第一章制冷與低溫的熱力學(xué)基礎(chǔ) 4 (1.2)_2015_09_29

1、1 Thermodynamic fundamentals of refrigeration and cryogenic engineering1.1 Methods of refrigeration1.2 Thermodynamic analysis of refrigeration cycles (First Law of thermodynamics)第一章 制冷與低溫的熱力學(xué)基礎(chǔ)第一節(jié) 制冷的方法第二節(jié) 制冷循環(huán)熱力學(xué)特性分析（熱一律）7/20/20222Cooling and refrigeration cycle制冷與制冷循環(huán)Normal Boiling PointCritical

2、PointInversion PointTb（K）Tb（）Tc（K）Tc（）Tmax（K）tmax（）N274.4-198.8126.3-146.9604331H220.4-252.833.3-239.9204-69He4.3-268.95.3-267.946-2270.01atm0.83K7/20/20223Refrigeration cycle制冷循環(huán)RefrigeratorTHTLHigh temperature heat source高溫?zé)嵩碙ow temperature heat source低溫?zé)嵩?.2 Thermodynamic analysis of refrigeratio

3、n cycles (First Law of thermodynamics)1.2.1 Reversed Carnot cycle 1.2.2 Reitlinger cycle 1.2.3 Lorents cycle1.1.4 Heat pump cycle 1.1.5 Heat driven refrigeration cycle 1.1.6 Gas liquefaction cycle第二節(jié) 制冷循環(huán)熱力學(xué)特性分析（熱一律）一、逆卡諾循環(huán)四、熱泵循環(huán)二、瑞特林循環(huán)五、熱能驅(qū)動(dòng)制冷循環(huán)三、洛侖茲循環(huán)六、氣體液化循環(huán)7/20/202251.2.1 Reversed Carnot cycle一、

4、逆卡諾循環(huán)RefrigeratorTHTLw0qkq0High temperature heat source高溫?zé)嵩碙ow temperature heat source低溫?zé)嵩?/20/202261.2.1 Reversed Carnot cycle一、逆卡諾循環(huán)7/20/202271.2.1.1 Cycle analysis based on the cycle （一）循環(huán)內(nèi)部分析法q0=T0 (s1-s4)=TL (s1-s4)qk= Tk (s1-s4)= TH (s2-s3)w0=qk - q0=(TH-TL)(s2-s3)RefrigeratorTHTLw0qkq0High te

5、mperature heat source高溫?zé)嵩碙ow temperature heat source低溫?zé)嵩?/20/202281.2.1.2 Cycle analysis based on the heat source （二）循環(huán)外部分析法RefrigeratorTHTLw0qkq0High temperature heat source高溫?zé)嵩碙ow temperature heat source低溫?zé)嵩?/20/20229Reversed Carnot cycle with temperature differences 具有傳熱溫差的卡諾型制冷循環(huán)q0=T0 (s1-s4) TL

6、 (s1-s4)qk= Tk (s1-s4) TH (s2-s3)w0=qk - q0=(Tk-T0)(s2-s3)w0qkq0RefrigeratorTHTLw0qkq0High temperature heat source高溫?zé)嵩碙ow temperature heat source低溫?zé)嵩?/20/202210Reversed Carnot cycle with temperature differences 具有傳熱溫差的卡諾型制冷循環(huán)w0qkq0RefrigeratorTHTLw0qkq0High temperature heat source高溫?zé)嵩碙ow temperature

7、 heat source低溫?zé)嵩?/20/202211Refrigeration ? ( Cooling ?)Refrigeration = Obtaining artificial cold sources熱量從溫度較低的物體轉(zhuǎn)移到溫度較高的物體熱量從溫度較高的物體轉(zhuǎn)移到溫度較低的物體Refrigerant冷源的獲取冷環(huán)境的獲取制造人工低溫環(huán)境7/20/202212Refrigeration ? ( Cooling ?)冷環(huán)境的獲取Heat sourceCold source (Heat sink)SurroundingsSecond refrigerantRefrigerationHeat

8、 transfer (cooling)7/20/2022131.2.2 Reitlinger cycle and constant temperature heat source二、瑞特林循環(huán)和等溫?zé)嵩碩HTLRefrigeratorTHTLw0qkq0High temperature heat source高溫?zé)嵩碙ow temperature heat source低溫?zé)嵩?/20/2022141.2.2 Reitlinger cycle and constant temperature heat source等溫?zé)嵩春妥儨責(zé)嵩幢鋬?nèi)空氣有限大等溫?zé)嵩?等溫?zé)嵩矗簾嵩吹臏囟仍谡麄€(gè)傳熱面上的

9、溫度均相等； 變溫?zé)嵩矗簾嵩吹臏囟仍谡麄€(gè)傳熱面上的溫度不完全相等。 有限大熱源：熱源的熱容量是有限值，其溫度分布隨換熱率的大小而變 無(wú)限大熱源：熱源的熱容量無(wú)限大，其溫度分布不隨換熱率的大小而變空調(diào)內(nèi)空氣有限大變溫?zé)嵩幢渫饪諝鉄o(wú)限大等溫?zé)嵩纯照{(diào)內(nèi)電熱絲無(wú)限大變溫?zé)嵩?/20/2022151.2.3 Lorents cycle and variable temperature heat source三、洛侖茲循環(huán)和變溫?zé)嵩碩H (TK)TL (T0)qKq0w0THmTLmRefrigeratorTHTLw0qkq0High temperature heat source高溫?zé)嵩碙ow tem

10、perature heat source低溫?zé)嵩?/20/202216Lorents cycle and Reitlinger cycle洛侖茲循環(huán)和瑞特林循環(huán)TH (TK)TL (T0)qKq0w0THTL在熱源溫度變化的條件下，由兩個(gè)和熱源之間無(wú)溫差的熱交換過(guò)程及兩個(gè)等熵過(guò)程所組成的逆向可逆循環(huán)（洛侖茲循環(huán)），是制冷系數(shù)最高的循環(huán)。7/20/2022171.2.3 Lorents cycle and variable temperature heat source三、洛侖茲循環(huán)和變溫?zé)嵩碩HTLTHmTLmTkT0THTLTHTLRefrigeratorTHTLw0qkq0High tem

11、perature heat source高溫?zé)嵩碙ow temperature heat source低溫?zé)嵩丛跓嵩礈囟茸兓臈l件下，由兩個(gè)和熱源之間無(wú)溫差的熱交換過(guò)程及兩個(gè)等熵過(guò)程所組成的逆向可逆循環(huán)（洛侖茲循環(huán)），是制冷系數(shù)最高的循環(huán)。7/20/2022181.2.4 Heat pump cycle四、熱泵循環(huán)Heat pumpTHTLHigh temperatureAmbient temperature環(huán)境溫度RefrigeratorTHTLAmbient temperature環(huán)境溫度Low temperaturew0qkq0w0qkq07/20/2022191.2.4 Heat pu

12、mp cycle四、熱泵循環(huán)Heat pumpTHTLHigh temperatureAmbient temperature環(huán)境溫度w0qkq07/20/202220小型風(fēng)力驅(qū)動(dòng)冷卻法獲取淡水裝置Cold endHot end7/20/202221小型風(fēng)力驅(qū)動(dòng)冷卻法獲取淡水裝置ColdHot7/20/2022221.2.5 Heat driven cycle五、熱能驅(qū)動(dòng)制冷循環(huán)CompressorHeatCompressor7/20/2022231.2.5 Heat driven cycle五、熱能驅(qū)動(dòng)制冷循環(huán)TLTHTHHRefrigeratorTHTHHTL7/20/2022241.2.6

13、 Gas liquefaction cycle六、氣體液化循環(huán)CompressedLiquefiedgasified?wmin = qk - q0 = T1(s1-s0) - (h1-h0) 7/20/202225Energy indexes of a refrigeration cycle制冷循環(huán)的能量指標(biāo) 性能系數(shù) (Coefficient of performance)熱力完善度(Thermodynamic perfect degree)制冷量 (Cooling capacity)(J)制冷率 (Cooling capacity rate)(W)RefrigeratorTHTLw0qkq0High temperature heat source高溫?zé)嵩碙ow temperature heat source低溫?zé)嵩?/20/202226Homework_4-64. Please try to derive the expression of COP for the Lorents cycle based on the heat sources. 5：尋找一種合適的比喻給沒(méi)