(2)内能、焓及熵的变化量 The change in Internal Energy, Enthalpy and Entropy dg=c, dr+ pdy du d =c, dr dh=c dt The amount of heat added to a closed system during a constant volume process equals to the increase in internal energy. 定容过程中加入闭口系统的热量等于系统的内能的增 加量
q c dT pdv = v + du = q = cv dT dh = c p dT (2)内能、焓及熵的变化量 The change in Internal Energy, Enthalpy and Entropy The amount of heat added to a closed system during a constant volume process equals to the increase in internal energy. 定容过程中加入闭口系统的热量等于系统的内能的增 加量
Entropy Change To find the Entropy change, start with the expression derived from the first law, replacing du using the definition of specific heat at constant volume and using the definition of entropy △ Ax三C. In 3) Work done and Heat transferred(功量和热量) Applying the first law of thermodynamics to the process dU=-6 Replacing ow with the reversible work du=5o-pdy since the volume is constant dv= o W=0∞=l=ln
Entropy Change To find the Entropy change, start with the expression derived from the first law, replacing dU using the definition of specific heat at constant volume and using the definition of entropy (3) Work done and Heat Transferred(功量和热量) Applying the first law of thermodynamics to the process Replacing δW with the reversible work since the volume is constant dV = 0 q = du Tds = cv dT 1 2 ln T T s c = v dU = Q −W dU = Q − PdV W = 0 Q = dU
using the definition of the specific heat at constant volume c du dt to replace du in the first law ∞Q=mCpd7 0=mCat The technical work done W1=|wc=v(p1-P2)
using the definition of the specific heat at constant volume to replace dU in the first law. The technical work done Q = mCV dT = 2 1 T T Q m CV dT = − = − 2 1 ( ) 1 2 p p wt vdp v p p
2等压过程 Isobaric-- Constant pressure P=250000Pa T=298K Y=0.0991m3 Heat +ye
2.等压过程 Isobaric-----Constant Pressure
(1)过程方程 Process equation For a constant pressure process the addition or removal of heat will lead to a change in the temperature and volume of the gas, as shown on the two graphs above Substitute p=c into 1v112V2 V v2 7172 112
(1) 过程方程 Process equation 2 2 2 1 1 1 T p v T p v = p = C 2 2 1 1 T v T v = For a constant pressure process, the addition or removal of heat will lead to a change in the temperature and volume of the gas, as shown on the two graphs above. Substitute into