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The scroll compressor is a kind of positive-displacement compressor applied in refrigeration systems, heat pump systems, and air conditioner systems. Using the spring smoothing method and considering the heat transfer, the numerical simulation model of the scroll compressor is established under standard working conditions. The results show that the CFD model is well validated by the experiment result. The compressor performance and the working process are analyzed. The pre-compression and the over-compression phenomenon are also studied. Moreover, the temperature distribution and velocity distribution of gas flow in the compressor are illustrated. The result shows that the pre-compression can improve the performance of the scroll compressor and the optimization of the suction channel geometry can provide a smoother suction process. Under the combined effect of the pre-compression and heat transfer, the refrigerating capacity is increased by approximately 0.54 kW and the volume efficiency is increased by approximately 2.2%. The additional power loss due to over-compression is 47.6615 W, and the setting of over-compression discharges can reduce the pressure and power loss. This study is helpful to the performance prediction and the structural optimization of the scroll compressor. [ABSTRACT FROM AUTHOR]

The dry scroll vacuum pump is a kind of variable capacity dry vacuum pump that is applied in chemical, pharmaceutical, semiconductor, and scientific instruments. Analyzing the thermodynamic characteristics of the scroll vacuum pump and studying the impact of operating temperature on its consistent performance are necessary for the design and application of the cooling system of the scroll vacuum pump. Based on the dynamics mesh method, the computational fluid dynamics (CFD) simulation model of a multi-stage dry scroll vacuum pump is established in this study. Under the suction pressure of 1000 Pa, the simulation calculation is carried out at different operating temperatures of fixed scrolls (25 °C, 45 °C, and 65 °C). The results show that the pumping speed, the gas compression power, and the energy efficiency ratio are significantly affected by different temperatures. The operating temperature of the pump has been reduced from 65 °C to 25 °C, the pumping speed is increased by approximately 5.97%, the gas compression power is increased by approximately 4.32%, and the energy efficiency ratio is increased by approximately 1.745%. This research provides a transient simulation method using dynamic mesh technology for the study of the dry scroll vacuum pump, and the results can provide a theoretical basis for the design and application of the cooling system of the dry scroll vacuum pump. [ABSTRACT FROM AUTHOR]

To predict the performance of a rotary compressor and study the dynamic coupling characteristics of the valve, a three-dimensional dynamic model of the compressor is constructed in this paper. The model adopts the fluid–solid interaction method and the dynamic grid technique to achieve coupled reed valve motion. Meanwhile, to solve the problem of grid deformation caused by large deformation of the valve plate, a user-defined dynamic grid method is used to realize grid updating in the deformed area based on computational fluid dynamics method and the ideas of spring smoothing method. The model is validated with a cooling capacity error of 6.07% and an indicated power error of 2%. The stress, the displacement, the velocity and the pressure of the valve is analyzed. The flow characteristics and the dynamic characteristics of the valve plate obtained provide a reference for the design of the compressor. [ABSTRACT FROM AUTHOR]

This paper carries out numerical simulation for pressure driven microscale gas flows in transition flow regime. The relaxation time of LBM model was modified with the application of near wall effective mean free path combined with a combination of Bounce-back and Specular Reflection (BSR) boundary condition. The results in this paper are more close to those of DSCM and IP-DSCM compared with the results obtained by other LBM models. The calculation results show that in transition regime, with the increase of Knudsen number, the dimensionless slip velocity at the wall significantly increases, but the maximum linear deviation of nonlinear pressure distribution gradually decreases. [ABSTRACT FROM AUTHOR]

Pressure pulsation has a critical importance in the design of refrigerant compressor since it acts as a noise and vibration source. For capturing the pressure pulsation and the transient flow structure, the numerical simulation based on detached eddy simulation and dynamic mesh approach was performed. Numerical results agree well with experimental data in the frequency band of 1000–2900 Hz. The results show that the vortex flows arise when the pressure disturbances propagate in the refrigerant gases and impact against the wall leading to the dramatic increase of the sound pressure level (the frequency band is about over 1800 Hz) in the cylinder and the noise radiated from compressor shell. Furthermore, we employed the numerical model to analyze the noise reduction mechanism of the muffler hole in the cylinder wall. [ABSTRACT FROM AUTHOR]