Modeling and Simulation of Multistage Microcompressor With Passive Microvalves for Micro Coolers Available to Purchase

A cascaded multistage (2-stage) micro gas compressor in series is investigated through a lump model simulation to determine its feasibility in increasing compressor performance. A dynamic model of the micro gas compressor which consists of a unimorph piezoelectric diaphragm and passive micro check valves is presented and simulated with a Matlab Simulink^® tool. Simulation is implemented for a 1 and 2-stage microcompressor design. Finite element analysis (FEA) is used to determine the lump model parameters from the fluid-structure interaction (FSI) between the microvalve and gas flow dynamics. FSI model parameters are extracted and developed as a lump model equation for Simulink^® numerical computation. Dynamic simulations confirm that there is an increase in pressure ratio for a multistage microcompressor when compared to a single stage, which is achievable with passive microvalves. However, there are negative effects of using passive microvalves at high frequency. Frequency response results gathered from simulation shows that mass flow rate through the microvalve decreases above the frequency threshold ∼1 kHz for our design. This is in two parts due to a smaller gap height opening of the microvalve plate at high frequency and the reverse flow leakage. Both losses in mass flow rate from the microvalves decrease the total flow rate of the microcompressor above ∼1 kHz. Increasing actuation frequency below the ∼1 kHz threshold increases the flow rate of the microcompressor in the design. Therefore, it is concluded that the maximum flow rate of the microcompressor increases with increasing operation frequency, but becomes limited by the negative effect of the microvalve at a high frequency threshold due to the attenuation of the microvalve gap height. Although flow rate is affected, maximum pressure ratio of the microcompressor is still achievable at various frequency range, assuming the stroke volume of the pump chamber is constant throughout all frequency ranges. Multistage simulations show that the operation frequency ratio between each stage can have some negative effect in achieving the maximum theoretical pressure ratio.