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提问人：网友jacksdu
发布时间：2022-01-07
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熵也是状态参数，只与状态有关，而与路径无关。类似焓，先计算等温下理想气体的熵，再计算压力影响。
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更多“熵也是状态参数，只与状态有关，而与路径无关。类似焓，先计算等温下理想气体的熵，再计算压力影响。”相关的问题
第1题
由热力学可知，理想气体的焓只与温度有关，对组分i理想气体在某状态下的焓，可由摩尔定压热容计算According to thermodynamics, the enthalpy of ideal gas is only related to temperature. For component I, the enthalpy of ideal gas in a certain state can be calculated by molar heat capacity at constant pressure： 
Cp,mi0—组分i理想气体摩尔定压热容Component I ideal gas molar heat capacity at constant pressure，kJ/(kmol•K)
Cp,mi0—组分i理想气体摩尔定压热容Component I ideal gas molar heat capacity at constant pressure，kJ/(kmol•K)
第2题
导热系数λ是在温差1K时，每秒通过面积为1m2、厚度为1m物料层的热量。热量的单位是J。因此λ的单位为J/(m·s·K），即W/(m·K). The coefficient of thermal conductivity is the heat that passes through a material layer of 1m2 or 1 meter thickness per second at 1K temperature difference. Heat is in joules. Lambda is equal to J over m sub K, which is equal to W over m sub K.
第4题
气体碳氢化合物的导热系数随温度或压力的升高而增大。求解方法有查图、查表和经验公式计算。The thermal conductivity of gaseous hydrocarbons increases with the increase of temperature or pressure. The solution methods include graph, table and empirical formula. 计算法：先求低压气体导热系数，然后计算混合气体与高压下导热系数Calculation method: the thermal conductivity of low pressure gas is calculated first, and then the thermal conductivity of mixed gas and high pressure is calculated
第5题
天然气和空气混合，当天然气浓度在一定范围内时，遇明火就会发生燃烧和爆炸。燃烧时，燃烧波的传播速度较慢，约0.3～2.4m/s，而爆炸时，会迅即产生高压高温，波速达到1000～3000m/s，对管线和容器的破坏力很大。天然气产生爆炸的浓度范围为5～15％，随温度、压力升高，爆炸浓度的上限提高，爆炸范围扩大。Natural gas and air mix, when the concentration of natural gas within a certain range, open fire will occur combustion and explosion. In combustion, the propagation speed of combustion wave is slow, about 0.3 ~ 2.4m/s, while in explosion, the high pressure and temperature will be generated immediately, and the wave speed reaches 1000 ~ 3000m/s, which is very destructive to pipelines and containers. The explosion concentration range of natural gas is 5 ~ 15%. With the increase of temperature and pressure, the upper limit of explosion concentration increases and the explosion range expands.
第6题
低压和中压下，压力对气体导热系数的影响较小，但在高压下气体导热系数是随压力而增加的。Low pressure and medium pressure have little influence on gas thermal conductivity, but gas thermal conductivity increases with pressure in high pressure.
第7题
节流过程是不可逆过程，在过程中流体处于非平衡状态，没有确定的状态参数。但可研究节流前后流体处于平衡状态的情况。例如：离节流足够远的两个截面1、2处，那里的气体已为平衡状态。Throttling process is an irreversible process, in which the fluid is in a non-equilibrium state and there are no determined state parameters. However, the equilibrium state of fluid before and after throttling can be studied. For example, two sections 1 and 2 far enough away from the throttle, where the gas is in equilibrium. Pressure: p1>p2; Specific volume: v1<v2; velocity:> A、压力 ：p1<p2<br> B、压力 ：p1>p2
C、比体积：v1<v2<br> D、流速：w1<w2<br>
第9题
膨胀后压力降低，无外力干预时不能回复到节流前的状态，因此是不可逆绝热膨胀The pressure decreases after expansion, and it cannot return to the state before throttling without external intervention, so it is irreversible adiabatic expansion.
第10题
气体在流道中经过突然缩小的断面（如管道上的针形阀、孔板等），产生强烈的涡流，使压力下降，这种现象称为节流。如果在节流过程中气体与外界没有热交换，就称为绝热节流。Gas in the flow channel through the sudden reduction of section (such as the needle valve on the pipe, orifice plate, etc.), the generation of strong eddy current, pressure drop, this phenomenon is called throttle. If there is no heat exchange between the gas and the outside world during throttling, it is called adiabatic throttling.
