Compression Process In Compressor Research Articles

Simulation on two-phase refrigerant compression in the cylinder of rotary compressors using CFD method

The two-phase compression process in the rotary compressor often occurs, such as defrosting and startup processes, which has a significant impact on the performance and reliability of air conditioning systems. In this paper, the CFD simulations predicting the two-phase refrigerant compression process in the compressor cylinder are conducted using the commercial software ANSYS Fluent. The dynamic mesh for the fluid domain and phase change model for the refrigerant are considered in the simulation. Effects of initial liquid volume fraction, refrigerant type and compressor type on the two-phase compression characteristics using R290 as refrigerant are carried out. Variations of the pressure, temperature, gas fraction distribution and evaporation rate in the cylinder are discussed. The results show that most liquid accumulates near the leakage gap and the bottom of the compression chamber during the two-phase compression process. The peak pressure during the two-phase compression decreases with the increase of the liquid volume fraction. The evaporation rate of R32 in the cylinder is much higher than that of R290. The maximum pressure of the reciprocating compressor is 2.26 times higher than that of the rotary compressor.

Analytical calculation of adiabatic processes in real gases

The impact of gases nonideality in the compression and expansion processes on the specific heat ratio and the heat capacity is analyzed. The specific heat ratio variation leads to temperature variation during compression in the compressor and expansion in the turbine and, consequently, the gas turbine cycle efficiency factor variation. It is also essential to consider the gases nonideality in the compression and expansion processes in the compression processes in compressor. Generally it is assumed during calculations that the heat capacities depend only on temperature, in this case the reference data presented by various authors differs markedly. In the real processes the heat capacity and the specific heat ratio depend on temperature and within the particular temperatures and pressures range depend on pressure. Consequently, the operating fluid nonideality in the gas turbine cycle should be considered.