The optimum pressure ratio distribution of a multistage reciprocating compressor is presented based on the assumption, i.e. the inter stage cooling is perfect and there are no pressure losses. The optimization of the...The optimum pressure ratio distribution of a multistage reciprocating compressor is presented based on the assumption, i.e. the inter stage cooling is perfect and there are no pressure losses. The optimization of the two or three stage pressure ratio is analyzed in two cases of constant heat transfer rate for the inter cooler or constant inter stage inlet temperature, based on the minimum of the sum of theoretical compression power at each stage about a multi stage reciprocating compressor. Furthermore, with an example of two stage compressor the influence on the sum of the power of each stage is analyzed when practical pressure ratio deviates from the optimum value. It is obtained that under different cooling conditions the optimum pressure ratio distribution of the multi stage compression is various, and the change of the optimum pressure ratio within a small range has little influence on the sum of the power each stage. For the two stage compression, this range can be represented as ε 1=(0 96～1 06)ε 1j .展开更多
In order to establish the rolling process parameters of grade-2 commercially pure titanium （CP-Ti）, it is necessary to understand the transformation mechanism and mechanical properties of this material. The β→α t...In order to establish the rolling process parameters of grade-2 commercially pure titanium （CP-Ti）, it is necessary to understand the transformation mechanism and mechanical properties of this material. The β→α transformation kinetics of the grade-2 CP-Ti during continuous cooling was measured and its hot compression behavior was investigated using Gleeble-1500 thermal mechanical simulator. Dynamic CCT diagram confirms that cooling rate has an obvious effect on the start and finishing transformation and microstructures at room temperature. The critical cooling rate for γ-phase transforms to a phase is about 15℃/s. When the cooling rate is higher than 15 ℃/s, some β phases with fine granular shape remain residually into plate-like structure. The plate-like a phase forms at cooling rate lower than 2 ℃/s, serrate a phase forms at medium cooling rates, about 5-15℃/s. The flow stress behavior of grade-2 CP-Ti was investigated in a temperature range of 700-900℃ and strain rate of 3.6-40 mm/min. The results show that dynamic recrystallization, dynamic recovery and work-hardening obviously occur during hot deformation. Constitutive equation of grade-2 CP-Ti was established by analyzing the relationship of the deformation temperature, strain rate, deformation degree and deformation resistance.展开更多
文摘The optimum pressure ratio distribution of a multistage reciprocating compressor is presented based on the assumption, i.e. the inter stage cooling is perfect and there are no pressure losses. The optimization of the two or three stage pressure ratio is analyzed in two cases of constant heat transfer rate for the inter cooler or constant inter stage inlet temperature, based on the minimum of the sum of theoretical compression power at each stage about a multi stage reciprocating compressor. Furthermore, with an example of two stage compressor the influence on the sum of the power of each stage is analyzed when practical pressure ratio deviates from the optimum value. It is obtained that under different cooling conditions the optimum pressure ratio distribution of the multi stage compression is various, and the change of the optimum pressure ratio within a small range has little influence on the sum of the power each stage. For the two stage compression, this range can be represented as ε 1=(0 96～1 06)ε 1j .
基金Project(J51504) supported by Shanghai Leading Academic Discipline Project,China
文摘In order to establish the rolling process parameters of grade-2 commercially pure titanium （CP-Ti）, it is necessary to understand the transformation mechanism and mechanical properties of this material. The β→α transformation kinetics of the grade-2 CP-Ti during continuous cooling was measured and its hot compression behavior was investigated using Gleeble-1500 thermal mechanical simulator. Dynamic CCT diagram confirms that cooling rate has an obvious effect on the start and finishing transformation and microstructures at room temperature. The critical cooling rate for γ-phase transforms to a phase is about 15℃/s. When the cooling rate is higher than 15 ℃/s, some β phases with fine granular shape remain residually into plate-like structure. The plate-like a phase forms at cooling rate lower than 2 ℃/s, serrate a phase forms at medium cooling rates, about 5-15℃/s. The flow stress behavior of grade-2 CP-Ti was investigated in a temperature range of 700-900℃ and strain rate of 3.6-40 mm/min. The results show that dynamic recrystallization, dynamic recovery and work-hardening obviously occur during hot deformation. Constitutive equation of grade-2 CP-Ti was established by analyzing the relationship of the deformation temperature, strain rate, deformation degree and deformation resistance.
