A thermopneumatically actuated microvalve for liquid expansion and proportional control

The analysis, design, fabrication, and testing of a thermopneumatic expansion valve to control single-phase and two-phase flow of liquids is described. The valve is normally open, and shuts off flow with low power consumption, below 0.5 watt, reducing the power consumption of earlier thermopneumatic designs by a factor of ten. The device has been applied as an expansion valve to the problem of proportional control of refrigerants. Differential pressures of 140 psid (/spl sim/1 MPa) are sustained across the valve. Flow rates up to 10 gm/sec for the refrigerant R-134a have been demonstrated.