecular) energy, P = absolute pressure, V = volume, J – is the factor to convert heat units to work units. It can be shown mathematically that if heat is added to or taken from a substance, the change in enthalpy equals the amount of heat
added or removed, provided that the pressure remains unchanged. Again, it can be shown that the increase in enthalpy during adiabatic compression is equivalent to the work done in compression.
What is entropy? Change of entropy, which is the only thing that concerns us in
thermodynamics, is equal to the amount of heat added or removed during a reversible process, divided by the absolute temperature; if the temperature changes during the process, as it does in the case of sensible heat, the entropy change must be evaluated by dividing the process into so many small steps that the temperature may be considered constant for each step, and adding the results (integration).
What is adiabatic compression? When a gas or vapor is compressed in such circumstances that there is insufficient time for any substantial exchange of heat between it and its surroundings, the compression is adiabatic. It can be shown that during such a process there is no change in entropy and it is mainly this fact that makes the conception of entropy so useful. The compression of vapor in a refrigerating compressor is nearly adiabatic unless a water jacket is fitted.

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Enthalpy, thermodynamic(s), calculation, equation, volume, provide, adiabatic, compression, entropy, reversible, evaluate, step, constant, integration, circumstances, insufficient, substantial, exchange, surroundings, conception, jacket, fit.

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[eidiЩ'bжtiс kЩm'preSn], ['entropi], ['enTqlpi], [ri'vq:sqbl], [sq'raundiN], [i'vxljueit], ['sq:kqmstqnsiz], [inti'greiSqn], [Tq:mqudQi'nxmiks], [sqb'stxnSl]

4. Переведите и прочитайте слова и выражения
адиабатическое сжатие, энтропия, энтальпия, обратимый, окружающая среда, оценивать, определять, условия, интегрирование, термодинамика, значительный, существенный.

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thermodynamic(s), compression, step, jacket, integration, adiabatic, equation, evaluate, circumstances, volume, provided, conception.

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объем
понятие
условия
термодинамика; термодинамический
при условии
оценивать; определять
этап; шаг
уравнение
интегрирование
рубашка
компрессия; сжатие
адиабатический

7. Переведите на английский язык
1. ... именно этот факт делает условие энтропии полезным.
2. ... пока не будет устроена водяная рубашка.
3. ... отсутствует изменение в энтропии ...
4. Можно математически доказать, что если добавить
тепло веществу или лишить его тепла, ...
5. ... рост энтальпии при адиабатическом сжатии
равняется работе, выполняемой при сжатии.

8. Закончите следующие предложения
1. The increase in enthalpy during adiabatic compression is
equivalent …
2. Enthalpy is the same …
3. Change of entropy is equal to …
4. The compression is adiabatic when …
5. The compression of vapor in a refrigerating compressor…
…
9. Ответьте на вопросы
1. What is thermodynamics?
2. What is enthalpy?
3. What is entropy?
4. What is adiabatic compression?