熱力學(xué)第一定律thefirstlawofthermodynamics-資料下載頁(yè)
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【正文】 Tqdshf??,Entropy transfer by mass flow (質(zhì)量熵流 ) Mass contains energy as well as entropy. Both entropy and energy are carried into or out of system by streams of matter.(物質(zhì)具有能量和熵的屬性 ,隨著物流的遷移 ,能量和熵都會(huì)被帶進(jìn)或帶出系統(tǒng) ) The rates of energy and entropy transport into or out of a system is proportional to the mass flow rate. (能量及熵流率與質(zhì)量流率成正比 .) The entropy of a system increases by when mass in the amount of enters and decreases by the same amount when the same amount of mass at the same amount leaves the system. (當(dāng)質(zhì)量為 的物質(zhì)進(jìn)入系統(tǒng)時(shí) ,系統(tǒng)的熵將增大 。 當(dāng)當(dāng)質(zhì)量為 的物質(zhì)離開(kāi)系統(tǒng)時(shí) ,系統(tǒng)的熵將減少 ) msS mf ?,msmmsmmsmsm4. Entropy Equation (熵方程 ) (1) Entropy balance of any system undergoing any process can be expressed as (任何系統(tǒng)經(jīng)過(guò)任何過(guò)程的熵平衡可表達(dá)為 ) (2) For closed system (對(duì)于閉口系統(tǒng) ) The entropy change of a closed system during a process is equal to the sum of the entropy transferred through the system boundary by heat transfer and the entropy generation within the system boundaries. (經(jīng)過(guò)一個(gè)過(guò)程 ,閉口系統(tǒng)的熵變等于通過(guò)邊界的熱量熵流與系統(tǒng)內(nèi)部的熵產(chǎn)之和 ) s y s te mg e noutin ssss ????12 ssssTqs y s te mg e nkk ??????For adiabatic closed system For any closed system and its surroundings s y s te ma d ia b a ticg e n ss ??g e ns u rs y s ssss ???????sursursur Tqs ??(2) For Open System (對(duì)于開(kāi)口系統(tǒng) ) The entropy change of a Open system during a process consists of （經(jīng)過(guò)一個(gè)過(guò)程 ,開(kāi)口系統(tǒng)的熵變由下列部分組成） A. the entropy transferred through the system boundary by heat transfer (通過(guò)邊界的熱量熵流 ) B. the entropy transfer into the system by mass flow (進(jìn)入系統(tǒng)的凈質(zhì)量熵流 ) C. the entropy generation within the system boundaries as the result of irreversibility. (系統(tǒng)內(nèi)部不可逆所導(dǎo)致的熵產(chǎn) ) s y s te mg e noutoutinin SSsmsmTQ ????? ??? For steadyflow system (對(duì)于穩(wěn)態(tài)穩(wěn)定流動(dòng)系統(tǒng)） For single stream, adiabatic, steady flow （對(duì)于單股絕熱的穩(wěn)態(tài)穩(wěn)定流動(dòng)系統(tǒng)） 0???? ??? g e noutin sssTqg e ninout sss ?? Significance of Entropy and its application (熵的意義及應(yīng)用 ) 1. Heat absorption and heat rejection during a reversible process can be calculated by resorting to Entropy. (可逆過(guò)程中的吸熱或放熱量可借助熵來(lái)計(jì)算） T d SQ re ?)(?放熱）絕熱吸熱(h eat r ej ec t 0,dS)( ad i ab at i c 0,dS)(h eat ab s o r b ,0???dS2. Entropy generation indicates the direction of process in isolated system. (熵產(chǎn)是孤立系統(tǒng)中過(guò)程進(jìn)行方向的標(biāo)志） ?????????)( p r o c e s s i m p o s s i b l e 0)( p r o c e s s r e v e r s i b l e 0)( p r o c e s s lei r r e v e r s i b 0不可能可逆過(guò)程不可逆過(guò)程g e ndSheat transfer across a finite temperature difference（溫差傳熱） Free or unrestrained expansion（自由膨脹） 3. Entropy is a measurement of the amount of thermal energy which can not be converted to work. (熵是熱量不可用能大小的量度） Generation indicates the amount of loss in energy which can be converted to work. (熵產(chǎn)是做功能力損失的量度） T s TH T0 s1 s2 heat transfer across a finite temperature difference（溫差傳熱） Friction Loss (摩擦損失） TL TH T s s1 s2 s3 TH TL T0 Q1 Q1 Q2 W T0 TH Wmax Q2 Q1 T0 Reading and Review (閱讀和復(fù)習(xí)） Introduction （簡(jiǎn)介） ~ Statement of the Second Law of Thermodynamics （熱力學(xué)第二定律的表述）~ Carnot cycle and Carnot Theorem （卡諾循環(huán)與卡諾定律） ~P281 Entropy, The increase principle of Entropy and Entropy Equation （熵、熵增原理及熵方程） Significance of Entropy and its application (熵的意義及應(yīng)用 ) ~359
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