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1、Refrigeration Cycles New and Old 新旧制冷循环,Ty Newell Air Conditioning and Refrigeration Center Department of Mechanical and Industrial Engineering University of Illinois at Urbana-Champaign,Ideal (Reversible) Cycle 理想(可反向)循环,Carnots idea: The ideal (reversible) cycle between two temperature reservoirs
2、is only dependent on the temperatures.卡诺的想法:在二个温度聚集体之间的理想(可反向)循环仅取决于温度 that is, any material used as a “refrigerant” should be capable of achieving the limit of a reversible cycle if an engineer is clever enough to determine the mechanisms and processes required to remove irreversible effects. 如果工程师
3、能聪明地解决不可反向效应,任何物质都能作为制冷剂 And, just as there is an infinite number of irreversible cycles, there is also an infinite number of reversible cycles.,Reversible Cycles 可反向循环,Cycle reversibility is achieved by: eliminating heat transfer with temperature differences avoiding free expansion and mixing proce
4、sses eliminating friction not allowing masses to collide irreversibly. 要达到可反向循环,应消除温差的热传递,避免自由膨胀及混合过程,消除混合过程,消除摩擦,不容许质量的不可反向的碰创。,Economic factors (infinite heat exchangers) dictate the optimal configuration, which is usually significantly below the reversible performance limit (conventional power an
5、d refrigeration cycles tend to be 0.5 Carnot cycle performance). 经济系数(无限热交换)取决优化结构,它通常远小于可反向性能极限(通常的功率和制冷循环小于0。5的卡诺循环性能系数),Carnot (Air) Cycle 卡诺(空气)循环,1: Isothermal compression等熵压缩 2: Adiabatic expansion绝热膨胀 3: Isothermal expansion等熵膨胀 4: Adiabatic compression绝热压缩,Ericsson CycleERICSSON循环,1,3,2,4,1,
6、Work功,QH,QL,3,2,4,1: Isothermal compression等熵压缩 2: Adiabatic expansion绝热膨胀 3: Isothermal expansion等熵膨胀 4: Adiabatic compression绝热压缩,Stirling Cycle斯特林循环,1,Work功,QH,QL,3,2,4,1: Isothermal compression等温压缩 2: Constant volume heat exchange 等容热交换 3: Isothermal expansion等温膨胀 4: Constant volume heat exchang
7、e 等容热交换,Note: constant volume heat exchange usually envisioned as piston-cylinder process 注:等容热交换通常见到活塞-汽缸过程,Reversible Vapor Compression Cycle 可反向压缩循环,4,Work,QH,QL,2,1,3,1,2,3,4,1: Isobaric heat exchange绝热热交换 2: Isentropic expansion等熵膨胀 3: Isobaric heat exchange绝热热交换 4: Isentropic compression等熵压缩,B
8、ut, how does one reversibly compress and expand a 2-phase fluid?但能否可反向的压缩膨胀二相的液体,Other Reversible Cycles? 是否有其他的可反向的循环,Do we have to think in terms of fluids (gases and liquids) with expansion and compression work processes?是否必须是流体(气体和液体) Magnetic Refrigeration磁制冷 Acoustic Refrigeration声制冷 Electroch
9、emical Processes电化学过程 Elastomer Refrigerants弹性制冷,Electrochemical Cell电化学小室,Fuel Cell燃料室,What Else?有其他的吗,Development of new cycles and improvement of cycle performance is dependent on the creativity of the engineers. 新循环和循环性能的改进取决于工程师的创造性,R134a T-s Diagram,R134a P-h Diagram,R22 T-s Diagram,R22 P-h Diagram,Isobutane T-s Diagram,Isobutane P-h Diagram,R152a T-s Diagram,R152a P-h Diagram,Ammonia T-s Diagram,Ammonia P-h Diagram,Propane T-s Diagram,Propane P-h Diagram,
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