热力学基础
2021-10-23 10:54:52 9 举报
AI智能生成
热力学基础
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热力学第一定律
Q=ΔE+A
系统从外界吸热时,Q为正<br>系统对外做功时,A为负<br>系统内能增加时,ΔE为正
热力学第一定律在等值过程中的应用
等体过程 <span class="equation-text" contenteditable="false" data-index="0" data-equation="Q_v=ΔE=\nu{i \over 2}RΔT"><span></span><span></span></span><br>等压过程 <span class="equation-text" contenteditable="false" data-index="1" data-equation="Q_p="><span></span><span></span></span><span class="equation-text" contenteditable="false" data-index="2" data-equation="\nu{i+2 \over 2}RΔT"><span></span><span></span></span><br>等温过程 <span class="equation-text" contenteditable="false" data-index="3" data-equation="Q_T=\nu RTln{V_2 \over V_1}"><span></span><span></span></span>
气体的摩尔定压热容 <span class="equation-text" contenteditable="false" data-index="0" data-equation="C_{V,m}={i \over 2}R"><span></span><span></span></span> <br>气体的摩尔定压热容 <span class="equation-text" contenteditable="false" data-index="1" data-equation="C_{p,m}=C_{V,m}+R={i+2 \over 2}R"><span></span><span></span></span> <br>比热比/泊松系数 <span class="equation-text" contenteditable="false" data-index="2" data-equation="\gamma={C_{p,m} \over C_{V,m}}={i+2 \over i}"><span></span><span></span></span>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="Q_V=\nu C_VΔT"><span></span><span></span></span>(不仅限于等体过程)<br><span class="equation-text" contenteditable="false" data-index="1" data-equation="Q_p=\nu C_pΔT"><span></span><span></span></span>
绝热过程
理想气体的绝热过程方程
<span class="equation-text" contenteditable="false" data-index="0" data-equation="pV^\gamma=常量"><span></span><span></span></span><br> <span class="equation-text" contenteditable="false" data-index="1" data-equation="V^{\gamma-1}T=常量"><span></span><span></span></span><br> <span class="equation-text" contenteditable="false" data-index="2" data-equation="p^{\gamma-1}T^{-\gamma}=常量"><span></span><span></span></span><br>
<span class="equation-text" contenteditable="false" data-index="0" data-equation="A={p_1V_1-p_2V_2 \over \gamma-1}"><span></span><span></span></span>
多方过程
循环过程 卡诺循环
热机的效率 <span class="equation-text" data-index="0" data-equation="\eta={A \over {Q_1}}={Q_1-Q_2 \over Q_1}=1-{ Q_2\over Q_1}" contenteditable="false"><span></span><span><br></span></span><span class="equation-text" data-index="1" data-equation="Q_1:吸收的热量 " contenteditable="false"><span></span><span></span></span> <span class="equation-text" data-index="2" data-equation="Q_2:放出的热量 " contenteditable="false"><span></span><span></span></span><br><span class="equation-text" data-index="3" data-equation="A:系统对外界所做的净功" contenteditable="false"><span></span><span></span></span><br><span style="font-size: inherit;">制冷机的效率/制冷系数 <span class="equation-text" contenteditable="false" data-index="4" data-equation="\omega={Q_2 \over A}={Q_2 \over Q_1-Q_2}"><span></span><span></span></span></span><br>
卡诺循环是由两个等温过程和两个绝热过程组成的
卡诺循环的效率 <span class="equation-text" contenteditable="false" data-index="0" data-equation="\eta_卡=1-{T_2 \over T_1}"><span></span><span></span></span>
热力学第二定律
开尔文表述:不可能从单一热源吸取热量,使之完全转化为有用的功而不产生其他影响。<br>克劳修斯表述:热量不可能自动地从低温物体传到高温物体。
可逆与不可逆过程 卡诺定理
卡诺定理:<br><span class="equation-text" data-index="0" data-equation="1. \eta=1-{T_2 \over T_1}" contenteditable="false"><span></span><span></span></span><br><span class="equation-text" contenteditable="false" data-index="1" data-equation="2. \eta_{不可逆}\leq\eta_{可逆}"><span></span><span></span></span><br>
热力学第二定律的统计意义
熵 熵增加原理
<span class="equation-text" contenteditable="false" data-index="0" data-equation="S=k\ln W"><span></span><span></span></span><br>W 任一宏观状态所包含的微观状态数
热温比 dS=<span class="equation-text" contenteditable="false" data-index="0" data-equation="{dQ\over T}"><span></span><span></span></span>
熵的增量仅有初、末态决定<br>孤立系统的熵永不减少,即<span class="equation-text" contenteditable="false" data-index="0" data-equation="\triangle S\geq0"><span></span><span></span></span>
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