机械功在热能与动力工程中的应用与优化

Applications and Optimization of Mechanical Works in Thermal Energy and Power Engineering

探讨了工程热力学中的体积功、流动功、技术功、轴功等几种机械功的物理意义和相互之间的关系,分析了其在热能与动力工程领域中的实际应用,提出了优化几种机械功的应用方案。通过调整混合气余气系数、调整滑油温度、废气利用等方式可提高航空活塞发动机曲轴功,提高发动机热效率;提高压气机增压比可提高燃气涡轮发动机热效率,增大发动机推力;采用定温压缩和级间冷却可降低空调、制冷装置压缩机的压缩功,节约电能;充分冷却热力发电装置中冲击汽轮机做功后的水蒸气可以减少水泵加压所消耗的轴功,减少水泵的功率和数目。

The various mechanical works in engineering thermodynamics are easy w be confused and used in thermal energy and power engineering widely. The meanings and relationships of volume work, flow work, shaft work and technique work are analyzed, and their applications in thermal energy and power engineering are studied. The schemes for the optimizing the mechanical works are put forward. The crankshaft power and thermal efficiency of aero piston engine can be improved by increasing the pressure ratio properly, adjusting the mixture ratio and the oil temperature, and making use of the exhaust gas. The thermal efficiency and thrust of gas turbine engine can be raised by increasing the pressure ratio of compressor. Adopting isothermal compression and intercooling can decrease the compressor work of refrigerator, thereby saving the electric energy. Sufficient cooling water vapour that impelled the steam turbine in power plant can reduce the shaft work of water pump, thereby reducing the power and number of water pump.